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+--- Thread: Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever (/showthread.php?tid=23402)
Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever - terracore - 08-08-2024
Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever after tremors earlier in the same area 'one of the world's deadliest earthquakes' hit nearly 80 years ago
Japan has issued its first ever megaquake warning following tremors earlier today in the same area 'one of the world's deadliest earthquakes' hit almost 80 years ago.
The 7.1 magnitude earthquake struck off the coast of Japan's southern island of Kyushu, close to the city of Nichinan, at 4.43pm local time.
Japan's Meteorological Agency issued a tsunami warning following the powerful quake. They also took the unprecedented decision to issue a formal warning about a potential 'megaquake.'
The agency said that submarines in the Nankai Trough, where part of the Eurasian tectonic plate meets with the Philippine tectonic plate, found that the chances of a major earthquake in the region was 'relatively higher than usual for the next week.'
Earthquakes in the Nankai Trough typically occur every 100 to 150 years. The most recent quake to hit the area was 78 years ago in December 1946...https://www.dailymail.co.uk/news/article-13724853/japan-earthquake-megaquake-warning.html
https://www.japantimes.co.jp/news/2024/08/08/japan/nankai-earthquake-alert/#Echobox=1723114085
Who had "megaquake" on their 2024 bingo cards?
https://www3.nhk.or.jp/nhkworld/en/news/backstories/3509/
RE: Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever - HereOnThePrimalEdge - 08-08-2024
For Hawaii - - if a Japan quake happens and there’s a tsunami warning, best to take this one seriously.
Here’s a link to the Pacific bouy system, used to predict tsunami heights. There are only a few between Japan and Hawaii, but gives us a heads up.
https://nctr.pmel.noaa.gov/Dart/
From NHK World:
if a maximum earthquake occurs, and a huge tsunami more than 30 meters high would hit coastal areas.
The latest estimate says about 230,000 people would be killed and about 2.09 million buildings would be damaged by fire or destroyed.
Converting meters to feet, that’s a 90 foot high tsunami in Japan, on their east coast which faces Hawaii, so it would probably pack a punch even half way across the Pacific in Hawaii. And we’re not necessarily safer on the east side of the islands - - there’s a wraparound effect.
RE: Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever - terracore - 08-09-2024
"if a maximum earthquake occurs, and a huge tsunami more than 30 meters high would hit coastal areas.
The latest estimate says about 230,000 people would be killed and about 2.09 million buildings would be damaged by fire or destroyed."
If I understand correctly, that is based on estimates of an 8.0 earthquake. The "megaquake" could be anything from 8-9. The magnitude scale for earthquakes is logarithmic, which means each whole number increase on the scale represents a tenfold increase in amplitude and roughly 31.6 times more energy release. They may not have been able to model the consequences of a 9.x earthquake because there have been too few of them to study. Most buildings in Japan are constructed to withstand earthquakes between 7.0 - 7.9, though that is an approximation because they use their own system of measurements for seismic activity and building resiliency.
As far as potential impacts to Hawaii, that would be dependent on what type of quake it is. I'm sure that was part of their data when they came up with "8 - 9". Obviously I'm not a seismologist but I think the biggest ones are megathrust earthquakes and they cause the largest tsunamis not just because of the intensity but because the type of movement on the seafloor.