Map of Yellowstone caldera, resurgent domes, and leveling benchmarks

Map of caldera and survey benchmarks in Yellowstone National Park, Wyoming

Simplified map of Yellowstone National Park, caldera, and resurgent domes
(locations of benchmarks and place names referred to in leveling data)

USGS scientists began precise leveling surveys across the Yellowstone caldera in 1983 between Lake Butte and Mount Washburn to determine the amount and rate of contemporary deformation across the caldera. The discovery of rapid uplift within the caldera between 1923 and 1975-77 clearly demonstrated the volcanic and tectonic unrest in the Yellowstone region.

The most recent caldera (note red caldera rim on map) formed about 600,000 years ago when more than 1,000 km³ of magma erupted onto the surface. After the caldera-forming eruption, as magma rose into the partially drained reservoir, the caldera floor was pushed upward to form two resurgent domes, the Mallard Lake and Sour Creek domes. During the same time, subsequent eruptions of thick lava flows with a volume of nearly 1000 km³ filled much of the caldera and completely buried the west rim of the caldera.

In historical time, there have been at least seven M 6+ earthquakes and one M 7+ earthquake in the Yellowstone region. The August 1959 M 7.5 Hebgen Lake earthquake and the June 1975 M 6.1 Yellowstone Park earthquake are shown on the map.