scholarly journals Analysis of Source Mechanism and Coulomb Stress Change (Case Study: Molucca Sea Earthquakes November 15th, 2014 and November 14th, 2019)

2021 ◽  
Vol 873 (1) ◽  
pp. 012029
Author(s):  
Indra Josua Purba ◽  
Iman Suardi ◽  
Gatut Daniarsyad ◽  
Defni Lasmita
Keyword(s):  
Moment Tensor ◽  
Source Mechanism ◽  
Philippine Sea Plate ◽  
Double Difference ◽  
Coulomb Stress ◽  
Plate Boundaries ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
The Moment ◽  
Fault Mechanism

Abstract On November 15, 2014, and November 14, 2019, two major earthquakes occurred in the Molucca Sea with a moment magnitude of Mw 7.0 and Mw 7.1, respectively. These earthquakes were caused by the convergence activity between the Sunda Plate and the Philippine Sea Plate which form a double subduction zone in the Molucca Sea. We carried out the moment tensor inversion using Kiwi Tools to analyze the source mechanism for both of the earthquakes. The results show a thrust fault mechanism with the strike, dip, and rake of the ruptured fault planes are 187°, 63°, 85° and 196°, 43°, 83°, for the first and second events, respectively. We refine the location of the two mainshocks and their aftershocks by performing hypocenter relocation using the double difference method. This resulted in NE-SW aftershocks distribution for both events which occured close to the Molucca Sea Plate boundaries with the mainshocks location are relatively close to each other (± 50.32 km). Finally, we calculate the Coulomb stress changes to analyze the triggering effect between the two major events and between the mainshock and its aftershocks for each event. The results show that the hypocenter of the November 14, 2019 earthquake is in the increased zone of Coulomb stress changes produced by the November 15, 2014 earthquake with the value of 1.2 bar. The aftershocks of both events also occurred in the increased Coulomb stress changes with the range value of 0.5 - 1.8 bar for the first event and 0.2 - 0.8 bar for the second event.

scholarly journals Indikasi Sesar Naik di Plampang, Pulau Sumbawa Berdasarkan Analisis Gempa Bumi 13 Juni 2020

EKSPLORIUM ◽  
2021 ◽  
Vol 42 (2) ◽  
pp. 111
Author(s):  
Priyobudi Priyobudi ◽  
Mohamad Ramdhan
Keyword(s):  
Active Fault ◽  
Fault Plane ◽  
Moment Tensor ◽  
Moment Tensor Inversion ◽  
Reverse Fault ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
The Moment ◽  
Splay Fault ◽  
Lower Angle

ABSTRAK. Keberadaan sesar aktif dengan pola sesar naik di daerah Plampang berhasil diungkap dari sebaran hiposenter terelokasi, hasil inversi momen tensor, dan pemodelan perubahan tegangan Coulomb. Studi ini juga berhasil mengungkap sumber gempa pada sesar aktif tersebut dengan kedalaman relatif dangkal yang bisa menjadi ancaman di Pulau Sumbawa jika magnitudo maksimumnya rilis di masa yang akan datang. Hasil relokasi hiposenter menunjukkan sebaran episenter berarah barat daya–timur laut. Hal ini didukung juga oleh hasil inversi momen tensor yang menunjukkan bidang sesar berarah barat daya–timur laut (N2240E) dengan dip cukup curam (490). Penampang seismisitas vertikal pada arah dip menunjukkan adanya pola sesar naik yang semakin landai seiring bertambahnya kedalaman. Bidang sesar yang landai menunjukkan struktur decollement pada kedalaman 10–15 km dan berangsur menjadi curam sebagai struktur splay fault pada kedalaman 0–10 km. Hal tersebut konsisten dengan hasil inversi momen tensor yang menunjukkan mekanisme pergerakan sesar naik terjadi pada kedalaman 7 km. Pemodelan perubahan tegangan Coulomb menunjukkan adanya penambahan stress di luar area bidang sesar sehingga memicu terjadinya aftershocks. Sebaran gempa susulan menunjukkan adanya bidang sesar hipotetik dengan panjang 19 km dan lebar 12 km. Sesar sebesar ini berpotensi membangkitkan gempa dengan kekuatan Mw 6,4. Gempa Sumbawa 13 Juni 2020 dengan magnitudo M 5,3 disebabkan oleh sebagian kecil aktivitas dari bidang sesar tersebut.ABSTRACT. The existence of an active fault with a reverse fault mechanism in the Plampang area is successfully delineated from the distribution of the relocated hypocenter, the moment tensor inversion, and the Coulomb stress changes. This study also reveals the source of the earthquake in the active fault with a relatively shallow depth which can be a threat on Sumbawa Island if the maximum magnitude is released in the future. Seismicity from hypocenter relocation shows the distribution of the epicenter with a southwest–northeast direction. It is also supported by the moment tensor inversion result which shows the fault plane trending southwest–northeast (N2240E) with a steep dip (490). The vertical section of seismicity in the dip direction shows that the slope of the plane has a lower angle with increasing depth. The lower angle of a fault plane shows a decollement structure at a depth of 10–15 km and gradually becomes steep as a splay fault structure at a depth of 0–10 km. It is consistent with the result of moment tensor inversion which shows the mechanism of a reverse fault that occurred at a depth of 7 km. The Coulomb stress changes show the stress increasing outside the fault plane area, which triggers aftershocks. The distribution of aftershocks shows a hypothetical fault plane of 19 km long and 12 km wide. A fault of this size has the potential to generate an earthquake with a magnitude maximum of Mw 6.4. The Sumbawa earthquake on June 13, 2020, having M 5.3 was caused by a small part of the activity from the fault.

