Do earthquakes large enough to collapse buildings and roads accompany volcanic eruptions?
Not usually. Earthquakes associated with eruptions rarely exceed magnitude 5, and these moderate earthquakes are not big enough to destroy buildings and roads.
The largest earthquakes at Mount St. Helens in 1980 were magnitude 5, large enough to sway trees and damage buildings, but not destroy them. During the huge eruption of Mount Pinatubo in the Philippines in 1991, dozens of light to moderate earthquakes (magnitude 3 to 5) were felt by several hundred thousand people. Many houses collapsed, but not primarily because of the shaking. Heavy ash from the eruption (made heavier by rain from a hurricane) accumulated on roofs and crushed them.
Stronger earthquakes sometimes DO occur near volcanoes as a result of tectonic faulting. For example, four magnitude 6 earthquakes struck Long Valley caldera, California, in 1980, and a magnitude 7.2 earthquake struck Kilauea Volcano, Hawaii, in 1975. Both volcanoes were quiet at the time. The Hawaii earthquake triggered a small eruption at the summit of Kilauea. No eruption occurred at Long Valley.
Learn more: Monitoring Volcano Seismicity Provides Insight to Volcanic Structure
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A unified catalog of earthquake hypocenters and magnitudes at volcanoes in Alaska—1989 to 2018
The Alaska Volcano Observatory (AVO) has maintained an earthquake catalog since 1989 that now contains over 120,000 hypocenters and magnitudes that occurred near Alaskan volcanoes. Since 1989 the seismic instrumentation and data acquisition and processing techniques have undergone numerous changes as computer systems and seismic processing...
Power, John A.; Friberg, Paul A.; Haney, Matthew M.; Parker, Thomas; Stihler, Scott D.; Dixon, James P.
California's restless giant: The Long Valley Caldera
Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil...
Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae
Mount St. Helens, 1980 to now—what’s going on?
Mount St. Helens seized the world’s attention in 1980 when the largest historical landslide on Earth and a powerful explosive eruption reshaped the volcano, created its distinctive crater, and dramatically modified the surrounding landscape. An enormous lava dome grew episodically in the crater until 1986, when the volcano became relatively quiet...
Dzurisin, Daniel; Driedger, Carolyn L.; Faust, Lisa M.
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Mauna Loa on the Island Hawaiʻi is the world’s largest volcano. People residing on its flanks face many hazards that come with living on or near an active volcano, including lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and local tsunami (giant seawaves). The County of Hawaiʻi (Island of Hawaiʻi) is the...
Trusdell, Frank A.
Earthquakes in Hawai‘i—an underappreciated but serious hazard
The State of Hawaii has a history of damaging earthquakes. Earthquakes in the State are primarily the result of active volcanism and related geologic processes. It is not a question of "if" a devastating quake will strike Hawai‘i but rather "when." Tsunamis generated by both distant and local quakes are also an associated threat and have...
Okubo, Paul G.; Nakata, Jennifer S.
Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska
The 2006 eruption of Augustine Volcano, Alaska, generated more than 3,500 earthquakes in a month-long time frame bracketing the most explosive period of activity. We examine two quantitative tools that, in retrospective analysis, were excellent indicators of imminent eruption. The first tool, referred to as the frequency index (FI), is based on a...
Power, John A.; Coombs, Michelle L.; Freymueller, Jeffrey T.; Buurman, Helena; West, Michael E.
Listen to Earthquakes
Seismometers record vibrations from a wide assortment of ground motion events. Each event type has a distinctive ground-motion signal with unique frequency and amplitude—its own seismic signature. Seismologists are trained to identify the source of seismic events seen on a webicorder based on its ‘seismic signature’. Although most ground vibrations have a frequency too low
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Volcano Hazards
The United States has 169 active volcanoes. More than half of them could erupt explosively, sending ash up to 20,000 or 30,000 feet where commercial air traffic flies. USGS scientists are working to improve our understanding of volcano hazards to help protect communities and reduce the risks.
Video Sections:
- Volcanoes: Monitoring Volcanoes
Volcano Web Shorts 3: Seismology
USGS volcano seismologist, Seth Moran, describes how seismology and seismic networks are used to mitigate volcanic hazards.
Volcano Web Shorts 4 - Instruments
USGS technologist Rick LaHusen describes how the development and deployment of instruments plays a crucial role in mitigating volcanic hazards.
Damage from 2011 Virginia Earthquake
Photo of chimney damage at a house in Louisa County, Virginia. This was a result from a magnitude 5.8 earthquake in Virginia on August 23, 2011.
Northridge, CA Earthquake Damage
Collection of USGS still images taken after the January 17, 1994 Northridge earthquake highlighting the damage to buildings and infrastructure.
USGS volcano seismologist analyzes Mount Pinatubo seismicity
USGS volcano seismologist David Harlow conducts analysis of Mount Pinatubo seismicity.