Numerical simulation of pre-seismic and coseismic continuous response of water level to the 2014 Ludian MS6.5 earthquake: A case study of Huize well

Abstract

Groundwater is sensitive to seismic and tectonic activity. Continuous response of well water levels pre-seismic and coseismic provides further evidence for the relationship between seismic activity and changes in water level. However, quantitatively analyzing factors such as crustal stress variations, aquifer deformation, pore pressure changes, and dynamic fluctuations in well water levels from seismogenesis to seismic rupture presents challenges due to their complex nature. Additionally, research on pre-seismic and coseismic response has been separated temporally due to different physical mechanisms and research objectives. In this study, pre-seismic and coseismic response are considered as continuous processes that involve a series of physical phenomena including stress–strain-pore pressure-water level changes before and during an earthquake event. This study aims to establish quantitative relationships between these response processes and hydrogeological parameters, as well as rock mechanical properties, thereby revealing the underlying physical mechanisms governing the continuous pre- and coseismic response of well water levels. A mathematical and numerical model was developed to continuously analyze the pre- and coseismic response of well water levels based on hydraulic-mechanical coupling near fault sections using near-field earthquakes under static stress as a case study. To validate the effectiveness of the numerical model, a simulation was conducted to replicate the continuous pre- and coseismic response of Huize well water levels during the Ludian earthquake. Through the design, identification, and correction of various parameter schemes, the simulated values align closely with measured water levels for both pre- and coseismic periods. This research holds significant practical implications for earthquake monitoring.