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Journal articles on the topic 'Seismická tomografie'
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Sari, Ayu Wita, and Gede Bayu Suparta. "PENCITRAAN TOMOGRAFI SEISMIK 3-D UNTUK STRUKTUR INTERNAL DI BAWAH GUNUNGAPI MERAPI MENGGUNAKAN SOFTWARE LOTOS-10." Spektra: Jurnal Fisika dan Aplikasinya 3, no. 2 (August 30, 2018): 105–16. http://dx.doi.org/10.21009/spektra.032.05.
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Abstrak
Telah dilakukan penelitian pencitraan tomografi seismik 3D untuk stuktur internal di bawah Gunung Merapi dengan empat stasiun pencatat gempa dan gempa vulkanik sebagai sumber sinar gelombang. Penelitian ini menggunakan perangkat LOTOS-10 (Local Tomography Software 10) untuk inversi tomografi seismik 3D. Karakteristik medium bawah Gunung Merapi dapat digambarkan oleh parameter fisis seperti kecepatan gelombang primer dan sekunder. Hasil pengolahan data seismograf menunjukkan metoda tomografi seismik dapat mengungkap struktur bawah permukaan Gunung Merapi melalui distribusi anomali deviasi kecepatan dan Vp/Vs ratio. Kualitas citra yang dihasilkan dengan menggunakan gelombang primer lebih jelas resolusinya dan waktu yang digunakan lebih efesien, sehingga dapat digunakan sebagai informasi mitigasi bencana sebelum gempa erupsi terjadi. Daerah anomali negatif yang diperoleh terletak di bawah puncak Gunung Merapi pada kedalaman 3 - 5 km mempunyai karakter fisis yaitu zona lemah, kurang kompak, panas dan heterogen. Daerah anomali tersebut dapat diinterpretasikan sebagai keberadaan zona materi panas yang berasosiasi dengan sisa dapur magma dangkal.
Kata-kata kunci: Gunung api Merapi, sifat fisis, tomografi seismic, lotos-10.
Abstract
3D seismic tomography imaging research conducted for internal structures under Merapi Volcano with four earthquake recording and volcanic earthquake stations as a source of wave rays. This study used LOTOS-10 (Local Tomography Software 10) for 3D seismic tomography inversion. Characteristics of the medium under Merapi Volcano described by physical parameters such as primary and secondary wave velocities. The result of seismograph data processing shows seismic tomography method can reveal the subsurface structure of the Merapi Volcano through the distribution of deviation anomaly speed and Vp / Vs ratio. Image quality generated by using primary wave more clearly the resolution and time used more efficient, so that can be used as disaster mitigation information before earthquake eruption happened. The negative anomaly area obtained under the peak of Merapi Volcano at a depth of 3 - 5 km has the physical characteristics of weak, less compact, hot and heterogeneous zones. The anomalous region can interpret as the existence of a zone of heat material associated with the rest of the shallow magma kitchen.
Keywords: Mount of Merapi, physical character, Seismic of Tomography, lotos-10.
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Timotius, Hagayudha, and Yulinar Firdaus. "QUALITY IMPROVEMENT OF SEISMIC IMAGE FROM 2D PSDM (PRE STACK DEPTH MIGRATION) USING TOMOGRAPHY FOR INTERVAL VELOCITY MODEL REFINEMENT." BULLETIN OF THE MARINE GEOLOGY 28, no. 2 (February 15, 2016): 43. http://dx.doi.org/10.32693/bomg.28.2.2013.59.
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The main goal of seismic exploration is to get an accurate image of subsurface section so it can be easily interpreted. Pre Stack Depth Migration (PSDM) is such a powerful imaging tool especially for complex area such an area where strong lateral velocity variations exist. The main challenge of PSDM is the need of accurate interval velocity model.In this research, Dix Transformation, coherency inversion, and tomography are used for initial interval velocity model, and then tomography is used for interval velocity model refinement. We compare also between seismic image resulted from PSDM and PSTM to determine the best method. The seismic data that processed in this paper is derived from north western part of Australian Waters.
Kata kunci: Pre Stack Depth Migration, Dix Transformation, coherency inversion, tomography.
Tujuan utama dari eksplorasi seismik adalah menghasilkan citra yang akurat dari penampang bawah permukaan sehingga diinterpretasi lebih mudah. Pre Stack Depth Migration (PSDM) merupakan suatu metode yang memberikan hasil peningkatan kualitas citra seismik pada daerah kompleks dimana terjadi variasi kecepatan lateral yang signifikan. Salah satu syarat penting yang harus dipenuhi agar hasil PSDM lebih optimal adalah model kecepatan interval yang akurat. Dalam penelitian ini Transformasi Dix, inversi koheren, dan tomografi digunakan untuk memenuhi syarat tersebut. Perbandingan hasil penampang seimik PSDM dan PSTM dilakukan untuk menentukan metode terbaik. Data seismik yang diolah dalam tulisan ini berasal dari wilayah Perairan Baratlaut Australia.
Kata kunci: Pre Stack Depth Migration, Transformasi Dix, inversi koheren, tomografi
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Murdiman, Imelda, and Elistia Liza Namigo. "Analisis Kecepatan Seismik Dengan Metode Tomografi Residual Moveout." Jurnal Fisika Unand 5, no. 4 (October 4, 2016): 384–89. http://dx.doi.org/10.25077/jfu.5.4.384-389.2016.
