EARTHQUAKES

During the 20 th century, earthquakes occurring in Alaska released 25 percent of all earthquake energy released in the world.

Each year in Alaska there are more than 5,000 earthquakes recorded, including 550 that measure greater than 3.0 on the Richter scale. There were 37 earthquakes recorded with a magnitude greater than 7.25 in Alaska during the 20th century.

Of the ten strongest earthquakes ever recorded on the world, three have occurred in Alaska : The great earthquake of 1964 was 2nd strongest with magnitude 9.2; the central Aleutians earthquake of 1957 was 3rd with magnitude 9.1; and the western Aleutians earthquake of 1965 was 6th with magnitude 8.7. Alaska has had seven out of the ten largest earthquakes recorded in the United States .

Recent geologic data show that the previous great earthquake (larger than magnitude 8) in the Anchorage area was about 800 years ago. The average recurrence interval for the largest earthquakes in this region is 600 to 800 years, but damaging earthquakes in the 7-8 range can occur more frequently.