What are the largest earthquakes to ever hit the United States?

Answer 1

In terms of magnitude, the largest earthquake ever measured in the United States occurred on March 27, 1964, in Alaska, registering a whopping 9.2 on the Richter scale.

If you’re looking for more information, here’s a breakdown of the largest U.S. earthquakes by magnitude. Note that when discussing the biggest earthquakes in history, there’s a minor issue: Charles Richter invented his magnitude scale in 1935, and earthquakes prior to that are assigned magnitudes based on comparing records of their effects to those of modern earthquakes. Therefore, there’s some degree of uncertainty with older ratings, so keep that in mind while reading.

1. Date: March 27, 1964
   • Location: Alaska
   • Magnitude: 9.2
   • The Impact: Now known as the Great Alaska Earthquake, this was a major turning point in geological science. It lasted for about four or five minutes and triggered a tsunami that caused devastating damage to California’s Kodiak Islands. In total, the quake caused over $2 billion in property damage (in modern dollars) and around 130 fatalities. However, it also gave scientists a wealth of data that was used to improve earthquake science.
2. Date: Jan. 26, 1700
   • Location: California, Oregon, and Washington
   • Magnitude: 8.7-9.2
   • The Impact: Known as the 1700 Cascadia earthquake, this disaster was not well-documented in North America, but indigenous peoples in the region have stories about the event. The quake caused a massive tsunami that affected Japan, and written accounts from Japanese sources have allowed scientists to estimate the quake’s size.
3. Date: Feb. 4, 1965
   • Location: Alaska
   • Magnitude: 8.7
   • The Impact: The Rat Islands earthquake was powerful enough to rupture a 600-kilometer segment of the Aleutian Islands. It caused a tsunami, but fortunately, it affected mostly uninhabited areas, causing only $10,000 in damage.
4. Date: April 1, 1946
   • Location: Alaska
   • Magnitude: 8.6
   • The Impact: If you haven’t caught on yet, Alaska’s a fairly active seismic zone. This quake resulted in 167 deaths and caused over $26 million of property damage. It also sent a massive tsunami to Hawaii, with waves reaching a height of 45 feet. Puzzlingly, the earthquake shouldn’t have been strong enough to create a tsunami of that size.
5. Date: March 9, 1957
   • Location: Alaska
   • Magnitude: 8.6
   • The Impact: Yet another Aleutian Islands earthquake. This one was centered near the Andreanof Islands on the southern arc of the Aleutians, and it caused severe damage to structures. Fortunately, no fatalities are linked directly to this earthquake, even though it caused a tsunami that reached all the way to Hawaii. Witnesses reported waves of up to 75 feet high.
6. Date: Jan. 9, 1857
   • Location: California
   • Magnitude: 7.9
   • The Impact: The most recent “big one" affecting the San Andreas fault, the Great Fort Tejon Earthquake caused extensive property damage and one fatality. It was technically larger in magnitude than the much more destructive 1906 San Francisco earthquake. Reports described a strong shaking lasting from one to three minutes, ground fissures, and sunken trees.
7. Date: April 2, 1868
   • Location: Hawaii
   • Magnitude: 7.9
   • The Impact: This was the largest earthquake ever recorded on Hawai’i (the largest of the Hawaiian Islands). Stone buildings were decimated, and the shaking caused landslides and a tsunami. It took 47 lives and permanently moved a large part of Hawai’i.
8. Date: April 18, 1906
   • Location: California
   • Magnitude: 7.9
   • The Impact: The Great 1906 San Francisco earthquake ruptured 296 miles of the San Andreas fault and left about 200,000 people homeless. An estimated 3,000 people lost their lives, and almost 500 city blocks were decimated. It also caused $400 million in damage—in 1906 dollars.
9. Date: Nov. 3, 2002
   • Location: Alaska
   • Magnitude: 7.9
   • The Impact: This quake occurred on the Denali fault, knocking sections of the trans-Alaska oil pipeline into disarray and opening an enormous fissure on the highway between Anchorage and Fairbanks. While it caused some property damage, it only caused one injury (a 76-year-old woman broke her arm).
10. Date: June 23, 2014
    • Location: Alaska
    • Magnitude: 7.9
    • The Impact: The most recent quake on this list struck Little Sitkin Island, and scientists initially estimated it at 8.0 magnitude. That estimate was later revised to 7.9. It created a small tsunami, which caused no damage, and no casualties were reported.