Earthquake Map: Dangerous US Earthquake Hot Spots Beyond California

This earthquake map shows that California isn’t the only state with a serious earthquake hazard.

There are several lesser-known fault zones striking other parts of the country. They are just as dangerous or even freakier than the San Andreas Fault.

This map gives you a closer look at the US most hazardous seismic hot spots:

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USGS

And now let’s visit these five other active and dangerous U.S. earthquake hot spots beyond California:

The Pacific Northwest: The Cascadia Subduction Zone

The biggest earthquakes in the country are not in California. A much greater hazard, at least in terms of sheer magnitude, exists to the north of the San Andreas Fault where the ocean crust is being forced beneath the North American continent.

Known as the Cascadia Subduction Zone, this 680-mile long stretch of colliding land mass 50 miles offshore of Oregon, Washington state and southern British Columbia is capable of generating magnitude 9 earthquakes 30 times more powerful than the worst the San Andreas can dish out.

Keep in mind: Cascadia is the same type of fault that caused the 2004 Sumatra quake and tsunami.

Fortunately, these mega quakes only come around once every few hundred years. Unfortunately, the fault may be due for another big one any day now. The last monster quake that ruptured the entire length of the Cascadia fault occurred in 1700 and was around a magnitude 9. It created a tsunami that crossed the entire Pacific Ocean and caused damage along parts of the Japanese coast.

Scientists had calculated an average time between these major quakes of around 270-530 years. So the next big one is around the corner!

Inside the continent: New Madrid

Most of the major earthquakes in the world occur at tectonic plate boundaries where land masses are colliding or pushing past one another. But in the middle of the country lurks a geological enigma near New Madrid, Missouri, that has produced some of the largest quakes on record for the United States but has yet to be fully explained by scientists.

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Bended trees after New Madrid earthquake

In 1811 and 1812, a swarm of at least three massive earthquakes struck near New Madrid, the largest of which exceeded a magnitude 8 and caused violent, damaging shaking in an area 10 times larger than did the 1906 earthquake. The quake was felt over an area of two million square miles — nearly two-thirds of the country. During the quakes, the ground rose and fell, trees were bent, deep cracks opened up in the ground, large landslides swept down hills, huge waves washed boats out of the Mississippi River and river banks, islands and sand bars gave way.

It has been estimated that an average time between earthquakes of 500 years. But earthquakes are impossible to predict! The USGS’s best estimate is that there is a seven to 10 percent chance of a major earthquake between magnitude 7.5 and 8 in the next 50 years.

Salt Lake City: The Wasatch Fault

The forces that have built Utah’s incredibly scenic landscape are also the source of a very serious and potentially deadly seismic hazard. Running along the base of the western edge of the Rocky Mountains, the 240-mile Wasatch Fault lies underneath Salt Lake City and the state’s urban corridor, home to 1.6 million people.

The Wasatch Fault has not delivered a major quake since the Mormon settlers arrived in 1847. But scientists have found that it is capable of unleashing jolts as big as magnitude 7.5.

Depending on where you are on the fault, earthquakes are recurent every 300 to 350 years or 1,300 years (near Salt Lake City). The last big one was 300, resp. 1,300 years ago. So we are basically due for an earthquake in this region.

Alaska

The second-largest earthquake ever recorded struck Alaska’s Prince William Sound in 1964. The magnitude 9.2 quake killed 128 people, most by the resulting tsunami.

In some places, the ground was uplifted almost 38 feet, and in others it dropped more than seven feet. The tsunami reached heights of around 220 feet locally, and killed 11 people 1,650 miles away in Crescent City, California.

The “mega-thrust” quake was the product of the collision of two tectonic plates, the oceanic plate being forced beneath the continental plate. The geologic record shows gaps of 350 to 900 years between monster quakes, which would seem to put the Alaskan coast in the clear.

Alaska’s biggest vulnerability is its transportation infrastructure. Virtually everything and everyone that goes anywhere in the state passes through Anchorage. The airport sits on ground that could suffer liquefaction — where sediments behave like a liquid when shaken in an earthquake — that could seriously damage runways and isolate the rest of the state.

Hawaii

Hawaii is well known for its volcanic hazard, but the islands are also susceptible to major earthquakes such as a magnitude 7.9 quake in 1868 that killed 77 people. Evidence of prehistoric quakes is hard to come by in Hawaii, making it especially difficult to guess when the next big one will strike.

With only the historical earthquake record to go by, scientists have little data to help them estimate the probability of another big quake in the future. The most recent giant quake was a magnitude 7.2 in 1975, 107 years after the previous one. Does this mean Hawaii can relax for another 70 years or so? It’s impossible to say. And since 1868, there have been seven quakes of magnitude 6.2 or greater, most recently a 6.7 in 2006 that caused $250 million in damage.

Hawaii is fortunate that most of its biggest earthquakes occur on the relatively sparsely populated Big Island. And the most active part of the Big Island is the south flank, which would send a tsunami out to sea instead of toward the other islands. But big ones that do sometimes strike the west flank of the island could send a tsunami to the much more populated shores of Maui and Oahu.

Hopefully will none of these faults create a dramatic quakes within the next 500 years. But, in any cases, be prepared!

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