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Telah dilakukan analisis kecepatan menggunakan metode tomografi pada data seismik 3D Lapangan Y lepas pantai Texas dengan software Opendtect. Model kecepatan baru dibuat dengan mengoreksi kurva residual moveout (RMO) pada gather CIG (common image point) dengan menggunakan model kecepatan awal yang diperoleh secara konvensional sebagai masukan. Iterasi dilakukan sampai diperoleh kurva RMO yang datar. Selanjutnya model kecepatan baru yang dihasilkan melalui metode tomografi digunakan sebagai acuan nilai kecepatan untuk proses stacking dan migrasi. Penampang seismik hasil migrasi dengan nilai kecepatan baru menunjukkan peningkatan yang cukup baik. Struktur geologi yang berupa patahan dan pola-pola reflektor di kedalaman terlihat lebih jelas dibandingkan dengan penampang seismik awal. Kata Kunci :tomografi, analisiskecepatan seismik, koreksi residual moveout
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Alfiansyah, Diva, and Eddy Hartantyo. "Kajian Inversi Tomografi Seismik Refraksi Menggunakan Kode PROFIT." Jurnal Fisika Indonesia 23, no. 2 (December 9, 2019): 15. http://dx.doi.org/10.22146/jfi.46842.
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Metode seismik refraksi merupakan salah satu metode geofisika yang digunakan dalam kajian geofisika dekat permukaan. Metode ini masih memiliki ambiguitas dalam penggambaran model kecepatan bawah permukaan, terutama untuk model geologi yang kompleks dan kasus low velocity layer. Pemodelan dengan inversi tomografi pada metode seismik refraksi dapat digunakan sebagai solusi. PROFIT (Profile Forward and Inverse Tomographic modeling) telah dikembangkan dengan kombinasi inversi dan forward modelling tomografi 2D yang dapat diaplikasikan pada data seismik aktif di laut dan di darat dengan kondisi geologis yang kompleks. Pada penelitian ini, kode PROFIT digunakan untuk pemodelan maju (forward modelling) dan pemodelan balik data sintetik dengan fitur low velocity layer, yaitu model goa dan model intrusi. Posisi goa sintetik dapat direkonstruksi cukup baik yaitu pada jarak 160 m hingga 270 m dari bagian awal lintasan dan elevasi 80 m hingga 30 m, namun nilai kecepatan yang dihasilkan berbeda dengan model sintetiknya, yaitu 1,2 km/s sampai 1,6 km/s. Pada model intrusi, tubuh intrusi batuan tipe dyke dapat direkonstruksi cukup baik yaitu pada jarak 250 m hingga 500 m dari bagian awal lintasan dengan elevasi 170 m serta memiliki kecepatan yang sama dengan model sintetik yaitu 4 km/s. Setengah tubuh intrusi tipe sill dapat direkonstruksi pada posisi yang cukup tepat yaitu pada jarak 1100 m sampai 1350 m dengan elevasi 90 m dan kecepatan yang tepat yaitu 4 km/s. Hasil inversi tomografi menggunakan PROFIT sangat dipengaruhi oleh rentang kecepatan model awal dan nilai SM (Smoothing Matrix) dan AM (Amplitude Matrix).
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Castillo-López, Luis Antonio, John Fredy González, and Alejandro Duitama. "Tomografía Sísmica 2.5D y rasgos geológicos en la Cuenca de Urabá (Colombia)." Revista Boletín de Geología 41, no. 3 (September 30, 2019): 163–74. http://dx.doi.org/10.18273/revbol.v41n3-2019008.
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Existe poca información y conocimiento geológico de la Cuenca de Urabá. A continuación, se presentan los resultados del estudio tomográfico pseudo-3D (o 2.5D) para la cuenca. Los datos de tipo sismológico (sísmica pasiva) permiten definir una aproximación de la disposición de algunos rasgos geológicos en el subsuelo, por ejemplo, lineamientos y fallas. Así, mediante la diferencia de tiempos de viaje de las ondas (P y S), registrados en campo e implementando un algoritmo de inversión de tomografía sísmica, se desarrolló un modelo para estimar las fuentes sísmicas y la distribución de velocidades en la región, además de evaluar la disposición de las capas de roca en el subsuelo hasta 30 km de profundidad, con las que se hizo posible identificar contrastes de velocidades y una posible extensión de las fallas; caso de la falla de Murindó hacia el norte, y otra falla con orientación transversal, ubicada en el sector de Riosucio.
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Soesilo, Joko, Indriati Retno Palupi, Wiji Raharjo, Sutanto Sutanto, Faris Ahad Sulistyohariyanto, Kevin Gardo Bangkit Ekaristi, and Fandi Budi Stiawan. "Subsurface S-type Granitoid Identification Based on Gravity and Seismic Tomography Models in Pacitan, East Java." EKSPLORIUM 39, no. 2 (January 31, 2019): 75. http://dx.doi.org/10.17146/eksplorium.2018.39.2.4954.
