Journal articles: 'Pyroclastic flow'

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Shimomura, Makoto, Wilfridus F. S. Banggur, and Agoes Loeqman. "Numerical Simulation of Pyroclastic Flow at Mt. Semeru in 2002." Journal of Disaster Research 14, no. 1 (February 1, 2019): 116–25. http://dx.doi.org/10.20965/jdr.2019.p0116.

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Mt. Semeru (3676 m asl.) is an active volcano in Indonesia. Mt. Semeru has a specific topography i.e., a large straight scar in its south-east flank. The geometry of the scar is approx. 2 km in length and 300–500 m width. The scar is connected to three major drainage channels: the Kobokan River, the Kembar River, and the Bang River. On December 29, 2002, a pyroclastic flow (PF) with an approximate volume of 3.25 × 106m3was generated and it traveled 9–11 km along the Bang River. This pyroclastic flow was the largest among the ones generated from 2002–2003 eruptions of Mt. Semeru. All prior recorded pyroclastic flows traveled 1–2.5 km along the Kembar channel. Thus, this pyroclastic flow suddenly changed its flow path, and it traveled more than three times longer than its antecedents. To investigate the cause of the sudden change, a simulated reproduction of this pyroclastic flow was carried out by employing the numerical simulation method proposed by Yamashita and Miyamoto (1993). Due to the uncertainty of the volume of each pyroclastic flow and the temporal change of deposition thickness, a total of 12 simulation cases were set up, with variations in the number of sequence events, the duration of inflow at the upper reach of the flow, and the inter-granular friction factor. The simulation results showed that to explain the sudden change in flow path, the Kembar channel, around 3 km from the vent, has to be buried by antecedent pyroclastic flows. Furthermore, the individual volumes of the prior flows must be less than 0.25–1× 106m3, with an inflow duration of less than 1 min. The friction factor must be set to be 0.5. By using the most acceptable case, the simulated pyroclastic flows were in good agreement with observed results. The results implied that careful investigation and continuous monitoring of the area at 1500–2000 m asl. on the south-east flank of Mt. Semeru are important to prepare for future pyroclastic flows.

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Battaglia, Maurizio. "On pyroclastic flow emplacement." Journal of Geophysical Research: Solid Earth 98, B12 (December 10, 1993): 22269–72. http://dx.doi.org/10.1029/93jb02059.

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Shimomura, Makoto, Raditya Putra, Niken Angga Rukmini, and Sulistiyani. "Numerical Simulation of Mt. Merapi Pyroclastic Flow in 2010." Journal of Disaster Research 14, no. 1 (February 1, 2019): 105–15. http://dx.doi.org/10.20965/jdr.2019.p0105.

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A pyroclastic flow is one of the most dangerous hazardous phenomena. To escape a pyroclastic flow, the influenceable area must be evacuated before the flow occurs. Therefore, to predict the inundation area of a pyroclastic flow is important, and numerical simulation is a helpful tool in this prediction. This study simulated a pyroclastic flow by reproducing the pyroclastic flow of Mt. Merapi that occurred in 2010. However, necessary detailed information of the flow to conduct the simulation, such as total volume and the property of the pyroclastic flow material, flow rate, etc., were not available. Therefore, 20 simulations were conducted, varying the important conditions, such as the volume of pyroclastic material, inter-granular friction factor, and duration of the flow. The results showed that the volume of the pyroclastic material and inter-granular friction factor strongly control the flow characteristics. However, the friction factor does not result in a wide range of values; therefore, volume is the most influencing factor. The most suitable condition is a total volume of pyroclastic material of 30 × 106m3, a 5 min duration of flow, and a 0.6 friction factor.

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Rukmini, Niken Angga, Sulistiyani, and Makoto Shimomura. "Numerical Simulation of Historical Pyroclastic Flows of Merapi (1994, 2001, and 2006 Eruptions)." Journal of Disaster Research 14, no. 1 (February 1, 2019): 90–104. http://dx.doi.org/10.20965/jdr.2019.p0090.

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Merapi has become one of the most enticing volcanoes due to its activity over the past century. Although we have to agree that the 2010 VEI = 4 (Volcanic Explosivity Index, [1]) eruption is the greatest in its recorded history, Merapi is more famous for its shorter cycle of smaller scale, making it one of the most active volcanoes on Earth. Many mechanisms are involved in an eruption, and pyroclastic flow is the most dangerous occurrence in terms of volcanic hazard. A pyroclastic flow is defined as a high-speed avalanche consisted of high temperature mixture of rock fragments and gas, resulted from lava dome collapse and/or gravitational column collapse. Researchers have studied Merapi’s history and behavior, and numerical simulations are an important tool for future hazard mitigation. By utilizing numerical simulation on basal part of pyroclastic flow, we investigated the applicability of the simulation on pyroclastic flows from historical eruptions of Merapi (1994, 2001, and 2006). Herein, we present a total of 32 simulations and discuss the areas affected by pyroclastic flows and the factors that affect the simulation results.

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Valentine, Greg A. "Stratified flow in pyroclastic surges." Bulletin of Volcanology 49, no. 4 (August 1987): 616–30. http://dx.doi.org/10.1007/bf01079967.

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Hayashi, Naoki, Yudzuru Inoue, Tatsuichiro Kawano, and Jun Inoue. "Phytoliths as an indicator of change in vegetation related to the huge volcanic eruption at 7.3 ka in the southernmost part of Kyushu, southern Japan." Holocene 31, no. 5 (April 19, 2021): 709–19. http://dx.doi.org/10.1177/0959683620988057.

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Volcanic eruptions can have a significant influence on adjacent ecosystems; however, little is known about the long-term vegetation change related to eruptions. In this study, we examined phytolith records in paleosols at multiple sites in the southern Kyushu District, Japan, to assess the influence of the Kikai caldera eruption 7300 years ago on vegetation. Our results show the vegetational difference before and after the eruption in the study region. Specifically, in the area where the pyroclastic flows distributed more thickly, the original evergreen forest was replaced by Andropogoneae grasslands after the eruption, which has been dominating the landscape in this area for at least 900 years. By contrast, in areas only mildly affected by pyroclastic flows, despite the temporary replacement of forest by grassland, the forest developed and flourished within several hundreds of years of the eruption. This is because a large amount of pyroclastic flow would have devastated all of the vegetation, whereas smaller amounts would have left some untouched forest sites within refugia. Our findings suggest that the vegetation varied significantly depending on the amount of pyroclastic flow reaching the area, even within the pyroclastic flow distributed region.

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Doyle, Emma E., Andrew J. Hogg, and Heidy M. Mader. "A two-layer approach to modelling the transformation of dilute pyroclastic currents into dense pyroclastic flows." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 467, no. 2129 (November 17, 2010): 1348–71. http://dx.doi.org/10.1098/rspa.2010.0402.

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Most models of volcanic ash flows assume that the flow is either dilute or dense, with dynamics dominated by fluid turbulence or particle collisions, respectively. However, most naturally occurring flows feature both of these end members. To this end, a two-layer model for the formation of dense pyroclastic basal flows from dilute, collapsing volcanic eruption columns is presented. Depth-averaged, constant temperature, continuum conservation equations to describe the collapsing dilute current are derived. A dense basal flow is then considered to form at the base of this current owing to sedimentation of particles and is modelled as a granular avalanche of constant density. We present results which show that the two-layer model can predict much larger maximum runouts than would be expected from single-layer models, based on either dilute or dense conditions, as the dilute surge can outrun the dense granular flow, or vice versa, depending on conditions.

