Migration of early aftershocks following the 2004 Parkfield earthquake

Peng, Zhigang; Zhao, Peng

doi:10.1038/ngeo697

Cited by 443 publications

(381 citation statements)

References 26 publications

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“…Freed [2005], Ratchkovski et al [2003], and Robinson et al [2006] show that zones of increased stress are spatially heterogeneous along faults with complex geometries or step overs, with higher aftershock activity in step over and branching regions. Studies of aftershock sequences also often show a migration of activity away from the main shock epicenter through time [e.g., Tajima and Kanamori, 1985;Peng and Zhao, 2009].…”

Section: Spatiotemporal Aftershock Behaviormentioning

confidence: 99%

“…[22] The spatiotemporal distribution of aftershock sequences can provide information about stress changes induced by a large main shock [Toda and Matsumura, 2006], aftershock rates and migration patterns [Dieterich, 1994;Helmstetter et al, 2003], postseismic deformation and/or afterslip [Peng and Zhao, 2009], fluid migration [Noir et al, 1997], and other phenomena. Several studies show increased aftershock activity adjacent to areas of high slip and high moment release [e.g., Wald et al, 1995;Thio and Kanamori, 1996;Ma and Chan, 2005].…”

Section: Spatiotemporal Aftershock Behaviormentioning

confidence: 99%

“…However, the limited background seismicity is not sufficient to fully investigate the fault structures. In addition, the aftershock rates and spatiotemporal distribution can provide insights into the stress changes induced by a large main shock [Omori, 1894;King et al, 1994;Toda et al, 2005], aftershock rates and migration patterns [Dieterich, 1994;Helmstetter et al, 2003], and postseismic deformation [Hill et al, 1993;Peng and Zhao, 2009]. Expansion of aftershocks away from the epicenter with time has been observed and may reflect nonuniform (in both space and time) stress changes following an instantaneous stress increase/decrease [Dieterich, 1994;Tajima and Kanamori, 1985] or perhaps post-seismic deformation and afterslip [Perfettini and Avouac, 2004].…”

Section: Introductionmentioning

confidence: 99%

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Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

et al. 2013

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[1] We detect and precisely locate over 9500 aftershocks that occurred in the Yuha Desert region during a 2 month period following the 4 April 2010 M w 7.2 El Mayor-Cucapah (EMC) earthquake. Events are relocated using a series of absolute and relative relocation procedures that include Hypoinverse, Velest, and hypoDD. Location errors are reduced to 40 m horizontally and 120 m vertically. Aftershock locations reveal a complex pattern of faulting with en echelon fault segments trending toward the northwest, approximately parallel to the North American-Pacific plate boundary and en echelon, conjugate features trending to the northeast. The relocated seismicity is highly correlated with published surface mapping of faults that experienced triggered surface slip in response to the EMC main shock. Aftershocks occurred between 2 km and 11 km depths, consistent with previous studies of seismogenic thickness in the region. Three-dimensional analysis reveals individual and intersecting fault planes that are limited in their along-strike length. These fault planes remain distinct structures at depth, indicative of conjugate faulting, and do not appear to coalesce onto a throughgoing fault segment. We observe a complex spatiotemporal migration of aftershocks, with seismicity that jumps between individual fault segments that are active for only a few days to weeks. Aftershock rates are roughly consistent with the expected earthquake production rates of Dieterich (1994). The conjugate pattern of faulting and nonuniform aftershock migration patterns suggest that strain in the Yuha Desert is being accommodated in a complex manner.

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Section: Spatiotemporal Aftershock Behaviormentioning

confidence: 99%

Section: Spatiotemporal Aftershock Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

et al. 2013

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“…First, we cross-correlate the two sources observed at each station, as in template matching approaches (e.g. Nadeau & McEvilly 1999;Ide et al 2007;Shelly et al 2007;Brown et al 2009;Gibbons & Ringdal 2009;Peng & Zhao 2009;Waldhauser & Schaff 2008;Bostock et al 2012). If the second source has the same Green's function as the template, this cross-correlation will eliminate the Green's functions' phases.…”

Section: Introductionmentioning

confidence: 99%

“…Matched filter techniques are often used to search for similar earthquakes within a seismogram, either to relocate the events or to detect small earthquakes (e.g. Nadeau & McEvilly 1999;Gibbons & Ringdal 2009;Peng & Zhao 2009;Waldhauser & Schaff 2008). Cross-correlation methods are also used to identify small low frequency earthquakes that occur repeatedly within tremor Shelly et al 2007;Brown et al 2009;Bostock et al 2012).…”

Section: Introductionmentioning

confidence: 99%

A phase coherence approach to identifying co-located earthquakes and tremor

Hawthorne

Ampuero

2017

Geophys. J. Int.