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ABSTRACT Granitoid outcrop has been observed in Montongan, Tulakan Subdistrict, Pacitan District, East Java. Geochemically, granitoid shows peralluminous S-type granitoid which consists of comparable plagioclase and potassium feldspar leading to adamelite and granodiorite variety with andalusite, fine size corundum and cordierite inside. These modal minerals are consistent with its bulk chemical analysis result that shows alumina rich rock. Highly weathered spotted pinkish soil with remaining quartz gravels characterizes its surface. Lateritic pink soil up to more than 25 meters thick covers the granitoid body and this feature is indicative to locate its surface distribution, while its subsurface distribution is remain uncertain. The research aimed to identify granitoid subsurface distribution. To identify the subsurface body, gravity and seismic tomography models were used. According gravity model, the pluton body is 5 km wide which is rootless downward and seems extends eastward. Meanwhile, the north-south seismic tomographic model across Pacitan Region indicates dense solid body override the recent Java subduction zone. The body is assumed to have correlation with surface granitic rock. It supports an idea that there is a micro continent trapped beneath Southern Mountain of East Java. ABSTRAK Singkapan granitoid telah teramati di daerah Montongan, Kecamatan Tulakan, Kabupaten Pacitan, Jawa Timur. Secara geokimia, granitoid Pacitan memperlihatkan granitoid peralumina tipe-S yang tersusun berdasarkan perbandingan plagioklas dan kalium felspar menunjuk pada varian adamelit dan granodiorit dengan andalusit, korundum halus dan kordierit di dalamnya. Mineral modal tersebut konsisten dengan hasil analisis kimia total yang menunjukkan batuan kaya alumina. Tanah berwarna merah muda yang sangat lapuk dengan kerikil sisa kuarsa menjadi ciri khas di permukaannya. Tanah laterit merah muda yang tebalnya lebih dari 25 meter menutupi tubuh granitoid tersebut dan menjadi petunjuk penyebaranya di permukaan, namun penyebaran di bawah permukaannya masih belum pasti. Penelitian ini bertujuan untuk mengetahui penyebaran granitoid di bawah permukaan. Untuk mengidentifikasi tubuh bawah permukaannya, digunakan pemodelan gravitasi dan tomografi seismik. Menurut model gravitasi tubuh pluton mempunyai lebar 5 km dan tampak memanjang ke arah timur yang tidak menentu ke bawahnya. Sementara itu, model tomografi seismik utara-selatan yang memotong wilayah Pacitan, menunjukkan suatu tubuh padat keras berada di atas zona subduksi Jawa saat ini. Tubuh tersebut diasumsikan memiliki hubungan dengan batuan granitik di permukaan. Hal tersebut mendukung ide bahwa terdapat mikro-kontinen terperangkap di bawah Pegunungan Selatan Jawa Timur.
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Oliveira, Naiane Pereira de, and Amin Bassrei. "SEISMIC TRAVELTIME TOMOGRAPHY IN THE DOM JOÃO FIELD, RECÔNCAVO BASIN, BRAZIL." Revista Brasileira de Geofísica 33, no. 1 (November 19, 2015): 89. http://dx.doi.org/10.22564/rbgf.v33i1.604.
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ABSTRACT. Tomography was incorporated in Exploration Geophysics with the intention of providing high-resolution images of regions in Earth’s subsurface that are characterized as potential reservoirs. In this work, seismic traveltime tomography in the transmission mode was applied to real data from the Dom João Field, Recôncavo Basin, State of Bahia, Brazil. This basin represents a landmark of oil exploration in Brazil and has been intensively studied since the 1950’s. Today, the Recôncavo Basin is still the principal oil producer in the State of Bahia, but there is a demand for new technologies, especially for mature fields, to improve hydrocarbon recovery. Acoustic ray tracing for the computation of traveltimes was used for forward modeling, and the conjugate gradient algorithm with regularization through derivative matrices was used as the inverse procedure. The estimated tomograms were consistent with available data from a sonic log near the acquisition area in terms of the layer geometry, as well as the P-wave velocity range. The results showed that traveltime tomography is feasible for the characterization of reservoirs with a high rate of vertical change, similar to the Dom Jo˜ao Field.Keywords: traveltime tomography, seismic inversion, regularization, reservoir characterization, Recˆoncavo Basin.RESUMO. A tomografia foi incorporada na Geofísica de Exploração justamente para fornecer imagens de alta resolução de regiões do interior da Terra, consideradas como potenciais reservatórios. Neste trabalho aplicamos a tomografia sísmica de tempos de trânsito no modo de transmissão em dados reais do Campo de Dom João, Bacia do Recôncavo, Estado da Bahia, Brasil. Esta bacia representa um marco da exploração de petróleo no Brasil e vem sendo exaustivamente estudada desde a década de 1950. Embora haja uma demanda por novas tecnologias, em especial para campos maduros, com o propósito de se aumentar a recuperação de hidrocarbonetos, a Bacia do Recôncavo é ainda a principal produtora do Estado da Bahia. Para o procedimento da modelagem direta foi utilizado o traçado de raios acústicos e para o procedimento inverso foi utilizado o algoritmo do gradiente conjugado com regularização através de matrizes de derivadas. Os tomogramas estimados foram consistentes com os dados provenientes do perfil sõnico de um poço próximo ao levantamento tomográfico analisado, tanto em termos de geometria de camadas, como também na faixa de velocidades da onda P. Os resultados mostraram que a tomografia de tempos de trânsito é viável para a caracterização de reservatórios com elevada taxa de variação vertical, que é o caso do Campo de Dom João.Palavras-chave: tomografia de tempos de trânsito, inversão sísmica, regularização, caracterização de reservatórios, Bacia do Recôncavo.
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Ramdhan, Mohamad, Said Kristyawan, Andry Syaly Sembiring, Daryono Daryono, and Priyobudi Priyobudi. "Uji Resolusi Tomografi Seismik Waktu Tempuh Lokal Menggunakan Dua Input Model Sintetik." Limits: Journal of Mathematics and Its Applications 16, no. 2 (January 29, 2020): 95. http://dx.doi.org/10.12962/limits.v16i2.6043.
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Sabiq, Hilman, Syamsurijal Rasimeng, and Karyanto Karyanto. "PENENTUAN LITOLOGI LAPISAN BAWAH PERMUKAAN BERDASARKAN TOMOGRAFI SEISMIK REFRAKSI UNTUK GEOTEKNIK BENDUNGAN AIR DAERAH “X”." Jurnal Geofisika Eksplorasi 4, no. 3 (January 17, 2020): 58–72. http://dx.doi.org/10.23960/jge.v4i3.41.
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Batang Toru river which is through Kecamatan Sipirok, Kabupaten Tapanuli Selatan, will be a hydro-electric power plant, in order to require the electricity in North Sumatera area. Therefore, refraction seismic survey needed to determine the subsurface litology, as a guide in the construction of river water dam in that area. This study aims to determine lithology in the research area based on cross-section of refraction seismic tomography, and to estimate the depth and thickness of the rock layers beneath the surface of the study area. Refraction seismic tomography produces a cross section which shows the distribution of velocity value to depth, so we obtain the interpretation of rock lithology and depth estimation of each layer. The first layer is a topsoil layer with a velocity range of 100-700 m/s, the thickness of the topsoil is estimated to be about 1-10 meters. The second layer is indicated as a tuff-sandstone with medium consolidation with a velocity range of 600-1800 m/s, with an estimated thickness about 10-35 meters. The third layer is indicated as a tuff-sand rock to tuff-breccia with a value range higher than 1800 m/s, with an estimated depth of 30-40 meters from the surface.
