In 2010, the Yellowstone caldera underwent a period of substantial seismic activity, followed by a period of subsidence. An analysis of the seismicity attributes the subsidence to the release of high-pressure, aqueous fluids.
David Shelly of the US Geological Survey and colleagues reanalysed data collected by the Yellowstone Seismograph Network during the 2010 Madison Plateau swarm. They identified a total of 8,710 earthquakes associated with the three-week-long event. The first burst of activity occurred in a localized area at depths between 8.5 and 11 km. The swarm then migrated along a plane, at a rate of roughly 750 m per day. The observed faulting generally indicated the weakening of existing fault surfaces, such as would occur when pore fluid pressures are suddenly elevated.
The researchers suggest that the initial deep rupturing was associated with the migration of high-pressure fluids from depth. The migration of these fluids into the surrounding rock generated the subsequent earthquake swarm, and the propagation of this swarm is consistent with the expected path of fluid diffusion. The release of these fluids could have reduced pressure in the caldera, promoting the subsidence of the surface.
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Newton, A. Shaky caldera. Nature Geosci 6, 900 (2013). https://doi.org/10.1038/ngeo2001
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DOI: https://doi.org/10.1038/ngeo2001
