Another big earthquake in Niigata. (It's not fair).

[SirJibAlot 0]

Didn't feel it at all here in Osaka. But i was sleeping in and on only the 2nd floor of a 2 floor house, so that doesn't surprise me.

[SirJibAlot 0]

Soubs, but I would guess that the waves would have to travel farther up the mountain so you'd feel less than if at sea-level.

[mina2 6]

It was very strong here in Minakami (northern Gunma, just to the south of Yuzawa). As with the Chuetsu, it moves more here than in Yuzawa which seems to have a relatively strong base or whatever you call it. Go out into the valley though Muikamachi and it is much more prone to moving.

[tsondaboy 0]

Actually attenuation works best through sediments rather than massive formations.

 

To give you a good example on that, it is the same as if you put a pillow over a clock and put your ear on the pillow to hear the ticking sound and try to do the same but cover the clock with a frying pan.

[soubriquet 0]

You'd want some compressibilty, and the water column won't give you that. I was thinking of attenuation of shear. That is trying to accelerate a mass horizontally by moving its base, and leaving the top behind.

[TJ OZ 0]

We had quite a big aftershock here about an hour ago as well. It's a strange feeling similar to being on a boat. I have now experienced a few over the last 9 months. I feel safe in my building as it it a very solid construction.

[muikabochi 208]

Here it was more like unwillingly being on a rickety old out-of-control wooden roller coaster.

[Snow-Woman 0]

It wasn't very strong here, but being so far away I don't want to imagine how such a quake feels when you are close by. Take care!

[grungy-gonads 54]

Been unlucky with them the last few years. Here's hoping for it to end sooner rather than later.

 

Roppongi Hills lifts had a bad time of it again apparently.

[gerard 6]

hope eveyone is OK!!!

 

Take care, folks

[nzlegend 1]

what is it with Niigata? are you guys low on Karma or what? the past few years have been hellish with quakes, floods, snowstorms. If any of you guys want move on down to Nara, you are welcome.

[scouser 4]

Very sad to see those scenes again.

[soubriquet 0]

I've found a focal mechanism solution for yesterday's main event.

 

The fault runs parallel with the coast and the movement was an oblique thrust to the NW. What that means it that the rocks on the SE side of the fault slipped under the rocks to the NW. FWIW, thrust, or reverse faults have the greatest capacity to store strain, and therefore are responsible for the strongest earthquakes.

[tsondaboy 0]

Soubs, here are some first results regarding yesterdays earthquake.

http://www.eri.u-tokyo.ac.jp/topics/niigata20070716/

It’s pretty early to be talking about fault geometry and staff, but all data point to an east dipping thrust. Probably on the northwest boundary of the Northern Fossa Magna basin.

 

[soubriquet 0]

I must have misread the beachball. You have a look. I haven't done a focal plane solution since about 1982. The USGS were the source.

 

[tsondaboy 0]

A Moment tensor solution always gives you 2 planes, like in the USGS pick. You can’t really say just by one solution, which is the plane that represents the fault. Usually the distribution of the aftershocks gives you a good idea of the geometry of the area that has slipped. The distribution up to now points to an East dipping thrust.

[soubriquet 0]

Damn, got the wrong one! That was in March

[tsondaboy 0]

Yap, you have the Noto peninsula event there.

[soubriquet 0]

Here it is. If it's east dipping, then it has to SE

 

 

[muikabochi 208]

Ah, I understand what you are saying... you're saying that there won't be another big one in this region while I'm still there. Good.....

[soubriquet 0]

Well, the strain has been released, so that part of the fault is relaxed. Strain is a slippery thing though. How long do you intend to stay in one of the most earthquake prone areas of one of the most earthquake countries?

[Tubby Beaver 209]

Can earthquakes trigger avalanches and if so have there been any of note in recent years?

[SerreChe 2]

Very good question.

Yes, earthquakes do trigger avalanches although I think it is pretty rare to have casualties as a result.

There was a case in my hometown quite a years back where 4 people got killed after an earthquake triggered an avalanche. Very very unlucky as earthquakes are very rare in that neck of the woods.

[SerreChe 2]

I wonder if the SJ mailbox survived the earthquake. May be a good opportunity to do something about it ;-)

[soubriquet 0]

Yes they can. One of the Niigata railways is closed by a landslip, as well as several roads.

 

Avalanche isn't just snow.