scholarly journals STUDI AWAL POLA STRUKTUR BUSUR MUKA ACEH, SUMATRA BAGIAN UTARA (INDONESIA): Penafsiran dan Analisis Peta Batimetri

2016 ◽  
Vol 8 (3) ◽  
pp. 105
Author(s):  
Haryadi Permana ◽  
L. Handayani
Keyword(s):  
Subduction Zone ◽  
Deformation Zone ◽  
Thrust Fault ◽  
Middle Part ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Zone Structure ◽  
Structural Pattern ◽  
Active Deformation ◽  
Plate Subduction

Analisis morfostruktur daerah penelitian menunjukan tiga unit struktur geologi yang berbeda, antara lain zona penunjaman, zona deformasi aktif dan busur muka termasuk didalamnya tinggian busur muka dan cekungan busur muka. Struktur geologi zona penunjaman lempeng teramati sepanjang Palung Sunda paralel dengan zona deformasi aktif. Struktur geologi pada Tinggian Busur Muka membentuk sistim prisma akresi yang disusun oleh sesar anjak, sesar geser, perlipatan dan perlipatan naik. Pola kelurusan struktur umumnya berarah berarah utara baratlaut-selatan tenggara di sebelah utara lintang 5°U, arah baratlaut-tenggara pada posisi 3°-5°U, kelurusan kemudian berbelok hampir barat-timur di sekitar 2°-3°U. Perubahan arah pola kelurusan struktur tersebut ditafsirkan sebagai jawaban terhadap naiknya tingkat kemiringan penunjaman lempeng dari daerah Simeulue ke arah Lintang 5°U -7°U atau secara umum dari selatan Sumatra ke arah utara Sumatra. Di bagian tengah daerah telitian berkembang kelurusan patahan berarah utara-selatan yang memotong kelurusan berarah baratlaut-tenggara. Kelurusan tersebut ditafsirkan sebagai patahan geser dekstral dan kemungkinan masih aktif. Kata Kunci: Analisis morfostruktur, zona penunjaman, zona deformasi aktif, busur muka, kelurusan, sesar anjak, sesar geser, perlipatan, perlipatan naik, kemiringan penunjaman lempeng Morphostructure analyses of study area demonstrate three different units of geological structures: subduction zone, active deformation zone and fore-arc region, which include Fore Arc High and Fore Arc Basin. The plate subduction zone observes along Sunda Trench parallel with active deformation zone. Structure geology in Fore Arc High builds an accretionary prism system. It was composed by thrust fault, strike slip fault, folding and thrust fold. General trend of structural pattern is NNE-SSE at the north of 5°N, NW-SE direction at around 3°-5°N and changed in direction relative to E-W at about 2°-3°N. This direction variation of structural pattern trend was interpreted as a response to increase of obliquity degree of subducted plate from Simeulue area to 5° -7°N, or in general, from southern of Sumatra to north of Sumatra. NS trend lineament has developed in the middle part of study area that also sliced the NW-SE main structural direction. These structural lineaments interpreted as dextral strike slip fault and it is possibly still active. Keywords: morphostructure analyses, subduction zone, active deformation zone, fore-arc lineament, thrust fault, strike slip, folding, thrust fold, plat, plate subduction obliquity

Continual interaction between the Minahassa subduction interface and the Palu-Koro strike-slip fault in Sulawesi, Indonesia.

2020 ◽  
Author(s):  
Nicolai Nijholt ◽  
Wim Simons ◽  
Riccardo Riva
Keyword(s):  
Subduction Zone ◽  
Fault Zone ◽  
Slip Rate ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Model Calculations ◽  
Transient Deformation ◽  
Subduction Earthquake ◽  
Bay Area ◽  
Gnss Velocities

<p>Two major fault systems host M<sub>w</sub>>7 earthquakes in Central and Northern Sulawesi, Indonesia: the Minahassa subduction interface and the Palu-Koro strike-slip fault. The Celebes Sea oceanic lithosphere subducts beneath the north arm of Sulawesi at the Minahassa subduction zone. At the western termination of the Minahassa subduction zone, it connects to the left-lateral Palu-Koro strike-slip fault zone. This fault strikes onshore at Palu Bay and then crosses Sulawesi. Interseismic GNSS velocities indicate that the Palu-Koro fault zone accommodates about 4 cm/yr of relative motion in the Palu Bay area, with a ~10 km locking depth. This shallowly locked segment of the Palu-Koro fault around the Palu Bay area ruptured during the devastating, tsunami-generating, 2018 M<sub>w</sub>7.5 Palu earthquake. This complex event highlights the high seismic hazard for the island of Sulawesi.</p><p>We have a >20-year record of GNSS velocities on Sulawesi, where the densest cluster of monument sites surrounds the Palu-Koro fault, specifically around Palu Bay, whereas the rest of the island is less densely covered. High quality estimates of interseismic velocities reveal second-order complex patterns of transient deformation in the wake of major earthquakes: the velocities in northern Sulawesi and around the Palu-Koro fault do not follow their interseismic trends after a major subduction earthquake has occurred, for several years after the event. This effect of transient deformation reaches more than 400km away from the epicentre of the major earthquakes. Surprisingly, a deviation from the background slip rate on the Palu-Koro fault is not accompanied by a deviation from the background (micro)seismic activity.</p><p>We construct a 3D numerical model based on the structural and seismological data in the Sulawesi region. We investigate the post-seismic relaxation pattern from a subduction earthquake and determine whether the slip rate on the Palu-Koro fault changes due to this earthquake through forward model calculations. With a modelling focus on the 1996 M<sub>w</sub>7.9 and 2008 M<sub>w</sub>7.4 earthquakes that ruptured the Minahassa subduction interface, this study outlines the triggering of transient deformation and continual interaction between the Minahassa subduction interface and the Palu-Koro strike-slip fault.</p>

