Analysis of the impact of earthquakes and industrial explosions on groundwater temperature (Gorny Altai)

This study was prompted by the major Chuya earthquake, which altered the chemical composition of groundwater in many springs across the Altai Republic. Several springs within the city of Gorno-Altaysk exhibited a significant rise in groundwater temperature. At one of these springs, a long-term monitoring station was established to record groundwater quality. The paper assesses the impact of seismic events on groundwater temperature at a highly tensio-sensitive subsurface site (observation borehole at the State Reference Observation Network (SRON) station " Severnaya", 16 Severnaya St.), located within the mountainfold structures of the Altai-Sayan orogenic region. An extensive monitoring dataset was analysed, revealing a correlation between the cumulative seismic energy released by earthquakes and industrial blasts and the temperature of the groundwater. The results demonstrate that even distant earthquakes and anthropogenic seismic impacts can induce noticeable temperature variations at the observation point. Possible mechanisms governing the influence of seismic events on groundwater temperature are discussed, including the periodically reversing correlation sign - from positive to negative - between spring temperature and the seismic energy released. Seismic energy values were derived by recalculating event magnitudes using a refined Gutenberg-Richter relationship. The findings indicate a direct link between groundwater temperature at the SRON (State Reference Observation Network) "Severnaya" station and seismic events of both natural and technogenic origin within the region. The abrupt reversal of the correlation sign 50-60 days after an event is attributed to the migration of deep fluids followed by infiltration of relatively cold groundwater. The influence of industrial explosions on the spring’s parameters, despite their considerably lower energy, is explained by induced seismicity manifested as an increase in the magnitude of recorded events. This work continues a series of investigations aimed at identifying hydrogeological and hydrogeochemical precursors of hazardous geodynamic events, a task made urgent by the very low predictive accuracy of current earthquake-forecasting methods. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

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