Agam's Gecko
Wednesday, September 12, 2007
Location and Details

magnitude 7.9 earthquake struck off the southwest coast of Sumatra at 6:10 pm local time (as well as my local time in Bangkok), almost two hours ago. The epicenter is 130 km southwest of Bengkulu, a seaside city. This quake is being judged by the Indonesian geo-physics authorities as a serious tsunami threat. This department's information screen broke into MetroTV's broadcast tonight within minutes of the reported time of the quake, over-riding the Metro signal several times, just long enough to read their information shown over a map (lat/long, depth only 10 km, 159 km to Bengkulu) and including the tsunami-generating potential threat. USGS puts the location a little closer at 130 km, depth 30 km.

Now at the two hour mark, and still no reports of a wave. One of the scientists was on the phone with Metro at about + 1 hour 20 minutes. He would have expected a tsunami wave to reach the nearest coastline -- at Bengkulu City -- within 30 minutes, if it was coming that way. There is also a straight shot at Padang, and many islands in the vicinity. The geo-physics guy said that such a quake-generated wave could be moving in any direction, and can be deflected back upon itself and into a new direction. Islands to the south of the area, including Java, could be affected by a south moving wave. Northwards. a lot of big, populated islands including Nias, and the rest of the long Sumatra and Aceh coast. The warning was immediately transmitted to all the Indian Ocean countries.

People in coastal communities are fleeing to the interior, and higher ground if they can find any. Padang now reports collapsed buildings, and a nine foot tsunami, about 20 minutes after the quake. Here it is in Google Maps. Tsunami alerts are out in Malaysia, the Andaman and Nicobar Islands of India, and Sri Lanka. Thailand too, I would expect. Burma, as in The Great Tsunami, will keep mum on the subject.

*UPDATE* : It's now just after 9 am, there have been a number of further quakes in the same area through the night and this morning. The quake of last evening has now been pegged at 8.4 magnitude. Eleven subsequent quakes with magnitude between Richter 5 - 6 have occurred, with the mag. 6 happening at 9:40 pm. Then another big one, mag. 7.8 took place this morning at 6:50 am. The tsunami warning on that one has just been lifted in Indonesia -- there have been three tsunami warnings put out since last night. A list of the earthquakes for this region is here.

I've contacted Tapaktuan this morning (which is the first day of Ramadan, by the way), and the quake last evening was felt there but not strongly -- and no tsunami yet. At least 6 deaths are reported in Padang, some by falling buildings and some by fires caused by the quake. Bengkulu also has casualties but communication remains difficult there. All of these quakes have been located at a shallow depth, a condition which makes tsunami generation more likely. The major quake this morning is not considered an aftershock, but a separate event. Its epicenter was much closer to Padang, map is here.


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