scholarly journals The M 6.5 Ambon earthquake 26 September 2019: the source mechanism and the aftershock sequence characteristics

2021 ◽  
Vol 873 (1) ◽  
pp. 012013
Author(s):  
S. Rohadi ◽  
Y.H. Perdana ◽  
N. Herayndoko ◽  
B. Sunardi ◽  
T. A. Prakoso ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Focal Depth ◽  
Aftershock Sequence ◽  
Time Decay ◽  
Eurasian Plate ◽  
Nodal Plane ◽  
Australian Plate ◽  
Rate Of Decay ◽  
Sequence Characteristics ◽  
Large Moment

Abstract The area of Ambon, Maluku is located in the subduction zone in bands where the Australian plate meets the Eurasian plate, thus causing tectonic activities. The Ambon earthquake on 26th September 2019 with 6.5 Magnitude, while the Epicentral coordinates of the earthquake were determined as 3,53° S and 128,39° E and a focal depth of 10 km, according to the Agency for Meteorology Climatology and Geophysics, Indonesia. This earthquake was strongly felt at the biggest shock was felt with intensity VI-VII as unified in Ambon City, while several other areas are reported to have experienced small shaking, such as Intensity V in Masohi, and Intensity IV in Namlea and Namrole. We used a dataset of 24 waveforms of seven sensors, we determine a tabular solution, which have a large moment of 0.4573 x 1019 N-m, the depth is 6 km by minimizing the inversion residual. The method resulting strike and rake fault, with strike: 341.8°; dip; 81.5°; rake: 158.4°, and second nodal plane strike: 75.1°; dip; 68.6°; rake: 9.14°. The mechanisms were compared with those from other agency in agreement. The time decay intervals between mainshocks and significant aftershocks follow Mogi and Utsu’s Law but with a relatively faster rate of decay than that of aftershocks in general.

scholarly journals Analisis Pengaruh Gempa Tektonik 10 Juli 2013 Terhadap Perubahan Koordinat Stasiun Pantau Segmen Mentawai

2020 ◽  
Vol 3 (1) ◽  
pp. 13
Author(s):  
Hilmiyati Ulinnuha ◽  
Aris Sunantyo ◽  
Nurrohmat Widjajanti
Keyword(s):  
Subduction Zone ◽  
Negative Impact ◽  
High Potential ◽  
Monitoring Station ◽  
Gps Data ◽  
Observation Data ◽  
Eurasian Plate ◽  
Tectonic Earthquake ◽  
Australian Plate ◽  
Continuous Gps

Mentawai Segment is located in Mentawai Islands, Sumatra, Indonesia. This segment is a subduction zone between Indo-Australian plate and Eurasian plate. This subduction zone can lead to high potential of tectonic earthquake in Mentawai Segment. The high potential of tectonic earthquake has negative impact for the community, so it is necessary to monitor the risk of tectonic earthquake in Mentawai Segment. This monitoring can be done by using GPS data of monitoring station that spread in Mentawai Segment. Therefore, this research aims to analyze the effect of tectonic earthquake on the coordinate change of Mentawai Segment, so that it can reduce the risk of negative impact of tectonic earthquake in Mentawai Segment. This research use observation data of 10 continuous GPS monitoring station (Sumatran GPS Data Array / SuGAr) in Mentawai Segment. Day of observation data was day of year (doy) at the time of tectonic earthquake occurence on July 10, 2013. Data processing used GAMIT / GLOBK software. The results of this research indicate that the tectonic earthquake (July 10, 2013) affected coordinates changes of the SuGAr station significantly two hours after the tectonic earthquake occurred.