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Imhof, Armando Luis, and Carlos Adolfo Calvo. "Design and implementation of a 2D circular domain seismic tomography general ray tracer algorithm." ingeniería y desarrollo 32, no. 2 (June 1, 2014): 242–59. http://dx.doi.org/10.14482/inde.32.2.5717.
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De Oliveira, Danian Steinkirch, Milton José Porsani, and Paulo Eduardo Miranda Cunha. "DETERMINATION OF THE STACKING VELOCITY FIELD VIA OPTIMIZATION METHODS." Revista Brasileira de Geofísica 33, no. 3 (August 10, 2015): 503. http://dx.doi.org/10.22564/rbgf.v33i3.951.
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ABSTRACT. We developed a strategy for automatic Semblance panels pick, that uses Genetic Algorithm optimization method. In conjunction with restrictions and penalties set from a priori information it’s obtained as a result a nonlinear fit of time interval velocities, that when converted at root mean square (RMS) velocity, better maximizes the sum of the Common Mid Point (CMP) group, corrected with normal moveout (NMO). Currently, a good imaging of deep reflectors, especially in Brazilian basins, below the salt layer, has proved to be a major challenge. Obtaining a seismic velocity field corresponding to the subsurface geology and resulting in a focused seismic image is the main target of seismic processing. In the last decade, the reflection tomography has established itself as one of the main methods of velocity model construction for seismic data migration. On the other hand the full waveform inversion (FWI), taken forward due to recent advances in computing, become feasible in inversion of 2D and 3D velocity models. Despite the stacking velocity analysis be, among these, the less accurate method for generating velocity fields, it is still used on a large scale by the oil and seismic processing companies, because of its low cost and can provide a good initial velocity field for tomography and FWI.Keywords: Genetic Algorithm, velocity analysis, Semblance.RESUMO. Foi desenvolvida uma estratégia de pick automático dos painéis de Semblance , que usa o método de otimização Algoritmo Genético. Em conjunto com restrições e sanções estabelecidas a partir de uma informação a priori, foi obtido como resultado um ajuste não-linear de velocidades intervalares em tempo, que quando convertidas em velocidade RMS, melhor maximiza a soma do grupo CMP, corrigida de NMO. Atualmente, provou ser um grande desafio a geração de uma boa imagem de refletores profundos, especialmente em bacias brasileiras abaixo da camada de sal. A obtenção de um campo de velocidades sísmica correspondente à geologia do subsolo, resultando em uma imagem sísmica focada é o principal alvo de processamento sísmico. Na última década, a tomografia de reflexão estabeleceu-se como um dos principais métodos de construção de modelo de velocidade de migração de dados sísmicos. Por outro lado, a inversão de onda completa (FWI) tomou a frente, devido aos seus excelentes resultados de inversão de modelos de velocidade 2D e 3D, que se tornaram viáveis somente pelos recentes avanços na computação. Apesar da análise de velocidade de empilhamento ser, entre estes, o método menos preciso para gerar campos de velocidade, ainda é utilizada em larga escala pelas companhias de petróleo e processamento sísmico, por causa do seu baixo custo e por poder proporcionar um bom campo de velocidade inicial para tomografia e FWI.Palavras-chave: Algoritmo Genético, análise de velocidade, Semblance.
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Granet, Michel, Sebastien Judenherc, and Annie Souriau. "Des images du systeme lithosphere-asthenosphere sous la France et leurs implications geodynamiques; l'apport de la tomographie telesismique et de l'anisotropie sismique." Bulletin de la Société Géologique de France 171, no. 2 (March 1, 2000): 149–67. http://dx.doi.org/10.2113/171.2.149.
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Abstract From seismic tomography and seismic anisotropy, images of the lithosphere-asthenosphere system beneath France for some remarkable tectonic areas have been computed : a continental rift system (the Upper Rhinegraben), an Hercynian structure reactivated by Neogene volcanism (Massif central), a region of a recent continental collision (Pyrenees) and finally a region of an ancient orogeny (Armorican Massif). These images have a horizontal spatial resolution of the order of 10 km and show not only the geometry of the deep geological structures but will also illustrate the link between surface observations and structures detected at depth. The images demonstrate the passive character of the Rhinegraben mainly because no low-velocity was found below the Moho, show the presence of a thermal anomaly beneath the Massif central interpreted as caused by a mantle plume in the decaying phase of its evolution and prove the lithospheric scale of the North Pyrenean fault and of the South-Armorican shear zone. The anisotropic measurements suggest a lithospheric deformation related to the most recent tectonic event. In the Pyrenees, the Armorican Massif or the Rhinegraben areas, the directions of the fast-polarisation azimuth (the polarisation direction of the fast shear wave) are parallel to the tectonic texture of the last events, but suggest also a reactivation of inherited Hercynian discontinuities. In the Massif central, the splitting parameters distinguish between two lithospheric units regions marked by a distinct fast-polarisation azimuth on each side of the Sillon Houiller fault zone.
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Brotopuspito, Kirbani Sri. "Pemikiran Eksploratif Tentang Kemungkinan Hubungan Antara Gempabumi Aceh 26 Desember 2004, Perubahan Pola Geoid, Dan Erupsi Gunungapi Sinabung 2010-2017." Jurnal Fisika Indonesia 21, no. 3 (February 20, 2018): 1. http://dx.doi.org/10.22146/jfi.42356.
