Soo-Hyoung Lee

Analysis of Groundwater Level Changes Due to Earthquake in Jeju Island (For the Indonesian Earthquake with Magnitude 7.7 in 2010)

This study was conducted to investigate the relationship between groundwater level change and a large earthquake using the data of groundwater and seawater intrusion monitoring wells in Jeju Island. Groundwater level data from 13 observation wells were analyzed with a large earthquake. The Earthquake occurred at Sumatra, Indonesia (Mw

Groundwater level changes on Jeju Island associated with the Kumamoto and Gyeongju earthquakes

ABSTRACT Groundwater levels on the monitoring wells on Jeju Island were monitored, which were caused by the M 5.4 earthquake in Gyeongju City area, South Korea, at 11:32:54 on 12 September 2016 (UTC time) and the Kumamoto earthquake, Kyushu, Japan, at 16:25:06 on 16 April 2016 (UTC time). The groundwater levels changed after 2–3 min by the generation of the Gyeongju and Kumamoto earthquakes and exhibited spikes or oscillations depending on the magnitude of the earthquakes. The groundwater level change caused by the Gyeongju earthquake (M 5.4) was mostly larger than that caused by the Kumamoto earthquake (M 5.4). The reason is explained by that the energy of the Kumamoto earthquake with high attenuation could not be effectively transmitted to Jeju Island since the earthquake took place in low Q region whereas a higher energy of the Gyeongju earthquake with low attenuation arrived on Jeju Island because the earthquake occurred in the south-eastern part of the Korean peninsula belonging to the high Q crust. Besides the seismic energy from the Kumamoto earthquake was scattered and reflected on the Tsushima-Goto fault zone between Kyushu and the Korean peninsula, with a strike in the ENE-WSW direction that elongates to the east of Jeju Island.

Analyzing groundwater change on a volcanic island caused by the impact of the M9 Sumatra earthquake

Changes in groundwater level have been recognized by the earthquakes at various epicentral distances. The M9 Sumatra earthquake resulted in changes in the groundwater level, electrical conductivity, and temperature in monitoring wells on Jeju Island, South Korea. In regions of different groundwater type (basal, lower parabasal, upper parabasal, and high-level groundwater), the changes in the groundwater levels at 25 monitoring wells ranged between 4.0 and 49.5 cm; changes in the electrical conductivity at six monitoring wells ranged between 1 and 27,975 μS/cm; and the changes in water temperature at three wells ranged between 0.02 and 1.37 °C. The irregular groundwater level changes at different locations on the island due to the earthquake reflect various interactions between hydrological properties and seismological processes. The impact of the earthquake was successfully recognized via transfer function modeling between the time series of groundwater level and the tidal oscillation. On the basis of the theoretical aquifer response to the earthquake, storage coefficient estimates for aquifers, which could not be determined from the single-well pumping tests, were determined to be within the range of 1.22·10−4-3.51·10−6.

Groundwater response analysis to multiple earthquakes on Jeju volcanic island

Earthquakes have been known to induce a groundwater response. This study statistically analyzed the relationship between the changes in groundwater level (oscillation) and seismic waves, as well as the relationship between the changes in groundwater level and earthquakes of various magnitudes and epicenters more than 1,000 km distance from Jeju Island. The analysis showed that the groundwater level in Jeju Island is changed mostly by earthquakes larger than M = 7.0 within a 3,000 km from the epicenter. A positive relationship appeared between the earthquake magnitude and groundwater level change. A similar positive trend was observed between the maximum groundwater level and the seismic amplitude of the earthquakes. Geologically and spatially, the northern area of the island showed the highest response to earthquakes, the southern area showed an intermediate response, and the western and eastern areas showed the lowest response. The highest groundwater response in the northern area might be linked to its permeable structures and geological layers.