What are the places with the highest seismic risk in the US?

California has always been listed as the state with the highest seismic risk in the United States, due to the San Andreas fault. However, in recent years other cities have been affected by earthquakes.

In 2020, the country had at least four earthquakes with a magnitude greater than 5.5 degrees, which occurred in Nevada, Idaho, Utah and Alaska. In fact, in July 2021, Alaska was rocked by the earthquake most powerful of the last half century in the United States, which was a degree of 8.2.

Considering the frequency of past earthquakes and fault slip rates, the data reveals that a major earthquake could occur in various parts of the country. According to the United States Geological Survey (USGS) and its National Seismic Hazard Maps that predict long-term seismic activity, these are the places with the highest seismic risk in the United States.



Seismic activity in California is widely known, and high-risk areas cover large parts of the state, including the San Francisco Bay Area, Los Angeles, and San Diego. According to him USGS, within the next 30 years the probability of a 6.7 earthquake in Los Angeles is 60 percent, while in San Francisco it is 72 percent.

The San Andreas fault has caused some of the most notable earthquakes in recent times, which have been especially destructive because they occur in overly populated places. In 1994, the 6.7-magnitude Northridge earthquake near Los Angeles left 57 dead, injured more than 8,700, and caused $13 to $40 billion in damage.

According to a 2013 report, it is estimated that every 6.7 years there could be an earthquake the size of Northridge or larger in some area of ​​the state.

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Pacific Northwest

Another major fault is the Cascadia fault, which runs along the Pacific Northwest from near Vancouver, Canada, to near Cape Mendocino, California. If a major earthquake occurs along this fault, it could affect the cities of Seattle, Tacoma, Portland, Eugene, Salem, and Olympia.

With a full margin rupture, the entire shelf from California to Canada could shift six feet down and 30 to 100 feet to the west, flattening the mountains and releasing current geocompression. According predicts According to the Federal Emergency Management Agency (FEMA), an earthquake and tsunami in Cascadia would leave 27,000 injured, 13,000 dead and would damage a million homes.

In the next 50 years, the chances of a major earthquake in this area are about 33 percent. However, even a small one has the potential to cause property damage and breakages.

Charleston, South Carolina

As it belongs to the Middleton Place-Summerville seismic zone, the Charleston area is at high risk of a damaging earthquake in the next 50 years. In 2014, University of Charleston seismologist Steve Jaume He said: “We are the target on the east coast.”

During the great Charleston earthquake of 1886, nearly every building in the city was damaged and most had to be demolished. Structural damage occurred within a radius of several hundred miles, stretching across South Carolina and reaching as far south as Virginia and central Ohio.

The latest USGS maps have slightly increased the risk of earthquake hazards in the area. This could mean building codes are updated and more homeowners repair the foundations of their homes to protect against a seismic threat.

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Anchorage and the south coast of Alaska

Alaska is one of the most seismically active places in the world. Some 11 percent of the world’s earthquakes occur there, and they occur frequently. They are of a significant proportion, averaging one per year with a magnitude of seven to eight, and a magnitude of eight or more every 13 years.

The active Alaska-Aleutian Megathrust fault makes seismic safety a concern for everyone in the state. Support beams could collapse, unsecured homes could be dragged or bounce off their foundations, and the ground under homes could slide down a slope.

New Madrid, Missouri

The New Madrid Seismic Zone (or Fault Line) in Missouri is one of the most active seismic areas east of the Rocky Mountains and has about 200 small earthquakes per year.

In the Mississippi Valley, near the junction of Missouri, Illinois, Kentucky, Tennessee, and Arkansas, a sequence of three earthquakes occurred between 1811 and 1812; one of the largest in US history. In fact, these reportedly caused the Mississippi River to recede.

Unlike coastal faults, an earthquake in the center of the country presents risks of a different magnitude. In particular, a disruption of the Mississippi River could cause severe inland flooding and levee failure; the rivers would take over parts of southern Missouri, Arkansas, or western Kentucky.

the island of hawaii

Along with its active volcanoes, Hawaii has thousands of earthquakes each year. Most of them are small, some can be felt, and some are large enough to cause significant damage.

An earthquake with a magnitude of 5.0 to 5.9 occurs once every 1.5 years on average. For a magnitude of 6.0 to 6.9, the average is once every 7.7 years. And an earthquake with a magnitude of more than 7 occurs approximately every 56 years.

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