Poster #122, Stress and Deformation Over Time (SDOT)

Pronounced Recharge and Discharge Phase Ground water in the Epicentral Region Caused Madoi (China) M 7.3 earthquake of 21 May 2021

Ramesh P. SINGH, Feng Jing, & Anhua He
Poster Image: 

Poster Presentation

2021 SCEC Annual Meeting, Poster #122, SCEC Contribution #11622 VIEW PDF
On 21 May 2021 (UTC time), an earthquake (magnitude 7.3, epicenter 34.59°N, 98.34°E) occurred in Madoi County, Guoluo Prefecture, Qinghai Province of China along the Yellow River. Numerous large lakes and wetland areas are located in the epicentral region. The epicentral region suffers with high and low temperature that caused thawing-freezing cycle and fluctuations in the ground water that are evident from GRACE Satellite and water well data. The focal mechanism of the main earthquake is the left-lateral strike-slip fault with NW-striking Kunlunshankou-Jiangcuo Fault and the co-seismic surface rupture of 160 km length located on the Jiangcuo segment, which is consistent with the InSAR obser...vation. In China, numerous water wells are deployed with borehole sensors for monitoring water level and temperature data. The water equivalence thickness from GRACE satellite, precipitation from field and satellite and water level data show a strong variability in water level. Pronounced increase in ground water level shows cyclic variability. The sudden changes after decline and increasing phase of ground water level may be the cause in the stress regime that may have triggered earthquake on 21 May 2021. The water well data located along the Kunlunshankou-Jiangcuo Fault shows increase and decline in phase (up and down) of water level across the fault line which is consistent with the focal mechanism. The detailed changes in observed water level and temperature will be discussed.