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A recent dramatic increase in seismicity in the midwestern United States may be related to increases in deep wastewater injection. Here, we demonstrate that areas with suspected anthropogenic earthquakes are also more susceptible to earthquake-triggering from natural transient stresses generated by the seismic waves of large remote earthquakes. Enhanced triggering susceptibility suggests the presence of critically loaded faults and potentially high fluid pressures. Sensitivity to remote triggering is most clearly seen in sites with a long delay between the start of injection and the onset of seismicity and in regions that went on to host moderate magnitude earthquakes within 6 to 20 months. Triggering in induced seismic zones could therefore be an indicator that fluid injection has brought the fault system to a critical state. [ABSTRACT FROM AUTHOR]

Advances in observational, laboratory, and modeling techniques open the way to the development of physical models of the seismic cycle with potentially predictive power. To explore that possibility, we developed an integrative and fully dynamic model of the Parkfield segment of the San Andreas Fault. The model succeeds in reproducing a realistic earthquake sequence of irregular moment magnitude (Mw) 6.0 main shocks—including events similar to the ones in 1966 and 2004—and provides an excellent match for the detailed interseismic, coseismic, and postseismic observations collected along this fault during the most recent earthquake cycle. Such calibrated physical models provide new ways to assess seismic hazards and forecast seismicity response to perturbations of natural or anthropogenic origins. [ABSTRACT FROM AUTHOR]

This article discusses how research facilitating the increased understanding of slow earthquakes may provide a more complete understanding of the processes associated with ordinary earthquakes. The term slow earthquake encompasses a number of phenomena, including slow-slip events and very-low-frequency earthquakes. Slow earthquakes are typically accompanied by deep tremor and occur as shear slip events of tectonic plates. These tremors can be sensitive to small variations in geophysical stress, as they have been triggered by lunar tides. Monitoring of tremor phenomena via seismic stations is discussed, and peculiarities associated with the San Andreas Fault are elucidated.

The article reports on a study which analyzes the aerial photograph of the Mw 7.6 Kashmir earthquake that struck northern Pakistan on October 8, 2005. The authors of the study note that the rupture broke through the surface. The displacement was evident in Advanced Spaceborne Thermal Emission and Reflection Radiometer images of the region that were taken a week after the event. The rupture surface was confined to a strip a few hundred meters wide in which horizontal slip along the faults measured ∼4 m on average. The authors point out that because of the shallow compact of the earthquake, it can cause intense but localized destruction.