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The Mainshock just hit us - A Recovering Physicist's Apology

About The Mainshock just hit us

Previous Entry The Mainshock just hit us Sep. 6th, 2004 @ 12:57 am Next Entry
I would say the first quake was a 3 or a 4 on the Richter scale this one was probably about the same but I don’t think lasted as long. I am pretty shaken up again. I was pretty close to being asleep when the room started shaking. This time I knew what was happening right away. I couldn’t find my glasses at first and that was pretty scary. I got them and got to the door. Dan was out of his apartment pretty shook up too. I am really not wanting to go into work tomorrow. Being in the earthquake makes you feel so utterly powerless. It is horrible. My friend Dave has never been in one and has lived in Japan for a year now, this is my second in 5 hours.

Doing some looking online I see what we are feeling. A 7.0 earthquake (the first quake I felt) happened off the coast of Japan diagonally down from Osaka. The epicenter happened approximately 205 km (125 miles) SSW of Osaka. Reports of feeling a 3.0 JMA (I think Japan uses a different scale than Richter so I don’t know the conversion or if JMA is even a unit) are coming in from Osaka. Here are some reports I found online:
http://www.reuters.com/newsArticle.jhtml?type=worldNews&storyID=6152634
http://newsobserver.com/24hour/world/story/1623980p-9318888c.html

This last earthquake I felt was in about the same location and a 7.2 on the Richter. It is being classified as the mainshock I believe. The foreshock was the 7.0, the mainshock was a 7.2. From what I have gathered, earthquakes come in clusters, a series of foreshocks, than the big shock (mainshock), then a series of aftershocks. The biggest jolt is classified as the mainshock, so currently the 7.2 holds that title. But if another earthquake happens in the near future greater than 7.2 than it will be the mainshock and the current mainshock will be reclassified as a foreshock. Needless to say I have felt both here in Daito and am hoping the worst is over. Here is the info on the two quakes:
http://earthquake.usgs.gov/recenteqsww/Quakes/usnaah.htm
http://earthquake.usgs.gov/recenteqsww/Quakes/at00000207.htm

The good news is that the first earthquake did damage but only 2 people were harmed, if even that. The second was not too much stronger than the first so I am hoping that the results will be about the same. It did happen later so more people where indoors so there is a greater chance of stuff falling on people, but my stuff didn't move around and if the quake follows the same patterns as it did the first time people in the Osaka region where hit the third hardest. The prefecture below us, the Wakayama prefecture, felt it the worst feeling a 5 JMA, still don't know what a JMA is most of the stuff I am pulling up about it are in Japanese so I can't read it. I do know that the Japanese scale is based on a 7 level scale, while the Richter is not. But I don't know the conversions.

Okay more research done. The Richter scale has been abandoned for some time. The media and popular press and even geologist have just kept the name, so I will be refering to it as "the Richter scale." Even though it technically isn't anymore. Stupid geology. Physics has quirks but nothing this lame. It looks like we in the States currently use a modified version of the Mercelli scale. I think the JMA (Japen Meteorological Agency) uses either a modified version or the origional version of the Omori scale. Here is how the two scales stack up:
Mercalli / Omori
I / 0
II / I
III / II
IV / II-III
V / III
VI / IV
VII / IV-V
VIII / V
IX / V-VI
X / VI
XI / VII
XII / ----
USA / Japan

So I felt probably two 5 Richter level quakes. I don't want to feel any others.

I should go to bed. I am really tired but still a bit nervious. I hope I don't have to work tomorrow.
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