Author(s): Suk-Hwan Jang, Kyoung Doo Oh, Jae-Kyoung Lee, Junwon Jo

Linked Author(s): Suk-Hwan Jang, Junwon Jo

Keywords: Earthquake; Groundwater; Monsoon; Hydrologic cycle;

Abstract: In this study, it was hypothesized that groundwater flow could trigger earthquakes both in the lands and seas due to its seasonal fluctuation following the wet and dry seasons. Using 1,157 earthquake data occurred in South Korea recorded from 1978 till 2017 by Korean Meteorological Agency monthly earthquake energies were analyzed to test the hypothesis. For the earthquakes occurred in the lands, following the wet Monsoon season from June to September the six-month earthquake active period (August-January) was identified with three cascades of earthquake energy releases peaking in September, November and January with descending energy levels and bimonthly cycles. For the earthquakes occurred in the seas the six-month earthquake active period (February-July) was identified which was the inactive period for the land earthquakes. The earthquake active period in the seas was comprised of two peaks in April and July with descending energy levels with four-month and two-month cycles respectively. The one month delay between the peak rainy month of August and the peak land earthquake energy month of September was supposed to be the time for groundwater recharge and pressure propagation in the fault zones. This hypothesis should be studied more thoroughly as more data are available. Also, triggering earthquakes by cyclic groundwater fluctuation was supposed to be the moderating effect of the hydrologic cycle by preventing excessive accumulation of geotectonic stress and the climatic change which could bring about abnormal behavior of groundwater recharge may cause change in earthquake patterns in South Korea.

DOI: https://doi.org/10.3850/38WC092019-0849

Year: 2019