scholarly journals ANALYSING POST-SEISMIC DEFORMATION OF IZMIT EARTHQUAKE WITH INSAR, GNSS AND COULOMB STRESS MODELLING

2016 ◽  
Vol XLI-B1 ◽  
pp. 417-421 ◽  
Author(s):  
R. Alac Barut ◽  
J. Trinder ◽  
C. Rizos
Keyword(s):  
Measurement Techniques ◽  
Satellite System ◽  
Northern Region ◽  
Strike Slip ◽  
Coulomb Stress ◽  
North West ◽  
Coulomb Stress Changes ◽  
Izmit Earthquake ◽  
The North ◽  
Stress Changes

On August 17<sup>th</sup> 1999, a M<sub>w</sub> 7.4 earthquake struck the city of Izmit in the north-west of Turkey. This event was one of the most devastating earthquakes of the twentieth century. The epicentre of the Izmit earthquake was on the North Anatolian Fault (NAF) which is one of the most active right-lateral strike-slip faults on earth. However, this earthquake offers an opportunity to study how strain is accommodated in an inter-segment region of a large strike slip fault. In order to determine the Izmit earthquake post-seismic effects, the authors modelled Coulomb stress changes of the aftershocks, as well as using the deformation measurement techniques of Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS). The authors have shown that InSAR and GNSS observations over a time period of three months after the earthquake combined with Coulomb Stress Change Modelling can explain the fault zone expansion, as well as the deformation of the northern region of the NAF. It was also found that there is a strong agreement between the InSAR and GNSS results for the post-seismic phases of investigation, with differences less than 2mm, and the standard deviation of the differences is less than 1mm.

The Stress Triggering of Aftershocks by Badong M5.1 Mainshock from Coulomb Stress Changes

2014 ◽  
Vol 971-973 ◽  
pp. 2172-2175
Author(s):  
Dong Ning Lei ◽  
Jian Chao Wu ◽  
Yong Jian Cai
Keyword(s):  
Stress Change ◽  
Coulomb Stress ◽  
Coulomb Stress Change ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
Stress Triggering

TheCoulomb stress changes are usually adopted to make analysis on faultinteractions and stress triggering. This paper mainly deals with Coulomb stresschange of mainshock and affect on aftershocks. We preliminarily conclude thatthe mainshock produce Coulomb stress change on aftershocks most behavingpositive and triggered them. By calculating it is obvious that more aftershocksfell into stress increasing area and triggering percentage is up to ninety ofmaximum and seventy-one of minimum.

An Evaluation of Coulomb Stress Changes from Earthquake Productivity Variations in the Western Gulf of Corinth, Greece

2015 ◽  
Vol 173 (1) ◽  
pp. 49-72 ◽  
Author(s):  
K. M. Leptokaropoulos ◽  
E. E. Papadimitriou ◽  
B. Orlecka–Sikora ◽  
V. G. Karakostas
Keyword(s):  
Coulomb Stress ◽  
Coulomb Stress Changes ◽  
Gulf Of Corinth ◽  
Stress Changes
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