The U.S. Geological Survey’s (USGS) National Volcanic Threat Assessment (SIR 2018-5140) classifies eight young volcanic areas in California as high or very high threat. The USGS California Volcano Observatory monitors these potentially hazardous volcanoes to help communities and decision-makers understand, prepare for, and respond to volcanic activity. The first step in mitigating volcanic risk and building community resilience to volcanic hazards is identifying what and who is in harm’s way. By integrating volcanic hazard zones with geospatial data on populations, infrastructure, and resources, the USGS provides estimates of impacts to people and our environment if an eruption were to occur. 

This geo-narrative is a GIS-based interactive dashboard that is meant to complement the original exposure report. It is organized in 6 tabs:  

• Introduction - Learn about volcanoes in California, the USGS National Volcanic Threat Assessment, and the Volcano Watch List. 

• Volcanic Hazards - Learn about volcanic hazards, their potential impacts to society, and how volcanic hazard zones are determined through interactive diagrams, maps, and photos. 

• California’s Volcanoes -  Learn about the California’s 8 moderate-to-very-high-threat volcanoes and their hazards through photographs, websites, and interactive maps. 

• Societal Exposure - Interact with 8 dashboards of potential societal asset exposure to volcanic hazards at the county level. Use the dashboards to understand the varying exposure of each volcano, its mapped hazards, and the counties that could be affected by those hazards. Watch the animation above to discover hidden features in the dashboards including legends, map layers, and tabular data. 

• Conclusion -  Read an infographic of state-wide exposure to volcanic hazards as well as  a brief summary of volcanic hazards risk in California. 

• References - Access a list of reports and documents used to write the original report, and data used in the exposure analysis. Links to the original report, the hazard zone data, and the tabular exposure results are provided. 

All information presented in the report and geo-narrative is intended to prompt site- and sector-specific vulnerability analyses and preparation of hazard mitigation and response plans. Please contact askcalvo@usgs.gov or the USGS contacts to the right with any questions about the report, data, and their use.