Volcanism in the American Southwest Conference – Summary Report

AZGS volcanologist and Extension Service Chief, Mike Conway reports that about 75 geoscientists – volcanologists, seismologists, geochemists and volcanic hazard specialists – and 10 individuals from the emergency management community met on October 18-19 at the USGS complex in Flagstaff to explore laying the groundwork for managing a low probability-high consequence volcanic event in the southwestern U.S, from precursory activity through eruption and recovery.   Jake Lowenstern (USGS Yellowstone Volcano Obs.) chaired the meeting.

Talks on Thursday and Friday were tailored to inform the emergency management crew of volcanic processes observed in Quaternary volcanic fields in the Southwest US.  The emphasis was on small-volume, basaltic eruptions, but there was some discussion of silicic volcanism (more explosive type) of the Jemez volcanic field in New Mexico.

There was considerable discussion on our collective capability – i.e., lack thereof - to recognize the precursors of a small-volume, basaltic eruption.  The NEIC (National Earthquake Information Center ) representative said they can identify ~M4 and above events, but unlikely to be of much assistance at the ~ M1-3 range, which is the range of seismic events likely to accompany rising basaltic magmas.  The consensus of seismologists was that given the present state of seismic monitoring,  it would prove difficult to identify and correctly interpret the low magnitude seismicity that might presage a small-volume, basaltic eruption.  

Among the action items that came out of the conference are a proposal to run a table-top emergency response exercise involving a violent Strombolian-type eruption in the eastern part of the San Francisco volcanic field, and to look for funding  to model the impacts of a violent Strombolian-type eruption on northern Arizona, and the skies overhead - the real issue.  The San Francisco volcanic field (SFVF) is a natural.  Another idea is to examine the potential impacts of an eruption in the Uinkaret volcanic field.  While even more remote than the SFVF, cinder cones of the Uinkaret have dumped basaltic lavas directly into the Colorado River at Grand Canyon on multiple occasions.  While the probability is low, the consequences of disrupting the water source for 20+ million people is dire.