How Do Statistical Parameters of Induced Seismicity Correlate with Fluid Injection? Case of Oklahoma

2021 ◽  
Author(s):  
Hideo Aochi ◽  
Julie Maury ◽  
Thomas Le Guenan
Keyword(s):  
Induced Seismicity ◽  
Aftershock Sequence ◽  
Statistical Parameters ◽  
Exponential Equation ◽  
Seismicity Rate ◽  
Epidemic Type Aftershock Sequence ◽  
Background Seismicity ◽  
Mechanical Interpretation ◽  
Independent Variable ◽  
Grid Points

Abstract The seismicity evolution in Oklahoma between 2010 and 2018 is analyzed systematically using an epidemic-type aftershock sequence model. To retrieve the nonstationary seismicity component, we systematically use a moving window of 200 events, each within a radius of 20 km at grid points spaced every 0.2°. Fifty-three areas in total are selected for our analysis. The evolution of the background seismicity rate μ is successfully retrieved toward its peak at the end of 2014 and during 2015, whereas the triggering parameter K is stable, slightly decreasing when the seismicity is activated. Consequently, the ratio of μ to the observed seismicity rate is not stationary. The acceleration of μ can be fit with an exponential equation relating μ to the normalized injected volume. After the peak, the attenuation phase can be fit with an exponential equation with time since peak as the independent variable. As a result, the evolution of induced seismicity can be followed statistically after it begins. The turning points, such as activation of the seismicity and timing of the peak, are difficult to identify solely from this statistical analysis and require a subsequent mechanical interpretation.

Point process modelling of reservoir-induced seismicity

2001 ◽  
Vol 38 (A) ◽  
pp. 232-242 ◽  
Author(s):  
Masajiro Imoto
Keyword(s):  
Point Process ◽  
Induced Seismicity ◽  
Earthquake Hazard ◽  
Information Criterion ◽  
Aftershock Sequence ◽  
Water Levels ◽  
Tectonic Activity ◽  
Reservoir Induced Seismicity ◽  
Epidemic Type Aftershock Sequence ◽  
Background Seismicity

A point process procedure can be used to study reservoir-induced seismicity (RIS), in which the intensity function representing earthquake hazard is a combination of three terms: a constant background term, an ETAS (epidemic-type aftershock sequence) term for aftershocks, and a time function derived from observation of water levels of a reservoir. This paper presents the results of such a study of the seismicity in the vicinity of the Tarbela reservoir in Pakistan. Making allowance for changes in detection capability and the background seismicity related to tectonic activity, earthquakes of magnitude ≥ 2.0, occurring between May 1978 and January 1982 and whose epicentres were within 100 km of the reservoir, were used in this analysis. Several different intensities were compared via their Akaike information criterion (AIC) values relative to those of a Poisson process. The results demonstrate that the seismicity within 20 km of the reservoir correlates with water levels of the reservoir, namely, active periods occur about 250 days after the appearance of low water levels. This suggests that unloading the reservoir activates the seismicity beneath it. Seasonal variations of the seismicity in an area up to 100 km from the reservoir were also found, but these could not be adequately interpreted by an appropriate RIS mechanism.

Point process modelling of reservoir-induced seismicity

2001 ◽  
Vol 38 (A) ◽  
pp. 232-242
Author(s):  
Masajiro Imoto
Keyword(s):  
Point Process ◽  
Induced Seismicity ◽  
Earthquake Hazard ◽  
Information Criterion ◽  
Aftershock Sequence ◽  
Water Levels ◽  
Tectonic Activity ◽  
Reservoir Induced Seismicity ◽  
Epidemic Type Aftershock Sequence ◽  
Background Seismicity

A point process procedure can be used to study reservoir-induced seismicity (RIS), in which the intensity function representing earthquake hazard is a combination of three terms: a constant background term, an ETAS (epidemic-type aftershock sequence) term for aftershocks, and a time function derived from observation of water levels of a reservoir. This paper presents the results of such a study of the seismicity in the vicinity of the Tarbela reservoir in Pakistan. Making allowance for changes in detection capability and the background seismicity related to tectonic activity, earthquakes of magnitude ≥ 2.0, occurring between May 1978 and January 1982 and whose epicentres were within 100 km of the reservoir, were used in this analysis. Several different intensities were compared via their Akaike information criterion (AIC) values relative to those of a Poisson process. The results demonstrate that the seismicity within 20 km of the reservoir correlates with water levels of the reservoir, namely, active periods occur about 250 days after the appearance of low water levels. This suggests that unloading the reservoir activates the seismicity beneath it. Seasonal variations of the seismicity in an area up to 100 km from the reservoir were also found, but these could not be adequately interpreted by an appropriate RIS mechanism.

