Mag 8.2 Earthquake and aftershocks ~ 104 km SE of Perryville, Alaska

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In summary, a 8.2 magnitude earthquake with a depth of 32.2 km occurred in Alaska on July 29, 2021. This caused a tsunami warning which was later canceled after communities reported minor wave sizes. A related 6.9 magnitude aftershock occurred on August 14, 2021 with a depth of 33.3 km, located 20.431 miles away from the site of the initial earthquake. This year has seen a higher number of major earthquakes compared to previous years, with a total of two M8+ events so far.
  • #1

Astronuc

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https://earthquake.usgs.gov/earthquakes/eventpage/ak0219neiszm/executive
https://earthquake.usgs.gov/earthquakes/eventpage/ak0219neiszm/region-info
  • 2021-07-29 06:15:47 (UTC)
  • 55.325°N 157.841°W
  • 32.2 km depth
A lot of aftershocks
https://earthquake.usgs.gov/earthqu...52.2816,-165.60791&extent=59.81168,-142.93213

https://www.usnews.com/news/us/articles/2021-07-29/tsunami-watch-issued-for-hawaii-after-82m-quake-hits-alaska
A tsunami warning for Alaska was canceled early Thursday when communities started reporting minor wave sizes, some just over a half foot (15.2 centimeters). A tsunami warning that also had been issued for https://www.usnews.com/news/best-states/hawaii was canceled, and officials said there was no threat to Guam, American Samoa or the Commonwealth of Northern Mariana Islands.

The tsunami warning for Alaska covered nearly a 1,000-mile (1,600-kilometer) stretch from Prince William Sound to Samalga Island, Alaska, near the end of the Aleutian Islands.
 
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One of my good friends was an MP at the largest Air Force Base in Alaska during the M9.2 earthquake in 1964. I've seen his presentation on the experience and the amazing damage; his description for how long it lasted is especially chilling and scary.

Here's a link to info on that previous event: https://earthquake.usgs.gov/earthquakes/events/alaska1964/

I'm glad that this one was lighter (relatively speaking) and that any injuries were minimal.
 
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Thanks @Astronuc :smile:

I haven't even had time to post info on this quake
It had my seismo maxing out, even tho it is at the other end of the Pacific

1628501589455.gif


showing the trace up to about 5 minutes before it was to overwrite the signal

The worldwide avg is 1 x M8.0 + event per year. Some years have none, other years have two.
From memory, there was one year that had 4 x M8 + events

This year there has been two so far, the previous one back in early March 2021

cheers
Dave
 
  • #5
Possibly related M 6.9 - 136 km SE of Perryville, Alaska
  • 2021-08-14 11:57:44 (UTC)
  • 55.085°N 157.540°W
  • 33.3 km depth
https://earthquake.usgs.gov/earthquakes/eventpage/ak021adyci6n/executive

Comparing the location of the 8.2 M earthquake: 55.325°N, 157.841°W, 32.2 km depth
with the location of the 6.9 earthquake: 55.085°N, 157.540°W, 33.3 km depth

The lateral separation assuming an ellipsoidal Earth 20.431 statute mi, 17.754 naut. mi, 32.880 km
Using https://stevemorse.org/nearest/distance.php
 
  • #6
Astronuc said:
Possibly related M 6.9 - 136 km SE of Perryville, Alaska

definitely related, as in, an aftershock... it's just a bit up dip from the 8.2 ( ~ 50km)

Clipboard01.jpg
Dave
 

1. What caused the Mag 8.2 Earthquake near Perryville, Alaska?

The Mag 8.2 Earthquake near Perryville, Alaska was caused by the movement of tectonic plates. The Pacific Plate and the North American Plate meet in this region, and the earthquake occurred along the boundary between these plates.

2. How often do earthquakes of this magnitude occur in this region?

Earthquakes of this magnitude are relatively rare in this region. The last earthquake of this size near Perryville, Alaska occurred in 1965. However, smaller earthquakes and aftershocks are more common in this area due to the ongoing movement of tectonic plates.

3. What is the impact of aftershocks following a major earthquake?

Aftershocks are smaller earthquakes that occur after a major earthquake. They can continue for days, weeks, or even months after the initial earthquake. Aftershocks can cause additional damage to already weakened structures and can also trigger landslides and tsunamis.

4. How do scientists predict and monitor earthquakes?

Scientists use various methods to predict and monitor earthquakes, including seismometers, GPS technology, and satellite imagery. These tools help scientists track the movement of tectonic plates and identify potential areas of seismic activity. However, earthquakes are still difficult to predict with complete accuracy.

5. What can people do to prepare for earthquakes and aftershocks?

There are several steps people can take to prepare for earthquakes and aftershocks. These include creating an emergency plan, securing furniture and objects that could fall during an earthquake, and stocking up on emergency supplies. It is also important to stay informed and follow any evacuation orders or safety precautions issued by local authorities.

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