Seismicity of the mendocino escarpment and the aftershock sequence of June 26, 1968: Ocean bottom seismic measurements

1973 ◽  
Vol 63 (2) ◽  
pp. 441-456
Author(s):  
Ali A. Nowroozi
Keyword(s):  
Subduction Zone ◽  
Fracture Zone ◽  
Focal Depth ◽  
Aftershock Sequence ◽  
Ocean Bottom ◽  
Time Intervals ◽  
Small Magnitude ◽  
Submarine Earthquakes ◽  
Gorda Ridge ◽  
Plane Solution

abstract Since May 1966, OBS 3, an ocean-bottom geophysical station located 220 km south of the Mendocino fracture zone at a depth of 3903 meters and PTA, a supporting land station at Point Arena, California, have been operating continuously. During a 5-year period OBS 3 recorded over 650 local earthquakes with suboceanic epicenters, about 200 of which were also recorded by PTA. Earthquakes recorded by OBS 3 have clear P, S, and T phases; those recorded by PTA have clear P and S phases but generally do not have clear T phases. The 200 earthquakes recorded by both stations were located on the basis of S —P time intervals at OBS 3 and at PTA. Readings from the Berkeley network of seismographic stations were also used when possible. Most of the submarine earthquakes located are related to the Mendocino and Gorda escarpments. Earthquakes do not occur beyond the intersection of the Mendocino fracture zone and the Gorda Ridge. The entire Gorda Basin is seismically active, implying that it is presently undergoing internal deformation. In an attempt to confirm a possible subduction zone in the vicinity of the coast and north of the Mendocino fracture zone, five earthquakes were relocated, two of which were probably subcrustal. One earthquake (August 23, 1962) had a focal depth of 59.4 km, which is confirmed by the time intervals of the pP—P and sP—P phases. The second (September 4, 1962) had a depth of 45 km, but because of the earthquake's small magnitude, its depth could not be confirmed. These subcrustal earthquakes do indicate a possible active subduction zone close to the coast north of the Mendocino fracture zone. The submarine aftershock sequence of June 26, 1968 indicates that (1) b = 0.5 ± 0.1 (This is slightly smaller than other b values given for the adjacent continental region.); (2) the magnitude versus the length of the fault for this sequence is approximately similar to that of other recent sequences in California; (3) the composite fault-plane solution for all of the aftershocks is similar to that of the main shock and gives a fault trend of N41°E.

scholarly journals Analisis Pergeseran Koseismik Gempa Sianok Tahun 2007 Berdasarkan Data Pengamatan GPS Tahun 1993-2007 dan Efek terhadap SRGI 2013

2019 ◽  
Vol 2018 (1) ◽  
Author(s):  
Joni Efendi ◽  
Kosasih Prijatna ◽  
Irwan Meilano
Keyword(s):  
Subduction Zone ◽  
Coseismic Deformation ◽  
Lake Area ◽  
Earthquake Cycle ◽  
Eurasian Plate ◽  
Earthquake Parameters ◽  
Australian Plate ◽  
Geodetic Control ◽  
Coordinate Changes ◽  
The Impact