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HIRANO, Muneo. "Debris Flow and Pyroclastic Flow at Unzen Volcano." JAPANESE JOURNAL OF MULTIPHASE FLOW 7, no. 3 (1993): 220–31. http://dx.doi.org/10.3811/jjmf.7.220.

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FREUNDT, A. "Chapter 6 Pyroclastic flow transport mechanisms." Developments in Volcanology 4 (1998): 173–245. http://dx.doi.org/10.1016/s1871-644x(01)80007-3.

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10

Sheridan, Michael F., Bernard Hubbard, Gerardo Carrasco-núñez, and Claus Siebe. "Pyroclastic Flow Hazard at Volcán Citlaltépetl." Natural Hazards 33, no. 2 (October 2004): 209–21. http://dx.doi.org/10.1023/b:nhaz.0000037028.89829.d1.

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Ghail, Richard C., and Lionel Wilson. "A pyroclastic flow deposit on Venus." Geological Society, London, Special Publications 401, no. 1 (November 19, 2013): 97–106. http://dx.doi.org/10.1144/sp401.1.

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12

Burgisser, Alain, and George W. Bergantz. "Reconciling pyroclastic flow and surge: the multiphase physics of pyroclastic density currents." Earth and Planetary Science Letters 202, no. 2 (September 2002): 405–18. http://dx.doi.org/10.1016/s0012-821x(02)00789-6.

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13

De Angelis, S., V. Bass, V. Hards, and G. Ryan. "Seismic characterization of pyroclastic flow activity at Soufrière Hills Volcano, Montserrat, 8 January 2007." Natural Hazards and Earth System Sciences 7, no. 4 (July 23, 2007): 467–72. http://dx.doi.org/10.5194/nhess-7-467-2007.

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Abstract. A partial dome collapse with concurrent pyroclastic flow (PF) activity occurred at Soufrière Hills Volcano (SHV), Montserrat on 8 January 2007. Pyroclastic density currents were observed to propagate from the Northwest and West sectors of the summit dome into the heads of Tyres Ghaut and Gages Valley, respectively. Between 10:00 and 10:15 UTC pyroclastic flows entered Tyres Ghaut and from there descended into the Belham Valley reaching a distance of about 5 km from the source. Pyroclastic flow activity on the Northwest and West side of the edifice continued at high levels over the following 1.5 h, although run-out distances of individual flows did not exceed 1.5 km. Subsequent observations showed that material had been removed from the lower Northwest side of the dome leaving an amphitheatre-like structure cutting through the old crater rim. The seismic waves excited by the propagation of pyroclastic flows were recorded by the Montserrat Volcano Observatory's network of broadband seismometers. The seismic records show the onset of a continuous signal before 09:30 UTC with gradually increasing amplitudes and spectral energy in the 1–8 Hz band. The signal rapidly increased in amplitude and a characteristic spindle-shaped waveform with broadband energy (1–25 Hz) was observed accompanying large PF that descended along the slopes of the volcano. The main phase was followed by a sequence of individual seismic pulses which correlated well with visual observations of PF. PF are a major hazard at SHV and pose significant risk for the population living in the proximity of the volcano. They can occur with little or no warning and have the potential to reach inhabited areas to the Northwest. The study of the seismic activity associated with the generation and propagation of pyroclastic flows can help to identify characteristic precursory seismic sequences providing valuable information to improve the understanding of the hazards posed by the SHV and to allow better warning to be given to the authorities.

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De Vita, P., and V. Piscopo. "Influences of hydrological and hydrogeological conditions on debris flows in peri-vesuvian hillslopes." Natural Hazards and Earth System Sciences 2, no. 1/2 (June 30, 2002): 27–35. http://dx.doi.org/10.5194/nhess-2-27-2002.

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Abstract. The paper illustrates some results of research carried out to assess factors triggering debris flows which involve the pyroclastic overburdens covering carbonate mountains around Vesuvius. The aims of the research were to reconstruct a relationship between rainfall and debris flow occurrence and to highlight empirical hydrological thresholds through rainfall pattern analysis. The research was also aimed at investigating hydrogeological features of a pyroclastic cover-carbonate bedrock system to analyse factors inducing temporary hydraulic flow, critical for pyroclastic soil stability. The results of research are the following: i) rainfall pattern highlights empirical hydrological thresholds that differentiate the Lattari and Salerno Mountains from the Sarno Mountains; ii) in some sample areas of the Sarno Mountains close to the trigger zones of the landslides of May 1998 strong variation in hydraulic conductivity has been found in the first few meters below the surface; iii) these permeability variations would seem to justify temporary perched water tables that might affect the stability of the pyroclastic mantle.

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Crosta, G. B., and P. Dal Negro. "Observations and modelling of soil slip-debris flow initiation processes in pyroclastic deposits: the Sarno 1998 event." Natural Hazards and Earth System Sciences 3, no. 1/2 (April 30, 2003): 53–69. http://dx.doi.org/10.5194/nhess-3-53-2003.

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Abstract. Pyroclastic soils mantling a wide area of the Campanian Apennines are subjected to recurrent instability phenomena. This study analyses the 5 and 6 May 1998 event which affected the Pizzo d’Alvano (Campania, southern Italy). More than 400 slides affecting shallow pyroclastic deposits were triggered by intense and prolonged but not extreme rainfall. Landslides affected the pyroclastic deposits that cover the steep calcareous ridges and are soil slip-debris flows and rapid mudflows. About 30 main channels were deeply scoured by flows which reached the alluvial fans depositing up to 400 000 m3 of material in the piedmont areas. About 75% of the landslides are associated with morphological discontinuities such as limestone cliffs and roads. The sliding surface is located within the pyroclastic cover, generally at the base of a pumice layer. Geotechnical characterisation of pyroclastic deposits has been accomplished by laboratory and in situ tests. Numerical modelling of seepage processes and stability analyses have been run on four simplified models representing different settings observed at the source areas. Seepage modelling showed the formation of pore pressure pulses in pumice layers and the localised increase of pore pressure in correspondence of stratigraphic discontinuities as response to the rainfall event registered between 28 April and 5 May. Numerical modelling provided pore pressure values for stability analyses and pointed out critical conditions where stratigraphic or morphological discontinuities occur. This study excludes the need of a groundwater flow from the underlying bedrock toward the pyroclastic cover for instabilities to occur.

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Xu, Duonian, Jianguo Pan, Shuxin Pan, Bin Gao, Lu Yin, Yongqiang Qu, and Lei Zhang. "Formation Mechanism and Prediction Method for the Permian Fused Breccia Tuff Reservoir, Wuxia Region, Junggar Basin." Geofluids 2021 (June 22, 2021): 1–12. http://dx.doi.org/10.1155/2021/5564707.

