Largest Earthquakes in US History: The USGS Top 10 List
The largest earthquake in US history is the magnitude 9.2 Great Alaska Earthquake of March 27, 1964, in Prince William Sound. It is also the second-largest earthquake ever recorded, after the magnitude 9.5 Chile earthquake of 1960, according to the USGS. Next on the US list are the magnitude 9.0 Cascadia earthquake of January 26, 1700, and the magnitude 8.7 Rat Islands earthquake of 1965 in Alaska.
What are the 10 largest earthquakes in US history?
The table below is ranked by magnitude in the USGS earthquake catalog (ComCat), as of November 2026. Nine of the ten struck Alaska. The only exception is the 1700 Cascadia earthquake off the Pacific Northwest coast.
| Rank | Date (UTC) | Place | Magnitude |
|---|---|---|---|
| 1 | March 28, 1964 (March 27 local time) | Prince William Sound, southern Alaska | 9.2 |
| 2 | January 27, 1700 (January 26 local time) | Cascadia subduction zone, northern California to British Columbia | 9.0 |
| 3 | February 4, 1965 | Rat Islands, Aleutian Islands, Alaska | 8.7 |
| 4 | March 9, 1957 | Andreanof Islands (Atka), Aleutian Islands, Alaska | 8.6 |
| 5 | April 1, 1946 | Unimak Island, Alaska | 8.6 |
| 6 | August 17, 1906 | Rat Islands, western Aleutian Islands, Alaska | 8.3 |
| 7 | November 10, 1938 | Semidi Islands, Alaska | 8.2 |
| 8 | July 29, 2021 (July 28 local time) | Chignik, Alaska Peninsula | 8.2 |
| 9 | September 10, 1899 | Yakutat Bay, Alaska | 8.2 |
| 10 | September 4, 1899 | Yakutat Bay, Alaska | 8.2 |
Ranks 7 to 10 differ only in the second decimal place in the catalog (8.23, 8.2, 8.16 and 8.16). The two 1899 entries are separate major shocks in the same September sequence. Next on the list is a magnitude 8.0 near Atka, Alaska, on May 7, 1986.
What do the USGS records say about the top five?
1964, Prince William Sound (M9.2). The earthquake struck at 5:36 p.m. local time and lasted about 4.5 minutes, according to the USGS 1964 event page. The earthquake and tsunamis took 131 lives, 122 of them from tsunamis. Property loss was about $311 million in 1964 dollars.
1700, Cascadia (M9.0). The USGS dates this earthquake to about 9 p.m. on January 26, 1700, using written records of a tsunami in Japan and tree rings from drowned coastal forests. A USGS fact sheet gives its magnitude as between 8.7 and 9.2. Our Cascadia subduction zone guide covers the evidence.
1965, Rat Islands (M8.7). The USGS catalog notes a tsunami reported to be about 10.7 meters (35 feet) high on Shemya Island, and cracks in buildings on Adak Island.
1957, Andreanof Islands (M8.6). This earthquake was once listed at magnitude 9.1, and the USGS has since revised it to 8.6. It destroyed two bridges on Adak Island, and its tsunami caused about $5 million in property damage on Oahu and Kauai in Hawaii.
1946, Unimak Island (M8.6). Shaking caused only minor damage, but the tsunami struck the Scotch Cap Lighthouse and swept away its five occupants. In Hilo, Hawaii, the same tsunami took 159 lives, according to the USGS catalog.
What are the largest earthquakes outside Alaska?
Outside Alaska, the largest events are spread across the West Coast, Hawaii, Puerto Rico and the central United States. Values are from the USGS catalog; magnitudes for pre-instrument events are estimates.