ABSTRAKTumbukan miring Lempeng Eurasia dengan Lempeng Indo-Australia membentuk zona subduksi di bagian barat Pulau Sumatra dan sejumlah segmen sesar di darat Pulau Sumatra. Zona subduksi dan segmen sesar yang terbentuk aktif bergerak sehingga sering menimbulkan gempa bumi di wilayah tersebut. Semenjak diberlakukannya Sistem Referensi Geospasial Indonesia 2013 (SRGI 2013) sebagai referensi tunggal dalam aktivitas pemetaan di Indonesia, maka perubahan posisi kerangka referensi koordinat sebagai fungsi waktu akibat dinamika bumi perlu diperhitungkan. Dengan terjadinya dua gempabumi yang berurutan pada tanggal 6 Maret 2007 di wilayah Danau Singkarak Sumatra Barat, akan menimbulkan deformasi koseismik yang dapat mempengaruhi SRGI2013. Dalam penelitian ini dilakukan analisis untuk menentukan model koseismik gempabumi Sianok yang paling sesuai dan sejauh mana dampaknya pada SRGI 2013. Berdasarkan hasil analisis terhadap nilai residual hasil validasi dengan koseismik pada 11 titik pengamatan GPS dapat disimpulkan bahwa model koseismik dari gempabumi Sianok adalah model koseismik menggunakan data parameter gempa dari Global CMT dengan residual misfit 47.5 mm. Secara umum, pola kosesimik gempabumi Sianok mendeskripsikan mekanisme gempabumi sesar geser. Nilai kosesimik terbesar terjadi pada titik KACA dan K108, yaitu 135,43 mm dan 84,74 mm. Besarnya koseismik gempabumi Sianok tidak berpengaruh terhadap peta dengan skala 1: 1000, akan tetapi akan mempengaruhi nilai koordinat Jaring Kontrol Geodesi (JKG) yang berada di sekitar daerah gempa, sehingga perlu adanya pemutakhiran koordinat dari JKG.Kata kunci: Gempabumi Sianok, GPS, Deformasi Koseismik, SRGI2013. ABSTRACTThe oblique movement of Eurasian Plate towards Indo-Australian Plate create subduction zone in the western part of Sumatra Island and some faults on the mainland of Sumatra. These subduction zone and faults actively produce some earthquakes. Since we used the Geospatial Reference System of Indonesia 2013 (SRGI 2013) as one reference on mapping activities in Indonesia, coordinate changes as a function of time caused by earthquake cycle need to be calculated. There are two earthquakes that had been occurred on March 6, 2007 in Singkarak Lake area which affected the SRGI 2013. We analyzed the data to estimate the coseismic model of Sianok earthquake and the impact to the SRGI 2013. The residual from the coseismic model by including 11 GPS displacements shows that the coseismic model of Sianok earthquake is a model that used earthquake parameters from Global CMT with the misfit of 47.5 mm. Overall, this coseismic pattern shows the shear mechanism. The largest displacements are on KACA and K108 sites, that are 135.43 mm and 84.74 mm respectively. The coseimic of Sianok earthquake does not affect a map with scale of 1:1000, but affect the Geodetic Control Network in this area. From this analysis, we conclude that we need to update our Geodetic Control Network.Keywords: Sianok Earthquake, GPS, Coseismic Deformation, SRGI2013.

EDUKASI DAN MITIGASI GEMPA PADA BANGUNAN

2021 ◽  
pp. 417
Author(s):  
Daniel Christianto ◽  
Sunarjo Leman ◽  
Alvira Nathania Tanika ◽  
Maria Kevinia Sutanto ◽  
Vryscilia Marcella
Keyword(s):  
General Information ◽  
Physical Contact ◽  
Eurasian Plate ◽  
Earthquake Mitigation ◽  
Natural Event ◽  
Australian Plate ◽  
The Pacific ◽  
Prone Area ◽  
Tectonic Earthquakes ◽  
The Impact

A natural disaster is a natural event that has a major impact on the human population. One of the natural events that became the focus of this PKM activity was an earthquake. Earthquakes are natural events in the form of vibrations or wavy movements on the earth's crust caused by internal forces. Earthquakes caused by shifting of the ground are called tectonic earthquakes and earthquakes caused by volcanoes are called volcanic earthquakes. Indonesia is an earthquake-prone area because it is located on three plates, namely the Eurasian Plate, the Pacific Plate, and the Indo-Australian Plate. Only in western, central and southern Kalimantan, the source of the earthquake was not found. To reduce the impact of risk during an earthquake, it is necessary to carry out an earthquake mitigation to the community in areas prone to earthquakes. Earthquake mitigation that will be carried out in this PKM activity is in the form of counseling through online webinars to prevent physical contact or crowds, related to the Covid19 pandemic. As a result, from the questions asked by participants, there is still a lack of understanding of the dangers of changing the function of the building or the building's use limit based on the design load and the condition of the building after the earthquake. So for the next PKM, it is recommended to make general information guidelines such as examples of photos or pictures about the condition of buildings that need to be reviewed for repairs or are no longer suitable for use after being hit by an earthquake.Bencana alam adalah suatu peristiwa alam yang mengakibatkan dampak besar bagi populasi manusia. Salah satu peristiwa alam yang menjadi fokus dalam kegiatan PKM ini adalah gempa bumi. Gempa bumi merupakan fenomena alam berupa getaran atau gerakan bergelombang pada lempeng bumi yang disebabkan oleh tenaga yang berasaldari dalam bumi. Gempa yang disebabkan oleh pergeseran tanah dinamakan gempa tektonik dan gempa yang disebabkan oleh gunung berapi dinamakan gempa vulkanik. Indonesia merupakan daerah rawan gempa karena terletak di atas tiga lempeng yakni Lempeng Eurasia, Lempeng Pasifik, dan Lempeng Indo-Australia. Hanya di Kalimantan bagian barat, tengah, dan selatan, sumber gempa bumi tidak ditemukan. Untuk mengurangi dampak resiko pada saat gempa perlu dilakukan suatu mitigasi gempa kepada masyarakat di daerah yang rawan terjadi gempa bumi. Mitigasi gempa yang akan dilakukan dalam kegiatan PKM ini berupa penyuluhan melalui webinar secara online untuk mencegah kontak fisik atau kerumunan, berhubungan dengan pandemi Covid19. Hasilnya, dari pertanyaan yang diajukan peserta, masih kurang pemahaman bahaya dari mengubah fungsi guna bangunan atau batas guna bangunan berdasarkan beban desain dan kondisi bangunan setelah gempa. Maka untuk PKM selanjutnya, disarankan membuat panduan informasi secara umum seperti contoh foto atau gambar tentang kondisi bangunan yang perlu ditinjau untuk perbaikan atau tidak layak guna lagi setelah terkena gempa.

