Evidence for long timescale (> 10(3) years) changes in hydrothermal activity induced by seismic events

摘要

The pollen C-14 age and oxygen isotopic composition of siliceous sinter deposits from the former Beowawe geyser field reveal evidence of two hydrothermal discharge events that followed relatively low-magnitude (10(-11)m(2)) following each earthquake. However, the timescale for onset of thermal convection implied by an overturned temperature profile in a geothermal well 300m from the Malpais fault is much shorter: 200-1000years. We speculate that individual segments of the Malpais fault become clogged on shorter timescales and that upward flow of groundwater subsequently follows new routes to the surface.