Spherical and ellipsoidal volcanic sources at Long Valley caldera, California, using a genetic algorithm inversion technique

Abstract

We model the second inflation period at Long Valley caldera, California using a genetic algorithm technique and high quality geodetic measurements of elevation changes and baseline extensions. We compare two source inversions for both spherical Mogi point sources and the finite prolate ellipsoid of Yang and Davis. A sensitivity analysis for the genetic algorithm is performed based upon synthetic data set inversions on similar sources in order to better constrain the areal location, orientation, and volume of the potential sources. The spherical sources are well constrained, the larger located at 9.9km beneath the resurgent dome, with a volume of 0.036km3, while the second, at only 0.008km3, is located at a depth of 7.3km beneath the south moat. The depths to the ellipsoidal sources are switched, with the larger source at a depth of 9.6km and the smaller at 11.8km, with volumes of 0.037 and 0.002km3, respectively.