scholarly journals Implementasi Google Maps API Pemetaan Jalur Evakuasi Bencana Alam di Kabupatem Lombok Utara

2019 ◽  
Vol 19 (1) ◽  
pp. 138-146
Author(s):  
Khaerul Yasin ◽  
Ahmat Adil
Keyword(s):  
Information System ◽  
Geographic Information System ◽  
Geographic Information ◽  
Eurasian Plate ◽  
Google Maps ◽  
Tectonic Plates ◽  
Plate Movement ◽  
The North ◽  
Australian Plate ◽  
Evacuation Routes

Basically, Indonesia is traversed by three active tectonic plates namely the Indo-Australian Plate in the south, and the Eurasian Plate in the north and the Pacific Plate in the east. The plates collide with each other because the Indo-Australian Plate movement drops below the Eurasian plate. As a result of this accumulation, it caused earthquakes, volcanoes, and faults or faults in parts of Indonesia. In the Geographic Information System evacuation routes will be used by Google maps Api to implement the spatial map making of evacuation routes. Google Map Api is an application interface that can be accessed via javascript so that Google Map can be displayed on the web page that we are building. The result or output to be achieved is the creation of a geographic information system mapping natural disaster evacuation route in the North Lombok district that can be run on a Web platform. Based on the trials conducted it can be concluded that this application can help the community to find the location of evacuation routes and gathering points in accordance with the districts and villages where they live.

The influence of fluids in the unusually high-rate seismicity in the Ometepec segment of the Mexican subduction zone

2021 ◽  
Author(s):  
D Legrand ◽  
A Iglesias ◽  
S K Singh ◽  
V Cruz-Atienza ◽  
C Yoon ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Temporal Distribution ◽  
Aftershock Sequence ◽  
High Rate ◽  
Earth Tides ◽  
P Value ◽  
Plate Interface ◽  
Flow Measurements ◽  
Slow Slip Events ◽  
Mexican Subduction Zone

