One way to probe earthquake nucleation processes and the relation between stress buildup and seismicity is to analyze the sensitivity of seismicity to stress perturbations. Here, we report evidence for seasonal strain and stress (~2–4 kPa) variations in the Nepal Himalaya, induced by water storage variations which correlate with seasonal variations of seismicity. The seismicity rate is twice as...

In most cases of reservoir-induced seismicity, seismicity follows the impoundment, large lake-level changes, or filling at a later time above the highest water level achieved until then. We classify this as initial seismicity. This ‘‘initial seismicity’’ is ascribable to the coupled poroelastic response of the reservoir to initial filling or water level changes. It is characterized by an increa...

Existing loading protocols for quasi-static cyclic testing of structures are based on recordings from regions of high seismicity. For regions of low to moderate seismicity they overestimate imposed cumulative damage demands. Since structural capacities are a function of demand, existing loading protocols applied to specimens that are representative of structures in low to moderate seismicity re...

A surprising increase in seismicity started in and around Monticello Reservoir, South Carolina in December 1996, and by the end of 1999, over 700 earthquakes with 0.4 ML 2.5 had been located. This seismicity occurred in a new hypocentral region and filled the gaps in earlier seismicity at depths shallower than 2 km. The seismicity occurred in four episodes each with at least one earthquake of m...

Continental intraplate seismicity seems often episodic, clustered, and migrating. The observed seismicity shows both spatial clustering in seismic zones and scattering across large plate interiors, temporal clustering followed by long periods of quiescence, and migration of seismicity from one seismic zone to another. Here, we explore the complex spatiotemporal patterns of intraplate seismicity...

Using the simple ETAS branching model of seismicity, which assumes that each earthquake can trigger other earthquakes, we quantify the role played by the cascade of triggered seismicity in controlling the rate of aftershock decay as well as in the overall level of seismicity in the presence of a constant external seismicity source. We show that, in this model, the proportion of triggered seismi...

In the year 2000, an anomalous sequence of off-fault seismicity was detected near Lake Pillsbury in northern California. The seismicity was interpreted by Hayes et al. (2005, 2006) to be associated with a dike injection. I completed a gravity survey over the location of the seismicity and used that data in gravity modeling, to test the hypothesis that the seismicity was directly linked to the i...

The Mw 7.9 Denali fault earthquake ruptured segments of the Susitna Glacier, Denali, and Totschunda faults in central Alaska, providing a unique opportunity to look for intermediate-term (weeks to months) responses of active volcanoes to shaking from a large earthquake. The Alaska Volcano Observatory (AVO) monitors 24 volcanoes with seismograph networks. We examined one station per volcano. Dig...

Induced seismicity has been observed near Monticello Reservoir, South Carolina, since December 1977. Deployment of a seismic network before impoundment allowed for detection and accurate location of pursuant seismicity since its inception. Corroborative fault-plane solutions, together with geological and borehole data on fracture orientations, made it possible to determine the structures associ...

The standard model of injection-induced seismicity considers changes in Coulomb strength due solely to changes in pore pressure. We consider two additional effects: full poroelastic coupling of stress and pore pressure, and time-dependent earthquake nucleation. We model stress and pore pressure due to specified injection rate in a homogeneous, poroelastic medium. Stress and pore pressure are us...