Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

• Published in: Hydrogeology journal Vol. 29; no. 4; pp. 1679 - 1689
• Main Authors: Lee, Soo-Hyoung, Lee, Jae Min, Moon, Sang-Ho, Ha, Kyoochul, Kim, Yongcheol, Jeong, Dan Bi, Kim, Yongje
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2021; Springer Nature B.V
• Subjects: Aquatic Pollution; Aquifer systems; Aquifers; Earth and Environmental Science; Earth Sciences; Earthquake damage; Earthquakes; Fluid pressure; Fractures; Geology; Geophysics/Geodesy; Groundwater; Groundwater chemistry; Groundwater levels; Groundwater resources; Hydrogeology; Hydrology/Water Resources; Information management; Joints (timber); Microcracks; Monitoring; P-waves; Seismic response; Seismic waves; Temperature changes; Waste Water Technology; Water level fluctuations; Water levels; Water Management; Water Pollution Control; Water Quality/Water Pollution; Water temperature; South Korea; Temperature; South Korea; Earthquake; Groundwater level; Hydrogeological system
• DOI: 10.1007/s10040-021-02328-w
• ISSN: 1431-2174

Hydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with M L 5.8 and M L 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The M L 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.