Abstract
The earth’s crust is a leaky geofluid system where surface trace gas
emissions relate to open migration pathways and the presence of
subsurface source(s). Seismic activity can open sealed migration
pathways leading to trace gas emissions from the surface intersection of
the active fault, which may not relate to observable surface fault
rupture or offset. After the M7.1 Ridgecrest earthquake, we collected
mobile surface trace gas and meteorology data with AMOG (AutoMObile
trace Gas) Surveyor, a mobile atmospheric chemistry and meteorology lab,
in the Death Valley Park and Searles Valley within 24 hours of the
quake, the following week, and after several weeks with air samples also
were collected for detailed later laboratory analysis. We found
widespread highly elevated CO2 emissions along Panamint Valley including
overall elevated SO2 and H2S with strong enhancements around Manly Pass,
where aftershocks occurred at the northern edge of the Slate Range and
along a trend parallel to Water Canyon. This is in contrast to AMOG data
collected in Death and Panamint Valleys in 2014, where concentrations
were typical of California desert levels–near ambient and uniform.
Significant sulfur trace gas emissions were discovered escaping from the
rim of Ubehebe Volcano, last active ~2500 B.P., 115-km
north of the Slate Range. Faults appear to play an important role in
these geogas emissions, activated by the major earthquake and
aftershocks. Further investigations are planned to characterize the
system’s return towards quiescence.