San Francisco after the infamous 1906 earthquake, which had a magnitude of at least 7.7 on the moment magnitude scale.
Six of the ten occurred in the state of California
The state of California is well known as one of the most active earthquake areas on Earth, although if Alaska was included for US quakes, it would take up most of this list. Alaska gets much larger earthquakes than California, although is far less populated, and the quakes therefore cause far less economic damage and casualties.
The earthquakes below don't show the full potential of what could someday happen in the USA, because the most recent massive earthquake to strike California occurred in 1906. Since this time, in 108 years, California's population has increased from about 2 million to 48 million persons. More people and larger cities mean more damage when the next "big one" hits.
Let the stories below serve as a good reminder for properly preparing for disasters, whether earthquakes or any of a variety of other things. Volcanic eruptions, meteors hitting the Earth, terrorist attacks, wars, floods, storms, droughts, and more are all possibilities that everyone should prepare for to whatever extent they can.
If you live on the East Coast and think you're safe from earthquakes, you're wrong. In 1886 there was a 7.3 earthquake in South Carolina, and in 1811 and 1812 there were four earthquakes in Missouri that were at least magnitude 7.1. Geologists say earthquakes like this may be possible even near New York City someday.
After going into the details below of the top three major quakes, I round out the top ten with info about the next seven largest to have occurred in the 48 continental US states.
About earthquake measurements
Since the 1970s earthquakes have most often been measured on the moment magnitude scale,which is the successor to the old Richter scale. Magnitude ratings in this article will be expressed in one or the other, and the MMS was designed to give similar numbers, although express the strength of earthquakes more accurately.
To read more about how the Richter and moment magnitude scales work, see my article here on InfoBarrel, Measuring Earthquakes: The Moment Magnitude Scale.
Locations of the ten major earthquakes discussed below
These are the locations of the ten largest earthquakes that have ever occurred in the 48 continental US states.
#1 - Fort Tejon Earthquake, magnitude 7.9
1857 near Paso Robles, California
Fort Tejon is a former military outpost, and is now a California state historic park.
This earthquake is named after Fort Tejon, a military outpost during the 19th century, which was damaged by the earthquake and located near the epicenter. Today it is a state historic park.
California’s infamous San Andreas Fault runs from the Salton Sea in Southern California’s Sonoran Desert northward past San Francisco, and it terminates just offshore near the northernmost part of the state. During the quake, 225 miles (362 km) of this fault ruptured, and on average moved 15 feet (4.5 meters), and in one place moved 30 feet (9 meters).
This was the most recent “big one” to hit Southern California, and as a resident of Southern California for most of my life, I’ve been hearing for more than 30 years, since I was a small child, that we’re overdue for another one. Earthquake drills are common, and small to moderate sized earthquakes are also common. Occasionally we get a larger one, but none have reached or exceeded magnitude 7.5 in quite some time.
Although I stated above that the epicenter was near Paso Robles, the town didn’t exist at the time. Much of California was still sparsely populated, and just two deaths occurred as a result of the quake. Enough is known from reports of the shaking in Los Angeles and San Francisco to give geologists confidence in the magnitude rating it’s been given.
#2 - San Francisco Earthquake, magnitude 7.7 to 8.3
1906 in San Francisco, California
San Francisco's earthquake damage in 1906 was made worse by dozens of fires which raged for four days, destroying 80% of the city.
This one may belong in the #1 position, although with varying estimates for the magnitude, I’ve placed it here. The most common estimate for the magnitude is 7.8 to 7.9.
The Great San Francisco Earthquake is one of the worst natural disasters in the history of the USA, with between 3,000 and 3,400 fatalities and 80% of San Francisco being completely destroyed. The population at the time was 410,000 and about 60 to 75% of the population was left homeless by this disaster.
Much of the destruction of the city was made worse by fires. About 30 fires raged for four days due to ruptured gas lines, a case involving a woman whose kitchen caught fire when she was making breakfast, and some others were caused by firefighters trying to use dynamite to level buildings heavily damaged by the quake.
The fires alone completely eliminated 25,000 buildings over 490 city blocks. Economic damages to San Francisco totaled at least $11 billion in today’s dollars, and other towns such as Santa Rosa to the north were heavily damaged as well. Reconstruction of San Francisco was mostly completed within a decade.
This was another case of a major rupture of the San Andreas Fault, and this quake featured 296 miles (500 km) shifting up to 28 feet (8 meters) in places. Shaking lasted for 42 seconds.
At Point Reyes National Seashore to the north, I’ve walked their Earthquake Trail which goes right over the San Andreas. There’s an old fence that’s been there since the 1906 disaster, which is offset by 18 feet (5.5 meters), the distance that it moved during the quake.
