The 11 Biggest Earthquakes Ever to Hit the US

Earthquakes have a history of rocking Earth and, sadly, Americans' lives. There are several ways to measure the size of an earthquake. Richter scale measurements count, but accumulated damages are also important to consider.

This list reveals some of the biggest quakes in U.S. history, including both those that topped magnitude scales and those with the most devastating effects.

We don't include every big earthquake that struck American soil, but the ones on this list were among the most impactful.

Measuring Earthquakes

Scientists measure earthquakes by magnitude and intensity. They formerly relied on the Richter scale to study magnitude, which is how many of the quakes on this list are ranked. For modern earthquakes, scientists prefer the moment magnitude scale.

In either case, scientists measure the magnitude of the quake's source. When looking at intensity, they study the total shaking and damage caused, which varies by location. An earthquake might cause greater damage miles away from its source simply because that's where a city or town is located.

1. Great Alaskan Quake

On March 27, 1964, the most powerful earthquake ever recorded in the U.S. hit Anchorage, Alaska. Measuring 9.2 on the Richter Scale, the quake shook the city for over four minutes and resulted in massive damage.

It was such a powerful earthquake that land masses moved. Some were thrown as high as 82 feet! It also destroyed buildings and took the lives of 124 Anchorage residents.

2. New Madrid Series

You caught us: this one isn't just one quake. Instead, the New Madrid Earthquakes refers to a series of three large earthquakes that occurred along the New Madrid Fault in Missouri between 1811 and 1812.

According to the United States Geological Survey (USGS), the area of shaking involved with these quakes was 2 to 3 times bigger than the Great Alaskan Quake in 1964. Though the population in the area was small, the quakes caused massive geological changes, including river bank failures, landslides, and sunken land.

3. Cascadia Quake

Well before the founding fathers signed the Declaration of Independence, the west coast of what would become the United States faced a devastating earthquake. Known as the 1700 Cascadia Quake, researchers know it occurred thanks to physical evidence and the oral histories of multiple Native American and First Nation tribes.

According to the USGS, the Cascadia Quake was an estimated 9.0-magnitude seismic event that triggered a tsunami. Unfortunately, scientists predict there's a significant chance another large earthquake could have a similar effect on the Pacific Northwest within the next 50 years.

4. Rat Islands Earthquake

Just off the coast of Alaska sits the Aleutian Arc, an island archipelago known for its significant seismic activity. The Rat Islands are just a few of the islands within this massive grouping of land masses.

Luckily, they're very remote and sparsely inhabited. If they weren't, the 8.7-magnitude quake that hit in 1965 would have been much worse. As it was, little damage was done, but there was a small tsunami recorded nearby.

5. Denali Quake

In 2002, a magnitude 7.9 earthquake hit the interior of Alaska, making it the largest seismic event to rock the interior of the U.S. in 150 years. Luckily, the Denali region is remote, and few people live there full-time.

While there were no fatalities and limited building damage, Alaska's infrastructure faced serious challenges after the quake. A section of major highway shifted sideways, and the Trans-Alaska Pipeline shut down.

6. Fort Tejon Earthquake

One of the largest earthquakes to have ever struck California, the Fort Tejon Quake, left a seismic scar nearly 220 miles long. Researchers believe the quake was 7.9 magnitude, but it did little harm.

In 1857, the Fort Tejon area was largely unpopulated. As a result, there were only two fatalities, and one collapsed adobe home. It's said if this same event occurred today, the damages would run into billions of dollars.

7. Big Hawaiian Quake

In 1868, the largest recorded earthquake ever to hit the Hawaiian islands struck. It was an estimated 7.9-magnitude quake accompanied by a series of slightly smaller earthquakes that lasted multiple days.

The big quake shifted roadways, destroyed buildings, and knocked people off their horses. However, the impact area wasn't overly populated, which meant the damage was not what it could have been.

8. Great San Francisco Quake

Though it wasn't the biggest in terms of magnitude, the 1906 San Francisco earthquake is certainly one of the most significant in U.S. history. Researchers disagree on the exact magnitude, but the quake and resulting fire caused an incredible amount of damage.

Though many say this event caused the loss of 700 lives, the USGS notes that it's highly likely that figure is underestimated by three to four-fold. The city was almost entirely destroyed, and it took nearly a decade to rebuild.

9. Arizona – Mexico Border Earthquake

Technically, this earthquake's epicenter was outside of the U.S. in Sonora, Mexico. However, the damage it did in the U.S. makes it worth mentioning.

The 7.6-magnitude quake that hit in 1887 was felt from Tucson, Arizona, to Albuquerque, New Mexico. It collapsed buildings, shattered roofs, ripped streets apart, and left many homeless.

10. Loma Prieta Quake

San Francisco is known for its seismic activity, in large part because of the 1906 earthquake and resulting fire. After that quake, it seems city builders failed to learn their lesson. They unwisely rebuilt several large structures on the same soft soil.

So, when the Loma Prieta Quake hit in 1989, the same areas of the city fell. This time, a freeway collapsed alongside several other buildings, resulting in over $6 billion in damages.

11. Northridge Quake

Considered the costliest earthquake in U.S. history, the Northridge Quake, which hit Southern California in 1994, racked up an estimated $20 billion in damages. It also caused over $40 billion in economic losses.

The 6.7-magnitude event took the lives of 57 people. It caused thousands of landslides and severe infrastructure damage as far away as the Port of Los Angeles, 30 miles from the epicenter.