Ongoing Inflation of Long Valley Caldera Abstract


  • A new episode of slow inflation began at Long Valley Caldera in late 2011, coinciding with increased swarm seismicity. Ongoing deformation is concentrated within the caldera. The deformation was studied in Montgomery-Brown et al. (2015) using a combination of GPS and InSAR (TerraSAR-X) data, processed with a persistent scatterer technique. The extension rate of the dome-crossing baseline during this episode (CA99 to KRAC) is 1?cm/yr, similar to past inflation episodes in 1990-1995 and 2002-2003, and about a tenth of the peak rate observed during the 1997 unrest. The current deformation is well explained by the inflation of a prolate spheroidal magma reservoir about 7?km beneath the resurgent dome, with a volume change of about 6 mcm/yr from 2011.7 through the end of 2014. The current data cannot resolve a second source, which was required to model the 1997 episode. This source appears to be in the same region as previous inflation episodes, suggesting a persistent reservoir. Since a major challenge in assessing the caldera uplift in the short-term is the large seasonal background noise and related signal from the ongoing drought, we also present a comparison of some methods that have been employed to isolate the volcanic signal.

publication date

  • 2016

presented at event