Groundwater-level Changes Due to Pressure Gradient Induced by Nearby Earthquakes off Izu Peninsula, 1997

Abstract

Anomalous water level changes were observed at two wells associated with seismic swarm activity off Izu Peninsula on March, 1997. These are coseismic water level drops followed by gradual postseismic water level rise at the time of large earthquakes during the swarm activity. The post-seismic water level rises, which can be fitted by an exponential function with a time constant of about six hours, are explained in terms of the horizontal pressure diffusion due to the pressure gradient in the aquifer induced by the coseismic static strain.

The 2006 November,ML= 5.0 earthquake near Lourdes (France): new evidence for NS extension across the Pyrenees

“…Changes in water levels, discharge rates or temperature have been reported following tectonic earthquakes (e.g. Wakita 1975; Mogi et al 1989; Roeloffs 1998; Ohno et al 2006). They have been attributed to various processes such as coseismic static strain changes, rock permeability increases, periodic oscillations due to surface wave propagation and pressure diffusion due to a pressure gradient or increase in a confined aquifer.…”

“…10 shows that anomalies persist beyond the timescale of seismic wave propagation at the site. Pressure diffusion, already evidenced as a post‐seismic process generating hydraulic head variations (Ohno et al 2006) can be ruled out as aquifers are hosted in independent lithologic units such as granites or carbonates. A fourth hypothesis to account for coseismic to post‐seismic hydraulic head changes is a permeability increase due to ground shaking that enhances groundwater flow rates (Rojstaczer & Wolf 1992).…”

Spatial variability of the poroelastic response of the heterogeneous medium

“…Seismic waves from distant earthquakes interacting with aquifers produce changes in pore pressure and a pressure gradient in the aquifer [10]. The changes in water level are attributed to the horizontal pressure diffusion caused by the pressure gradient.…”

Variability quantification of excess pressure head in heterogeneous deformable aquifers

“…However, pore pressure perturbations in response to the geologic loading changes can be significant in some situations, such as earth and oceanic tides [1,2] , wave propagation [3][4][5][6] , erosion [7][8][9] , sedimentation [10][11][12] , subsidence [13,14] , pumping [15][16][17][18] and even changes in atmospheric pressure [19,2] . Therefore, it is of great importance to understand the fluid-to-solid mechanical coupling for the prediction of groundwater movement.…”