Earthquake-induced chemical changes in the thermal waters of the Umbria region during the 1997-1998 seismic swarm.

Favara, R.; Italiano, F.; Martinelli, G.

The compositional data collected at three thermal springs in the Umbria region over a sampling period lasting two and a half hydrological years included the entire seismic sequence striking the Central Apennines (Italy) in 1997-1998. Wide temporal variations in the chemical composition and temperature of thermal waters were observed at all the sampling sites. The widest were recorded at the Triponzo sampling site, where a temperature drop of 2 °C and 20 °C preceded, by 4 days and 2 days, respectively, the occurrence of the event characterized by the deepest hypocentre of the entire seismic sequence. Despite such a macroscopic preseismic anomaly, the recorded variations were not related to single seismic events or to the release rate of the seismic energy. They actually seem to have been induced by permeability variations related to crustal deformation in the absence of elastic energy release and were thus linked to the whole seismogenic process.

ITALY; UMBRIA (Italy); GEOTHERMAL resources; EARTHQUAKE swarms

Terra Nova, 2001, Vol 13, Issue 3, p227

0954-4879

Academic Journal

10.1046/j.1365-3121.2001.00347.x