Earthquakes, also referred to as tremors, occur when seismic waves generated from the Earth’s lithosphere due to a sudden release of energy cause the Earth’s surface to shake. Earthquakes range in magnitude, as some are weak and barely detectable, while violent earthquakes can cause significant property destruction and death. When an earthquake’s epicenter is offshore and displaces the sea bed, it can cause a tsunami. Hundreds of earthquakes have occurred in the United States (US) since the early 1700s, most of which had epicenters within the country's borders. Some of the worst and most powerful earthquakes ever recorded in US history are listed below.
The Three Biggest Earthquakes in United States History
Alaska: March 27, 1964
The most powerful earthquake in North American history was recorded in Alaska on March 27, 1964. Nicknames for the earthquake include the Good Friday Earthquake, Great Alaskan Earthquake, or the 1964 Alaskan earthquake. The 9.2 magnitude quake, which occurred on Good Friday, lasted for 4 minutes and 38 seconds, causing ground fissures, tsunamis, destroying structures, and ultimately resulted in an estimated 131 deaths. In an instant, 600 miles of fault line broke and the adjacent ground was raised by as much as sixty feet, and dropped by up to eight feet in other areas. The earthquake also resulted in additional fissures, property and infrastructure damage, and landslides. The 1964 Alaskan earthquake ranks as the second most powerful earthquake ever recorded worldwide.
Washington, Oregon, and California: January 26, 1700
Referred to as the 1700 Cascadia Earthquake, the earthquake that occurred on January 26 had an estimated magnitude of between 8.2 and 9.2 and caused destruction in that area that now exists as Washington, Oregon, and California. Its name is derived from the fact that the earthquake occurred along the Cascadia Subduction zone. The earthquake caused a 620-mile fault line rupture that had an average slip of 66 ft, and also resulted in a tsunami off the coast of Japan. There is not enough information to accurately quantify the level of destruction and the number of fatalities caused by the 1700 Cascadia Earthquake.
Alaska: February 4, 1965
Almost one year after the Good Friday earthquake, Alaska experienced the 1965 Rat Islands earthquake. The earthquake had a magnitude of 8.7 and triggered a 32-ft high tsunami on Shemya Island. Records show that the impacts of the tsunami were experienced as far away as Peru, California, Mexico, Russia, Japan, and Ecuador. The earthquake originated from the boundary between the Pacific Plate and the North American Plate, called the Alaskan-Aleutian megathrust. Despite the earthquake's high magnitude, no deaths and little property damage were reported. However, tsunami flooding caused approximately $10,000 worth of damage on Amchitka Island.
Other Notable High-Magnitude Earthquakes in the United States
The state of Alaska has experienced several other earthquakes with magnitudes greater than 7.0. For example, on April 1, 1946, the 1946 Aleutian Islands earthquake and tsunami, which had a magnitude of 8.6, caused 165 fatalities and substantial property destruction. The 1957 Andreanof Islands earthquake and tsunami that occurred on March 9 had a magnitude of 8.6 but no reports of fatalities. On November 3, 2002, the Denali earthquake, which had a magnitude of 7.9, occurred in Alaska but also had no fatalities. Other earthquakes in Alaska include the 2014 Aleutian Islands earthquake (magnitude 7.9), 2018 Gulf of Alaska earthquake (magnitude 7.9), and 1958 Lituya Bay earthquakes and mega-tsunami (magnitude 7.8, five fatalities). In California, the 1857 Fort Tejon earthquake and the 1906 San Francisco earthquake both had magnitudes of 7.9. While only two fatalities resulted from the 1857 earthquake, the 1906 quake caused more than 3,000 deaths.