The trifurcation area of the San Jacinto fault zone has produced more than 10% of all earthquakes in southern California since 2000, including the June 2016 Mw (moment magnitude) 5.2 Borrego Springs earthquake. In this area, the fault splits into three subparallel strands and is associated with broad VP /VS anomalies. We synthesize spatiotemporal properties of historical background seismicity a...

The observation of foreshocks preceding large earthquakes and the suggestion that foreshocks have specific properties that may be used to distinguish them from other earthquakes have raised the hope that large earthquakes may be predictable. Among proposed anomalous properties are the larger proportion than normal of large versus small foreshocks, the power law acceleration of seismicity rate a...

Earthquakes are usually clustered in both time and space and, within each cluster, the event of highest magnitude is conventionally identified as mainshock, while foreshocks aftershocks events that occur before after it, respectively. Mainshocks earthquakes considered classical formulation probabilistic seismic hazard analysis (PSHA), where contribution neglected. In fact, it has been shown pos...

S U M M A R Y The arrival pattern (AP) method and teleseismic data have been used to relocate aftershocks following three major (M w >= 7.8) interplate earthquakes that occurred in eastern Papua New Guinea in 2000 November. The first event was an M w = 8.0 strike-slip earthquake that ruptured the Weitin fault over a length of ∼100 km. No aftershocks were located in the upper 15 km, suggesting t...

[1] We study stress levels and radiated energy to infer the rupture characteristics and scaling relationships of aftershocks and other southern California earthquakes. We use empirical Green functions to obtain source time functions for 47 of the larger (M 4.0) aftershocks of the 1994 Northridge, California earthquake (M6.7). We estimate static and dynamic stress drops from the source time func...

Estimates of the tectonic stress state including loading rate and magnitude of background stress are derived from the spatial and temporal distribution of Loma Prieta aftershocks. This technique was previously applied to the Landers aftershock sequence Gross and Kisslinger, 1997] and is based upon the seismicity model of Dieterich 1994]. Dieterich's theory suggests that background seismicity sh...

Megathrust earthquakes rupture a broad zone of the subducting plate interface in both along-strike and along-dip directions. The along-dip rupture characteristics of megathrust events, e.g., their slip and energy radiation distribution, reflect depth-varying frictional properties of the slab interface. Here, we report high-resolution frequency-dependent seismic radiation of the four largest meg...

Because seismic activity within mid-continents is usually much lower than that along plate boundary zones, even small earthquakes can cause widespread concerns, especially when these events occur in the source regions of previous large earthquakes. However, these small earthquakes may be just aftershocks that continue for decades or even longer. The recent seismicity in the Tangshan region in N...

We use time-domain pulse widths to estimate static stress drops for 279 M L 2.5 to 4.0 aftershocks of the 17 January 1994, M w 6.7 Northridge, California, earthquake. The stress drops obtained range from 0.02 to 40 bars, with a log average of 0.75 bar. Error bars computed for our estimates are typically a factor of 5, indicating that the three order of magnitude scatter in stress drops is not s...