| Region | Earthquake | Year | Magnitude |
|---|---|---|---|
| Pacific Northwest | Cascadia subduction zone | 1700 | 9.0 |
| California | Fort Tejon, San Andreas fault | 1857 | 7.9 |
| California | San Francisco, San Andreas fault | 1906 | 7.9 |
| Hawaii | Great Kaʻū earthquake, Island of Hawaii | 1868 | 7.9 |
| Central US | New Madrid seismic zone (two principal shocks) | 1811 and 1812 | 7.5 |
| Puerto Rico | Offshore, north of Puerto Rico | 1943 | 7.7 |
| Montana | Hebgen Lake | 1959 | 7.2 |
| Nevada | Fairview Peak | 1954 | 7.1 |
| South Carolina | Charleston | 1886 | 7.0 |
The USGS catalog calls the 1868 earthquake the largest in Hawaii’s recorded history; it caused 77 deaths, 46 from a tsunami and 31 from a landslide. The New Madrid shocks of December 16, 1811, and February 7, 1812, are each listed at magnitude 7.5. Our New Madrid seismic zone guide explains why shaking from them spread so far.
Why are most of the largest US earthquakes in Alaska?
Alaska sits on the Alaska-Aleutian subduction zone, where the Pacific plate slides beneath the North American plate. The USGS says the 1964 earthquake was caused by this under-thrusting motion. It describes the 2021 Chignik earthquake as thrust faulting on or near the same subduction zone interface, and says large earthquakes are common there. Our guide to why Alaska has so many earthquakes covers the other fault types in the state.
The 1700 Cascadia earthquake was also a subduction zone megathrust earthquake, according to the USGS. California’s two largest, in 1857 and 1906, came from the San Andreas fault, a strike-slip fault where the plates slide past each other.
Is the largest earthquake also the deadliest?
No. Magnitude measures the size of the earthquake, not its toll. The 1906 San Francisco earthquake (M7.9) and the fires that followed caused an estimated 3,000 deaths, according to the USGS. The much larger 1964 Alaska earthquake (M9.2) took 131 lives. The USGS says more damage in 1906 is thought to have come from the fires than from the shaking itself, and in 1964, 122 of the 131 deaths were caused by tsunamis. Our guide to earthquake magnitude explains what the number does and does not measure.
How does the USGS estimate the size of old earthquakes?
There were no seismographs for many of these events, so their magnitudes are estimates that can change. For the 1811–1812 New Madrid earthquakes, five studies between 1996 and 2011 gave values from 6.8 to 8.1 for the first shock. The USGS adopted 7.5 as the best average for its 2014 National Seismic Hazard Map. The 1700 Cascadia magnitude comes from modeling of the tsunami described in Japanese records. The 1957 Andreanof Islands earthquake shows that newer instrument-era events can be revised too.
How can you look up large earthquakes yourself?
- Open the USGS Lists, Maps, and Statistics page and choose the United States magnitude 8+ or 7+ list. The USGS notes these lists also include some earthquakes outside the US, because the search area is a rectangle.
- Click any event to open its USGS event page, where the impact and tectonic summaries give the details quoted above.
- For current activity, see our live list of USGS earthquakes worldwide or recent earthquakes in Alaska.
Bottom line
The 1964 magnitude 9.2 Alaska earthquake tops the US list and ranks second in the world. Nine of the ten largest US earthquakes in the USGS catalog struck Alaska, and the other is the 1700 Cascadia earthquake. Outside Alaska and Cascadia, the largest events in the catalog are magnitude 7.9, in California and Hawaii.
FAQ
What is the largest earthquake ever recorded in the US?
The largest is the magnitude 9.2 earthquake in Prince William Sound, Alaska, on March 27, 1964 (March 28 UTC). The USGS calls it the most powerful recorded earthquake in US history.
What is the largest earthquake in the contiguous United States?
In the USGS catalog, it is the 1700 Cascadia earthquake, listed at magnitude 9.0. Since 1800, the largest are the 1857 Fort Tejon and 1906 San Francisco earthquakes, both magnitude 7.9 on the San Andreas fault.
Has the US had a magnitude 9 earthquake since 1964?
No. The largest US earthquake in the USGS catalog since 1964 is the magnitude 8.7 Rat Islands earthquake of 1965. The most recent magnitude 8 is the 2021 magnitude 8.2 Chignik earthquake in Alaska.
What is the largest earthquake ever recorded in the world?
The largest recorded earthquake in the world was a magnitude 9.5 in Chile on May 22, 1960, according to the USGS.