scholarly journals Foreshocks explained by cascades of triggered seismicity

2003 ◽  
Vol 108 (B10) ◽  
Author(s):  
Agnès Helmstetter ◽  
Didier Sornette
Keyword(s):  
Triggered Seismicity

Seasonal trends of reservoir-triggered seismicity in Song Tranh 2 reservoir, Vietnam

2021 ◽  
Author(s):  
Grzegorz Lizurek ◽  
Konstantinos Leptokaropoulos ◽  
Jan Wiszniowski ◽  
Izabela Nowaczyńska ◽  
Nguyen Van Giang ◽  
...  
Keyword(s):  
Water Level ◽  
Pore Pressure ◽  
Seismic Activity ◽  
Water Level Fluctuations ◽  
Response Type ◽  
Seasonal Trends ◽  
Triggered Seismicity ◽  
Stress Orientation ◽  
Water Level Changes ◽  
Pressure Changes

<p>Reservoir-triggered seismicity (RTS) is the longest known anthropogenic seismicity type. It has the potential to generate seismic events of M6 and bigger. Previous studies of this phenomenon have proved that major events are triggered on preexisting major discontinuities, forced to slip by stress changes induced by water level fluctuations and/or pore-pressure changes in the rock mass in the vicinity of reservoirs. Song Tranh 2 is an artificial water reservoir located in Central Vietnam. Its main goal is back up the water for hydropower plant. High seismic activity has been observed in this area since the reservoir was first filled in 2011. The relation between water level and seismic activity in the Song Tranh area is complex, and the lack of clear correlation between water level and seismic activity has led to the conclusion that ongoing STR2 seismic activity is an example of the delayed response type of RTS. However, the first phase of the activity observed after impoundment has been deemed a rapid response type. In this work, we proved that the seismicity recorded between 2013 and 2016 manifested seasonal trends related to water level changes during wet and dry seasons. The response of activity and its delay with respect to water level changes suggest that the main triggering factor is pore pressure change due to the significant water level changes observed. A stress orientation difference between low and high water periods is also revealed. The findings indicate that water load and related pore pressure changes influence seismic activity and stress orientation in this area.</p><p>This work was partially supported by research project no. 2017/27/B/ST10/01267, funded by the National Science Centre, Poland, under agreement no. UMO-2017/27/B/ST10/01267.</p>

A numerical study of the mechanism of injection-induced and triggered seismicity at the Pohang Enhanced Geothermal Systems project, South Korea

2021 ◽  
Author(s):  
Kwang-Il Kim ◽  
Hwajung Yoo ◽  
Seheok Park ◽  
Juhyi Yim ◽  
Linmao Xie ◽  
...  
Keyword(s):  
South Korea ◽  
Numerical Study ◽  
Geothermal System ◽  
Enhanced Geothermal Systems ◽  
Hydraulic Stimulation ◽  
Triggered Seismicity ◽  
Induced Stress ◽  
Shear Slip ◽  
Stress Dependent ◽  
The Impact

<p>Hydraulic stimulation for the creation of an Enhanced Geothermal System (EGS) reservoir could potentially reactivate a nearby fault and result in man-made earthquakes. In November 15, 2017, an M<sub>w</sub> 5.5 earthquake, the second largest after the initiation of the South Korean national instrumental monitoring system, occurred near an EGS project in Pohang, South Korea. The earthquake occurred on a previously unmapped fault, that is here denoted the M<sub>w</sub> 5.5 Fault. A number of previous studies to model the hydraulic stimulation in the Pohang EGS project have been carried out to identify the mechanism of seismic events. Those previous studies focused on coupled hydro-mechanical processes without the consideration of pre-existing fractures and thermal effects. This study presents an investigation of the mechanisms of induced and triggered seismicity in the Pohang EGS project through three-dimensional coupled thermo-hydro-mechanical numerical simulations. Fractures intersecting the open-hole sections of two deep boreholes, PX-1 and PX-2, clearly indicated by field observations are modeled along with the M<sub>w</sub> 5.5 Fault. Models of stress-dependent permeability models are calibrated based on the numerical reproduction of the pressure-time evolution during the field hydraulic stimulations. The Coulomb failure stress change at the M<sub>w</sub> 5.5 Fault is calculated to quantify the impact of five hydraulic stimulations. In the case of PX-2 stimulations, the pore pressure buildup results in a volumetric expansion of the reservoir and thereby the perturbation of stresses is transferred to the M<sub>w</sub> 5.5 Fault. The volumetric contraction of the reservoir by the temperature reduction could slightly perturb the stress distribution at the M<sub>w</sub> 5.5 Fault. In the case of PX-1 stimulations, shear slip of the PX-1 fracture is explicitly modeled. The modeling shows that transfer of the shear stress drop by the shear slip stabilizes the M<sub>w</sub> 5.5 Fault, which is consistent with the field observation that the seismicity was not induced at the M<sub>w</sub> 5.5 Fault by the PX-1 stimulations. The cooling-induced thermal stress additionally reduces the effective normal stress of PX-1 fracture. Thus, some additional shear slip of the PX-1 fracture is induced by the thermal effect. However, the modeling shows that for both PX-1 and PX-2 stimulations, thermally-induced stress perturbations are very small compared to pressure-induced stress perturbations.</p>

scholarly journals Remote triggered seismicity caused by the 2011, M9.0 Tohoku-Oki, Japan earthquake

2012 ◽  
Vol 39 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Hector Gonzalez-Huizar ◽  
Aaron A. Velasco ◽  
Zhigang Peng ◽  
Raul R. Castro
Keyword(s):  
Triggered Seismicity

Annual modulation of triggered seismicity following the 1992 Landers earthquake in California

Nature ◽  
2000 ◽  
Vol 406 (6795) ◽  
pp. 500-504 ◽  
Author(s):  
Stephen S. Gao ◽  
Paul G. Silver ◽  
Alan T. Linde ◽  
I. Selwyn Sacks
Keyword(s):  
Annual Modulation ◽  
Landers Earthquake ◽  
Triggered Seismicity ◽  
1992 Landers Earthquake

Location of the pilot borehole for investigations of reservoir triggered seismicity at Koyna, India

2017 ◽  
Vol 42 ◽  
pp. 133-139 ◽  
Author(s):  
Harsh K. Gupta ◽  
D. Shashidhar ◽  
C.R. Mahato ◽  
H.V.S. Satyanarayana ◽  
K. Mallika ◽  
...  
Keyword(s):  
Triggered Seismicity

Aftershocks series monitoring of the September 18, 2004 M=4.6 earthquake at the western Pyrenees: A case of reservoir-triggered seismicity?

2006 ◽  
Vol 424 (3-4) ◽  
pp. 223-243 ◽  
Author(s):  
M. Ruiz ◽  
O. Gaspà ◽  
J. Gallart ◽  
J. Díaz ◽  
J.A. Pulgar ◽  
...  
Keyword(s):  
Triggered Seismicity ◽  
Western Pyrenees
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