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OK, Here's some details from the USGS: http://earthquake.usgs.gov/eqinthenews/2004/usslav/ NOTE THE DEPTH OF THE HYPOCENTER is 30Km! (considered relatively shallow?) but still 98,000 feet down. Seems to me it'd be worth investigating if possible what magnitude and character of slides, debris flows and scarps resulted from this event, if any? FOLLOWING INFO IS FROM THE USGS: _________________________________________ Magnitude 9.0 Date-Time Sunday, December 26, 2004 at 00:58:53 (UTC) = Coordinated Universal Time Sunday, December 26, 2004 at 7:58:53 AM = local time at epicenter Time of Earthquake in other Time Zones Location 3.307° N 95.947° E Depth 30 km (18.6 miles) set by location program Region OFF THE WEST COAST OF NORTHERN SUMATRA Distances 250 km (155 miles) SSE of Banda Aceh, Sumatra, Indonesia 310 km (195 miles) W of Medan, Sumatra, Indonesia 1260 km (780 miles) SSW of BANGKOK, Thailand 1605 km (990 miles) NW of JAKARTA, Java, Indonesia Location Uncertainty horizontal +/- 5.6 km (3.5 miles); depth fixed by location program Parameters Nst=370, Nph=370, Dmin=644.5 km, Rmss=1.17 sec, Gp= 29°, M-type=teleseismic moment magnitude (Mw), Version=U ________________________________________ Source USGS NEIC (WDCS-D) THE USGS view of what it takes to cause a significant Tsunami is a thrust solution and >7.5magnitude seismic event. Magnitudes below 6.5 Earthquakes of this magnitude are very unlikely to trigger a tsunami. Magnitudes between 6.5 and 7.5 Earthquakes of this size do not usually produce destructive tsunamis. However, small sea level changes may be observed in the vicinity of the epicenter. Tsunamis capable of producing damage or casualties are rare in this magnitude range but have occurred due to secondary effects such as landslides or submarine slumps. Magnitudes between 7.6 and 7.8 Earthquakes of this size may produce destructive tsunamis especially near the epicenter; at greater distances small sea level changes may be observed. Tsunamis capable of producing damage at great distances are rare in the magnitude range. Magnitude 7.9 and greater Destructive local tsunamis are possible near the epicenter, and significant sea level changes and damage may occur in a broader region. Note that with a magnitude 9.0 earthquake, the probability of an aftershock with a magnitude exceeding 7.5 is not negligible. To date, the largest aftershock recorded has been magnitude 7.1 that did not produce a damaging tsunami. ____________________________________________ OTHER TIDBITS: from USGS Q&A: Question: What was the size of the fault that produced the earthquake? Answer: An initial estimate of the size of the rupture that caused the earthquake is obtained from the length of the aftershock zone, the dimensions of historical earthquakes, and a study of the elastic waves generated by the earthquake. The aftershocks suggest that the earthquake rupture had a maximum length of 1200 -- 1300 km parallel to the Sunda trench and a width of over 100 km perpendicular to the earthquake source. An early estimate from the study of elastic waves show the majority of slip was concentrated in the southernmost 400 km of the rupture. ____________________________________________ Question: What was the maximum displacement on the rupture surface between the plates ? Answer: The maximum displacement estimated from a preliminary study of the seismic body waves is 20 meters. ____________________________________________ Question: What was the maximum displacement of the sea bottom above the earthquake source? Answer: The displacement of the ground surface will be related to, but somewhat less than, the displacement on the earthquake fault at depth. In places, the block of crust beneath the sea floor and overlying the causative fault is likely to have moved on the order of 10 meters to the west-southwest and to have been uplifted by several meters. ____________________________________________ Question: What is the angle of subduction of the India plate beneath the Burma plate? Answer: At the source of the earthquake, the interface between the India plate and the Burma plate dips about 10 degrees to the east-northeast. The subducting plate dips more steeply at greater depths. ____________________________________________ Question: How much energy was released by this earthquake? Answer: Es 20X10^17 Joules, or 475,000 kilotons (475 megatons) of TNT, or the equivalent of 23,000 Hiroshima bombs. ____________________________________________ Question: How long did the earthquake shake? (What was the duration?) Answer: The actual rupture duration on the fault (the time it took for the earthquake to take place on the fault and rupture the entire length) was approximately 3 to 4 minutes. The exact length of time that people felt the shaking varied from place to place, depending on their distance to the fault, and other factors, such as what type of bedrock they were on, what the crustal structure was below them and between them and the fault, etc. In northern Sumatra , which lies almost above the fault, shaking may have been experienced for up to several minutes. ____________________________________________ ____________________________________________ It may be interesting to note that the sumatran seismic event is at least the 2nd most devestating after Tangshan quake of 1976. A major earthquake devastated the industrial city of Tangshan, China (between Peking and the sea) in July 1976. The first tremor, at 3:45 A.M. on July 28, was measured at 8.2 on the Richter scale, making it the strongest in the world in a dozen years. The industrial city of Tientsin and Peking were also badly shaken by the quake. The death toll in Tangshan reportedly was estimated by Chinese officials to be more than 655,000, though the later official estimation was much lower. to be more than 655,000, though the later official estimation was much lower." Sincerely, Joshua Turner BP Houston (no earthquakes here) TX