(1997) 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.

The potential for reservoir-induced seismicity, which is the triggering of earthquakes by the physical processes that accompany the impoundment of large reservoirs, was recognized during the seismic hazard studies for the original Auburn Dam. It remains an important issue for the present project because of the potential to increase the probability of earthquakes near the dam.

(April 9, 1994) The earthquake that killed 10,000 people in India last September struck within 15 kilometers of a reservoir filled just 2 years earlier. That proximity in time and space seems more than coincidental to two U.S. seismologists who propose that filling the reservoir may have set off the quake.