#3 - Lone Pine Earthquake, magnitude 7.6 to 8.0
1872 near Lone Pine, California
Owens Valley on the east side of the Sierra Nevada Mountains in California is the location of the epicenter of the 1872 Lone Pine Earthquake.
Here’s the largest one that’s occurred in California that was not on the San Andreas Fault. This one is given a minimum rating of 7.6, although the exact magnitude is difficult to estimate. It could have potentially been 8.0 or larger, and may even belong at #1 on this list.
The Lone Pine Fault is located in the southern portion of the Sierra Nevada Mountains, and the earthquake caused it to move vertically 15 to 20 feet (5 to 6 meters), and laterally 35 to 40 feet (10 to 12 meters). Geologists have said that the fault produces earthquakes like this every few thousand years.
The quake leveled the small town of Lone Pine, killing 27 of its 270 or so residents. Other nearby settlements had almost all buildings leveled as well. It occurred at 2:10 am and was felt strongly in Sacramento and in Yosemite Valley. It was felt in San Diego and throughout the state of Nevada.
In Yosemite Valley, giant rockslides occurred as a result. Famed naturalist John Muir was there at the time and ran out of his cabin yelling, “A noble earthquake!” He immediately began surveying the rocks that fell, under the moonlight.
Economic damages were estimated at $250,000. In 2015 dollars, this translates to about $4.8 million.
The next seven largest earthquakes in the continental 48 states
Joshua Trees grow in California's High Desert, also called the Mojave Desert, the site of the 1992 Landers Earthquake. I was right near the epicenter, and it's the largest earthquake I've been in.
#4 – 1959 Yellowstone Earthquake, 7.3 to 7.8 (Montana)
Also called the Hebgen Lake Earthquake, this one may have been large enough to be in second place. It occurred to the west of Yellowstone National Park and its supervolcano, on the other side of the state border, in Montana. There were 28 deaths, many caused by landslides, and it was felt throughout Montana, Idaho, Wyoming, and Northern Utah.
#5 – 1952 Kern County Earthquake, 7.3 to 7.5 (California)
Centered near Bakersfield at the southern end of California’s San Joaquin Valley, this quake originated with the White Wolf Fault which is near but not connected to the San Andreas Fault. Twelve deaths occurred, and the town of Tehachapi was the most heavily damaged. It may have been larger than the Yellowstone Earthquake.
#6 – 1992 Landers Earthquake, 7.3 (California)
I was in a car traveling on a highway in the Mojave Desert near the epicenter when it hit, and the road moved in front of me in waves. Three people died but there was not much damage overall because it occurred in an area not very heavily populated. It involved six different faults, although did not involve the nearby San Andreas Fault.
#7 – 1983 Borah Peak Earthquake, 7.3 (Idaho)
The largest quake to ever hit Idaho heavily damaged some towns northeast of the capital Boise, and two fatalities occurred. This is another of the largest earthquakes known in the Rocky Mountains, and possibly as large as the 1959 Yellowstone Earthquake discussed above.
#8 – 1886 Charleston Earthquake, 7.3 (South Carolina)
Perhaps the most mysterious on this list, the cause of this quake is unknown. Some estimates put it at 6.6, although this is still much larger than what is typically seen in the eastern USA. At least 60 fatalities resulted, and thousands of buildings in Charleston were heavily damaged.
#9 – 1992 Cape Mendocino Earthquake, 7.2 (California)
Two months before the Landers Earthquake, this one occurred in Northern California near Eureka and involved the San Andreas and two other faults. Two large aftershocks the next morning registered 6.5 and 6.6. Although the quake heavily damaged buildings and homes, and caused hundreds of injuries, no one died.
#10 – 1811 to 1812 New Madrid Earthquakes (total of four), 7.1 to 7.4 (Missouri)
Magnitude estimates vary, although the most plausible in my opinion is for the range stated. A fault zone exists near the border of Missouri and Tennessee, and geologists aren’t sure why it’s there. If it were to happen again, heavy damage could be expected in Memphis, Nashville, St. Louis, Little Rock, and other cities in the region.
Other earthquakes magnitude 7.0 or greater
Here are other large earthquakes that have occurred in the continental 48 US states:
Pleasant Valley Earthquake, Nevada, 1915 – 7.1
Olympia Earthquake, Washington, 1949 – 7.1
Hector Mine Earthquake, California, 1999 – 7.1
North Cascades Earthquake, Washington, 1872 – 7.0
Hayward Earthquake, California, 1868 – 7.0
Costa Rica 7.6 earthquake in 2012
If you’ve never experienced a large earthquake, this video should give you a good idea of how hard the earth can shake. Of course, earthquakes get bigger than this – although the magnitude of this one is similar to many on this page.
This is security camera footage in a supermarket, and you can see how easily the shelves and everything are shaken and many items fall.