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Fused breccia tuff occurs globally, but its formation mechanism is very controversial. Volcanic reservoirs have developed at the bottom of the Permian Fengcheng Formation in the Wuxia region of the Junggar Basin, and here, the lithology is fused breccia tuff. The reservoir porosity is mainly vesicles, but the development and relative filling of the vesicles vary spatially, resulting in strong reservoir heterogeneity. Through core and thin section observations and structural analysis, and combined with reconstructions of the paleosedimentary environment, we discussed in detail the formation mechanism of the fused breccia tuff reservoir. Our conclusions are as follows. In the high-temperature and high-pressure environment of the deep crust, intermediate acidic lava containing volatile components rapidly rose to the earth’s surface along a fault. The volatile components in the lava foamed strongly and then exploded due to the sharp decline of pressure and temperature. A small part of the volcanic dust and pyroclastic material was erupted into the upper atmosphere. Most of the magma became magmatic pyroclast, vitric pyroclast, rock debris, dust, and other matter. This material was in a semimolten state and overflowed into a nearby low-lying lake. The extremely high-temperature pyroclastic flow quickly vaporized the water into high-pressure water vapor, which was squeezed into the pyroclastic flow and became mixed with other volatiles in the foam. On cooling, the pyroclastic material solidified into rock, and the vesicles were preserved. In a later period, due to strong tectonic movement, faults and fractures developed, surface water penetrated into the vesicles along the faults and fractures, and silica and other substances were deposited, filling the primary vesicles. To quantify the development and relative filling of vesicles, drilling parameters were used to establish different geologic models, and wave equation forward modeling was used to obtain a relationship between the development and filling of vesicles, and the seismic amplitude. The 3D seismic amplitude attributes were then extracted to predict the extent of the reservoir, yielding prediction results consistent with the drilling observations.

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Bo, ZHAO, XU Jiandong, and LIN Chuanyong. "Study of Distal Pyroclastic-flow Stratum from Tianchi Volcano in 1215 (±15) Eruption: Pyroclastic-flow Over Water." Acta Geologica Sinica - English Edition 87, no. 1 (February 2013): 73–81. http://dx.doi.org/10.1111/1755-6724.12031.

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Cho, Minji, Saro Lee, and Chang-Wook Lee. "Analysis of Optical Satellite Images and Pyroclastic Flow Inundation Model for Monitoring of Pyroclastic Flow Deposit Area." Korean Journal of Remote Sensing 30, no. 2 (April 30, 2014): 173–83. http://dx.doi.org/10.7780/kjrs.2014.30.2.2.

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Virgiawan, Dhimas Bagus. "ANCAMAN ERUPSI KAWAH IJEN TERHADAP MASYARAKAT LERENG IJEN (KABUPATEN BONDOWOSO)." ASANKA: Journal of Social Science And Education 1, no. 1 (March 16, 2020): 22–30. http://dx.doi.org/10.21154/asanka.v1i1.1945.

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Ijen caldera complex is a volcano that has a 7 km diameter elliptical caldera which only leaving a northern caldera wall curving towards the southward. Ijen crater as a youngest volcano and still active today stratigraphically composed of lava flow, pyroclastic flow sediments, and pyroclastic fallout. Threats that arise if an eruption occur is pyroclastic flow, pyroclastic fallout, lava flow, lahar flow, and water of ijen crater. The existance of vulcanic activity of Ijen crater impact positively to the society which live around the Ijen mountain region. Their economy rest on sulphur mining and the soil fertility which is used to potato, cabbage and coffee crop cultivation. If this happen it could be a serious threat for the environment, include the population settled around volcano and along the river upstream in the lake of this crater and is a catastrophe. The disaster can be huge because water volume of large enough crater lake and very acidic, besides the result of explotion such as hot clouds, phreatic eruption in the form of lava eruption is also possible to happen.

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Groves, D. A., R. L. Morton, and J. M. Franklin. "Physical volcanology of the footwall rocks near the Mattabi massive sulphide deposit, Sturgeon Lake, Ontario." Canadian Journal of Earth Sciences 25, no. 2 (February 1, 1988): 280–91. http://dx.doi.org/10.1139/e88-030.

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Subaerial and shallow subaqueous mafic hyalotuffs, lava flows, and flow breccias, felsic lava flows, and pyroclastic flows and falls form a 2 km thick succession beneath the Mattabi massive sulphide deposit. The lowermost 800 m of section comprises massive to amygdaloidal mafic flows and flow breccias interlayered with repetitive sequences of thinly bedded felsic tuff: pillow lavas and hyaloclastites are absent. Amygdaloidal felsic lavas overlie the mafic flows and are locally capped by coarse explosion breccia. This breccia is believed to represent the start of mafic hydrovolcanism, which produced ash falls, surges, and flows. These pyroclastic deposits formed thin- to thick-bedded hyalotuffs that contain highly vesicular and quenched juvenile and accessory lithic fragments. Periods of water influx probably led to the construction of a tuff cone, which represents a submergent hydrovolcanic cycle.In the Mattabi area, pyroclastic flow deposits form the immediate mine footwall strata and include (i) massive basal beds and overlying bedded ash tuffs and (ii) massive pumiceous units. These deposits overlie and, to the west in the Darkwater Lake area, are intercalated with the mafic hyalotuff sequence. The morphology of the footwall volcanic rocks indicates that the Mattabi and the F-zone massive sulphide deposits formed in a shallow subaqueous environment.

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SCOTTO DI SANTOLO, A., A. M. PELLEGRINO, A. EVANGELISTA, and P. COUSSOT. "Rheological behaviour of reconstituted pyroclastic debris flow." Géotechnique 62, no. 1 (January 2012): 19–27. http://dx.doi.org/10.1680/geot.10.p.005.

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Dobran, Flavio, Augusto Neri, and Micol Todesco. "Assessing the pyroclastic flow hazard at Vesuvius." Nature 367, no. 6463 (February 1994): 551–54. http://dx.doi.org/10.1038/367551a0.

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NAGASAWA, MIKIO, and KUNIO KUWAHARA. "SMOOTHED PARTICLE SIMULATIONS OF THE PYROCLASTIC FLOW." International Journal of Modern Physics B 07, no. 09n10 (April 20, 1993): 1979–95. http://dx.doi.org/10.1142/s0217979293002729.

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We apply the Smoothed Particle Hydrodynamics (SPH) to the three-dimensional simulation of pyroclastic flow over the terrain in Unzen area. The actual flow was observed in June 1991. The comparison of the simulation with the observation tells us the proper parameter sets for this kind of particle simulation. The gas particle and the lava particle are approximated by the polytropic gas which has a hard adiabatic index, that is, the weak compressibility. Theoretical modeling of eruption, movement and emplacement of lava are in success. The covered area by the pyroclastic flow can be estimated in this simulation with a given volume of initial lava dome. Cohesion force modeled by two-point potential could be the source of surface tension, which halts the flow due to the bunching of fragments. Porous pressure and auto-suspension of transported sediment are reproduced by introducing the buoyancy of gaseous components in the flow.

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Loeqman, Agoes, Nana Sulaksana, A. Helman Hamdani, and Wening Sulistri. "Pemodelan Aliran Awanpanas (Aliran Piroklastik) Sebagai Data Pendukung Peta Kawasan Rawan Bencana Gunungapi (Studi Kasus Gunungapi Sinabung Sumatra Utara) Pyroclastic Flows Modeling As A Supporting Data For Volcanic Hazard Map (Case Study Sinabung Volcano-North Sumatra)." Jurnal Lingkungan dan Bencana Geologi 8, no. 1 (April 1, 2017): 1. http://dx.doi.org/10.34126/jlbg.v8i1.162.