Maximum Earthquake Size and Seismicity Rate from an ETAS Model with Slip Budget

2020 ◽  
Vol 110 (2) ◽  
pp. 874-885
Author(s):  
David Marsan ◽  
Yen Joe Tan
Keyword(s):  
Seismic Moment ◽  
Aftershock Sequence ◽  
Physical Parameters ◽  
Model Parameters ◽  
Seismicity Rate ◽  
Omori Law ◽  
Epidemic Type Aftershock Sequence ◽  
Earthquake Size ◽  
Maximum Earthquake ◽  
Seismicity Model

ABSTRACT We define a seismicity model based on (1) the epidemic-type aftershock sequence model that accounts for earthquake clustering, and (2) a closed slip budget at long timescale. This is achieved by not permitting an earthquake to have a seismic moment greater than the current seismic moment deficit. This causes the Gutenberg–Richter law to be modulated by a smooth upper cutoff, the location of which can be predicted from the model parameters. We investigate the various regimes of this model that more particularly include a regime in which the activity does not die off even with a vanishingly small spontaneous (i.e., background) earthquake rate and one that bears strong statistical similarities with repeating earthquake time series. Finally, this model relates the earthquake rate and the geodetic moment rate and, therefore, allows to make sense of this relationship in terms of fundamental empirical law (the Gutenberg–Richter law, the productivity law, and the Omori law) and physical parameters (seismic coupling, tectonic loading rate).

scholarly journals Strong foreshock signal preceding the L'Aquila (Italy) earthquake (<i>M</i><sub>w</sub> 6.3) of 6 April 2009

2010 ◽  
Vol 10 (1) ◽  
pp. 19-24 ◽  
Author(s):  
G. A. Papadopoulos ◽  
M. Charalampakis ◽  
A. Fokaefs ◽  
G. Minadakis
Keyword(s):  
Hanging Wall ◽  
B Value ◽  
Aftershock Sequence ◽  
Earthquake Catalogue ◽  
Seismicity Rate ◽  
Background Seismicity ◽  
Before And After ◽  
Spatially Distributed ◽  
Drastic Increase ◽  
Seismogenic Area

Abstract. We used the earthquake catalogue of INGV extending from 1 January 2006 to 30 June 2009 to detect significant changes before and after the 6 April 2009 L'Aquila mainshock (Mw=6.3) in the seismicity rate, r (events/day), and in b-value. The statistical z-test and Utsu-test were applied to identify significant changes. From the beginning of 2006 up to the end of October 2008 the activity was relatively stable and remained in the state of background seismicity (r=1.14, b=1.09). From 28 October 2008 up to 26 March 2009, r increased significantly to 2.52 indicating weak foreshock sequence; the b-value did not changed significantly. The weak foreshock sequence was spatially distributed within the entire seismogenic area. In the last 10 days before the mainshock, strong foreshock signal became evident in space (dense epicenter concentration in the hanging-wall of the Paganica fault), in time (drastic increase of r to 21.70 events/day) and in size (b-value dropped significantly to 0.68). The significantly high seismicity rate and the low b-value in the entire foreshock sequence make a substantial difference from the background seismicity. Also, the b-value of the strong foreshock stage (last 10 days before mainshock) was significantly lower than that in the aftershock sequence. Our results indicate the important value of the foreshock sequences for the prediction of the mainshock.

Comparison of the seismicity evolution during the 2000 and 2003 stimulations at Soultz-sous-Forêts.

2021 ◽  
Author(s):  
Julie Maury ◽  
Hideo Aochi
Keyword(s):  
Stress Transfer ◽  
Aftershock Sequence ◽  
Operational Parameters ◽  
Hydraulic Stimulation ◽  
Background Rate ◽  
Seismicity Rate ◽  
Wellhead Pressure ◽  
Existing Structures ◽  
Background Seismicity ◽  
Two Peaks

