Reservoir-induced seismicity in the Danjiangkou Reservoir: A quantitative analysis

Abstract

Reservoir-induced seismicity (RIS) was observed, following the impoundment in 1967 of the Danjiangkou Reservoir in Henan and Hubei provinces in central ChinaStarting with low-level seismicity, the magnitude increased with increasing lake levels, thereafter culminating in a damaging M 4.7 earthquake in 1973 NovemberAlthough the lake levels increased, the seismicity decreasedThe spatial and temporal patterns of the RIS show that it was associated with through-going, deep crustal faults, especially in the vicinity of surface exposures of karsts and limestone rocksThere was a systematic increase with time of the calculated hydraulic diffusivity (and hence the permeability) of the fractures associated with pore pressure diffusionIncreases in lake levels over the previous highest levels were directly correlatable with increasing magnitudes of the earthquakes that followed-providing evidence of stress memory in the rocksThe seismicity was associated with increases in diffused pore pressures at hypocentral locations which ranged from < ∼100 to ∼400 kPa for M 1+ to M 4+ events© 2011 The Authors Geophysical Journal International © 2011 RAS.