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S U M M A R YWe present and use a phase coherence approach to identify seismic signals that have similar path effects but different source time functions: co-located earthquakes and tremor. The method used is a phase coherence-based implementation of empirical matched field processing, modified to suit tremor analysis. It works by comparing the frequency-domain phases of waveforms generated by two sources recorded at multiple stations. We first cross-correlate the records of the two sources at a single station. If the sources are co-located, this cross-correlation eliminates the phases of the Green's function. It leaves the relative phases of the source time functions, which should be the same across all stations so long as the spatial extent of the sources are small compared with the seismic wavelength. We therefore search for cross-correlation phases that are consistent across stations as an indication of co-located sources. We also introduce a method to obtain relative locations between the two sources, based on back-projection of interstation phase coherence. We apply this technique to analyse two tremor-like signals that are thought to be composed of a number of earthquakes. First, we analyse a 20 s long seismic precursor to a M 3.9 earthquake in central Alaska. The analysis locates the precursor to within 2 km of the mainshock, and it identifies several bursts of energy-potentially foreshocks or groups of foreshocks-within the precursor. Second, we examine several minutes of volcanic tremor prior to an eruption at Redoubt Volcano. We confirm that the tremor source is located close to repeating earthquakes identified earlier in the tremor sequence. The amplitude of the tremor diminishes about 30 s before the eruption, but the phase coherence results suggest that the tremor may persist at some level through this final interval.

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Imaging the high‐frequency energy radiation process of a main shock and its early aftershock sequence: The case of the 2008 Iwate‐Miyagi Nairiku earthquake, Japan

Sawazaki

Enescu

2014

JGR Solid Earth

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To understand the energy release process that operates at the end of the main shock rupture and start of the aftershock activity, we propose an inversion method that uses continuous high-frequency seismogram envelopes of the main shock and early aftershocks (i.e., events that occur at short times after the main shock). In our approach, the aftershock sequence is regarded as a continuous energy release process, rather than a discrete time series of events. To correct for the contribution of coda wave energy excited by multiple scattering, we use the theoretical envelope synthesized on the basis of the radiative transfer theory as a Green's function. The site amplification factors are corrected considering the conservation of energy flux and using the coda normalization method. The inverted temporal energy release rate for the 2008 M W 6.9 Iwate-Miyagi Nairiku earthquake, Japan, decays following t À1.1, at the lapse time t of 40-900 s after the main shock origin time. This exponent of the decay rate is similar to the p value of the modified Omori law. The amount of estimated energy release is consistent with that calculated from the magnitude listed in the aftershock catalog. Although the uncertainty is large, the location of large energy release at the lapse times of 40-900 s approximately overlaps to that of the aftershocks, which surrounds the large energy release area during the main shock faulting. The maxima of the energy release rate normalized by the average decay rate distributes following a power law, similar to the Gutenberg-Richter law.

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Migration of early aftershocks following the 2004 Parkfield earthquake

Cited by 443 publications

References 26 publications

Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

A phase coherence approach to identifying co-located earthquakes and tremor

Imaging the high‐frequency energy radiation process of a main shock and its early aftershock sequence: The case of the 2008 Iwate‐Miyagi Nairiku earthquake, Japan

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Migration of early aftershocks following the 2004 Parkfield earthquake

Cited by 443 publications

References 26 publications

Aftershocks of the 2010 Mw 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

Aftershocks of the 2010 Mw 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

A phase coherence approach to identifying co-located earthquakes and tremor

Imaging the high‐frequency energy radiation process of a main shock and its early aftershock sequence: The case of the 2008 Iwate‐Miyagi Nairiku earthquake, Japan

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Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California

Aftershocks of the 2010 M_w 7.2 El Mayor‐Cucapah earthquake reveal complex faulting in the Yuha Desert, California