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ABSTRAKIndonesia mempunyai 127 gunungapi aktif dan berdasarkan sejarah erupsi 67 di antaranya merupakan gunungapi berbahaya. Erupsi gunungapi memiliki risiko merusak dan mematikan tidak hanya bagi masyarakat yang bermukimdi sekitarnya tapi juga menyebabkan bencana bagi masyarakat luas. Salah satu bahaya primer erupsi gunungapi adalah aliran awanpanas, produk erupsi gunungapi yang sampai saat ini paling banyak menyebabkan jatuhnya korban jiwa, untuk itu diperlukan suatu simulasi/pemodelan untuk mengetahui pola aliran awanpanas guna mendukung penentuan Kawasan Rawan Bencana (KRB) erupsi gunungapi.Simulasi/pemodelan aliran awanpanas ini dibuat berdasarkan data Model Elevasi Digital (DEM) dan memanfaatkan aplikasi Sistem Informasi Geografis (GIS), dengan output berupa representasi dinamis dari kecepatan aliran awanpanas, ketebalan deposit, dan daerah terdampak, dengan studi kasusGunungapi Sinabung Sumatra Utara. Setelah erupsi terakhir 1200 tahun lalu peningkatan aktivitas Gunungapi sinabung ditandai dengan terjadinya letusan freatik pada periode Agustus-September 2010. Setelah 3 tahun beristirahat, aktivitas erupsi kembali terjadi sejak September 2013 hingga saat ini. Aktivitas erupsi berupa pertumbuhan kubah lava dan luncuran awanpanas telah mengakibatkan jatuhnya korban jiwa serta memaksa penduduk mengungsi menjauhi daerah bahaya.Simulasi/pemodelan aliran awanpanas Gunungapi Sinabung karena runtuhnya kubah lava dibuat ke berbagai arah dengan skenario volume kubah lava ; 1, 2 dan 3 juta m3. Hasil overlay antara daerah landaaan awanpanas dengan skenario 3 juta m3 pada Peta KRB menunjukan jangkauan aliran awanpanas pada sektor tenggara, barat dan timurlaut telah sedikit melewati batas KRB III (kawasan sangat berpotensi terlanda awan panas, aliran lava, guguran lava dangas beracun).Kata kunci : awanpanas, Simulasi/model, titan2d, KRBABSTRACTIndonesia has 127 active volcanoes and based on historical eruption, 67 of them are dangerous. Volcano eruption having destructive risk and deadly, not only for the people who lived around, but also caused disaster for large society. One of the primary danger of volcano eruption is the pyroclastic flow, volcano eruption products that until recently was the most caused the loss of life, therefore necessary creating a simulation/modeling to know pyroclastic flow pattern to support of a determination the Volcanic hazard map. Pyroclastic flow Simulation/modeling is made based on the Digital Elevation Model (DEM) data and using Geographical Information System (GIS) application, with output of representation dynamic from the pyroclastic flow velocity, the thickness of deposit, and affected areas, with case Sinabung Volcano in North Sumatra.Since lates eruption about 1.200 years ago, Increased activity Sinabung volcano started by phreatic eruptions during August – September 2010. After three years of rest, eruption activity occurs again on September 2013 until today, with lava dome growth and pyroclastic flow acitvity have caused casualties and forcing residents were being evacuated away from the danger area.The pyroclastic flow simulation/modeling due the lava dome collapse is made into various directions with scenario of lava dome volume ; 1, 2 and 3 million m3. The results of overlay between areas affected by pyroclastic flow model with scenario 3 million m3 and volcanic hazard map showed the range of pyroclastic flow to the southeast, west and northeast sector reached the limit of zone III at volcanic hazard map (Very potentially affected by pyroclastic flow, lava flow, lava avalanche, and toxic volcanic gas ).Keywords : pyroclastic, simulation/modeling Titan2D, volcanic hazard map

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Loeqman, Agoes. "Pemodelan Aliran Awanpanas (Aliran Piroklastik) Sebagai Data Pendukung Peta Kawasan Rawan Bencana Gunungapi (Studi Kasus Gunungapi Sinabung Sumatra Utara)." Jurnal Lingkungan dan Bencana Geologi 8, no. 1 (April 1, 2017): 1. http://dx.doi.org/10.34126/jlbg.v8i1.163.

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ABSTRAK Indonesia mempunyai 127 gunungapi aktif dan berdasarkan sejarah erupsi 67 di antaranya merupakan gunungapi berbahaya. Erupsi gunungapi memiliki risiko merusak dan mematikan tidak hanya bagi masyarakat yang bermukim disekitarnya tapi juga menyebabkan bencana bagi masyarakat luas. Salah satu bahaya primer erupsi gunungapi adalah aliran awanpanas, produk erupsi gunungapi yang sampai saat ini paling banyak menyebabkan jatuhnya korban jiwa, untuk itu diperlukan suatu simulasi/pemodelan untuk mengetahui pola aliran awanpanas guna mendukung penentuan Kawasan Rawan Bencana (KRB) erupsi gunungapi. Simulasi/pemodelan aliran awanpanas ini dibuat berdasarkan data Model Elevasi Digital (DEM) dan memanfaatkan aplikasi Sistem Informasi Geografis (GIS), dengan output berupa representasi dinamis dari kecepatan aliran awanpanas, ketebalan deposit, dan daerah terdampak, dengan studi kasus Gunungapi Sinabung Sumatera Utara. Setelah erupsi terakhir 1200 tahun lalu (sutawidjaja, 2013), peningkatan aktivitas Gunungapi sinabung ditandai dengan terjadinya letusan freatik pada periode Agustus-September 2010. Setelah 3 tahun beristirahat, aktivitas erupsi kembali terjadi sejak September 2013 hingga saat ini. Aktivitas erupsi berupa pertumbuhan kubah lava dan luncuran awanpanas telah mengakibatkan jatuhnya korban jiwa serta memaksa penduduk mengungsi menjauhi daerah bahaya. Simulasi/pemodelan aliran awanpanas Gunungapi Sinabung karena runtuhnya kubah lava dibuat ke berbagai arah dengan skenario volume kubah lava ; 1, 2 dan 3 juta m3 . Hasil overlay antara daerah landaan awanpanas dengan skenario 3 juta m3 pada Peta KRB menunjukan jangkauan aliran awanpanas pada sektor tenggara, barat dan timurlaut telah sedikit melewati batas KRB III (kawasan sangat berpotensi terlanda awan panas, aliran lava, guguran lava dan gas beracun). Kata kunci : awanpanas, Simulasi/model, titan2d, KRB ABSTRACT Indonesia has 127 active volcanoes and based on historical eruption, 67 of them are dangerous. Volcano eruption having destructive risk and deadly, not only for the people who lived around, but also caused disaster for large society One of the primary danger of volcano eruption is the pyroclastic flow, volcano eruption products that until recently was the most caused the loss of life, therefore necessary creating a simulation/modeling to know pyroclastic flow pattern to support of a determination the Volcanic hazard map. Pyroclastic flow Simulation/modeling is made based on the Digital Elevation Model (DEM) data and using Geographical Information System (GIS) application, with output of representation dynamic from the pyroclastic flow velocity, the thickness of deposit, and affected areas, with case Sinabung Volcano in North Sumatra. Since lates eruption about 1.200 years ago, Increased activity Sinabung volcano started by phreatic eruptions during August – September 2010. After three years of rest, eruption activity occurs again on September 2013 until today, with lava dome growth and pyroclastic flow acitvity have caused casualties and forcing residents were being evacuated away from the danger area. The pyroclastic flow simulation/modeling due the lava dome collapse is made into various directions with scenario of lava dome volume ; 1, 2 and 3 million m3 . The results of overlay between areas affected by pyroclastic flow model with scenario 3 million m3 and volcanic hazard map showed the range of pyroclastic flow to the southeast, west and northeast sector reached the limit of zone III at volcanic hazard map (Very potentially affected by pyroclastic flow, lava flow, lava avalanche, and toxic volcanic gas ). Keywords : pyroclastic, simulation/modeling Titan2D, volcanic hazard map

