Mw 7.5 South of Alaskan Peninsula

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In summary, an Mw 7.5 earthquake struck 40km south of Sand Point, Alaska about an hour ago. The temblor was detected by seismographs in Alaska and nearby Hawaii. There is no tsunami warning currently in effect.
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davenn
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Couldnt get to post this earlier in the day, work duties took precedence

A Mw 7.5 off shore south of Sand Point, Alaskan Peninsula some hours ago today
I will have to look through my records but I recall another similar sized event in the
same region within the last 10 -12 months2020-10-19 20:54:40 (UTC) at 40 km deep and appears to be an oblique slip
rather than a pure strike slip eventIt's still on my seismo for another ~ 15 hours
http://www.sydneystormcity.com/seismograms.htm

USGS report ...
https://earthquake.usgs.gov/earthquakes/eventpage/us6000c9hg/executivecheers
Dave
 
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Knew the other event wasn't so long ago

Mw 7.8 on the 22 July 2020
They are classifying today's Mw 7.5 an aftershock of the 7.8 ... just WOW

I have edited one of their maps to show both events
Today's event is about 80km SW of the July event

20200722 and 1019  Mw 7.8 and 7.5.JPG
 
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  • #4
berkeman said:
It looks like there was no Tsunami warning caused by it? Is that because it was 40km deep?

EDIT -- It looks like there was indeed a Tsunami warning, but just for Alaska (not Northern California):

Yes, just a local warning which was canceled within the hour

Yes, the depth played a part, as did the type of motion on the fault that ruptured. Tho the event was on a major subduction zone,
the fault that ruptured was primarily a strike/slip (sideways) motion rather than a thrust motion. As a result, the seafloor didn't
move with any significant vertical offset.Dave
 
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here's a screen dump of the seismogram from my system ...
201019 2054UT Mw7.5 S of Alaska Penin zhi1.gif
 

What is the significance of "Mw 7.5 South of Alaskan Peninsula"?

"Mw 7.5" refers to the magnitude of the earthquake, which is a measure of the energy released at the earthquake's source. "South of Alaskan Peninsula" indicates the location of the earthquake's epicenter, which is the point on the Earth's surface directly above the earthquake's focus.

How strong was the earthquake?

The earthquake was measured at a magnitude of 7.5 on the moment magnitude scale. This is considered a major earthquake and can cause significant damage.

Where exactly did the earthquake occur?

The earthquake occurred south of the Alaskan Peninsula, which is a region in the southern part of the state of Alaska in the United States. The epicenter was located in the Pacific Ocean, approximately 60 miles southeast of Sand Point, Alaska.

Was there any damage or casualties from the earthquake?

As of now, there have been no reports of damage or casualties from the earthquake. However, the earthquake was felt in nearby communities and may have caused some minor damage.

Is there a risk of a tsunami following this earthquake?

There is a possibility of a tsunami following this earthquake, as the Pacific Tsunami Warning Center issued a tsunami warning for parts of the Alaskan coastline. However, the warning has since been cancelled and no tsunami has been reported.

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