7.4-magnitude earthquake off coast of japan , page

channel6newsonline.com...

TOKYO (BNO NEWS) -- Japan issued a tsunami warning for some of its islands on early Wednesday morning after a powerful earthquake struck nearby. The 7.4-magnitude earthquake at 3.19 a.m. local time (1719 GMT Tuesday) was centered about 153 kilometers (95 miles) east of Chichi-shima on the Bonin Islands, located some 1049 kilometers (652 miles) south-southeast of Tokyo. It struck about 10 kilometers (6.2 miles) deep, making it a shallow earthquake, according to the Japan Meteorological Agency (JMA). JMA immediately issued a tsunami warning for the Ogasawara Islands, while tsunami advisories haveb een issued for the Izu Islands, Shizuoka Pref., the Pacific Coast of Aichi Pref., the southern part of Mie Pref., Wakayama Pref., Tokushima Pref., Kochi Pref., Miyazaki Pref., the Tanegashima and Yakushima areas, and the Amami Islands and Tokara Islands.

This seem to have just happened , and i hope no tsunamis have been generated , but the warnings are up.

reply to post by bluemooone2

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earthquake in japan

wow a big one there

reply to post by bluemooone2

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Even though this quake's depth has now been revised to 14.9 km on USGS this is still quite a shallow quake and that's not good news: this much energy being released so near the surface increases the likelihood of follow-on tsunami effects. Hopefully though the results will not be too severe; a mag 7.4 is still way less powerful than one in the mid-mag-8 range (and which would be far more likely to produce a larger tsunami).

Please note that the P-waves from this quake will be picked up by many siesmographs in various parts of the world and will likely have registered on US-based equipment around 10 to 14 minutes after the quake struck, meaning around 17:30 to 17:44 UTC. So if you are watching US-based seismographs (eg Yellowstone's) and you see a major trace around that time then it's most likely from this quake. (I'm just trying to head off any alarmist or misinformed "major seismic event across the US" types of threads.)

The USGS Theoretical P-Wave Travel Times Map can be found here.

Mike

reply to post by thegoodearth

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On average, there are two or three mag-6 range quakes per week and about 1 mag 7 per month. A lot of the mag 6 quakes don't get much coverage unless they cause serious damage or kill people. Mag sevens and bigger are uncommon enough that they usually get reported by the media.

I think it simply depends on how damaging they are, and also if much else is happening in terms of "news" at the time.

Regards,

Mike

reply to post by bluemooone2

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Thanks for reporting this. I have been wondering if we'd see an earthquake with the eclipse as there was one in '99 after an eclipse in Turkey and the moon was full I think in '04 for the Indonesian quake. Let's hope people are safe.

Okay, here's confirmation that this quake has been recorded in the US. The trace below is from station LKWY (Yellowstone Lake) and the you can clearly see where the quake's P-wave arrived at 17:32 UTC.

You will find similar traces on many other seismographs in various parts of the world.

Here's a LINK to the clickable seismograph station map for Yellowstone.

I have used Yellowstone as a n example because the servers there are pretty good and the traces run in near real-time and are also easy for US-based members to access and follow. About the times on the trace: those on the right are UTC. (Equivalent to GMT and "Zulu" time.) Those on the left are for local time at Yellowstone.

I hope this helps members to see how these larger quakes are "felt" so far away by these very sensitive seismographs. It also gives an idea of just how fast these P-waves travel.

EDIT: the scrolling function for the above image isn't woking. Just right-click the image and click "view image" to see the times on the right side of the page.

Regards,

Mike

reply to post by GBP/JPY

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Local time (in Japan) for the quake was 3:19 am on Wednesday, Dec 22. Most quake records also list the time as UTC (like GMT or Zulu time). So, for people based in the US or Europe, it happened on Tuesday.

EDIT: here's a LINK to the USGS data that shows the quake's time in UTC, local time, and also the time for other places around the world.

Mike

reply to post by JustMike

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Local time (in Japan) for the quake was 3:19 am on Wednesday, Dec 22.

3:19 at epicenter near Bonin Islands
2:19 in Japan

It woke me up, unfortunately, and I never got back to sleep...

WOW HUGE ACTIVITY RIGHT NOW
hisz.rsoe.hu...

i counted 54 and to just happend now

reply to post by kygre

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You are quite correct. I only gave the time for the quake in the "Japan region" (as USGS has it) and not also the actual time in Japan. Even the list of times I linked to shows that it was 2:19 a.m. in Tokyo and it was my error to not also refer to this directly.

I apologise. Please excuse my oversight.

reply to post by tamenie

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Yes, we can expect a large number of aftershocks to follow a quake of this magnitude. They may also continue for several days. Fortunately these (mainly) mag-5-range quakes release nowhere near the energy of the original mag 7.4. It would take 1,000 mag 5.4 quakes to equal the energy release of just one mag 7.4: the magnitude scale is logarithmic, not simply linear. Each full magnitude higher on the scale converts to about 32x the actual energy release.

Regards,

Mike

This is getting strange:


JAPAN has had EIGHTY-SIX LARGE QUAKES between Tuesday and Thursday (their time) in the BONIN ISLANDS. I have never seen so many large quakes in one location, rapidly occurring one after the other, in the past three years since I have been monitoring quakes worldwide.

Full Story:
www.allvoices.com...

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