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de' Michieli Vitturi, Mattia, Tomaso Esposti Ongaro, Giacomo Lari, and Alvaro Aravena. "IMEX_SfloW2D 1.0: a depth-averaged numerical flow model for pyroclastic avalanches." Geoscientific Model Development 12, no. 1 (February 1, 2019): 581–95. http://dx.doi.org/10.5194/gmd-12-581-2019.

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Abstract. Pyroclastic avalanches are a type of granular flow generated at active volcanoes by different mechanisms, including the collapse of steep pyroclastic deposits (e.g., scoria and ash cones), fountaining during moderately explosive eruptions, and crumbling and gravitational collapse of lava domes. They represent end-members of gravity-driven pyroclastic flows characterized by relatively small volumes (less than about 1 Mm3) and relatively thin (1–10 m) layers at high particle concentration (10–50 vol %), manifesting strong topographic control. The simulation of their dynamics and mapping of their hazards pose several different problems to researchers and practitioners, mostly due to the complex and still poorly understood rheology of the polydisperse granular mixture and to the interaction with the complex natural three-dimensional topography, which often causes rapid rheological changes. In this paper, we present IMEX_SfloW2D, a depth-averaged flow model describing the granular mixture as a single-phase granular fluid. The model is formulated in absolute Cartesian coordinates (whereby the fluid flow equations are integrated along the direction of gravity) and can be solved over a topography described by a digital elevation model. The numerical discretization and solution algorithms are formulated to allow for a robust description of wet–dry conditions (thus allowing us to accurately track the front propagation) and an implicit solution to the nonlinear friction terms. Owing to these features, the model is able to reproduce steady solutions, such as the triggering and stopping phases of the flow, without the need for empirical conditions. Benchmark cases are discussed to verify the numerical code implementation and to demonstrate the main features of the new model. A preliminary application to the simulation of the 11 February pyroclastic avalanche at the Etna volcano (Italy) is finally presented. In the present formulation, a simple semi-empirical friction model (Voellmy–Salm rheology) is implemented. However, the modular structure of the code facilitates the implementation of more specific and calibrated rheological models for pyroclastic avalanches.

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Huguet, David, Jean-Claude Thouret, Pierre Nehlig, Jeannine Raffy, and Pierre Rochette. "Les lahars du strato-volcan du Cantal (Massif central, France); stratigraphie, modes de mise en place et implications paleo-geomorphologiques." Bulletin de la Société Géologique de France 172, no. 5 (September 1, 2001): 573–85. http://dx.doi.org/10.2113/172.5.573.

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Abstract Introduction: The study of lahar (Lh) deposits (a) describes sedimentary facies associations in a volcano-sedimentary system, (b) establishes the identification of criteria to recognize epiclastic deposits in fossil volcanic successions [Thouret, 1999] and (c) reconstructs paleo-landforms (stratocones, paleovalleys, and volcaniclastic fans) in an old volcanic massif. Lh deposits form the "complexe conglomeratique superieur" ("upper conglomeratic complex") [Brousse et al., 1972, 1975, 1977, 1980, 1989] associated with pyroclastic deposits and streamflow deposits above the "breche inferieure" ("lower breccia"), reinterpreted as debris-avalanche (DAv) deposits. From 9.5 to 6.5 Ma, a trachyandesitic stratovolcano has been built up. Several sector collapses generated DAv and an explosive activity produced pyroclastic-flow deposits. Pyroclastic deposits and both Lh and DAv deposits built up volcaniclastic fans. The study aims (a) to determine Lh deposit generations associated with paleo-landforms and (2) to use Lh deposits as landmarks to recognize some geomorphologic stages in the history of Cantal volcano (45 degrees N-2.5 degrees E; 2500 km 2 , approximately 380 km 3 , 1 855 m). Lahar generations: Lh deposits (9 km 3 ) cover 280 km 2 (fig. 1). They show two facies, clast-supported and matrix-supported debris-flow deposits (fig. 2 and 3), located as far as 20 km from the geographic centre (Puy Griou). Firstly, field observations and geochronological data enable us to distinguish as much as five Lh deposit generations. Secondly, geometric and stratigraphic relations, between Lh deposits and both pyroclastic and DAv deposits, allow us to decipher the genetic relations between distinct volcaniclastic formations. The Cere valley shows three Lh generations. The "Faillitoux" generation is interbedded with the schistose basement and the lava and pyroclastic deposits of the Elanceze massif (1571 m) (fig. 4). An ankaramitic lava (9.53+ or -0,5 Ma, K/Ar) [Nehlig et al., 1999], fitting into Lh deposits of the Elanceze massif post-dates the apparition of the first lahar generation. The "Curebourse" generation was emplaced above DAv deposits (fig. 2A and 5). Both DAv and Lh deposits of the "Curebourse" generation filled the paleo-Cere valley about 7.1 Ma. The "Thiezac" generation (>6.7 Ma, K/Ar) [Nehlig et al., 1999] (fig. 2C) overlies a thick pyroclastic deposit (fig. 4) and is not related to the DAv and the "Curebourse" generation. The fourth generation (Impradine valley) is stratigraphically and genetically associated with pyroclastic deposits located in the upper Impradine valley (fig. 5). These pyroclastic deposits are older than 7.96 Ma (K/Ar age on a trachyandesitic lava overlying Lh deposits) and result from pyroclastic deposits removed as Lh deposits downvalley. The fifth identified lahar generation is located in the Petite-Rhue valley, to the north of the volcano, where a 5-m-thick pumiceous pyroclastite (7.6+ or -0.03 Ma; 40 Ar/ 39 Ar) [Platevoet, 2000] is interstratified with Lh deposits in Cheylade. Genetic relations with pyroclastic deposits: To determine the nature of the relationships between Lh deposits and DAv deposits, we observed geometric relationships between both formations. Some Lh deposits of "Curebourse" generation filled paleothalwegs (fig. 6) cut into DAv deposits suggesting a remission stage after emplacement of DAv deposits. We did not identify sedimentologic features such as dewatering structures indicating that lahars evolved from the top or the front of DAv deposits. Thus, no obvious genetic link was clearly determined between Lh and DAv deposits. In the Impradine valley, we observe the transformation of these pyroclastic deposits in Lh deposits. A proximal pyroclastic facies (upper Impradine) (fig. 5), intruded by numerous dykes and intercalated with trachyandesitic lava, shows the proximity of a stratocone located 1,5 km to the South-East. Field observations indicate a stratigraphic link between pyroclastic and Lh deposits. Debris flows have removed pyroclastic deposits over a 6 km distance. Lh deposits are ungraded or inversely graded and show matrix- or clast-supported facies. About 50% of dense subrounded to rounded clasts were incorporated during the flow. The remaining 50% are dense trachyandesitic juvenile clasts derived from primary pyroclastic-flow deposits. Geomorphological implications: Determinations of five Lh deposit generations and observations of geometrical relations with volcaniclastic deposits (DAv and pyroclastic deposits) enable us to reconstruct paleo-landforms and some stages of the geomorphic evolution of Cantal. In this way, the Impradine volcaniclastic unit is a fragment of a volcaniclastic fan facing north-east (fig. 7). In the Cere valley, the "Faillitoux" generation is the remnant of a proximal section of a volcaniclastic fan facing south-west. These lahars flowed from a trachyandesitic stratocone located close to the Elanceze massif about 9.5 Ma ago (fig. 7). These paleo-stratocones were eroded and are no longer visible in the present geomorphic landscape. Lh deposits allow us to determine geomorphic inheritances, contemporaneous with the activity of the stratovolcano from 9.5 to 6.5 Ma. About 7.1 Ma, the paleo-Cere valley was filled with DAv and Lh deposits of the "Curebourse" generation. The "Curebourse" generation formed a volcaniclastic fan on the top of DAv deposits. DAv and Lh deposits, that are less resistant than the trachyandesitic Elanceze massif and Plomb-du-Cantal range, have been eroded. Accordingly, the Cere valley is being exhumed. The present-day drainage pattern occupies the paleothalweg. However, in distal positions, paleo-landforms are not as well preserved. The current drainage pattern does not use any more paleothalwegs in contrast to what is seen in proximal position (fig. 8).