&lt;p&gt;The research site of Soultz-sous-For&amp;#234;ts (Alsace, France) was a pioneer pilot geothermal site in Europe. In this study, we use the available data from 2000 and 2003 hydraulic stimulation tests to analyze the seismicity evolution. We apply the ETAS (Epidemic-Type Aftershock Sequence) model to extract the background seismicity rate during the two stimulation periods.&lt;/p&gt;&lt;p&gt;For the 2003 sequence, to retrieve the nonstationary seismicity component, we use a moving window of 400 events for the whole catalog. The evolution of the background seismicity rate &amp;#956; is successfully retrieved with an evolution in two peaks coherent with the wellhead pressure evolution, while the triggering parameter &amp;#922; is stable. At the end of the stimulation &amp;#956; decrease significantly. Then we look at the evolution of ETAS parameter by selecting five clusters of seismicity. The evolution of &amp;#956; for each cluster is in agreement with a propagation of the pressure away from the well with the cluster closer to the well showing one early peak only, the middle clusters showing two peaks and the far cluster showing a later peak. All clusters show a decrease of &amp;#956; at the end of stimulation.&lt;/p&gt;&lt;p&gt;For the 2000 sequence, the background seismicity rate is less well constrained but it stays globally constant during the stimulation with some decrease after its end. We see no clear peak in &amp;#956; as was present during 2003 and K is relatively low. However, &amp;#956; also decreases at the end of the stimulation. The selection of clusters does not change this global behavior and all clusters present grossly the same characteristics.&lt;/p&gt;&lt;p&gt;Our results are in agreement with the different characteristics observed by several authors (e.g. Calo and Dorbath, 2013; Dorbath et al, 2009) between these two stimulations. On one hand, the 2003 stimulation consists in an activation of several existing structures that yields a seismicity well explained by the ETAS model with a combined effect of Coulomb stress transfer and perturbation induced by the stimulation (e.g. pore pressure variation).&amp;#160; The evolution in space is also coherent with the finding of Calo and Dorbath (2013) that the injected water goes far from the well avoiding increase in effective stress near the well. In this case, background seismicity rate can be related to the measured pressure. On the other hand, the 2000 stimulation developed a 3D reservoir with the creation of a fresh shear zone (Cornet et al, 2015) and so the direct effects of the stimulation are dominants. However, no clear relation between the background seismicity rate and the operational parameters can be observed. At the end of stimulation, we observe a decrease of background rate corresponding to a progressive return to a natural background rate, similar to what is observed in other settings (Oklahoma, Rousse).&lt;/p&gt;

Background Seismicity before and after the 1976 Ms 7.8 Tangshan Earthquake: Is Its Aftershock Sequence Still Continuing?

2020 ◽  
Author(s):  
Yue Liu ◽  
Jiancang Zhuang ◽  
Changsheng Jiang
Keyword(s):  
Aftershock Sequence ◽  
Tangshan Earthquake ◽  
Aftershock Activity ◽  
Background Rate ◽  
Epidemic Type Aftershock Sequence ◽  
Aftershock Sequences ◽  
Background Seismicity ◽  
Before And After ◽  
Large Earthquakes ◽  
Current Stage

Abstract The aftershock zone of the 1976 Ms 7.8 Tangshan, China, earthquake remains seismically active, experiencing moderate events such as the 5 December 2019 Ms 4.5 Fengnan event. It is still debated whether aftershock sequences following large earthquakes in low-seismicity continental regions can persist for several centuries. To understand the current stage of the Tangshan aftershock sequence, we analyze the sequence record and separate background seismicity from the triggering effect using a finite-source epidemic-type aftershock sequence model. Our results show that the background rate notably decreases after the mainshock. The estimated probability that the most recent 5 December 2019 Ms 4.5 Fengnan District, Tangshan, earthquake is a background event is 50.6%. This indicates that the contemporary seismicity in the Tangshan aftershock zone can be characterized as a transition from aftershock activity to background seismicity. Although the aftershock sequence is still active in the Tangshan region, it is overridden by background seismicity.

scholarly journals Weighted complex networks applied to seismicity: the Itoiz dam (Northern Spain)

2011 ◽  
Vol 18 (4) ◽  
pp. 477-487 ◽  
Author(s):  
A. Jiménez ◽  
F. Luzón
Keyword(s):  
Complex Networks ◽  
Induced Seismicity ◽  
Aftershock Sequence ◽  
Northern Spain ◽  
Topological Features ◽  
Epidemic Type Aftershock Sequence ◽  
Main Shocks ◽  
Random Models ◽  
Seismic Clusters ◽  
Weighted Complex Networks

Abstract. On 18 September 2004, an earthquake of magnitude mbLg = 4.6 was recorded near the Itoiz dam (Northern Spain). It occurred after the first impoundment of the reservoir and has been catalogued by some authors as induced seismicity. We analyzed the seismicity in the region as weighted complex networks and tried to differentiate this event from others that occurred nearby. We calculated the main topological features of the networks formed by the seismic clusters and compared them. We compared the results with a series of simulations, and showed that the clusters were better modelled with the Epidemic-Type Aftershock Sequence (ETAS) model than with random models. We found that the properties of the different clusters are grouped according to the magnitude of the main shocks and the number of events in each cluster, and that no distinct feature could be obtained for the 18 September 2004 series. We found that the nodes with the highest strength are the most important in the networks' traffic, and are associated with the events with the highest magnitude within the clusters.

