Volcanic Activity
Volcanic Activity occurs via vents that act as a conduit between the Earth's surface and inner layers, and erupt gas, molten rock, and volcanic ash when gas pressure and buoyancy drive molten rock upward and through zones of weakness in the Earth's crust.
In the National Risk Index, a Volcanic Activity Risk Index score and rating represent a community's relative risk for Volcanic Activity when compared to the rest of the United States. A Volcanic Activity Expected Annual Loss score and rating represent a community's relative level of expected building and population loss each year due to Volcanic Activity when compared to the rest of the United States.
Volcanic Activity Exposure
A Volcanic Activity exposure value represents a community's building value (in dollars) and population (in both people and population equivalence) exposed to Volcanic Activity.
Volcanic Activity Annualized Frequency
A Volcanic Activity annualized frequency value represents the average number of recorded Volcanic Activity hazard occurrences (events) per year over the period of record (11,332 years).
Source Data
United Nations Office for Disaster Risk Reduction's Volcano-Population Exposure Index
Smithsonian Institution's Global Volcanism Program's Volcanoes of the World
Volcanic Activity Historic Loss Ratio
A Volcanic Activity historic loss ratio is the representative percentage of the exposed consequence type value (building or population) expected to be lost due to a Volcanic Activity hazard occurrence.
Volcanic Activity Processing Methodology
For comprehensive details about the Volcanic Activity processing methodology, see the National Risk Index Technical Documentation.