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Schaefer, Stephen J., and Penelope Morton. "Two komatiitic pyroclastic units, Superior Province, northwestern Ontario: their geology, petrography, and correlation." Canadian Journal of Earth Sciences 28, no. 9 (September 1, 1991): 1455–70. http://dx.doi.org/10.1139/e91-128.

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Two Archean komatiitic pyroclastic rock units occur on opposite sides of the Quetico Fault in northwestern Ontario. The eastern unit, the Dismal Ashrock, is located 3 km north of Atikokan, Ontario, on the north side of the Quetico Fault within the Wabigoon Subprovince of the Superior Province. It is part of a suprascrustal sequence, the Steep Rock Group. The Grassy Portage Bay ultramafic pyroclastic rock unit (GUP) is located 100 km to the west, on the south side of the Quetico Fault, and is part of an overturned succession comprising mafic metavolcanic rocks, GUP, and metasedimentary rocks. The Dismal Ashrock dips steeply, is little deformed, has undergone greenschist metamorphism, and is divided into komatiitic lapilli tuff, komatiitic volcanic breccia, komatiitic volcaniclastic rocks, and a mafic pillowed flow. GUP outcrops form an arcuate fold interference pattern, are strongly deformed, and have undergone amphibolite metamorphism. GUP is divided into komatiitic lapilli tuff and komatiitic volcanic breccia. Both pyroclastic units contain cored and composite lapilli, evidence for explosive volcanism. Locally, some of the lapilli fragments are highly vesicular (up to 30% by volume), greater than reported for any other komatiites. Other fragments show no vesicularity. The low vesicularity of some of the pyroclasts and, in the case of the Dismal Ashrock, their association with pinowed lava flows may indicate explosive hydrovolcanic activity. The Dismal Ashrock and GUP are high in MgO, Cr, and Ni and are unusually enriched in Fe, Ti, Zr, Mn, P, Ba, Nb, Rb, and Sr compared with other komatiites. These unique geochemical compositions are not understood at this time.

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Kato, Yuzo, and Ryuji Nomura. "Accretionary lapilli in pyroclastic flow deposits containing pipes." JOURNAL OF MINERALOGY, PETROLOGY AND ECONOMIC GEOLOGY 84, no. 3 (1989): 97–103. http://dx.doi.org/10.2465/ganko.84.97.

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Liew, Soo Chin, Jean-Claude Thouret, Avijit Gupta, and Leong Keong Kwoh. "First Satellite Image of a Moving Pyroclastic Flow." Eos, Transactions American Geophysical Union 89, no. 22 (2008): 202. http://dx.doi.org/10.1029/2008eo220002.

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Takahashi, T., and H. Tsujimoto. "A mechanical model for Merapi-type pyroclastic flow." Journal of Volcanology and Geothermal Research 98, no. 1-4 (May 2000): 91–115. http://dx.doi.org/10.1016/s0377-0273(99)00193-6.

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Mellors, RA, and RSJ Sparks. "Spatter-rich pyroclastic flow deposits on Santorini, Greece." Bulletin of Volcanology 53, no. 5 (June 1991): 327–42. http://dx.doi.org/10.1007/bf00280225.

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Martí, J., and A. Baraldo. "Pre-caldera Pyroclastic deposits of Deception Island (South Shetland Islands)." Antarctic Science 2, no. 4 (December 1990): 345–52. http://dx.doi.org/10.1017/s0954102090000475.

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The youngest pre-caldera volcanism of Deception Island is represented by a thick sequence of subaerial pyroclastic deposits which has been grouped as the Yellow Tuff Formation. Most of these deposits were related to the explosive activity of a central vent which was destroyed during the formation of the caldera. Two members can be distinguished in this formation. The lower member is mainly composed of 1 to 12 m thick massive pyroclastic flow deposits with interbedded air-fall and surge deposits. The upper member is in stratigraphical continuity with the lower member and consists of base surge deposits with minor air-fall and thin pyroclastic flow deposits. The pre-caldera deposits have undergone a palagonitic alteration which produced crystallization of smectites, Fe-oxides, zeolites and calcite.

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Roche, O., M. Gilbertson, J. C. Phillips, and R. S. J. Sparks. "Experiments on deaerating granular flows and implications for pyroclastic flow mobility." Geophysical Research Letters 29, no. 16 (August 15, 2002): 40–1. http://dx.doi.org/10.1029/2002gl014819.

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Tinti, S., G. Pagnoni, and A. Piatanesi. "Simulation of tsunamis induced by volcanic activity in the Gulf of Naples (Italy)." Natural Hazards and Earth System Sciences 3, no. 5 (October 31, 2003): 311–20. http://dx.doi.org/10.5194/nhess-3-311-2003.