Summary The rate of earthquakes with magnitudes Mw ≤ 7.5 in the Ometepec segment of the Mexican subduction zone is relatively high as compared to the neighboring regions of Oaxaca and Guerrero. Although the reason is not well understood, it has been reported that these earthquakes give rise to a large number of aftershocks. Our study of the aftershock sequence of the 2012 Mw7.4 Ometepec thrust earthquake suggests that it is most likely due to two dominant factors: (1) The presence of an anomalously high quantity of over-pressured fluids near the plate interface, and (2) the roughness of the plate interface. More than 5,400 aftershocks were manually detected during the first ten days following the 2012 earthquake. Locations were obtained for 2,419 events (with duration magnitudes Md ≥ 1.5). This is clearly an unusually high number of aftershocks for an earthquake of this magnitude. Furthermore, we generated a more complete catalog, using an unsupervised fingerprint technique, to detect more smaller events (15,593 within one month following the mainshock). For this catalog, a high b-value of 1.50 ± 0.10 suggests the presence of fluid release during the aftershock sequence. A low p-value (0.37 ± 0.12) of the Omori law reveals a slow decaying aftershock sequence. The temporal-distribution of aftershocks shows peaks of activity with two dominant periods of 12h and 24h that correlate with the Earth tides. To explain these observations, we suggest that the 2012 aftershock sequence is associated with the presence of over-pressured fluids and/or a heterogeneous and irregular plate interface related to the subduction of the neighboring seamounts. High fluid content has independently been inferred by magneto-telluric surveys and deduced from heat flow measurements in the region. The presence of fluids in the region has also been proposed to explain the occurrence of slow slip events, low frequency earthquakes, and tectonic tremors.

scholarly journals Resilience measurement of Padang city’s infrastructures toward multi-hazard

2020 ◽  
Vol 156 ◽  
pp. 01003
Author(s):  
Giani Ananda ◽  
Taufika Ophiyandri ◽  
Edi Hasymi
Keyword(s):  
High Risk ◽  
Data Collection ◽  
Qualitative Methods ◽  
Fault Line ◽  
Eurasian Plate ◽  
Assessment Data ◽  
Meeting Point ◽  
Australian Plate ◽  
Infrastructure Resilience ◽  
The Impact

The complexity of geographical conditions and regional morphology of Padang City have caused it to be at high risk of multi-hazard. Padang City is located near the meeting point of the Indo-Australian Plate and the Eurasian Plate, and also on the Sumatra Fault line (Semangko Fault). Therefore, strong infrastructures are needed in order to minimize the impact of the risk of multi-hazard. This study is conducted to measure the resilience of Padang City’s infrastructures toward multi-hazard and provide recommendations to improve the resilience of Padang City’s infrastructures toward Multi-hazard. This study was conducted with qualitative methods and presented quantitatively in the form of diagrams. The measurement is carried out based on the concept of city toughness measurements made by UNISDR known as the "Scorecard". This study only focuses on essential 8 about "Increase Infrastructure Resilience" and essential 10 about "Expedite Recovery and Build Back Better". From this study, it can be concluded that the resilience of Padang City infrastructures is still relatively low so several recommendations that are expected will increase the resilience of Padang City’s infrastructures are proposed, that are; in-depth assessment, data collection and supervision monitoring of infrastructures, important assets, and protective infrastructure.

Classification of volcanic and tectonic earthquakes in Kamchatka (Russia) with different machine learning techniques

2020 ◽  
Author(s):  
Natalia Galina ◽  
Nikolai Shapiro ◽  
Leonard Seydoux ◽  
Dmitry Droznin
Keyword(s):  
Machine Learning ◽  
Subduction Zone ◽  
Aftershock Sequence ◽  
Machine Learning Techniques ◽  
Support Vector ◽  
Learning Approaches ◽  
Shiveluch Volcano ◽  
Agglomerative Clustering ◽  
Learning Techniques ◽  
Single Station

<p>Kamchatka is an active subduction zone that exhibits intense seismic and volcanic activities. As a consequence, tectonic and volcanic earthquakes are often nearly simultaneously recorded at the same station. In this work, we consider seismograms recorded between December 2018 and April 2019. During this time period when the M=7.3 earthquake followed by an aftershock sequence occurred nearly simultaneously with a strong eruption of Shiveluch volcano. As a result, stations of the Kamchatka seismic monitoring network recorded up to several hundreds of earthquakes per day. In total, we detected almost 7000 events of different origin using a simple automatic detection algorithm based on signal envelope amplitudes. Then, for each detection different features have been extracted. We started from simple signal parameters (amplitude, duration, peak frequency, etc.), unsmoothed and smoothed spectra and finally used a multi-dimensional signal decomposition (scattering coefficients). For events classification both unsupervised (K-means, agglomerative clustering) and supervised (Support Vector Classification, Random Forest) classic machine learning techniques were performed on all types of extracted features. Obtained results are quite stable and do not vary significantly depending on features and method choice. As a result, the machine learning approaches allow us to clearly separate tectonic subduction-zone earthquakes and those associated with the Shiveluch volcano eruptions based on data of a single station.</p>

