Inter event times of fluid induced earthquakes suggest their Poisson nature

Langenbruch, C.; Dinske, C.; Shapiro, Serge A.

doi:10.1029/2011gl049474

Cited by 85 publications

(71 citation statements)

References 17 publications

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“…2. On short time scales, the earthquake occurrence can be approximated by a stationary Poisson process, which is in agreement with the observation that seismicity is usually well described by the superposition of stationary and nonstationary Poisson models accounting for tectonic background activity, Omori-type aftershock occurrences, and transient aseismic forcing (Langenbruch et al, 2011;Zhuang et al, 2012). 3.…”

Section: Theoretical Approachsupporting

confidence: 54%

Rate‐Dependent Incompleteness of Earthquake Catalogs

Hainzl

2016

Seismological Research Letters

122

114

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Important information about the earthquake generation process can be gained from instrumental earthquake catalogs, but this requires complete recordings to avoid biased results. The local completeness magnitude M c is known to depend on general conditions such as the seismographic network and the environmental noise, which generally limit the possibility of detecting small events. The detectability can be additionally reduced by an earthquake-induced increase of the noise level leading to shortterm variations of M c , which cannot be resolved by traditional methods relying on the analysis of the frequency-magnitude distribution. Based on simple assumptions, I propose a new method to estimate such temporal excursions of M c solely based on the estimation of the earthquake rate resulting in a high temporal resolution of M c . The approach is shown to be in agreement with the apparent decrease of the estimated Gutenberg-Richter b-value in high-activity phases of recorded data sets and the observed incompleteness periods after mainshocks. Furthermore, an algorithm to estimate temporal changes of M c is introduced and applied to empirical aftershock and swarm sequences from California and central Europe, indicating that observed b-value fluctuations are often related to rate-dependent incompleteness of the earthquake catalogs.Online Material: MATLAB code to compute rate-dependent completeness magnitude, and figures showing variation in the estimated M c values in equalized time scale.

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Section: Theoretical Approachsupporting

confidence: 54%

Rate‐Dependent Incompleteness of Earthquake Catalogs

Hainzl

2016

Seismological Research Letters

122

114

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“…The latter typically is in the order of a few MPa, even at larger distance from the stimulated wells [ Dorbath et al , 2009, Figure 6]. The study by Langenbruch et al [2011] supports this result by showing that induced seismicity can be described by a Poisson process, i.e. the events are not causally related to each other.…”

Section: Discussionmentioning

confidence: 74%

The role of triggering by static stress transfer during geothermal reservoir stimulation

Schoenball¹,

Baujard²,

Köhl³

et al. 2012

J. Geophys. Res.

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[1] During creation of an Enhanced Geothermal System, massive fluid injections are conducted to induce fracture shear which generates reservoir permeability. In this study we analyze coseismic static stress transfer caused by induced seismic events during a stimulation at the European research project at Soultz-sous-Forêts (Alsace, France). For this purpose we developed an efficient method to calculate coseismic static stress changes from an elliptical slip distribution on a circular fracture using superposition of rectangular sources, which enables us to apply an analytical solution for fast computation. This method is applied on a data set of 715 focal mechanisms derived from seismic recordings of the stimulation of the well GPK2 to calculate temporal evolution of static stress transfer. We find that the resulting structure of coseismic stress changes can be divided into three parts: a quiet zone where no spreading of seismicity occurs, an active zone within the created reservoir with ongoing fracturing and a process zone where the growth of the reservoir occurs. Static stress changes in the active zone are of the order of 1 MPa, both positive and negative, but may exceed this value considerably on a local scale. Analysis of stress changes from a cluster of events that occurred after shut-in lets us conclude that triggering by coseismic static stress changes is possible for some events. Our analysis shows that triggering by static stress transfer plays a minor role for injection induced seismicity in a volumetric reservoir, whereas it can be quite effective for rupture propagation along single large fault zones.Citation: Schoenball, M., C. Baujard, T. Kohl, and L. Dorbath (2012), The role of triggering by static stress transfer during geothermal reservoir stimulation,

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“…Fundamentally, the SI incorporates the volume concentration of preexisting faults and the state of stress (termed the seismotectonic state) ( 14 ). In contrast to the Gutenberg-Richter relation associated with natural earthquake sequences, Eq.…”

Section: Resultsmentioning

confidence: 99%