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Abstract. The paper explores the potential of tsunami generation by pyroclastic flows travelling down the flank of the volcano Vesuvius that is found south of Naples in Italy. The eruption history of Vesuvius shows that it is characterised by large explosive eruptions of plinian or subplinian type during which large volume of pyroclastic flows can be produced. The most remarkable examples of such eruptions occurred in 79 AD and in 1631 and were catastrophic. Presently Vesuvius is in a repose time that, according to volcanologists, could be interrupted by a large eruption, and consequently proper plans of preparedness and emergency management have been devised by civil authorities based on a scenario envisaging a large eruption. Recently, numerical models of magma ascent and of eruptive column formation and collapse have been published for the Vesuvius volcano, and propagation of pyroclastic flows down the slope of the volcanic edifice up to the close shoreline have been computed. These flows can reach the sea in the Gulf of Naples: the denser slow part will enter the waters, while the lighter and faster part of the flow can travel on the water surface exerting a pressure on it. This paper studies the tsunami produced by the pressure pulse associated with the transit of the low-density phase of the pyroclastic flow on the sea surface by means of numerical simulations. The study is divided into two parts. First the hydrodynamic characteristics of the Gulf of Naples as regards the propagation of long waves are analysed by studying the waves radiating from a source that is a static initial depression of the sea level localised within the gulf. Then the tsunami produced by a pressure pulse moving from the Vesuvius toward the open sea is simulated: the forcing pulse features are derived from the recent studies on Vesuvian pyroclastic flows in the literature. The tsunami resulting from the computations is a perturbation involving the whole Gulf of Naples, but it is negligible outside, and persists within the gulf long after the transit of the excitation pulse. The size of the tsunami is modest. The largest calculated oscillations are found along the innermost coasts of the gulf at Naples and at Castellammare. The main conclusion of the study is that the light component of the pyroclastic flows produced by future large eruptions of Vesuvius are not expected to set up catastrophic tsunamis.

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Lee, Chang-Wook, Zhong Lu, Jin-Woo Kim, and Sung-Jae Park. "Mapping Pyroclastic Flow Inundation Using Radar and Optical Satellite Images and Lahar Modeling." Journal of Sensors 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/8217565.

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Sinabung volcano, located above the Sumatra subduction of the Indo-Australian plate under the Eurasian plate, became active in 2010 after about 400 years of quiescence. We use ALOS/PALSAR interferometric synthetic aperture radar (InSAR) images to measure surface deformation from February 2007 to January 2011. We model the observed preeruption inflation and coeruption deflation using Mogi and prolate spheroid sources to infer volume changes of the magma chamber. We interpret that the inflation was due to magma accumulation in a shallow reservoir beneath Mount Sinabung and attribute the deflation due to magma withdrawal from the shallow reservoir during the eruption as well as thermoelastic compaction of erupted material. The pyroclastic flow extent during the eruption is then derived from the LAHARZ model based on the coeruption volume from InSAR modeling and compared to that derived from the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image. The pyroclastic flow inundation extents between the two different methods agree at about 86%, suggesting the capability of mapping pyroclastic flow inundation by combing radar and optical imagery as well as flow modeling.

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Lepore, S., and C. Scarpati. "New developments in the analysis of column-collapse pyroclastic density currents through numerical simulations of multiphase flows." Solid Earth 3, no. 1 (June 8, 2012): 161–73. http://dx.doi.org/10.5194/se-3-161-2012.

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Abstract. A granular multiphase model has been used to evaluate the action of differently sized particles on the dynamics of fountains and associated pyroclastic density currents. The model takes into account the overall disequilibrium conditions between a gas phase and several solid phases, each characterized by its own physical properties. The dynamics of the granular flows (fountains and pyroclastic density currents) has been simulated by adopting a Reynolds-averaged Navier-Stokes model for describing the turbulence effects. Numerical simulations have been carried out by using different values for the eruptive column temperature at the vent, solid particle frictional concentration, turbulent kinetic energy, and dissipation. The results obtained provide evidence of the multiphase nature of the model and describe several disequilibrium effects. The low concentration (≤5 × 10−4) zones lie in the upper part of the granular flow, above the fountain, and above the tail and body of pyroclastic density current as thermal plumes. The high concentration zones, on the contrary, lie in the fountain and at the base of the current. Hence, pyroclastic density currents are assimilated to granular flows constituted by a low concentration suspension flowing above a high concentration basal layer (boundary layer), from the proximal regions to the distal ones. Interactions among the solid particles in the boundary layer of the granular flow are controlled by collisions between particles, whereas the dispersal of particles in the suspension is determined by the dragging of the gas phase. The simulations describe well the dynamics of a tractive boundary layer leading to the formation of stratified facies during Strombolian to Plinian eruptions.

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Dávila, Norma, Lucia Capra, Dolors Ferrés, Juan Carlos Gavilanes-Ruiz, and Pablo Flores. "Chronology of the 2014–2016 Eruptive Phase of Volcán de Colima and Volume Estimation of Associated Lava Flows and Pyroclastic Flows Based on Optical Multi-Sensors." Remote Sensing 11, no. 10 (May 16, 2019): 1167. http://dx.doi.org/10.3390/rs11101167.

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The eruption at Volcán de Colima (México) on 10–11 July 2015 represents the most violent eruption that has occurred at this volcano since the 1913 Plinian eruption. The extraordinary runout of the associated pyroclastic flows was never observed during the past dome collapse events in 1991 or 2004–2005. Based on Satellite Pour l’Observation de la Terre (SPOT) and Earth Observing-1 (EO-1) ALI (Advanced Land Imager), the chronology of the different eruptive phases from September 2014 to September 2016 is reconstructed here. A digital image segmentation procedure allowed for the mapping of the trajectory of the lava flows emplaced on the main cone as well as the pyroclastic flow deposits that inundated the Montegrande ravine on the southern flank of the volcano. Digital surface models (DSMs) obtained from SPOT/6 dual-stereoscopic and tri-stereopair images were used to estimate the volumes of some lava flows and the main pyroclastic flow deposits. We estimated that the total volume of the magma that erupted during the 2014–2016 event was approximately 40 × 107 m3, which is one order of magnitude lower than that of the 1913 Plinian eruption. These data are fundamental for improving hazard assessment because the July 2015 eruption represents a unique scenario that has never before been observed at Volcán de Colima. Volume estimation provides complementary data to better understand eruptive processes, and detailed maps of the distributions of lava flows and pyroclastic flows represent fundamental tools for calibrating numerical modeling for hazard assessment. The stereo capabilities of the SPOT6/7 satellites for the detection of topographic changes and the and the availability of EO-1 ALI imagery are useful tools for reconstructing multitemporal eruptive events, even in areas that are not accessible due to ongoing eruptive activity.

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Andrés, Nuria, Josè J. Zamorano, Josè J. Sanjosé, Alan Atkinson, and David Palacios. "Glacier retreat during the recent eruptive period of Popocaté petl volcano, Mexico." Annals of Glaciology 45 (2007): 73–82. http://dx.doi.org/10.3189/172756407782282598.

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AbstractPopocatépetl (19°02’ N, 98°62’W; 5424 m) is one of the largest active stratovolcanoes in the Transmexican Volcanic Belt. A glacier located on the north side has undergone severe ablation since the volcano reinitiated eruptive activity in December 1994. In our study, we calculate the extent of the glacier recession and the loss in glacial mass balance during the period of greatest laharic activity (1994–2002), using photogrammetric treatment of 20 pairs of aerial photographs. The results indicate that from November 1997 to December 2002, the glacier released approximately 3 967 000 m3 of water. A period of intense glacier melting occurred from 4 November 2000 to 15 March 2001 during which time 717 000 m3 of water was released. Much of the melting was attributed to the pyroclastic flow that took place on 22 January 2001 and produced a 14.2 km lahar with 68 000 m3 of water. Among the many types of volcanic events, pyroclastic flows were the most effective in causing sudden snowmelt, although small explosions were also effective since they deposited incandescent material on the glacier. The collapse of the plinian columns covered the glacier with pyroclasts and increased its volume. The existence of control points for georeferencing and a knowledge of the topography underlying the glacier previous to the eruption would have provided more accurate and useful results for hazard prevention.