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Aktivitas volkanik Gunungapi Sinabung sejak 27 Agustus 2010 yang menerus sampai dengan 2017 telah menarik banyak perhatian, karena Gunungapi ini sudah tidak aktif dalam kurun waktu yang lama, yaitu lebih dari 400 tahun dari tahun 1600. Melanjutkan penelitian pada tahun 2016, penulis ingin mengkaji apa penyebab Gunungapi Sinabung aktif kembali. Maka dari itu, penelitian ini mengkaji kemungkinan penyebab aktifnya kembali Gunungapi Sinabung, terutama berdasarkan kejadian gempabumi Aceh 2004 dan Nias 2005 yang menyebabkan terjadinya undulasi geoid rendahan di Selat Malaka di sebelah timur Sumatra Utara, dan keberadaan Gunungapi Sinabung yang tidak terlalu jauh dari komplek Kaldera Danau Toba. Pemodelan komplek kantong magma Gunungapi Toba berdasarkan hasil tomografi seismik mengindikasikan adanya zona rasio kecepatan gelombang P dan S (vp/vs) rendah pada bagian yang berdekatan dengan lokasi Gunungapi Sinabung, yang dapat ditafsirkan sebagai batuan dengan material lelehan. Hal ini juga akan dikaji kemungkinan terjadinya aliran material lelehan/magma ke atas di bawah Gunungapi Sinabung, yang mungkin dipicu oleh adanya pembukaan rekahan akibat tarikan gaya gravitasi oleh undulasi geoid rendahan yang terjadi setelah gempabumi Aceh 2004 dan Nias 2005.
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Hosseini, Navid, Kazem Oraee, Kourosh Shahriar, and Kamran Goshtasbi. "Passive seismic velocity tomography and geostatistical simulation on longwall mining panel / Tomografia pasywna pola prędkości i symulacje geostatystyczne w obrębie pola ścianowego." Archives of Mining Sciences 57, no. 1 (October 29, 2012): 139–55. http://dx.doi.org/10.2478/v10267-012-0010-9.
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Generally, the accurate determination of the stress in surrounding rock mass of underground mining area has an important role in stability and ground control. In this paper stress redistribution around the longwall face has been studied using passive seismic velocity tomography based on Simultaneous Iterative Reconstructive Technique (SIRT) and Sequential Gaussian Simulation (SGS). The mining-induced microseismic events are used as a passive source. Since such sources are used, the ray coverage is insufficient and in order to resolve this deficiency, the wave velocity is estimated in a denser network and by the SGS method. Consequently the three-dimensional images of wave velocity are created and sliced into the coal seam. To analyze the variations of stress around the panel during the study period, these images are interpreted. Results show that the state of stress redistribution around the longwall panel can be deduced from these velocity images. In addition, movements of the stressed zones, including front and side abutments and the goaf area, along the longwall face are evident. The applied approach illustrated in this paper can be used as a useful method to monitoring the stress changes around the longwall face continuously. This can have significant safety implications and contribute to improvements in operational productivity
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Arief Troa, Rainer, Eko Triarso, and Ira Dillenia. "GEODINAMIKA KAWASAN TIMUR INDONESIA DAN IMPLIKASINYA TERHADAP POTENSI SUMBER DAYA DASAR LAUT." Jurnal Kelautan Nasional 11, no. 1 (April 3, 2016): 1. http://dx.doi.org/10.15578/jkn.v11i1.6062.
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Kawasan Timur Indonesia menyimpan potensi sumber daya dasar laut yang tinggi. Interaksi tiga lempeng besar dunia: Lempeng Pasifik, Hindia-Australia, dan Eurasia menjadikan kondisi geodinamikanya aktif dan kompleks. Tujuan penulisan untuk mengungkap potensi sumber daya dasar laut sebagai implikasi kondisi geodinamika. Metode penelitian menggunakan analisis tektonika berdasarkan tinjauan regional evolusi tektonik yang ditunjang metode tomografi seismik dengan hipotesis bahwa potensi sumber daya dasar laut sebagai implikasi kondisi geodinamikanya berkaitan erat dengan keberadaan gunungapi bawah laut dan aktivitas hidrotermal. Hasil penelitian menunjukkan potensi tersebut berada pada zona aliran fluida magma di bawah kerak bumi, diindikasikan anomali kecepatan rendah gelombang-S pada tomogram seismik. Hasil pengamatan ROV di Perairan Sangihe-Talaud mengindikasikan adanya peluruhan sebagian magma menerobos kerak bumi, muncul ke permukaan dasar laut membentuk cerobong hidrotermal gunungapi bawah laut Kawio Barat pada kedalaman 1890 meter. Di perairan dangkal Halmahera, manifestasi aktivitas hidrotermal berupa semburan air panas dari dasar laut. Di dataran pasang surut, temperatur mata air panas mencapai 80-100oC, sedangkan dari tipe alterasi batuannya diindikasikan temperatur bawah permukaan >200oC. Disimpulkan bahwa potensi sumber daya dasar laut terkait aktivitas hidrotermal dan gunungapi bawah laut di perairan Sangihe-Talaud adalah berasosiasi dengan mineralisasi logam pada cerobong hidrotermal. Di Halmahera, potensinya berupa uap panas hidrotermal yang dapat dimanfaatkan untuk energi terbarukan berbasis panas bumi. Implikasi kebencanaan juga melekat akibat kondisi geodinamika sehingga penelitian mitigasi bencana dan model adaptasinya disarankan dilakukan juga pada Kawasan Timur Indonesia.
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Terra, Felipe A., Jessé C. Costa, and Amin Bassrei. "STEREOTOMOGRAPHY FOR VELOCITY MODEL ESTIMATION IN SEISMIC IMAGING: APPLICATION TO REAL DATA FROM JEQUITINHONHA SEDIMENTARY BASIN." Revista Brasileira de Geofísica 30, no. 4 (December 1, 2012): 473. http://dx.doi.org/10.22564/rbgf.v30i4.234.
