Slip on normal faults in the Tibetan Plateau contributes to the rift evolution. Piedmont of the Nyainqentanglha Mountains. The rupture plane is about 15km×14km with strike S190°W and dip 55° to NW, located at a secondary fault of the Southeastern W6.3, and the earthquake is dominated by oblique normal and right-lateral slip with a maximum slip of 2.86m at depth of 8km. We model a linear elastic dislocation in a homogeneous half space and use a nonlinearĬonstraint optimized algorithm to estimate the fault location, geometry and slip distribution. Of ~0.3m along the satellite line of sight. Significant coseismic surface deformation occurred within 20km×20km of the epicenter with a maximum displacement W6.3 Damxung earthquake were obtained from interferometric synthetic aperture radar by using three descending and two ascendingĮnvisat images. The cross-correlation coefficients were observed to be relatively stable against frequency for the 0.5–5.0-Hz frequency band.Ĭoseismic deformation fields of the 6 October 2008 M To check the frequency dependence of the cross-correlation coefficient, we analyzed a group of seismograms of a ‘multiplet’ in Xiuyan, Liaoning, northeast China, recorded by the Regional Seismographic Network of Liaoning Province. Simulation shows that in the 0.5–5.0-Hz frequency band, even if for simple synthetic seismograms without considering lateral heterogeneity or scattering, the exponential dependence is only a first order approximation concept.
In this article, using a simple layered structure model, we investigated the cross-correlation coefficient of the filtered synthetic seismograms of two closely located events, that is, a ‘doublet.’ We investigated the relation between the cross-correlation coefficient and the inter-event separation distance. The second is the convention that in processing regional seismograms, a 0.5–5.0-Hz band pass filter is used. The first is the assumption that the cross-correlation coefficient of the filtered seismograms of closely spaced ‘repeaters’ depends exponentially on the inter-event separation distance. Our results imply that previously identified repeaters and associated interpretations/hypotheses may be unreliable and hence need a systematic reexamination.įor the identification and analysis of ‘repeating earthquakes,’ there are two empirical concepts. Quantitatively, we define a repeating pair if their interevent distance is smaller than the rupture area of the larger event. To more reliably identify repeaters, we should rely on the overlap of the source areas. Our results undoubtedly suggest that waveform similarity alone is insufficient for repeater identification. Therefore, higher degree of waveform similarity does not necessarily imply a smaller hypocenter separation, and vice versa. With both synthetic and real data, we find that waveform similarity is controlled by many factors, in addition to interevent distance. The identification of repeaters is usually solely based on waveform similarity, but the criteria can vary significantly from one case to another. They provide important insights into a variety of geophysical subjects such as fault behavior, subsurface structure change, inner core rotation, and nucleation process of earthquakes and landslides.
Instacal repeating events Patch#
Repeating earthquakes (repeaters) are events that occur repeatedly on the same fault patch with the same fault directional motion and similar amount of slip.
These events are of great importance in many aspects of geophysics, such as monitoring subtle temporal changes of crustal properties (e.g., Poupinet et al., 1984 Schaff and Beroza, 2004 Sawazaki et al., 2015 Pacheco et al., 2017) and oceanic temperature (Wu et al., 2020), estimating fault creep (e.g., Nadeau and Johnson, 1998 Uchida et al., 2003Uchida et al.,, 2006Matsubara et al., 2005 Yu, 2013 Materna et al., 2018), investigating inner core rotation (e.g., Li and Richards, 2003 Zhang et al., 2005Zhang et al.,, 2008Tkalčić et al., 2013), evaluating the precision of earthquake locations (e.g., Li and Richards, 2003 Meier et al., 2004 Schaff and Richards, 2011 Jiang et al., 2014), and providing insights into the nucleation process of earthquakes (Kato et al. Repeating earthquakes (repeaters) are events that recurrently rupture the same fault patch with the same focal mechanisms, often characterized by nearly identical waveforms (Uchida and Bürgmann, 2019 Abercrombie et al, 2020 Gao and Kao, 2020 Hatch et al., 2020 Sheng et al., 2021).