Hydrocarbon Play of Ordovician Carbonate Dominated by Faulting and Karstification—A Case Study of Yingshan Formation on Northern Slope of Tazhong Area in Tarim Basin, NW China

2011 ◽  
Vol 29 (6) ◽  
pp. 743-758 ◽  
Author(s):  
Xiuxiang Lü ◽  
Xiang Wang ◽  
Jianfa Han ◽  
Weiwei Jiao ◽  
Hongfeng Yu ◽  
...  
Keyword(s):  
Tarim Basin ◽  
Thrust Fault ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Weathering Crust ◽  
Northern Slope ◽  
Nw China ◽  
Yingshan Formation ◽  
Lower Ordovician ◽  
Tazhong Area

Large-scale weathering crust karsted carbonate reservoir beds were developed in the Lower Ordovician Yingshan Formation on the northern slope of the Tazhong area in the Tarim Basin, NW China. The research on weathering crust karsted reservoir beds and faulting showed strongly heterogeneous karsted reservoir beds characterized by horizontal contiguous distribution and vertical superimposition, with fracture-hole as the main reservoir space. High quality reservoir beds were developed in the vertical seepage zone and horizontal phreatic zone, 0–200 meters below the unconformity. Reservoir bed quality of karsted carbonate rock was greatly improved by faulting, which increased the depth and size of karstification. A strike-slip fault developed over a long period in the NE direction and a thrust fault in the NW direction crossed each other, and caused distinct segmentation of the Tazhong No.1 Fault and dissection of the Yingshan Formation into multiple structural units. The strike-slip fault was the significant hydrocarbon migration pathway. Multiple hydrocarbon charging points were formed by the thrust fault and strike-slip fault, as the important fill-in of late-stage gas accumulation. Under the dual control of faulting and karstification, accumulation of hydrocarbons in the Lower Ordovician Yingshan Formation showed distinct segment-wise and block-wise features. Oil distribution is “high in the west and interior, low in the east and exterior”, while gas distribution is the opposite. The hydrocarbon play extends within 0.8–4.5 kilometers from the strike-slip fault and appeared layered vertically at 10–220 meters below the unconformity.

scholarly journals Aplikasi Multi Hill Effect Untuk Mempermudah Analisis Geomorfologi Dalam Mengidentifikasi Sesar Aktif di Pidie Jaya

2017 ◽  
Vol 21 (1) ◽  
pp. 16
Author(s):  
Irwandi Irwandi
Keyword(s):  
Open Source ◽  
Subduction Zone ◽  
Open Source Software ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Free Open Source Software ◽  
Free Open Source

Sumatera memiliki dua sesar aktif utama yaitu Sunda Subduction Zone dan Great Sumatra Strike-slip fault. Namun gempabumi Pidie Jaya 7 Desember 2016 magnitudo 6.5 dan 102 korban jiwa tidak terjadi pada sesar aktif tersebut. Banyak sesar aktif yang masih luput dari pengamatan. Memetakan sesar aktif bukan pekerjaan yang mudah, ditambah lagi frekuensi gempa untuk sesar cabang relatif lebih kecil dibandingkan di sesar utama. Sehingga, penulis mencoba melakukan kajian geomorfologi dengan menganalisis hill effect dari data topografi digital dari sesar utama Sumatera hingga pantai Pidie Jaya.  Multi hill effect akan menghasilkan efek yang lebih baik sehingga lebih mudah mengidentifikasi sesar aktif. Semua proses menggunakan software Quantum GIS (QGIS) yang merupakan FOSS (Free Open Source Software). Rumitnya geomorfologi Aceh tentunya dengan hanya menggunakan metode tersebut belum mampu memberikan jawab yang memuaskan tentang teka-teki sesar aktif penyebab gempa Pidie Jaya. Namun metode tersebut dapat digunakan sebagai metode pendahuluan dan masih perlu digabungkan dengan informasi dari metode lainnya.

Parametric study of near-field ground motions for oblique-slip and dip-slip dislocation models

1983 ◽  
Vol 73 (1) ◽  
pp. 45-57 ◽  
Author(s):  
John G. Anderson ◽  
J. Enrique Luco
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Thrust Fault ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Dislocation Model ◽  
Finite Width ◽  
Rupture Velocity ◽  
Slip Direction ◽  
Dislocation Models

abstract The near-field motion on the surface of a uniform half-space for oblique-slip and dip-slip faults has been studied by the use of a dislocation model. The fault is modeled by an infinitely long buried dislocation of finite width; rupture propagates horizontally along the fault and past the observation points with a constant rupture velocity lower than the Rayleigh wave velocity. In addition to those parameters which control peak amplitudes near a vertical, strike-slip fault (depth of the top of the fault, horizontal rupture velocity), the dip of the fault plays an important role. The slip direction and the angle between the rupture front and the down-dip direction of the fault also become increasingly important in determining amplitudes of peak ground motions as the dip of the fault decreases from vertical to shallow angles. In some regions near a thrust fault, peak amplitudes are significantly greater than the largest values near a vertical, strike-slip fault.

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