scholarly journals Analysis of the Spatial and Temporal Distribution of the 2011 Earthquakes in Lake Van Area and Rupture Complexity of the Aftershock Sequence in Eastern Anatolia, Turkey

2018 ◽  
Author(s):  
Mustafa Toker
Keyword(s):  
Seismic Activity ◽  
Focal Depth ◽  
Temporal Distribution ◽  
Aftershock Sequence ◽  
Spatial And Temporal Distribution ◽  
Upper Crust ◽  
Lake Van ◽  
Spatial Clusters ◽  
Central Cluster ◽  
Aftershock Sequences

This study presents an analysis of the spatial and temporal distribution of the two large destructive earthquakes that occurred in Lake Van area on October 23, and November 9, 2011, together with the azimuth-dependent distribution of the seismic activity and microseismicity clusters after the mainshocks, associated with the complex rupture processes of their aftershock sequence. The sequence began with the magnitude Mw 7.1 earthquake of 23 October and a second destructive earthquake of Mw 5.6. The aftershock sequences of the two mainshocks were linked to the local crustal faults beneath Lake Van area, followed successively and produced unusually intense activity and significant damage in the area. The main purposes of this study are to document the spatial and temporal distribution and evolution of the October 23, 2011 aftershock hypocenters and the azimuth-dependent distribution of seismic activity, and to understand the spatial and temporal character of the aftershock sequence using the distributional and evolutional patterns of the aftershock hypocenters. A total of 10,000 aftershocks were obtained from seismic data with a high signal-to-noise ratio over collected over three years from October 23, 2011 to March 2014. These aftershocks were plotted for the time periods from November 2011 through March 2012 to March 2014 and ≈ 5000 aftershocks were retained in the depth versus distance cross-sections to detect the clusters in the first step of study (November 2011–March 2012). The focal depth distribution of the aftershock clusters, the migration of hypocenter activity and microseismicity clusters were analyzed and the distributional patterns of the detected clusters were assessed using the geometric distribution of the aftershock hypocenters. The spatial and temporal distribution of aftershocks reveal interesting key features of the deep rupture complexity of the Van earthquake: (1) most prominent aftershocks have been located in the upper crust at depths shallower than 10 km beneath ruptured area, indicating that the upper crust is brittle and seismogenic; (2) two spatial clusters have been detected at 8-10 km depths and the upward extrapolation of these clusters intersects with faults; the main cluster (60 km wide) bounded by inferred reverse faults (f3 and f4) and the central cluster (25–30 km wide) bounded by faults (f1 and f2); (3) these spatial clusters form the largest volumetric pattern of the conical-shaped cluster at depths of about 25–30 km of the azimuth-dependent rotational projections, suggesting azimuthal distributions of deep rupture characteristics; and (4) the strongest temporal cluster of microseismicity derived from temporal distribution of aftershocks has been detected within an area of about 2.5–3.0 km2 and it is spatially observed at 20 km depth within the central cluster, suggesting progressive failure of the adjacent patches of possible fault.

scholarly journals STRUCTURAL AND EARTHQUAKE EVALUATIONS ALONG JAVA SUBDUCTION ZONE, INDONESIA

2020 ◽  
Vol 30 (1) ◽  
pp. 65
Author(s):  
Adi Patria ◽  
Atin Nur Aulia
Keyword(s):  
Subduction Zone ◽  
Normal Fault ◽  
Thrust Fault ◽  
Earthquake Activity ◽  
Accretionary Wedge ◽  
Forearc Basin ◽  
Plate Interface ◽  
Seafloor Morphology ◽  
Australian Plate ◽  
Seismic Reflection Profiles

