Although most evidence suggests that the 28 June 1992 M 7.3 Landers earthquake ruptured unilaterally north, significant surface rupture was mapped on the Eureka Peak and Burnt Mountain faults, to the south of the Landers epicenter. An eyewitness account reports that surface rupture occurred on the northern Eureka Peak fault within approximately 35 sec of the mainshock initiation. Array analysis...

The observed seismicity rate increase after large earthquakes in sites that are located several source lengths away from the mainshock centroid poses a major problem. This is because the static stress change induced by a mainshock in that region seems to be insignificant, and the dynamic stress changes can only enhance the seismicity during the passage of the seismic waves but not at later time...

1, Path calibration using the aftershock The calibration is obtained by convolving the mainshock data with the 1D synthetic of the aftershock and then deconvolving with the data of the aftershock. We have applied a 1Hz low-pass filter to the calibrated data because the effect of 3D slab structure in the source region cannot be ignored at higher frequency (>1Hz) (Fig.S1). The mechanism of the af...

[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...

This report addresses the broad role of aftershocks in the Performance-based Earthquake Engineering (PBEE) process. This is an area which has, to date, not received careful scrutiny nor explicit quantitative analysis. We begin by introducing Aftershock Probabilistic Seismic Hazard Analysis (APSHA). APSHA, similar to conventional mainshock PSHA, is a procedure to characterize the timevarying aft...

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...

The inverse Omori law for foreshocks discovered in the 1970s states that the rate of earthquakes prior to a mainshock increases on average as a power law ∝ 1/(tc − t) p ′ of the time to the mainshock occurring at tc. Here, we show that this law results from the direct Omori law for aftershocks describing the power law decay ∼ 1/(t − tc) p of seismicity after an earthquake, provided that any ear...

The (Mw6.1, 7.3, 6.2) 1992 Landers earthquakes began on April 23 with the Mw6.1 1992 Joshua Tree preshock and form the most substantial earthquake sequence to occur in California in the last 40 years. This sequence ruptured almost 100 km of both surficial and concealed faults and caused aftershocks over an area 100 km wide by 180 km long. The faulting was predominantly strike slip and three mai...

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...

The 1999 Mw 7.1 Hector Mine mainshock showed right-lateral strikeslip faulting, with an initial strike of N6 W and vertical dip. The mainshock was preceded within 20 hours by 18 recorded foreshocks of 1.5 M 3.8 within a few kilometers distance of the mainshock hypocenter. The aftershocks delineate how the Hector Mine earthquake ruptured with strike N6 W to the south for a distance of 15 km, and...