Changes in Permeability Caused by Two Consecutive Earthquakes—Insights From the Responses of a Well‐Aquifer System to Seismic Waves. Issue 17 (4th September 2019)

• Record Type: Journal Article
• Authors: Sun, Xiaolong; Xiang, Yang; Shi, Zheming
• Is Part Of: Geophysical research letters. Volume 46:Issue 17/18(2019)
• Page Start: 10367
• Page End: 10374
• Publication Date: 2019-09-04
• Subjects: permeability change -- well‐aquifer system -- piezometric level -- coseismic oscillation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL084704
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Earthquake‐induced aquifer permeability changes have been observed both in the laboratory and the field. However, the effects of multiple earthquakes on aquifer systems have rarely been differentiated. In this study, we analyze the piezometric response to earthquake pairs that occurred on the same day. The results show that events with higher seismic energy may result in a rise in piezometric level, and the seismic waves enhanced the permeability of the aquifer by different magnitudes. Stress/strain history from consecutive earthquakes may be retained, and permeability increased much more following the second earthquake than the first one. The method proposed in this study is useful in evaluating the permeability enhancement induced by consecutive earthquakes. The stress/strain memory of aquifers also has important implications for understanding aftershocks. Plain Language Summary: Earthquake‐related piezometric level changes have been widely documented, and change in permeability is a favored explanatory mechanism. However, piezometric level changes induced by close‐in‐time earthquakes are not well understood owing to the low temporal resolution of the standard method of calculating permeability. In this study, we calculated the permeability by comparing the coseismic piezometric level oscillation and seismic wave data. For each earthquake pair, permeability increased more after the second earthquake than the first one, indicating that the aquifer system retains the earthquake stress/strain history for a certain period. The method presented in this study is helpful in differentiating the effects of sequential earthquakes. Key Points: Stress/strain history from consecutive earthquakes may be retained Events with higher seismic energy may result in a rise in piezometric level Permeability increased more following the second earthquake than the first one