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...

We analyze the spatial relationship of relocated aftershocks to the principal rupture planes of the Mw 7.3 1992 Landers mainshock from a structural point of view. We find that the aftershocks constitute primarily a several-kilometer-wide damage zone centered on the mainshock rupture planes. The intensity of damage decreases away from the principal faults. Less than half of the aftershocks occur...

The 2016 Ecuador M 7.8 earthquake ruptured the subduction zone boundary between the Nazca plate and the South America plate. This M 7.8 earthquake may have promoted failure in the surrounding crust, where six M ≥ 6 aftershocks occurred following this mainshock. These crustal ruptures were triggered by the high coulomb stress changes produced by the M 7.8 mainshock. Here, we investigate whether ...

The potential locations of aftershocks, which can be large and damaging, are often forecast by calculating where the mainshock increased stress. We find, however, that the mainshock-induced stress field is often rapidly altered by aftershock-induced stresses. We find that the percentage of aftershocks that are secondary aftershocks, or aftershocks triggered by previous aftershocks, increases wi...

We analyzed the most relevant seismic sequences occurred from 1977 to 2007 in the FriuliVenezia Giulia region (northeastern Italy) and western Slovenia. The 8 aftershock sequences were triggered by low to moderate magnitude earthquakes with mainshock duration magnitude ranging from 3.7 to 5.6. The b-value of the Gutenberg-Richter law varies from 0.8 to 1.1. The modified Omori’s modeling of the ...

[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...

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...

[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...

Repeated earthquakes and explosions recorded at the San Andreas fault (SAF) near Parkfield before and after the 2004 M6 Parkfield earthquake show large seismic velocity variations within an approximately 200m-wide zone along the fault to depths of approximately 6 km. The seismic arrays were co-sited in the two experiments and located in the middle of a high-slip part of the surface rupture. Wav...

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...