[1] We analyze the seismicity rate immediately after the 2004 Mw6.0 Parkfield, California, earthquake from nearsource seismograms. By scrutinizing high-frequency signals, we can distinguish mainshock coda from early aftershocks occurring as soon as 30 s after the mainshock. We find, as expected, that a significant fraction of aftershocks in the first few hours after the main shock are missing i...

[1] We analyze the early aftershock activity of the 2004 mid-Niigata earthquake, using both earthquake catalog data and continuous waveform recordings. The frequencymagnitude distribution analysis of the Japan Meteorological Agency (JMA) catalog shows that the magnitude of completeness of the aftershocks changes from values around 5.0, immediately after the main shock, to about 1.8, 12 hours la...

[1] To explore aftershock-triggering mechanisms for the 2003 Big Bear, California earthquake sequence, we determined differential travel-times and applied the double-difference technique to relocate these events, which formed three clusters. The main cluster coincides with the 3 km long northwest striking sub-vertical mainshock fault. The other two sub-vertical clusters, located at opposite end...

We present an analytical solution and numerical tests of the epidemic-type aftershock (ETAS) model for aftershocks, which describes foreshocks, aftershocks and mainshocks on the same footing. In this model, each earthquake of magnitude m triggers aftershocks with a rate proportional to 10. The occurrence rate of aftershocks triggered by a single mainshock decreases with the time from the mainsh...

1) quantile points at the selected times, S, corresponding to the expected probability and ± 1 SD (Table 1). The standard error in P rapidly decreases with increasing time after the mainshock due to the inclusion of current data. For example, at S = 1 day after the mainshock, the ± 1 SD range about the generic 1-day interval probability (0.052) is 0.034 to 0.075 (Table 1). Rydelek suggests esti...

[1] The 27 February 2010 Maule, Chile (Mw=8.8) earthquake is one of the best instrumentally observed subduction zone megathrust events. Here we present locations, magnitudes and cumulative equivalent moment of the first 2 months of aftershocks, recorded on a temporary network deployed within 2 weeks of the occurrence of the mainshock. Using automatically-determined onset times and a back projec...

The effect of aftershocks on the fragility single-story masonry structures is investigated using probabilistic seismic demand analysis Finite element models an unreinforced (URM) structure and a confined (CM) are established their response characteristics when subjected to mainshock, aftershock, mainshock-aftershock sequence then comparatively investigated. effects use confining members studied...

An approximation technique is introduced that greatly facilitates the estimation of the Epidemic-Type Aftershock Sequence (ETAS) model introduced by Ogata (1988), which is widely used to describe earthquake catalogs. The proposed approximation greatly simplifies the integral term in the log-likelihood, the computation of which is by far the greatest hurdle in maximum likelihood estimation. The ...

We investigated by means of nonlinear tools the temporal distribution of 1983–2003 seismicity of the Umbria-Marche region, Central Italy, that was struck by a strong event (M=5.8) on 26 September 1997. Information entropy analysis has been performed over the full and the aftershock-depleted catalogue. We analysed the series of the interevent times between successive earthquakes and the series o...