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Title: Delayed Seismicity Rate Changes Controlled by Static Stress Transfer

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1399758
Report Number(s):
LLNL-PROC-739403
Journal ID: ISSN 2169-9313
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Conference: Presented at: Earthquake Triggering and Nucleation, Cargese, France, France, Oct 02 - Oct 06, 2017
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Kroll, K A, Richards-Dinger, K B, Dieterich, J H, and Cochran, E S. Delayed Seismicity Rate Changes Controlled by Static Stress Transfer. United States: N. p., 2017. Web. doi:10.1002/2017JB014227.
Kroll, K A, Richards-Dinger, K B, Dieterich, J H, & Cochran, E S. Delayed Seismicity Rate Changes Controlled by Static Stress Transfer. United States. doi:10.1002/2017JB014227.
Kroll, K A, Richards-Dinger, K B, Dieterich, J H, and Cochran, E S. 2017. "Delayed Seismicity Rate Changes Controlled by Static Stress Transfer". United States. doi:10.1002/2017JB014227. https://www.osti.gov/servlets/purl/1399758.
@article{osti_1399758,
title = {Delayed Seismicity Rate Changes Controlled by Static Stress Transfer},
author = {Kroll, K A and Richards-Dinger, K B and Dieterich, J H and Cochran, E S},
abstractNote = {},
doi = {10.1002/2017JB014227},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Conference:
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  • The US Bureau of Mines conducts research at the Galena Mine, Wallace, ID, with the aim of mitigating the effects of rock bursting. Destress blasting is commonly used as a stress control technique at the mine. A digital seismic array and an array of borehole pressure cells (BPC's) had been installed near the site of a slope undergoing mining and periodic destressing. The instrumentation was being monitored at the time of a destress blast of the 46-99 slope. No significant seismic events occurred coincident with the destress. However, the destress was followed by a 2 1/2-week period of increased seismicmore » activity, including two damaging events on February 7, 1990, at 034500 (hour, minute, and second) and 122020 Pacific standard time. BPC measurements indicated coseismic ground pressure changes on the order of 200 to 300 kPa associated with the damaging events. Fault plane solutions and dislocation models established that stress changes induced by the event at 034500 may have been significant in promoting the occurrence of the event of 122020. Theoretical investigations suggest that applying knowledge of the existing field, an understanding of rock burst mechanics, and fracture mechanics principles can improve destress effectiveness.« less
  • Destress blasting is commonly used as a stress control technique at the Galena Mine, Wallace, Idaho, where the U.S. Bureau of Mines maintains a cooperative research program with the mine operators (ASARCO). A digital seismic array and an array of borehole pressure cells (BPC's) had been installed near the site of a stope undergoing mining and periodic destressing. Fault plane solutions and dislocation models established that stress changes induced by the event at 034500 PST on February 7, may have been significant in promoting the occurrence of the event at 122020 PST the same day. Theoretical investigations suggest that destressmore » effectiveness can be improved by applying knowledge of the existing stress field, an understanding of rock burst mechanics, and fracture mechanics principles to the design of the destress.« less
  • Seismicity accompanying hydraulic injections into granitic rock is often diffuse rather than falling along a single plane. This diffuse zone of seismicity cannot be attributed to systematic errors in locations of the events. It has often been asserted that seismicity occurs along preexisting joints in the rock that are favorably aligned with the stress field so that slip can occur along them when effective stress is reduced by increasing pore fluid pressure. A new scheme for determining orientations and locations of planes along which the microearthquakes occurred was recently developed. The basic assumption of the method, called the three pointmore » method, is that many of the events fall along well defined planes; these planes are often difficult to identify visually in the data because planes of many orientations are present. The method has been applied to four hydraulic fracturing experiments conducted at Fenton Hill as part of a hot dry rock geothermal energy project. While multiple planes are found for each experiment; one plane is common to all experiments. The ratio of shear to normal stress along planes of all orientations is calculated using a best estimate of the current stress state at Fenton Hill. The plane common to all experiments has the highest ratio of shear to normal stress acting along it, so it is the plane most likely to slip. The other planes found by the three point method all have orientations with respect to current principal stresses that are favorable for slip to occur along preexisting planes of weakness. These results are consistent with the assertion that the rock contains pre-existing joints which slip when the effective stress is reduced by the increased pore fluid pressure accompanying the hydraulic injection. Microearthquakes occur along those planes that are favorably aligned with respect to the current stress field.« less
  • No abstract prepared.