How many quakes are there in Alaska

Earthquake in the USA

The most significant earthquakes in the United States have been recorded along the Pacific coast. The earth in the “Midwest” (especially in the state of Oklahoma) or even on the east coast of the United States shakes again and again. The geological background has not been fully clarified in every case. Current: On January 23, 2018, an earthquake off the south coast of Alaska triggered a tsunami warning. Despite a magnitude of 8.2, the risk to humans was only moderate, as the coastal regions of Alaska and Canada are mostly sparsely populated. The tsunami warning could be lifted again.

Tectonic causes

Well over half of all earthquakes take place in the immediate vicinity of the Pacific Ocean. The North American tectonic plate, on which the USA also lies, migrates westward, pushes itself over the Pacific plate and pushes it down at the edge of the plate. In some regions the tectonic plates collide head-on, in other regions the plates slide past one another. Strong earthquakes can occur in both variants.

The west coast of the USA is one of them "Pacific Ring of Fire", a particularly active volcanic and earthquake zone that spans the entire Pacific Ocean. It also includes the US state of Alaska with the Aleutian archipelago.

The tectonic situation is more complex off the coast of the states of Washington and Oregon, as here the small one Juan de Fuca earth plate (and probably other “microplates”) stand between the Pacific plate and the continental mass. The basic seismic dynamics are hardly changed as a result.

Selected historical earthquakes

The earthquake centers of California and Alaska are also easy to identify on the map. In Alaska only the very strongest quakes are marked.

USA earthquake map:

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A: Seaquake off the west coast, "Cascadia earthquake" (January 26, 1700) - magnitude at least 8.7
B: New Madrid / Missouri (December 16, 1811) - magnitude approx.8.1
C: Fort Tejon / California (January 9, 1857) - magnitude 7.9
D: Seaquake off Hawaii (April 2, 1868), not in the picture - magnitude 7.9
E: Lone Pine / California (March 26, 1872) - Magnitude at least 7.6
Q: San Francisco (April 18, 1906) - magnitude 7.9
G: Santa Barbara (June 19, 1925) - magnitude 7.9
H: Seaquake in the Aleutian Islands / Alaska (April 1, 1946) - magnitude max. 8.6
I: Seaquake off the south coast of Alaska (March 27, 1964) - magnitude 9.2
J: San Fernando (February 9, 1971), like mark L - magnitude 6.6
K: Borah Peak / Idaho (February 9, 1983) - magnitude 7.3
L: Northridge, California (January 17, 1994) - magnitude 6.7

Particularly severe tremors

Compared to poor regions of the world, earthquakes in the USA have remarkably few deaths. The reason is above all the comparatively solid construction. Most buildings withstand small to medium-sized earthquakes without significant problems.

The most energetic earthquake occurred in the year 1964 in Alaska (Marking I): With a magnitude of 9.2, it was one of the strongest earthquakes in the world. Among other things, Anchorage, the capital of Alaska, was affected. The official number of victims was only 139.

The only truly destructive quake occurred in 1906 San Francisco (Mark F). More than 3,000 people died and well over 200,000 were left homeless. What the tremors themselves did not destroy fell victim to a major fire. The notorious one was the concrete trigger San Andreas Fault turned off. This tectonic boundary runs through most of California and will continue to threaten large cities such as San Francisco and Los Angeles in the future.