Effective Stress Drop of Earthquake Clusters

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F17%3A10363702" target="_blank" >RIV/00216208:11310/17:10363702 - isvavai.cz</a>

Result on the web

<a href="http://dx.doi.org/10.1785/0120170035" target="_blank" >http://dx.doi.org/10.1785/0120170035</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1785/0120170035" target="_blank" >10.1785/0120170035</a>

Result language

angličtina

Original language name

Effective Stress Drop of Earthquake Clusters

Original language description

The static stress drop is a standard measure of the average decrease of shear stress on a fault during an earthquake. It has been observed that stress drop does not vary significantly with earthquake magnitude and may be regarded as an invariant parameter of the rupture process at different scales. Although typical stress drops of earthquakes range between 1 and 10 MPa, much smaller stress drops in fractions of MPa are reported for slow earthquakes and in some cases also for earthquake swarms. For the latter cases, the effective stress drop was introduced as an alternative parameter that makes use of the cumulative seismic moment and total activated area of the seis-mic cluster. In this article, we test how the effective stress drop is comparable to the static stress drop of a single earthquake rupturing the same fault portion. To this pur-pose, we compare the spatiotemporal evolution of the seismic moment release and analyze the uncertainties of the estimated stress drops. We show that the effective stress drop is only comparable to earthquake stress drops in specific cases. In particu-lar, the effective stress-drop values significantly underestimate the earthquake stress drops in the presence of aseismic deformation. The values are only scale independent if prestress and poststress conditions are uniform in space. Our analysis of data from injection-induced seismicity, natural earthquake swarms, and aftershock sequences shows that in most cases the effective stress-drop estimate is rather stable during the cluster evolution. However, slightly increasing estimates for injection-induced seismicity are indicative for the local forcing of the system. Although the effective stress drops of natural and induced seismicity in geothermal projects range from 0.1 to 3 MPa, those related to fracking in hydrocarbon formations are anomalous low, from 0.08 to 1.8 kPa, which hints to the important role of aseismic deformations.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10505 - Geology

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2017

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Bulletin of the Seismological Society of America

ISSN

0037-1106

e-ISSN

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Volume of the periodical

107

Issue of the periodical within the volume

5

Country of publishing house

US - UNITED STATES

Number of pages

11

Pages from-to

2247-2257

UT code for WoS article

000412920500020

EID of the result in the Scopus database

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