Java Subduction is a zone of trench perpendicular convergence of Australian Plate and Southeast Asia in the south of Java. It is characterized by an almost E-W trending trench with an eastward increase of convergence velocity. Three major earthquakes with tsunamis have been caused by deformation along this subduction zone. Although many studies have undertaken to understand the nature of the subduction system, a clear relationship between structures and earthquake activities remains poorly explained. In this study, we used bathymetry, residual bathymetry, and published seismic reflection profiles to evaluate structural and morphological elements, then link the observations to earthquake activity along Java Subduction Zone. Based on seafloor morphology, characteristics of the accretionary wedge and forearc basin varies along the trench in response to the variation of seafloor morphology. Features such as seamounts and ridges which were observed in the oceanic basin may be subducted beneath accretionary wedge and disrupt the morphology of accretionary wedge, forearc basin, and trench. Earthquake activities are generally dominated by normal fault solutions in the trench, which is attributed to plate bending faults while thrust fault solution is observed in the forearc basin area. Thrust fault activities in accretionary wedge are decreased to the east, where there is no thrust fault solution observed in the eastern end of the subduction zone. Few strike-slip focal mechanisms are observed and mainly located within the subducting oceanic plate. Structures and subducting oceanic features may control the earthquake activity where deformation occurred at the edge of these features. The two largest thrust fault earthquakes in 1994 and 2006 are interpreted as a result of deformation along with plate interface on soft or unconsolidated sediment above the incoming plate. The largest normal fault earthquake with a magnitude 8.3 is possibly caused by a crustal scale-fault that breaks the entire oceanic crust.ABSTRAK - Evaluasi struktur dan gempa bumi di sepanjang zona subduksi Jawa, Indonesia. Subduksi Jawa adalah zona konvergensi yang tegak lurus palung antara Lempeng Australia dan Asia Tenggara di selatan Jawa. Hal ini ditandai dengan palung berarah hampir barat–timur dengan peningkatan kecepatan konvergensi ke arah timur. Tiga gempa bumi besar dengan tsunami disebabkan oleh deformasi di sepanjang zona subduksi ini. Meskipun banyak penelitian telah dilakukan untuk memahami sifat sistem subduksi, hubungan antara struktur dan kegiatan gempa bumi masih kurang jelas. Dalam studi ini, kami menggunakan batimetri, batimetri residual, dan profil refleksi seismik untuk mengevaluasi elemen struktur dan morfologi, kemudian menghubungkan pengamatan dengan aktivitas gempa bumi di sepanjang zona subduksi Jawa. Berdasarkan morfologi dasar laut, karakteristik prisma akresi dan cekungan busur muka bervariasi di sepanjang palung sebagai respon terhadap variasi morfologi dasar laut. Fitur seperti seamount dan punggungan yang diamati di cekungan samudera menunjam di bawah prisma akresi dan mengganggu morfologi prisma akresi, cekungan busur muka, dan palung. Aktivitas gempa bumi umumnya didominasi oleh patahan normal di palung, yang dikaitkan dengan patahan tekukan lempeng sedangkan patahan naik diamati di daerah cekungan busur muka. Aktivitas sesar naik di dalam prisma akresi berkurang ke arah timur, di mana tidak ada patahan naik yang teramati di ujung timur zona subduksi. Beberapa mekanisme patahan mendatar diamati dan terutama terletak di dalam lempeng samudera yang menunjam. Struktur dan fitur di kerak samudra yang menunjam dapat mengontrol aktivitas gempa bumi di mana deformasi terjadi di tepian fitur ini. Dua gempa bumi besar dengan sifat patahan naik pada tahun 1994 dan 2006 ditafsirkan sebagai hasil dari deformasi di sepanjang antarmuka lempeng pada sedimen lunak atau tidak terkonsolidasi di atas lempeng yang masuk. Gempa bumi besar dengan sifat sesar normal magnitude 8,3 mungkin disebabkan oleh patahan skala-kerak yang menghancurkan seluruh kerak samudera.

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