scholarly journals Analysis of M 5.3 Sumbawa, Indonesia earthquake 2020 and its aftershocks based on hypocenter relocation from BMKG seismic stations

2021 ◽  
Vol 873 (1) ◽  
pp. 012070
Author(s):  
M Ramdhan ◽  
Priyobudi ◽  
A Mursityanto ◽  
K H Palgunadi ◽  
Daryono
Keyword(s):  
Focal Mechanism ◽  
Difference Method ◽  
Fault Plane ◽  
Active Faults ◽  
Disaster Mitigation ◽  
Double Difference ◽  
Seismic Stations ◽  
Hypocenter Relocation ◽  
Splay Faults ◽  
Moderate Magnitude

Abstract The 2020 Sumbawa earthquake of moderate magnitude (M 5.3) produced very significant aftershocks. Based on the computation of Utsu’s method, those aftershocks would be ended after the 20th day. Those earthquakes along 20 days were relocated using double-difference method. The relocation results show the southwest-northeast orientation and getting deeper into the northwest direction. Those two directions show the strike and the dip from the fault plane of the earthquake which was consistent with the focal mechanism released by the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). Those results showed the majority of earthquakes occurred at a depth of shallower than 20 km. Those earthquake depths were fit with the previous study showing the crustal thickness beneath Sumbawa Island that was about 28 km. We also found that those earthquakes occurred at splay faults propagating to decollement structure. This study is beneficial for earthquake disaster mitigation especially in updating active faults on Sumbawa Island.

scholarly journals Analysis of Hypocenter Relocation by Using Double Difference Method in a Deep Underground Mining

2021 ◽  
Vol 873 (1) ◽  
pp. 012099
Author(s):  
Wahyu Hidayat ◽  
David P. Sahara ◽  
Sri Widiyantoro ◽  
I Putu Raditya Ambara Putra ◽  
Nabiel H. Shihab ◽  
...  
Keyword(s):  
Difference Method ◽  
Underground Mining ◽  
Measurement Data ◽  
Underground Mine ◽  
Underground Mines ◽  
Double Difference ◽  
Overburden Thickness ◽  
Deep Underground ◽  
Hypocenter Relocation ◽  
Geological Complexity

Abstract Hypocenter relocation is one of the keys to success in the analysis of seismicity induction in underground mines. Overburden thickness, topography, geological complexity, and mining activities can result in newly induced seismicity that can endanger the safety of underground mine workers. The relatively narrow underground mine area requires the most accurate hypocenter location information possible. The double-difference algorithm approach is one of the keys to overcoming this problem. The double-difference method is a relative location method that tries to minimize the residuals between the observed and calculated travel time differences for pairs of microseismic events at each station, by adjusting the differences between all pairs of events at each station repeatedly. In this study, we utilized microseismic measurement data in the deepest underground mine in Indonesia. A total of 1783 seismic events were successfully relocated. The relocation results show the rock mass stress which is illustrated by the distribution of events around the cave, especially the abutment area and underground mining tunnels.

scholarly journals Relocation and Focal Mechanism of Aftershocks Pidie Jaya Earthquake (Mw6.5) Dec 7th, 2016 using BMKG Network

2017 ◽  
Vol 15 (3) ◽  
pp. 17 ◽  
Author(s):  
Pepen Supendi ◽  
Andri D. Nugraha ◽  
Tony Agus Wijaya
Keyword(s):  
Data Processing ◽  
Focal Mechanism ◽  
Difference Method ◽  
Active Fault ◽  
Strike Slip ◽  
Double Difference ◽  
Mechanism Analysis ◽  
Residual Value ◽  
Focal Mechanism Solutions ◽  
Focus Depth

We have successfully relocated 74 out of 89 aftershocks until December 19, 2016, by using hypocenter double-difference method. We also have conducted focal mechanism analysis to estimate the type of fault slip. The results indicate improvement in hypocenter location, where the initial earthquakes focus depth at a fixed depth of 10 km have been updated and have described the patterns of active fault in the area trending Northwest-Southeast. The validity through the histogram of travel-time residual shows fairly good data processing where the residual value is close to zero (t.obs - t.cal ~ 0). Based on focal mechanism solutions of mainshock and two selected aftershocks, the type of fault is right lateral strike-slip.

scholarly journals Analysis of the Mw 6.5 Ambon Earthquake (September 26, 2019) based on the aftershocks hypocenter relocation

2021 ◽  
Vol 873 (1) ◽  
pp. 012001
Author(s):  
P Supendi ◽  
A D Nugraha ◽  
S Widiyantoro ◽  
C I Abdullah ◽  
Daryono ◽  
...  
Keyword(s):  
Difference Method ◽  
Seismic Network ◽  
Double Difference ◽  
National Authority ◽  
Hypocenter Relocation

Abstract On September 26, 2019, an earthquake (Mw 6.5) occurred in the northern part of Ambon Island, Molucca, East Indonesia. The National Authority show this earthquake caused infrastructures damage and 28 fatalities. Up to October 31, 2019, the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) seismic network had recorded 479 aftershock events. We have relocated 463 out of the 479 aftershocks using the double-difference method. Our results show that some improvements in the hypocenter locations, where the focal depths of initial earthquakes fixed at 10 km have been updated to ~9.8 km depth on average. There are two aftershock clusters in a North-South direction of ~35 km length between Ambon Island and Haruku Island and in a West-East direction of ~30 km length in the Ambon Island, each with a width of ~8 km.

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