...swarms" of local earthquakes also occurred near hydrothermal systems that saw such changes, the study said. Within...affected pressure on faults in proximity to the hydrothermal systems and set off small quakes - a possible explanation...

...fractures of the mountain that resonates and produces a distinct signal. "We think it's associated with the hydrothermal system there. It's being reinvigorated," Waythomas said. The tremors lasted about four hours and then settled down...