scholarly journals SEISMICITY CHANGES DETECTION DURING THE SEISMIC SEQUENCES EVOLUTION AS EVIDENCE OF STRESS CHANGES

2017 ◽  
Vol 43 (4) ◽  
pp. 1994
Author(s):  
A.C. Astiopoulos ◽  
E. Papadimitriou ◽  
V. Karakostas ◽  
D. Gospodinov ◽  
G. Drakatos
Keyword(s):  
Temporal Distribution ◽  
Aftershock Sequence ◽  
Occurrence Rate ◽  
Generation Process ◽  
Seismicity Rate ◽  
Seismic Sequences ◽  
Epidemic Type Aftershock Sequence ◽  
Stress Changes ◽  
Lefkada Island ◽  
Seismicity Rate Changes

The statistical properties of the aftershock occurrence are among the main issues in investigating the earthquake generation process. Seismicity rate changes during a seismic sequence, which are detected by the application of statistical models, are proved to be precursors of strong events occurring during the seismic excitation. Application of these models provides a tool in assessing the imminent seismic hazard, oftentimes by the estimation of the expected occurrence rate and comparison of the predicted rate with the observed one. The aim of this study is to examine the temporal distribution and especially the occurrence rate variations of aftershocks for two seismic sequences that took place, the first one near Skyros island in 2001 and the second one near Lefkada island in 2003, in order to detect and determine rate changes in connection with the evolution of the seismic activity. Analysis is performed through space–time stochastic models which are developed, based upon both aftershocks clustering studies and specific assumptions. The models applied are the Modified Omori Formula (MOF), the Epidemic Type Aftershock Sequence (ETAS) and the Restricted Epidemic Type Aftershock Sequence (RETAS). The modelling of seismicity rate changes, during the evolution of the particular seismic sequences, is then attempted in association with and as evidence of static stress changes

scholarly journals Long-term earthquake forecasts based on the epidemic-type aftershock sequence (ETAS) model for short-term clustering

2012 ◽  
Vol 2 (1) ◽  
pp. 8 ◽  
Author(s):  
Jiancang Zhuang
Keyword(s):  
Time Window ◽  
Space Time ◽  
Aftershock Sequence ◽  
Maximum Magnitude ◽  
Short Term ◽  
Magnitude Distribution ◽  
Seismicity Rate ◽  
Distribution Of The Maximum ◽  
Epidemic Type Aftershock Sequence ◽  
Term Clustering

Based on the ETAS (epidemic-type aftershock sequence) model, which is used for describing the features of short-term clustering of earthquake occurrence, this paper presents some theories and techniques related to evaluating the probability distribution of the maximum magnitude in a given space-time window, where the Gutenberg-Richter law for earthquake magnitude distribution cannot be directly applied. It is seen that the distribution of the maximum magnitude in a given space-time volume is determined in the longterm by the background seismicity rate and the magnitude distribution of the largest events in each earthquake cluster. The techniques introduced were applied to the seismicity in the Japan region in the period from 1926 to 2009. It was found that the regions most likely to have big earthquakes are along the Tohoku (northeastern Japan) Arc and the Kuril Arc, both with much higher probabilities than the offshore Nankai and Tokai regions.

scholarly journals A fault and seismicity based composite simulation in northern California

2011 ◽  
Vol 18 (6) ◽  
pp. 955-966 ◽  
Author(s):  
M. B. Yıkılmaz ◽  
E. M. Heien ◽  
D. L. Turcotte ◽  
J. B. Rundle ◽  
L. H. Kellogg
Keyword(s):  
Aftershock Sequence ◽  
Northern California ◽  
Earthquake Simulator ◽  
Epidemic Type Aftershock Sequence ◽  
Main Shocks ◽  
Background Seismicity ◽  
Characteristic Earthquakes ◽  
Recurrence Intervals ◽  
Virtual California ◽  
Frequency Magnitude

Abstract. We generate synthetic catalogs of seismicity in northern California using a composite simulation. The basis of the simulation is the fault based "Virtual California" (VC) earthquake simulator. Back-slip velocities and mean recurrence intervals are specified on model strike-slip faults. A catalog of characteristic earthquakes is generated for a period of 100 000 yr. These earthquakes are predominantly in the range M = 6 to M = 8, but do not follow Gutenberg-Richter (GR) scaling at lower magnitudes. In order to model seismicity on unmapped faults we introduce background seismicity which occurs randomly in time with GR scaling and is spatially associated with the VC model faults. These earthquakes fill in the GR scaling down to M = 4 (the smallest earthquakes modeled). The rate of background seismicity is constrained by the observed rate of occurrence of M > 4 earthquakes in northern California. These earthquakes are then used to drive the BASS (branching aftershock sequence) model of aftershock occurrence. The BASS model is the self-similar limit of the ETAS (epidemic type aftershock sequence) model. Families of aftershocks are generated following each Virtual California and background main shock. In the simulations the rate of occurrence of aftershocks is essentially equal to the rate of occurrence of main shocks in the magnitude range 4 < M < 7. We generate frequency-magnitude and recurrence interval statistics both regionally and fault specific. We compare our modeled rates of seismicity and spatial variability with observations.

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