- A 7.8 magnitude earthquake rocked Turkey on Monday, leaving a devastating death toll of nearly 24,000.
- The U.S., particularly along the west coast, is susceptible to large earthquakes.
- Here's where they could happen and how to prepare for them.
A 7.8 magnitude earthquake struck southern Turkey and Syria on Monday night in what's being recorded as the countries' worst natural disaster in recent memory — a stark reminder of the devastating tolls of strong earthquakes when regions are underprepared.
The U.S. is also prone to earthquakes of large magnitudes, particularly along the west coast, since there are many faults — put simply, a fracture between two very large rocks — in the country, Alex Hatem, a research geologist at the United States Geological Survey, told Insider.
"We're always monitoring the seismic network, called the Global Seismic Network," Hatem said. "So of course, that includes the United States as well as every other place on Earth. And we know in the U.S. that there are several places where we could have an earthquake this big."
Fault lines and studying the history of earthquakes can provide geologists and seismologists with a clue into where the next major earthquake might occur.
Turkey, for example, sits on the nexus of several large and small tectonic plates, making the country a highly seismically active region, John Louie, a geophysics professor at the University of Nevada, Reno, told Insider. The last time Turkey experienced an earthquake this large was in 1939, which left nearly 33,000 people dead.
The fault lines and a combination of a populous area, outdated building practices, and a yearslong civil war in Syria that hobbled the region's infrastructure left the two countries in a particularly vulnerable position.
"It just hit one of the worst prepared areas within Turkey and, of course, the war zone in Syria," Louie said. "There's no way to be prepared there, so it really is a terrible catastrophe."
There's no standard measurement of what makes an earthquake the "Big One," but there are several US states that can experience a shake at the magnitude of Turkey's earthquake.
Here are where the biggest earthquakes in the US can occur, and what you can do to prepare for them.
The west coast, including California, is capable of the largest magnitude events, Hatem said.
The state sits on the San Andreas fault, which is the 750 mile-split between two plates — the Pacific and North American plates — sliding past each other.
Previous earthquakes give researchers an idea of what the fault is capable of, Hatem said.
She noted the 1906 earthquake in San Francisco and the 1857 earthquake in Fort Tejon of southern California, both of which were a 7.9 magnitude.
It's impossible to say when the next major event will occur, but it is inevitable, Hatem said.
"We do know how frequently these earthquakes have occurred in the past," she said. "We know that they occur in the order of hundreds of years. But we can't really say, 'Okay, from the last earthquake plus 100 years is when we'll expect the next one."
Because California is better equipped with up-to-date building codes and standards, the impact won't be quite as large as the earthquake in Turkey but it can still be devastating.
According to a 2008 report from the USGS that simulated a "Shakeout Scenario," a 7.8 magnitude in southern California can bring a death toll of 1,800 people, with most deaths concentrated in Los Angeles County.
About 50,000 people could be injured and between 500,000 to 1 million people could be displaced from their homes.
Above the San Andreas fault is the Cascadia subduction zone, Hatem said.
It's a convergent plate boundary in which the oceanic plate is sliding underneath Washington, Oregon, and the northernmost parts of California. To compare, the San Andreas fault is made up of plates slipping laterally.
The Cascadia Fault is Oregon's most active subduction zone, according to the Oregon Department of Geology and Mineral Industries, and produces magnitude 8 to 9 earthquakes every 450 to 500 years on average.
The last time an earthquake in that range of magnitude hit the state was in 1700.
There are several other faults in Oregon that produce magnitude 5 to 6 earthquakes, according to the state department.
Washington is also vulnerable to the Cascadia Subduction Zone.
While the state lies on faults lines that are similar to the faults in Turkey, in that they lie shallow in the Earth's crust, the major earthquake will most likely come from the Cascadia fault, Harold Tobin, a director of the Pacific Northwest Seismic Network told KUOW radio station.
It's uncertain when that "big one" will come, however.
"We think that it doesn't happen very often, centuries apart. But, we don't know," Tobin told KUOW.
Near the southern coast of Alaska is the Alaskan subduction zone, Hatem said, in which the Pacific plate is being pushed underneath the state.
"Each year, the Pacific Plate pushes a couple of inches towards Alaska, which is generally considered to be part of the North American Plate," according to the University of Alaska Fairbanks's earthquake center.
In 1964, a magnitude 9.2 earthquake struck south-central Alaska, making the event the largest earthquake in North American history and the second largest worldwide.
Midwestern and eastern United States
Though the west coast is most vulnerable to "The Big One," there are also a few areas throughout the midwestern and eastern US that experience earthquakes more frequently than other areas.
According to Michigan Tech, "the most earthquake-prone areas include Charleston, South Carolina, eastern Massachusetts, the St. Lawrence River area, and the central Mississippi River Valley."
"Earthquakes can happen in the eastern part of the US. They're just far less frequent than that are on the west," Hatem said, noting that they probably also won't experience the same magnitude as events on the west coast.
How to prepare.
The moment an earthquake strikes, the Earthquake Country Alliance recommends three steps: drop, cover, and hold on.
The thinking behind the steps is to reduce the risk of being knocked down and hit by falling or flying objects.
As you crawl, you'll also want to search for cover, ideally a sturdy table. If a table is not available go to the nearest interior wall away from windows.
In the aftermath of a large event, there's a high likelihood that major utilities will be disrupted, Hatem said.
"I would say to make sure you have enough water for you and your family for a few days," she said. "Having some water, non-perishable food, maybe some charged battery packs, a blanket, and some basic safety equipment like a flashlight would be advisable."
Louie, the University of Nevada, Reno, geophysics professor, also recommends having enough resources to shelter for at least 72 hours to a week.
The Earthquake County Alliance has an extensive guide on how to secure your space before an earthquake, what emergency supplies to collect, and what to do after a major event.
Shakeout.org also shows state-by-state resources that are available, Louie said.
"Earthquakes, at least for us in the US who don't live in a big apartment, if you have your own property, you really can make yourself safe from earthquakes," Louie said.