Seismic‐related variations in the chemical and isotopic composition of thermal springs near Acapulco, Guerrero, Mexico

Abstract

Chemical and isotopic analyses of waters from 4 thermal springs of the Guerrero Pacific coast, the most seismically active area in Mexico, were performed weekly during a period of 1.5 years (October 2002–March 2004). Within the same time interval more than 200 earthquakes with 3.8 ≤ M ≤ 5.3 occurred in the area. The data display several anomalies in Cl−, SO42−, δD and δ18O, always immediately after an event, with a relaxation time of 3–4 weeks. The responses occurred only to earthquakes with the estimated epicenters very close to the location of a spring. These results indicate that: 1) at least for earthquakes with M < 5.3 within the Guerrero “seismic gap” there were no precursors in the chemical (ionic) and isotopic composition of thermal waters (on a weekly basis); 2) two groups of springs near Acapulco, Dos Arroyos and Paso Real, are sensitive to seismic activity and therefore further monitoring of these springs may help to unravel the mechanisms of the “hydro‐seismo‐interaction” in the area.

Reactive Transport Process of Earthquake‐induced Hydro‐chemical Changes in Guanding Thermal Spring, Western Sichuan, China

“…Fault zone hydrothermal systems with deep fluid circulation are considered as the ideal place to monitor tectonic activities such as volcanic activity and earthquakes (Favara et al, 2001;Martinelli and Dadomo, 2017;Wang et al, 2023). Geochemical changes before and following earthquakes in such systems have been documented for decades (Bolognesi, 2000;Taran et al, 2005;Reddy et al, 2011;Skelton et al, 2014;Chen et al, 2015). Bolognesi (2000) and Shi et al (2019) have demonstrated that earthquakes can have a significant impact on the chemical components and temperature of hydrothermal systems.…”

Earthquake impact on iron isotope signatures recorded in mineral spring water

“…Such earthquake‐related hydrochemical signals were also observed in other tectonically active regions. Several anomalies in hydrogen and oxygen stable isotope ratios occurred immediately after seismic events near Acapulco, Mexico [ Taran et al, ], and related to a M = 5.1 earthquake in 2005 at Koyna, India [ Reddy et al, ], respectively. Similarly, a transient geochemical groundwater anomaly occurred after the 1998 Adana earthquake in Turkey [ Woith et al, ].…”