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Lepore, S., and C. Scarpati. "New developments in the analysis of volcanic pyroclastic density currents through numerical simulations of multiphase flows." Solid Earth Discussions 4, no. 1 (January 26, 2012): 173–202. http://dx.doi.org/10.5194/sed-4-173-2012.

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Abstract. A granular multiphase model has been used to evaluate the action of differently sized particles on the dynamics of fountains and associated pyroclastic density currents. The model takes into account the overall disequilibrium conditions between a gas phase and several solid phases, each characterized by its own physical properties. The dynamics of the granular flows has been simulated by adopting a Reynolds Average Navier-Stokes model for describing the turbulence effects. Numerical simulations have been carried out by using different values for the eruptive column temperature at the vent, solid particles frictional concentration, turbulent kinetic energy, and dissipation. The results obtained underline the importance of the multiphase nature of the model and characterize several disequilibrium effects. The low concentration (≤ 5 · 10–4) sectors lie in the upper part of the granular flow, above the fountain, and above the pyroclastic current tail and body as thermal plumes. The high concentration sectors, on the contrary, form the fountain and remain along the ground of the granular flow. Hence, pyroclastic density currents are assimilated to granular flows constituted by a low concentration suspension flowing above a high concentration basal layer (boundary layer), from the proximal regions to the distal ones. Interactions among solid, differently sized particles in the boundary layer of the granular flow are controlled by collisions between particles, whereas particles dispersal in the suspension is determined by the dragging of the gas phase. The simulations describe well the dynamics of a tractive boundary layer leading to the formation of stratified facies during eruptions having a different magnitude.

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Stix, John. "Flow Evolution of Experimental Gravity Currents: Implications for Pyroclastic Flows at Volcanoes." Journal of Geology 109, no. 3 (May 2001): 381–98. http://dx.doi.org/10.1086/319980.

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Ui, Tadahide, Keiko Suzuki-Kamata, Rumi Matsusue, Kei Fujita, Hideya Metsugi, and Mami Araki. "Flow behavior of large-scale pyroclastic flows ? Evidence obtained from petrofabric analysis." Bulletin of Volcanology 51, no. 2 (March 1989): 115–22. http://dx.doi.org/10.1007/bf01081980.

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Moore, Richard B., and Meyer Rubin. "Radiocarbon Dates for Lava Flows and Pyroclastic Deposits on São Miguel, Azores." Radiocarbon 33, no. 1 (1991): 151–64. http://dx.doi.org/10.1017/s0033822200013278.

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We report 63 new radiocarbon analyses of samples from São Miguel, the largest (ca 62 × 13km) and most populous (ca 150,000 inhabitants) island in the Azores archipelago (Fig 1). The samples are mainly carbonized tree roots and other plant material collected from beneath 20 mafic lava flows and spatter deposits and from within and beneath 42 trachytic pyroclastic flow, pyroclastic surge, mudflow, pumice-fall, and lacustrine deposits and lava flows. One calcite date is reported. The samples were collected during geologic mapping of the entire island (Moore, in press A; sample locations are shown on this map). Nine 1:25,000-scale topographic maps, published in 1983 by the Portuguese Army Cartographic Service, cover the island; samples and locations described below refer to these named sheets.

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WOHLETZ, K. "Chapter 7 Pyroclastic surges and compressible two-phase flow." Developments in Volcanology 4 (1998): 247–312. http://dx.doi.org/10.1016/s1871-644x(01)80008-5.

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Rossano, S., G. Mastrolorenzo, G. De Natale, and F. Pingue. "Computer simulation of pyroclastic flow movement: An inverse approach." Geophysical Research Letters 23, no. 25 (December 15, 1996): 3779–82. http://dx.doi.org/10.1029/96gl03570.

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Kokelaar, Peter, and Michael J. Branney. "Comment [on “On pyroclastic flow emplacement” by Maurizio Battaglia]." Journal of Geophysical Research: Solid Earth 101, B3 (March 10, 1996): 5653–55. http://dx.doi.org/10.1029/95jb00972.

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Valentine, Greg A., Kenneth H. Wohletz, and Susan W. Kieffer. "Sources of unsteady column dynamics in pyroclastic flow eruptions." Journal of Geophysical Research: Solid Earth 96, B13 (December 10, 1991): 21887–92. http://dx.doi.org/10.1029/91jb02151.

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Hayashi, J. N., and S. Self. "A comparison of pyroclastic flow and debris avalanche mobility." Journal of Geophysical Research 97, B6 (1992): 9063. http://dx.doi.org/10.1029/92jb00173.

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Katpady, Dhruva Narayana, Koji Takewaka, and Toshinobu Yamaguchi. "Development of geopolymer with pyroclastic flow deposit called Shirasu." Advances in materials Research 4, no. 3 (September 25, 2015): 179–92. http://dx.doi.org/10.12989/amr.2015.4.3.179.

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SOMMER, CARLOS AUGUSTO, EVANDRO FERNANDES DE LIMA, LAURO VALENTIM STOLL NARDI, JOAQUIM DANIEL DE LIZ, and RONALDO PIEROSAN. "Depósitos de Fluxo Piroclástico Primários: Caracterização e Estudo de um Caso no Vulcanismo Ácido Neoproterozóico do Escudo Sul-rio-grandense." Pesquisas em Geociências 30, no. 1 (June 30, 2003): 3. http://dx.doi.org/10.22456/1807-9806.19576.

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Abstract:

Volcanic deposits can be included in two main groups: coherent and volcaniclastic. The former results from volcanic and sub-volcanic (syn-volcanic intrusions) effusive events, excluding autoclastic portions, and the second group, which is related to deposits constituted by volcanic fragments, encompassing primary deposits (pyroclastic) generated from fragment dispersion through gases and hot vapour, syn-eruptive resedimented deposits, besides volcanogenic sedimentary deposits. Clast transport processes are separated in three broad categories: mass-flow, traction and suspension. Basic concepts that are used in the study of volcanic rocks, classification and characterization of the main subaerial pyroclastic deposits are discussed in this paper, considering lithological and genetic aspects. Lithological aspects are mainly related to composition, components and grain-size of the deposits, while genetic aspects and interpretations are based on clast-forming and depositional processes, allowing understanding about eruption and emplacement conditions. Emphasis is given to pumiceous pyroclastic flow deposits, describing their main textural features and the post-depositional modifications associated to them. The discussed concepts are applied in the reconstruction of the Neoproterozoic pyroclastic flow deposits of two plateaus in the Sul-rio-grandense Shield, southernmost Brazil. The main characteristic of the Taquarembo Plateau is the occurrence of stratified/partially welded ignimbrites and high-grade welded deposits, while massive and crystal-rich ignimbrites are more common in the Ramada Plateau. The facies association of both plateaus suggests a fissural volcanic regime in a subaerial setting, associated to the post-collisional stages of the Brasiliano-Pan African Orogenic Cicle.

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Journal articles on the topic 'Pyroclastic flow'

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