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O imageamento sísmico em profundidade é um desafio em áreas geologicamente complexas, onde a velocidade sísmica apresenta variação lateral. Porém, para se obter sucesso no imageamento sísmico em profundidade é necessário que se tenha uma estimativa confiável do modelo de velocidade. A estereotomografia é uma ferramenta efetiva para se alcançar esse propósito. Também denominada de tomografia de inclinação, ela utiliza as vagarosidades e os tempos de trânsito selecionados de famílias de fonte comum e de receptor comum. Nós avaliamos uma alternativa da estereotomografia para a construção do modelo de velocidades. O algoritmo foi validado no conjunto de dados sintéticos Marmousoft e também em dados reais provenientes da Bacia do Jequitinhonha, Brasil, numa região de talude continental. Este conjunto de dados com complexidade estrutural demandou um controle de alta qualidade na seleção de eventos, numa escolha criteriosa dos parâmetros de regularização, e a atenuação de múltiplas de superfície livre. Os resultados tanto para os dados sintéticos como para os reais mostraram a viabilidade computacional e precisão do método. ABSTRACT. Seismic imaging in depth is a challenge in geologically complex areas, where the seismic velocity varies laterally. The estimation of a reliable velocity model is necessary in order to succeed in seismic depth imaging. Stereotomography is an effective tool to achieve this purpose. Also called slope tomography, it uses the slowness and picked traveltimes from reflection events picked in common source and common receiver gathers. We evaluate an alternative implementation of stereotomography for velocity model building. The algorithm was validated in the Marmousoft synthetic data set and also used for velocity model estimation in acontinental slope region, using real data from Jequitinhonha Basin, Brazil. This data set of structural complexity demanded a high quality control of event selection forpicking, judicious choice of regularization parameters and free surface multiple attenuation. The results for both the synthetic and real data have shown the computational feasibility and accuracy of this method.Keywords: stereotomography, regularization, Jequitinhonha Basin
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Leite, Lourenildo W. B., J. Mann, and Wildney W. S. Vieira. "PROCESSING AND IMAGING OF MARINE SEISMIC DATA FROM THE JEQUITINHONHA BASIN (BAHIA, BRAZIL)." Revista Brasileira de Geofísica 33, no. 3 (August 6, 2015): 403. http://dx.doi.org/10.22564/rbgf.v33i3.946.
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ABSTRACT. The present study results from a consistent processing and imaging of marine seismic data from a set collected over sedimentary basins of the East Brazilian Atlantic. Our general aim is first to subsidize geological interpretations with plausible subsurface images for oil and gas exploration. In second place, to verify published schematic geological interpretation for these basins by underlying the sediment/basement contact, from where subvertical faults are projected upwards through the basin followed by folded structures. The data-driven results can be used to trace the reflector boundaries in the time sections, submitted to time-to-depth axis transformation, and to be used as a first model for further basin pressure prediction, where natural pumps necessarily develop for the mechanism of oil and gas accumulation. The applied fundamental techniques are mainly based on the data-driven common reflection surface stack, where it is shown the improvement of the signal-to-noise ratio, the lateral continuity of the reflection events, the resolution, and that time migration collapses the diffraction events. The CRS migration strongly collapsed the diffraction events, allowing some subsurface structures be more evident. The free surface and some shallow internal multiples can be clearly traced for further processing aiming at their attenuation. The interpretation lines are meant to show the geometry of selected reflectors, and to help comparing the results with other similar sections. One can trace some subvertical fault systems starting from the lower part of the section (interpreted as the basement), and their extension upwards through the sedimentary sequence.Keywords: CRS stack, CRS migration, residual static correction, NIP wave tomography. RESUMO. O presente artigo resulta de um processamento e imageamento consistentes de dados sísmicos marinhos de levantamento realizado em bacias sedimentares do Atlântico do Nordeste brasileiro. Nossos objetivos gerais são em primeiro lugar subsidiar as interpretações geológicas com imagens plausíveis do subsolo, e voltadas à exploração de óleo e gás. Em segundo lugar, verificar as interpretações geológicas esquemáticas publicadas para estas bacias, para conferir o delineamento do contato sedimento/embasamento, de onde falhas subvertical são projetadas através da bacia, seguidas de estruturas dobradas. Os resultados baseados em dados reais podem ser usados para delinear interfaces refletoras contidas nas seções tempo, submetidos à transformação da coordenada tempo para profundidade, e que podem ser usados posteriormente como um primeiro modelo para a predição de pressão em bacias sedimentares, onde se desenvolve um bombeamento natural necessário para a acumulação de óleo e gás. As técnicas fundamentais aplicadas baseiam-se principalmente no denominado empilhamento de superfície de reflexão comum, baseado em dados observados, onde se mostra a evolução da relação sinal-ruído, da continuidade lateral dos eventos de reflexão, da resolução, e o colapso dos eventos de difração nas seções de migração do tempo. A migração CRS colapsa fortemente os eventos de difração permitindo que algumas estruturas do subsolo sejam mais evidentes. Múltiplas da superfície livre, e algumas internas rasas, podem ser claramente traçadas para processamento adicional que visam a atenuação. As linhas de interpretação trac¸adas visam mostrar a geometria dos refletores selecionados, e ajudar na comparação com outros resultados de seções semelhantes. Pode-se traçar um sistema de falhas subvertical a partir da base inferior (interpretada como o embasamento) da seção escolhida como referência, e os seus prolongamentos através da sequência sedimentar.Palavras-chave: empilhamento CRS, migração CRS, correção estática residual, tomografia NIP.
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Senkaya, Mustafa, and Hakan Karslı. "A semi-automatic approach to identify first arrival time: the Cross-Correlation Technique." Earth Sciences Research Journal 18, no. 2 (March 15, 2015): 107–13. http://dx.doi.org/10.15446/esrj.v18n2.35887.
