Publication Date

Spring 2012

Degree Type


Degree Name

Master of Arts (MA)




Richard Taketa


Earthquake exposure, GIS, ShakeMap, Washington

Subject Areas

Geography; Geographic information science and geodesy


The U.S. Geological Survey conducted an earthquake exposure assessment for the State of Washington using peak ground acceleration (PGA) shaking from the USGS ShakeMap Project grouped to approximate Modified Mercalli Intensity (MMI) classes. Since ShakeMap datasets also have data representing official MMI classes, a companion exposure assessment was performed to determine whether MMI-grouped PGA data and official MMI data are interchangeable. Along with the exposure assessment, a spatial sampling process was used to further check how MMI-grouped PGA and official MMI data compared. Results indicated that significant variations existed spatially between the two ShakeMap datasets; generalizations by ShakeMap in creating their publically available data as well as the formulae ShakeMap's model uses to calculate MMI from PGA and peak ground velocity generally explain the variations. Though the two datasets differ significantly spatially, these results simply demonstrated that MMI-grouped PGA and official MMI are not interchangeable and did not identify one dataset as more appropriate than another for exposure assessments.