Recent magmatotectonic activity in the Eastern Snake River Plain-Island Park region revealed by SAR interferometry

Synthetic Aperture Radar Interferometry (InSAR) has been applied in this study to address crustal deformation in a 10,000-km(2) region located immediately west of the Yellowstone hotspot. InSAR results show that surface movements in the study area were non-linear and episodic during the period of observation (1993-2006). The Island Park region and its adjacent Eastern Snake River Plain (ESRP) were characterized by northeast-trending zones of uplift (+1 cm yr(-1)) and subsidence (-1 cm yr(-1)) with various extents through time. The western edge of Yellowstone caldera experienced episodes of subsidence (-1 cm yr(-1)) during 1997-2000 and uplift (+3 cm yr(-1)) during 2004-2006. Differential surface movements of varying rates were also detected between 1993 and 2006 in the vicinity of Basin and Range normal faults to the north of Henrys Fork caldera. Throughout the study area, surface displacements across the Island Park region, the ESRP, and the adjacent Basin and Range province generally reversed the movement direction in 2004, in concert with displacement reversal to uplift in the Yellowstone caldera. Crustal deformation in the general vicinity of major Basin and Range faults is interpreted to reflect diffuse extensional strain adjacent to the deeper segments of faults, rather than near-surface slip. The northeast-trending displacement zones in the ESRP and the Island Park region may indicate folding in response to converging zones of extension in the surrounding Basin and Range province. Surface displacements of the Yellowstone caldera are interpreted to reflect migration of magma or hydrothermal fluids. The inverse relation between vertical displacements in Yellowstone and its surrounding regions may reflect an upper crustal flexural response or a large-scale movement of hydrothermal fluids, though neither hypothesis is completely supported by the processed data. (C) 2009 Published by Elsevier B.V.