Hydrothermal response to a volcano-tectonic earthquake swarm, Lassen, California

Geophysical Research Letters
By: , and 



The increasing capability of seismic, geodetic, and hydrothermal observation networks allows recognition of volcanic unrest that could previously have gone undetected, creating an imperative to diagnose and interpret unrest episodes. A November 2014 earthquake swarm near Lassen Volcanic National Park, California, which included the largest earthquake in the area in more than 60 years, was accompanied by a rarely observed outburst of hydrothermal fluids. Although the earthquake swarm likely reflects upward migration of endogenous H2O-CO2 fluids in the source region, there is no evidence that such fluids emerged at the surface. Instead, shaking from the modest sized (moment magnitude 3.85) but proximal earthquake caused near-vent permeability increases that triggered increased outflow of hydrothermal fluids already present and equilibrated in a local hydrothermal aquifer. Long-term, multiparametric monitoring at Lassen and other well-instrumented volcanoes enhances interpretation of unrest and can provide a basis for detailed physical modeling.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Hydrothermal response to a volcano-tectonic earthquake swarm, Lassen, California
Series title Geophysical Research Letters
DOI 10.1002/2015GL065826
Volume 42
Issue 21
Year Published 2015
Language English
Publisher American Geophysical Union
Publisher location Washington D.C.
Contributing office(s) National Research Program - Western Branch
Description 8 p.
First page 9223
Last page 9230
Country United States
State California
Online Only (Y/N) N
Additional Online Files (Y/N) N
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