Powerful Aftershocks Arrive in Alaska for Beginning of the New Year

Powerful Aftershocks Arrive in Alaska for Beginning of the New Year
A tow truck holds a car that was pulled from on an off-ramp that collapsed during a morning earthquake in Anchorage, Alaska, on Nov. 30, 2018. Mike Dinneen/AP
Chris Jasurek
Updated:

A magnitude 5.0 aftershock struck the Anchorage capitol area on the morning of New Year’s Eve—and ushered in two days filled with many more tremors.

That 5.0 was the strongest aftershock since the Nov. 30 quake.

Alaska has endured thousands of aftershocks since the 7.0 magnitude quake powerfully shook Anchorage and its environs on Nov. 30. This was the second-largest earthquake ever recorded in Alaska, and the most powerful since the record-breaking 1964 quake.

The 1964 quake measured 9.2 and the strongest to hit the United States in recorded history and the second strongest ever recorded on earth.
This aerial photo shows damage on Vine Road, south of Wasilla, Alaska, after earthquakes hit on Nov. 30, 2018. (Marc Lester/Anchorage Daily News/AP)
This aerial photo shows damage on Vine Road, south of Wasilla, Alaska, after earthquakes hit on Nov. 30, 2018. Marc Lester/Anchorage Daily News/AP

The November temblor was not as severe but still tore up roads all around Anchorage—and spawned aftershocks for days.

In just the first week after the November quake, the United States Geological Survey (USGS) counted nearly 3,000 serious tremors. Another few thousand more in the next three weeks raised the total to more than 6,100.

Five aftershocks measured 5.0 or greater on the Richter scale, 23 were 4.0, and 185 measured more than 3.0, according to the USGS.

Those tremors had ebbed, and for the next three weeks, things were relatively more peaceful. Probably a lot of South-Central Alaskans had let the November earthquake fade into memory—until another magnitude-5 quake shook the region at 6 a.m. on Dec. 30.

Since the main tremor, the Alaska Earthquake Center detected more than 100 further aftershocks in the first two days of 2019.

A 4.2-magnitude aftershock hit just five miles outside of Anchorage just after 6 a.m. on Jan. 2. A 4.9 magnitude temblor hit 10 miles northwest of Anchorage on Dec. 27 but was 22 miles below the surface and did not create much of a stir in the city.

What Makes it an Aftershock?

The USGS defines aftershocks as “earthquakes that follow the largest shock of an earthquake sequence.“ They are smaller than the mainshock and within one to two rupture length’s distance from the mainshock. Aftershocks can continue over a period of weeks, months, or years. ”In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue,” USGS said on its website.

As KTVA reported, aftershocks can themselves trigger aftershocks—all of which are considered to have been caused by the major quake (the Nov. 30 event.)

A 5.0 earthquake is still arguably severe regardless of whether scientists blame it on an earlier quake.

People walk along Vine Road in Wasilla, Alaska, after the 7.0 earthquake, on Nov. 30, 2018, (Jonathan M. Lettow via AP)
People walk along Vine Road in Wasilla, Alaska, after the 7.0 earthquake, on Nov. 30, 2018, Jonathan M. Lettow via AP

Besides the aftershocks Alaska has its fair share of quakes. The Alaska Earthquake Center recorded 51,612 shocks in 2018 but many of them are simply overlooked.

For instance, a magnitude 6.1 quake hit about 61 miles off the coast of King Cove and 600 miles southwest of Anchorage. It was far out to sea and thus not near any major population centers, so little attention was given.
From NTD.com 
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