Hydrochemical Changes in Spring Waters in Taiwan: Implications for Evaluating Sites for Earthquake Precursory Monitoring

Abstract

ABSTRACT1 Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC 2 Central Geological Survey, MOEA * Corresponding author address: Dr. Sheng-Rong Song, Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC; E-mail: srsong@ntu.edu.twTo evaluate potential monitoring sites as well as useful ions which are capable of serving as earthquake precursors, ten subsurface water bodies in different tectonic domains in southwestern, northern and northeastern Taiwan were selected. They included the deep circulation of hot springs, shallower artesian springs and groundwater. Most of the hot springs clearly show chemical anomalies which correlate with earthquake events during the monitoring periods. Against this, the groundwater does not correspond to any events. Hot springs from deeper reservoirs are superior to artesian springs and groundwater from shallower reservoirs. The artesian spring from the smaller subsurface water body is superior to the groundwater from larger reservoirs. Aside from this, anions, especially chloride, outperform cations as geochemical precursors for earthquake monitoring. It is unambiguous that the major factors that determine the usefulness of chemical anomalies in the waters for earthquake precursory monitoring are the kinds, the depths and the size of reservoirs and the ion species of the subsurface water bodies.

Variations in the Cl, SO4, δD and δ18O in Water from Thermal Springs near Acapulco, Guerrero, Mexico, Related to Seismic Activity

“…In the Paso Real case Cl-enriched waters could be from a deeper part of the same aquifer. Our data confirm the earlier suggestions (Barsukov et al 1985;Igarashi and Wakita 1990;Toutain et al 1997;Italiano et al 2005;Song et al 2005) that the mechanism of the coseismic chemical (and isotopic) anomalies in most of the cases is related to a mixing of waters from adjacent aquifers with different water composition. The steady-state fluxes of water during a "quiet" period can be perturbed due to an earthquake by sudden changes in the pore and fracture pressure after releasing of elastic energy.…”

Geochemical Monitoring of Cold Waters during Seismicity: Implications for Earthquake-induced Modification in Shallow Aquifers

“…The ample literature on the subject [see Thomas (1988) and cited references; Toutain and Baubron (1999) and literature therein] and more recently Ramirez-Guzman et al (2005), Song et al (2005) shows that seismogenic-induced geochemical modifications occur in anomalous fluids (i.e., thermal waters, acidic gases, etc.) circulating in seismic-prone areas.…”

Hydrochemical characteristics of hot spring waters in the Kangding district related to the Lushan <i>M</i><sub>S</sub> = 7.0 earthquake in Sichuan, China

“…Enhanced water-rock interactions and a greater increase in different fluids were proposed as two possible mechanisms for the variations in geochemical parameters before and after earthquakes (Etiope et al, 1997;Song et al, 2005;Du et al, 2010;Reddy et al, 2011;İnan et al, 2012;Dadomo et al, 2013).…”