scholarly journals Study on Coulomb Stress Triggering of the April 2015 M7.8 Nepal Earthquake Sequence

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jianchao Wu ◽  
Qing Hu ◽  
Weijie Li ◽  
Dongning Lei
Keyword(s):  
Main Shock ◽  
Earthquake Sequence ◽  
Coulomb Stress ◽  
Coulomb Stress Changes ◽  
Nepal Earthquake ◽  
Rupture Plane ◽  
Stress Changes ◽  
Stress Triggering ◽  
Source Models ◽  
Earthquake Sequences

In April 2015, a M7.8 earthquake occurred less than one month before a M7.3 earthquake near Kodari, Nepal. The Nepal earthquake sequences also include four larger (M > 6) aftershocks. To reveal the interrelation between the main shock and the aftershocks, we check the role of coseismic coulomb stress triggering on aftershocks that follow the M7.8 main shock. Based on the focal mechanisms of the aftershocks and source models of the main shock, the coulomb failure stress changes on both of the focal mechanism nodal planes are calculated. In addition, the coulomb stress changes on the focal sources of each aftershock are also calculated. A large proportion of the M > 6 aftershocks occurred in positive coulomb stress areas triggered by the M7.8 main shock. The secondary triggering effect of the M7.3 aftershock is also found in this paper. More specifically, the M7.3 aftershock promoted failure on the rupture plane of the M6.3 aftershock. Therefore, we may conclude that the majority of larger aftershocks, which accumulated positive coulomb stress changes during the sequence, were promoted or triggered by the main shock failure. It suggests that coulomb stress triggering contributed to the evolution of the Nepal M7.8 earthquake sequence.

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.

scholarly journals Fault interactions in a complex fault system: insight from the 1936–1997 NE Lut earthquake sequence

2020 ◽  
Vol 224 (2) ◽  
pp. 1157-1173
Author(s):  
M Marchandon ◽  
M Vergnolle ◽  
O Cavalié
Keyword(s):  
Fault System ◽  
Coulomb Stress ◽  
Coulomb Stress Changes ◽  
Fault Systems ◽  
Complex Fault ◽  
Stress Changes ◽  
Fault Interactions ◽  
Seismic Deformation ◽  
Earthquake Sequences ◽  
Conjugate Fault

SUMMARY Calculations of Coulomb stress changes have shown that moderate to large earthquakes may increase stress at the location of future earthquakes. Coulomb stress transfers have thus been widely accepted to explain earthquake sequences, especially for sequences occurring within parallel or collinear fault systems. Relating, under this framework, successive earthquakes occurring within more complex fault systems (i.e. conjugate fault system) is more challenging. In this study, we assess which ingredients of the Coulomb stress change theory are decisive for explaining the succession of three large (Mw 7+) earthquakes that occurred on a conjugate fault system in the NE Lut, East Iran, during a 30-yr period. These earthquakes belong to a larger seismic sequence made up of 11 earthquakes (Mw 5.9+) from 1936 to 1997. To reach our goal, we calculate, at each earthquake date, the stress changes generated by the static deformation of the preceding earthquakes, the following post-seismic deformation due to the viscoelastic relaxation of the lithosphere, and the interseismic deformation since 1936. We first show that accurately modelling the source and receiver fault geometry is crucial to precisely estimating Coulomb stress changes. Then we show that 7 out of 10 earthquakes of the NE Lut sequence, considering the uncertainties, are favoured by the previous earthquakes. Furthermore, the last two M7+ earthquakes of the sequence (1979 and 1997) have mainly been favoured by the moderate Mw ∼ 6 earthquakes. Finally, we investigate the link between the Coulomb stress changes due to previous earthquakes and the rupture extension of the next earthquake and show that a correlation does exist for some earthquakes but is not systematic.

Effects of secondary static stress triggering on the spatial distribution of aftershocks, a case study, 2003 Bam earthquake (SE Iran)

2020 ◽  
Author(s):  
Behnam Maleki Asayesh ◽  
Hamid Zafarani ◽  
Mohammad Tatar
Keyword(s):  
Spatial Distribution ◽  
Static Stress ◽  
Coulomb Stress ◽  
Secondary Stress ◽  
Nodal Plane ◽  
Bam Earthquake ◽  
Coulomb Stress Changes ◽  
Main Shocks ◽  
Stress Changes ◽  
Stress Triggering

<p>Immediate after a large earthquake, accurate prediction of spatial and temporal distribution of aftershocks has a great importance for planning search and rescue activities. Currently, the most sophisticated approach to this goal is probabilistic aftershock hazard assessment (PASHA). Spatial distribution of the aftershocks fallowing moderate to large earthquakes correlate well with the imparted stress due to the mainshock. Furthermore the secondary static stress changes caused by smaller events (aftershocks) could have effect on the triggering of aftershocks and should be considered in the calculations. The 26 December 2003 (Mw 6.6) Bam earthquake with more than 26000 causalities is one of the most destructive events in the recorded history of Iran. This earthquake was an interesting event and was investigated in a majority of aspects. Good variable-slip fault model and precise aftershocks data enabled us to impart Coulomb stress changes due to mainshock and secondary static stress triggering on the nodal planes of aftershocks to learn whether they were brought closer to failure.</p><p>We used recently published high-quality focal mechanisms and hypocenters to reassess the role of small to moderate earthquakes for static stress triggering of aftershocks during the Bam earthquake. By imparting Coulomb stress changes due to the mainshock on the nodal planes of the 158 aftershocks we showed that 77.8% (123 from 158) of the aftershocks received positive stress changes at least in one nodal plane. We also calculated Coulomb stress changes imparted by the mainshock and aftershocks (1≤M≤4.1) onto subsequent aftershocks nodal planes and found that 81.6% (129 of 158) of aftershocks received positive stress changes at least in one nodal plane. In summary, 77.8% of aftershocks are encouraged by the main shocks, while adding secondary stress encourages 81.6%. Therefore, by adding secondary stress the Coulomb Index (CI), the fraction of events that received net positive Coulomb stress changes compared to the total number of events, increased from 0.778 to 0.816.</p>

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

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