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<p class="MsoNormal" style="line-height: 200%;">The high-quality interpretation of seismic refraction data depends on the accurate and reliable identification of the first arrival times. First arrivals can be identified on a graphic or image by conventional picking, but this process depends on external factors, such as the scale and quality of the imaging data, amplitude ratio, sensitivity of the picking cursor and user experience. Under these considerations, identifying first arrivals in noisy data becomes more complex and unstable. In this study, the Cross-Correlation Technique (CCT), which is widely used in the process of analyzing reflection data, has been used to pick the first arrival times in noisy or noiseless seismic refraction data by a semi-automatic process. The CCT has reduced the dependence on user and decreased incorrect picking caused by environmental noise, displaying characteristics and scaling factors. The CCT has been tested with synthetic models with different noise contents and various field data. The Chi-square error criterion was used to assess the performance of the pickings. In addition, effects of small-time differences between the conventional picking process and the CCT have been demonstrated on a refraction tomography velocity section. Therefore, we believe that our proposed method is a useful contribution to the existing methods of first arrival picking.</p><p class="MsoNormal" style="line-height: 200%;"> </p><p class="MsoNormal" style="line-height: 200%;"><strong>Resumen</strong></p><p class="MsoNormal" style="line-height: 200%;">La buena interpretación de datos estadísticos de refracción sísmica depende de la identificación acertada y confiable de los tiempos de llegada. Los primeros tiempos de llegada se pueden identificar en un gráfico o imagen por picado convencional, pero este proceso depende de factores externos como la escala y la calidad de información de la imagen, el índice de amplitud, la sensibilidad del cursor de recolección y la experiencia del usuario. Bajo estas consideraciones, la identificación de los tiempos de llegada bajo información ruidosa se vuelve más compleja e inestable. En este estudio, la técnica de Correlación Cruzada (CCT, en inglés), que es ampliamente trabajada en el proceso de análisis de datos de reflexión, se utilizó para seleccionar los primeros tiempos de llegada en información sísmica ruidosa o no ruidosa con un proceso semiautomático. La CCT redujo la dependencia en el usuario y bajó el nivel de selección incorrecta causada por el ruido ambiental al desplegar características y factores de escala. La CCT se ha probado en modelos sintéticos con diferentes contenidos de ruidos y diversa información de campo. El error de la norma Chi-cuadrado se utilizó para evaluar el desempeño de las selecciones. En adición, los efectos de las pequeñas diferencias de tiempo entre el proceso convencional de selección y la CCT se han demostrado en una tomografía reflexiva de velocidad. Además, se estima que el método propuesto es una contribución útil a los métodos existentes de la recolección de los primeros tiempos de llegada.</p>
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Rodrigues, Vitor Hugo Serravalle Reis, and Amin Bassrei. "SEISMIC TRAVELTIME TOMOGRAPHY APPLIED TO DATA FROM MIRANGA FIELD, RECÔNCAVO BASIN, BRAZIL." Revista Brasileira de Geofísica 34, no. 3 (September 14, 2016). http://dx.doi.org/10.22564/rbgf.v34i3.856.
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ABSTRACT. The growing global demand for hydrocarbons has tested the limits of oil exploration and exploitation technologies. Among the seismic methods, tomography is an alternative means for high-resolution characterization of reservoirs, and it enables a more efficient...Keywords: reservoir characterization, traveltime tomography, seismic inversion, regularization, Recôncavo Basin. RESUMO. A crescente demanda mundial por hidrocarbonetos tem testado os limites das tecnologias de exploração e explotação de petróleo. Dentro dos métodos sísmicos, a tomografia surge como alternativa de caracterização de alta resolução dos reservatórios,...Palavras-chave: caracterização de reservatórios, tomografia de tempos de trânsito, inversão s´ísmica, regularização, Bacia do Recôncavo.
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Ramdhan, Mohamad, Said Kristyawan, Andry Syaly Sembiring, D. Daryono, and P. Priyobudi. "Struktur Kecepatan Seismik di Bawah Gunung Merapi dan Sekitarnya Berdasarkan Studi Tomografi Seismik Waktu Tempuh." RISET Geologi dan Pertambangan 29, no. 2 (December 31, 2019). http://dx.doi.org/10.14203/risetgeotam2019.v29.1047.
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Suantika, Gede, and Sri Widiyantoro. "PENCITRAAN TOMOGRAFI ATENUASI SEISMIK TIGA-DIMENSI GUNUNG GUNTUR MENGGUNAKAN METODE RASIO SPEKTRA." Jurnal Meteorologi dan Geofisika 9, no. 2 (November 1, 2008). http://dx.doi.org/10.31172/jmg.v9i2.26.
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Silva, Caio Jean Matto Grosso da, and Amin Bassrei. "SINGULAR VALUE SELECTION AND GENERALIZED CROSS VALIDATION IN MULTI-FREQUENCY SEISMIC DIFFRACTION TOMOGRAPHY FOR CO2 INJECTION MONITORING." Revista Brasileira de Geofísica 34, no. 2 (December 14, 2016). http://dx.doi.org/10.22564/rbgf.v34i2.791.
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ABSTRACT. Regardless of whether the cause of the greenhouse effect is anthropogenic, carbon dioxide (CO2) exacerbates global warming because it contributes directly to the increased temperature of the planet. In a geologic context, CO2 can occur in conjunction with porous oil reservoirs...Keywords: seismic diffraction tomography, reservoir monitoring, Gassmann’s equation, CO2 injection RESUMO. Independentemente se a causa do efeito de estufa é antropogênico, o dióxido de carbono (CO2) agrava o aquecimento global porque contribui diretamente para o aumento da temperatura do planeta. Em um contexto geológico, o CO2 pode ocorrer em conjunto com reservatórios de petróleo porosos.Palavras-chave: tomografia sísmica de difração, monitoramento de reservatórios, equação de Gassmann, injeção de CO2.
