Live Updates: Earthquake in Yellowstone National Park Damages major Roads creating commotion

Yellowstone is one of the most seismically active areas in the United States. Approximately 700 to 3,000 earthquakes occur each year in the Yellowstone area; most are not felt. They result from the extensive network of faults associated with the volcano and surrounding tectonic features. Yellowstone earthquakes tend to occur in swarms—close together in time and space. This phenomenon is related to transport of volcanic fluids along the many small fractures in the shallow rocks over the magma, a pattern that has been noted in volcanos around the world.

 

Earthquakes occur along fractures in the crust where stress from crustal plate movement and volcanic activity build to a significant level. The rock along these faults becomes so strained that eventually it slips or breaks. Energy is then released as shock waves (seismic waves) that reverberate throughout the surrounding rock. Once a seismic wave reaches the surface of the Earth, it may be felt. Surface waves affect the ground, which can roll, crack open, or be vertically and/or laterally displaced. Structures are susceptible to earthquake damage because the ground motion is dominantly horizontal.

 

In Yellowstone, earthquakes help to maintain hydrothermal activity by keeping the “plumbing” system open. Without periodic disturbance from relatively small earthquakes, the small fractures and conduits that supply hot water to geysers and hot springs might be sealed by mineral deposition. Some earthquakes generate changes in Yellowstone’s hydrothermal systems. For example, the 1959 Hebgen Lake (7.3 M) and 1983 Borah Peak (6.9 M) earthquakes caused measurable changes in Old Faithful Geyser and other hydrothermal features.

 

Yellowstone commonly experiences “earthquake swarms”—a series of earthquakes over a short period of time in a localized area. The largest swarm occurred in 1985, with more than 3,000 earthquakes recorded during three months on the northwest side of the park. Hundreds of quakes were recorded during swarms in 2009 near Lake Village and 2010 between Old Faithful area and West Yellowstone. Scientists posit these swarms are due to shifting and changing pressures in the Earth’s crust that are caused by migration of hydrothermal fluids, a natural occurrence of volcanoes.