A Novel Multidisciplinary Approach for the Thermo‐Rheological Study of Volcanic Areas: The Case Study of Long Valley Caldera

Abstract

The Long Valley caldera formed 0.760 Ma ago, as a result of a paroxysmal Bishop Tuff eruption. This event released 650-700 km 3 of gas-rich rhyolitic magma and drove the caldera collapse (Bailey, 1989; Carle, 1988; Hildreth & Wilson, 2007). Nowadays, the caldera has roughly an elliptical shape (∼17 km by 31 km) and hosts a magmatic-hydrothermal system which manifests itself at surface as hot springs and fumaroles. Geothermal facilities near the Casa Diablo locality supply 40 MW e from three binary power plants, exploiting ∼850 kg s −1 of 160-180°C water that circulates within the volcanic sediments, having depths spanning from 200 m to 350 m (Campbell, 2000). Since geothermal exploration began in 1960s the understanding of the geothermal system has continuously improved. Moreover, after the occurrence of the May 1980 earthquake swarm (D. P. Hill et al., 2017) many geological, geochemical, and geophysical studies focused on this area. The earthquakes were linked to a ∼0.25 m uplift of the old resurgent dome, located in the central part of the caldera (Battaglia et al., 1999; Tizzani et al., 2007, 2009). The seismic swarms and the inflation of the resurgent dome continue to date. Nowadays its center is ∼0.80 m higher. The seismic activity is associated with changes in discharge rates of hot springs and fumaroles in the southern and eastern sectors of the caldera, as well as with increased CO 2 emissions around Mammoth Mt. (at the southwestern border of the present-day caldera rim; Rogie et al., 2001; Sorey & Clark, 1981). These critical events leading to the creation of a multi-parameter monitoring network (managed by USGS), which in turn delivered the data through periodic public reports and monographies (e.g.

Stress fields around magma chambers influenced by elastic thermo-mechanical deformation: implications for forecasting chamber failure

“…These include the presence of hot magma rich in volatiles (increasing Pe) and a delayed (viscous) response associated with the thermal expansion. In the latter case, it must be noted that the upper range of temperatures modelled could induce melting or a change from brittle to ductile rheology and as such the rocks could deform in a visco-elastic manner (Currenti and Williams, 2014;Degruyter and Huber, 2014;Gola et al, 2021). Visco-elastic deformation has been used to explain deformation signals at volcanoes (Del Negro, 2009;Castaldo et al, 2017) and some have suggested that such deformation mechanics may suppress the development of magmatic overpressures (de Silva and Gregg, 2014).…”