Response plan for volcano hazards in the Long Valley Caldera and Mono Craters region, California

PDF versionPDF version


Publication Year: 



Persistent unrest in Long Valley Caldera—characterized by recurring earthquake swarms, inflation of the resurgent dome in the central sections of the caldera, and emissions of magmatic carbon dioxide around Mammoth Mountain—during the last two decades and continuing into the 21st century emphasize that this geologically youthful volcanic system is capable of further volcanic activity. This document describes the U.S. Geological Survey’s (USGS) response plan for future episodes of unrest that might augur the onset of renewed volcanism in the caldera or along the Inyo-Mono Craters chain to the north. Central to this response plan is a four-level color code with successive conditions, GREEN (no immediate risk) through RED (eruption under way), reflecting progressively more intense activity levels as summarized in table 1 and 2 and described in detail in section II of this report.

Document Type: 

  • Report


  • critical issues, database publication, volcano, hazards, california