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Sande, Danilo, Amin Bassrei, and Jerry Harris. "NEW ITERATIVE AND MULTIFREQUENCY APPROACHES IN GEOPHYSICAL DIFFRACTION TOMOGRAPHY." Brazilian Journal of Geophysics 37, no. 2 (July 12, 2019). http://dx.doi.org/10.22564/rbgf.v37i2.2000.
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ABSTRACT. Seismic tomography is used in reservoir geophysics as an important method for high-resolution imaging. The classical Born approach, which is used in single-frequency diffraction tomography under the condition of weak scattering, is limited by the requirement to know the background velocity in advance. We propose tomographic inversion approaches within matrix formalism and the Born approximation conditions. These approaches are iterative (in the sense that the background velocity field is updated at each iteration) and do not require knowledge of the true background velocity. In the first approach, a single-frequency that is kept constant is used. In the second approach, several frequencies are also kept constant and are used simultaneously. In the third approach, in addition to the background velocity, the working frequency is also updated. Finally, in the last approach, the multiple frequencies used simultaneously are updated throughout the iteration. The proposed approaches were tested on a synthetic model containing a dipping layer and a paleochannel, with cross-well acquisition geometry, and the data were contaminated with Gaussian noise. When compared to the standard, single-frequency non-iterative approach, the iterative process with the use of multiple frequencies generated results with smaller RMS errors for model parameter, velocity and data.Keywords: seismic inversion, seismic tomography, wave numerical modeling, reservoir characterization.RESUMO. A tomografia sísmica é usada na geofísica de reservatórios como um método importante para obtenção de imagens de alta resolução. A abordagem clássica de Born, usada na tomografia de difração de única frequência sob a condição de espalhamento fraco, é limitada pela necessidade de se conhecer antecipadamente a velocidade do fundo homogêneo. Propomos abordagens iterativas de inversão tomográfica dentro do formalismo matricial e sob a condição da aproximação de Born. Essas abordagens têm uma natureza iterativa, onde o campo de velocidade de fundo é atualizado em cada iteração, sendo que o conhecimento da velocidade verdadeira do fundo homogêneo não é necessário. Na primeira abordagem é usada uma única frequência mantida constante. Na segunda abordagem são usadas simultaneamente várias frequências também mantidas constantes. Na terceira abordagem, além da velocidade do fundo homogêneo, a frequência de trabalho também é atualizada. Finalmente, na última abordagem, as múltiplas frequências usadas simultaneamente são atualizadas durante a iteração. As abordagens propostas foram testadas em um modelo sintético contendo uma camada inclinada e um paleocanal, com geometria de aquisição poço a poço, sendo os dados contaminados com ruído gaussiano. Quando comparado com a abordagem padrão não-iterativa de única frequência, o processo iterativo com o uso de múltiplas frequências gerou resultados com erros menores de RMS para o parâmetro de modelo, a velocidade e o vetor de dados.Palavras-chave: inversão sísmica, tomografia sísmica, modelagem numérica de ondas, caracterização de reservatórios.
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LONDOÑO BONILLA, John Makario, and Sandra Patricia RODRÍGUEZ G. "Mapeo tridimensional del valor b en el Volcán Nevado del Ruíz, Colombia [3D mapping of b-value at Nevado del Ruiz Volcano, Colombia]." Ventana Informatica, no. 29 (March 28, 2014). http://dx.doi.org/10.30554/ventanainform.29.249.2013.
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Resumen Se realizó un mapeo tridimensional del valor-b para la sismicidad volcano-tectónica del Volcán Nevado del Ruiz (VNR) para el período comprendido entre 1985 y 2002.Se pudieron definir cuatro zonas anómalas (altos valores) de b en el VNR, localizadas, unaal oeste del cráter activo cerca al cráter la Olleta (b=1.3-1.8), asociada con un sistema hidrotermal en superficie (z=1Km) y una zona de alimentación magmática en profundidad (z=6Km); otra zona (b=1.4),ubicada bajo el cráter activo Arenas (z=1Km) asociada con un sector de acumulación de vapor y fluidos que harían parte del sistema hidrotermal del VNR; otra zona (b=1.7), localizada al sur del cráter activo (Z=6Km) asociada posiblemente a la localización de una de las cámaras magmáticas del VNR; y otra zona (b=1.7), ubicada al NE del cráter activo (z=3Km) cerca al cráter la Piraña, asociada también a una zona de alimentación magmática. Estas zonas son coincidentes con las halladas en otros estudios usando tomografía sísmica para el VNR, al igual que con estudios petrológicos y geoquímicos. Palabras clave:valor-b, mapeo 3D, sismicidad, distribución frecuencia-magnitud de sismos Abstract Three-dimensional mapping of b-value (frequency-magnitude distribution) was done for Nevado del Ruiz Volcano (NRV), Colombia for the period 1985-2002.Four high b-value zones were detected. The first zone (b=1.3 -1.8), located to the west of the active crater (Arenas), close to the Olleta crater. This zone was associated with a hydrothermal system at surface (z=1Km),andwith a zone ofmagma supply atdepth(z >6Km). The second zone (b=1.4), located beneath the Arenas crater (z=1Km) was associated with a zone of fluid and vapor accumulation related with the hydrothermal system of NRV. The third zone (b=1.7), located to the south of Arenas crater (z=6Km) was associated with one of the magmatic chambers of NRV; and the forth zone (b=1.7), located to theNE of the Areas crater (z=3Km) near to the Piraña crater, was associated with another magma supply zone. Those zones are in agreement with studies of seismic tomography, geochemistry and petrology done previouslyat NRV. Keywords: b-value, 3d mapping, seismicity, earthquake frequency-magnitude distribution