7.3 Magnitude Quake Hits North Japan

In summary: Japan is part of the Pacific Plate that is moving under the Okhotsk Plate. This movement has caused earthquakes and the flow of the seafloor.
  • #1
gmax137
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7.3 Magnitude Quake Hits North Japan, Tsunami Alert Issued
3-16-2022_quake.JPG
https://www.bloomberg.com/news/arti...e-quake-hits-north-japan-tsunami-alert-issued
 
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  • #2
Yikes. That's not good...

Although, if it really is only 1 meter above normal tidal levels, that's a lot less than the previous one, right?

https://www.cnn.com/2022/03/16/asia/japan-earthquake-fukushima-intl/index.html

The tsunami advisory was made for Fukushima and Miyagi prefectures in eastern Japan following the quake that had a preliminary epicenter depth of 60 kilometers (37 miles), according to the Japan Meteorological Agency.

The advisory warns of tsunami heights reaching up to 1 meter above normal tidal levels, with the initial waves reaching shore around midnight local time (11 a.m. ET).
 
  • #3

M 7.3 - 57 km ENE of Namie, Japan​

https://earthquake.usgs.gov/earthquakes/eventpage/us6000h519/executive
  • 2022-03-16 14:36:33 (UTC)
  • 37.702°N 141.587°E
  • 63.1 km depth
The Mag 7.3 was preceded by a Mag 6.4 earthquake occurring only 2 minutes before and slightly shallower.

M 6.4 - 62 km ENE of Namie, Japan​

https://earthquake.usgs.gov/earthquakes/eventpage/us6000h518/executive
  • 2022-03-16 14:34:27 (UTC)
  • 37.633°N 141.685°E
  • 56.3 km depth
An aftershock

M 5.5 - 77 km SE of Ishinomaki, Japan​

https://earthquake.usgs.gov/earthquakes/eventpage/us6000h518/executive
  • 2022-03-16 15:52:31 (UTC)
  • 37.853°N 141.827°E
  • 67.2 km depth (slightly deeper than the Mag 7.3)
 
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  • #4
Those earthquakes are very deep.
Maybe they are aftershocks of the big tsunami earthquake.
 
  • #5
Baluncore said:
Those earthquakes are very deep.
Maybe they are aftershocks of the big tsunami earthquake.
I would consider that a moderate depth, but perhaps enough to mitigate a tsunami. Of course, it all depends on how and how much of the ocean floor and volume of ocean water is displaced.

In contrast, the 9.1/9.2 Mag Great Tohoku earthquake of 2011 was at a depth of 29 km.
https://earthquake.usgs.gov/earthquakes/eventpage/official20110311054624120_30/executive

M 9.1 - 2011 Great Tohoku Earthquake, Japan​

  • 2011-03-11 05:46:24 (UTC)
  • 38.297°N 142.373°E
  • 29.0 km depth
Rather than aftershocks, the current quakes are simply part of the ongoing seismic activity induced by the flow of the seafloor under crust of which Japan is a part, i.e., subduction of the western edge of the Pacific Plate under the Okhotsk Plate.
https://en.wikipedia.org/wiki/Japan_Trench#Seismicity
https://en.wikipedia.org/wiki/Okhotsk_Plate
https://earthquake.usgs.gov/earthquakes/eventpage/official20110311054624120_30/dyfi/intensity
 

1. What is the significance of a 7.3 magnitude earthquake?

A 7.3 magnitude earthquake is considered a major earthquake and can cause significant damage and destruction. It is 10 times more powerful than a 6.3 magnitude earthquake and 100 times more powerful than a 5.3 magnitude earthquake.

2. Where exactly did the earthquake hit in North Japan?

The earthquake hit off the coast of Miyagi prefecture in North Japan, approximately 60 kilometers southeast of the city of Sendai.

3. Was there a tsunami warning issued after the earthquake?

Yes, a tsunami warning was issued for the coastal areas of Miyagi prefecture and surrounding areas. However, it was later cancelled as the tsunami waves were not as high as initially predicted.

4. How often do earthquakes of this magnitude occur in Japan?

Japan experiences frequent earthquakes due to its location on the Pacific Ring of Fire. However, earthquakes of this magnitude (7.3) are less common and occur every few years.

5. What precautions should people take after a 7.3 magnitude earthquake?

After a 7.3 magnitude earthquake, it is important to stay alert for aftershocks, as they can cause additional damage. People should also be aware of any potential tsunami warnings and evacuate to higher ground if necessary. It is also important to check for any injuries or damage and follow any instructions from local authorities.

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