Are US earthquakes becoming more costly?

Damages from earthquakes in the US have nearly doubled in the last five years, according to the latest data from the federal government.

A 2023 report from the US Geological Survey (USGS) and the Federal Emergency Management Agency (FEMA) estimates that damages from earthquakes total around $14.7 billion per year, up from the inflation-adjusted 2017 estimate of $7.5 million. The report attributes the rise to increased exposure as more people move to earthquake-prone areas and more is invested in infrastructure in those areas.

Where are earthquake damages highest?

Nearly two-thirds of the nation’s estimated annual losses — $9.6 billion — hit California, with another $1.2 billion in Washington and $745 million in Oregon. Aside from the Pacific Coast, damages are highest in Utah ($367 million) and Puerto Rico ($327 million).

In North Dakota, $132,000 of damages are projected annually, less than four times lower than any other state.

How many people are injured in earthquakes in the US?

The USGS and FEMA report also makes annualized estimates of how many people are injured and killed in earthquakes in the US: 6,394 minor injuries, 183 major injuries, and 360 fatalities per year.

Over 60% of those injuries happen in California, while Washington and Oregon rank second and third in all categories.

Seven states average zero annual injuries due to earthquakes.

How common are earthquakes in the US?

In 2023, 2,296 earthquakes of magnitude 2.5 or higher struck in or near the continental US, including 22 with magnitudes of 4.5 or higher.

From January 1 to May 21, 2024, there were 981 2.5+ earthquakes in the continental US, putting the country on track for 2,528 total in the year. Thirty of those were 4.5s or higher — continuing at that pace will give the US its highest total since 1992.

There have been 30 earthquakes of magnitude 6 or higher near the continental US since the turn of the century, most recently in 2022.

What causes an earthquake?

Earthquakes happen when the tectonic plates that make up the Earth’s crust shift suddenly, causing shaking at the planet’s surface. Earthquakes are typically felt along the plates’ edges, called faults.

The San Andreas Fault is a major locus of earthquakes in the US. The San Andreas Fault Zone, which includes the main fault line and its branches, runs over 800 miles between the Pacific Plate and the North American Plate and extends more than 10 miles into the earth’s crust.

Can earthquakes be caused by human activity?

Earthquakes can also be induced by the disposal of waste products from oil production. Fracking induces some earthquakes, but the more common cause is wastewater disposal. This has caused an increase in earthquakes in the central United States — particularly in Oklahoma — in recent decades.

According to the US Geological Survey (USGS), there were an average of 25 overall earthquakes of magnitude 3 or higher in the central and eastern US from 1973 to 2008. That number began increasing in 2009, and each year from 2013 to 2022 hit a minimum of 100, peaking at 1,010 in 2015. The USGS attributes this increase primarily to wastewater disposal.

How are earthquakes measured?

A global network of seismic stations records vibrations in the earth’s crust. The size of an earthquake (also called its magnitude) is measured by charting these vibrations on a logarithmic scale — in this case, that means that a difference of one whole number of measured magnitude indicates a tenfold increase in the size of the earthquake.

According to USGS, the experience of an earthquake depends on how close you are to its epicenter and how large it is. A large earthquake nearby will cause a sudden jolt followed by violent shaking. If you’re farther away, it will be a gentler bump followed by rolling shaking that may last seconds or even minutes. Smaller earthquakes will pass quicker, if felt at all.

While magnitude measures the vibrations in the earth, the way people experience an earthquake is measured by the Modified Mercalli Intensity Scale, which is indicated by Roman numerals I–X. An earthquake with an intensity of I is not felt by more than very few people; a moderate earthquake with an intensity of V is felt by nearly everyone and may break windows or overturn some objects; a severe earthquake (VIII) will cause considerable damage in substantial buildings.

For reference, the October 1989 earthquake that struck the San Francisco Bay Area was measured at magnitude 6.9 and an intensity of IX. The March 2011 Great Tohoku Earthquake in Japan had a magnitude of 9.1 and an intensity of VIII. The February 2023 earthquake that struck near the border of Turkey and Syria had a magnitude of 7.8 and an intensity of IX.

How high do earthquake magnitudes go?

There is no upper limit to earthquake magnitude. In hundreds of years of USGS earthquake data, six earthquakes have surpassed 9.0. The largest was Great Chilean Earthquake, which struck with a magnitude of 9.5 near Valdivia, Chile, on May 22, 1960.

The largest earthquake ever recorded in the US was a 9.2-magnitude earthquake that struck Prince William Sound in Alaska on March 28, 1964.

The largest event recorded near the contiguous US predated the country itself. The 9.0-magnitude 1700 Cascadia Earthquake struck off the coast of what is now Oregon on January 27 of that year. No other earthquake near the US has reached 8.0 on the magnitude scale, and none of the largest 10 earthquakes have come in the last 70 years.

Where do earthquakes happen most often?

Smaller earthquakes occur daily in the US. In 2023, there were more than six earthquakes of 2.5+ magnitude per day. About 1% of those reached 4.5.

Globally, larger earthquakes happen daily. There were 7,643 earthquakes of magnitude 4.5 or higher in 2023 — nearly 21 a day — including 1,780 over 5.0, 147 over 6.0, and 19 over 7.0.

Most global fault lines are beneath the oceans, so many earthquakes aren’t felt by humans. But there are some major global population centers on faults, where earthquakes can and do cause major damage and loss of life.

In the continental US, the vast majority of earthquakes at 4.5+ happen on the west coast, within the San Andreas Fault Zone.

In 2023, the most epicenters of smaller earthquakes were on or around the California coast (839), in Texas (453), and in New Mexico (323), though residents of abutting states may have also felt their effects.

Alaska

Alaska’s Aleutian Islands lie along a tectonic fault line, making Alaska a common earthquake location. In 2023, there were 122 earthquakes of magnitude 4.5 or higher in Alaska, most of which struck along the Aleutians.

Earthquakes in Pacific islands

America’s Pacific island states and territories also fall in earthquake-prone regions. Hawaii, Guam, the Northern Mariana Islands, and American Samoa all experience earthquakes of magnitude 4.5 or higher.

In 2023, USGS listed the Northern Mariana Islands as the nearest location to the epicenter of 160 such events, while Guam was the location for another 62, Hawaii for 3, and American Samoa for 2. (This count may not include all earthquakes felt in these regions, since earthquakes may be felt across a broad swath of territory, not only at the central location.)

In the Caribbean, Puerto Rico and the US Virgin Islands are also subject to earthquake activity, though less frequently. From 2000–2023, Puerto Rico was the central location of 98 4.5+ earthquakes, and the USVI experienced 87.

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