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Estimated travel times of a tsunami, from the NOAA. Looks like it would’ve hit somewhere by now.

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UPDATE UPDATE: another tremor has been felt. So we’re not nearly out of the woods. Basically just stay away from the coast. I think Sri Lanka has so far responded a lot better than last time.

Today’s Sumatran earthquake is looking less likely to cause a tsunami, but the situation still looks dodge. Please stay away from the coast. I say less likely because of two things, the quake moved horizontally, thus not displacing a large amount of water. Also, no tsunami seems to have hit Aceh or Indonesia (or the Andamans), and they would get it first. The ETA of a potential tsunami on the east coast would be, like, now, so I guess we’ll see. So far it’s not likely. If it did come up to Colombo, it’d be in about 40 minutes.

Horizontal Quake

Last time the Sumatran earthquake moved vertically, lifting a huge column of water that was then propelled, somewhat invisibly, until it hit the shallows of our coast and crested into a vicious tsunami. This time, however, the quake seems to have been horizontal. We felt it here, but it seems unlikely to generate the same sort of water displacement.

Bruce Presgrave of the USGS later told the BBC that the nature of this quake made it less likely a tsunami would be generated, as the earth had moved horizontally, rather than vertically, therefore had not displaced large volumes of water.

“We can’t rule out the possibility, but horizontal motion is less likely to produce a destructive tsunami,” he said. (BBC)

So that’s one thing.

No Tsunamis Elsewhere

The tragic thing last time was that we had hours to save thousands of lives. The tsunami hit Indonesia, Thailand, then the east coast of Sri Lanka, then slowly wrapped around the island. People died for lack of information, and for lack of understanding of what a tsunami was. This time, however, we do know, and we can see if a tsunami has hit those regions yet. It seems like it hasn’t.

FLASH: Indonesia’s disaster mitigation agency says no detection of low tide that would indicate tsunami in Aceh

— Reuters India (@ReutersIndia) April 11, 2012

#SRILANKA RT @PTI_News: No waves noticed so far in Andaman/Nicobar Islands; tsunami virtually ruled out, says NDMA vice presSasidhra Reddy.

— Amantha (@AmanthaP) April 11, 2012

Reax In SL

That said, people in Sri Lanka have freaked out a bit, which I think is good. Coastal trains have stopped, CEB has cut off power there (not sure exactly how that helps), and the Southern Expressway has been opened without a toll to get people off the coastal Galle Road. People have already gone home for Avurudu, but I hear that offices are letting out early. Phone lines also cloggy.

But I think there won’t be a tsunami. But still stay away from the coast, for the next hour or two at least.