Macroseismic Intensity Dataset in Western North America

A new dataset for macroseismic intensity from crustal earthquakes in the Western United States is developed by combining the USGS Did You Feel It? (DYFI) data set with historical intensity data (Atkinson et al., 2014; Salditch et al., 2020). The metadata compiled for the data set includes the earthquake magnitude, rupture distance, time-averaged shear-wave velocity in the upper 30 m (VS30; Thompson, 2022), surface geology from Wills et al. (2015), earthquake hypocenter, and site coordinates for the intensity observation, and the intensity data is given as Modified Mercalli Intensity (MMI). The rupture distances are estimated from finite-rupture models for large magnitude earthquakes and from the hypocentral distance for small-magnitude earthquakes. The VS30 values are based on the topographic slope and surface geology (Thompson, 2022). The full data set includes about 696,000 intensity observations from about 5,600 earthquakes that occurred between 1857-2023. In addition to the intensity values, the dataset includes peak acceleration and peak velocity data for intensity observations located near seismic stations from the Next Generation Attenuation -West3 dataset (Buckreis et al., 2025). The dataset is predominantly composed of DYFI observations, which account for 96% of the intensity values and 98% of the earthquakes recorded. For earthquakes with magnitudes of 6 or greater occurring at distances less than 30 km, historical intensity data (earthquakes occurring between 1857- 2007) contribute 20% of the intensity values.