ENS一篇蠻用心的英文報導，以下摘錄重點 Scientists Identified Earthquake Faults in Sichuan Last Year http://www.ens-newswire.com/ens/may2008/2008-05-18-01.asp Research published by earth scientists last summer in the international journal "Tectonics" found that geological faults in China's Sichuan Basin "are sufficiently long to sustain a strong ground-shaking earthquake, making them potentially serious sources of regional seismic hazard." The international team of Chinese, British, Swiss and American scientists mapped and analyzed a series of geologically young faults that cross Sichuan province like recently healed scars. The team mapped the densely populated Sichuan Basin and adjacent mountains using a technique known as tectonic geomorphology. With this technique, scientsts can demonstrate changes in ground movement over time, such as offset river channels, disrupted floodplains, abnormally shaped valleys and uplifted landscape features. Two long faults in particular, running almost the entire length of the Longmen Shan range, showed clear evidence of slip during the last few thousands, and in some cases, the last few hundreds, of years, they found. One of these faults is "likely" to be the one that gave rise to the 7.9 magnitude May 12 earthquake, the scientists said today in a statement. "Exactly why the Longmen Shan are here is a mystery. Unlike the Himalaya, which form the southern boundary of Tibet and whose faults chatter continuously with small earthquakes, faults in the Longmen Shan, remnants perhaps of geological events hundreds of millions of years ago, have historically only produced earthquakes up to magnitude 6," the authors write. Geomorphological evidence, described in the "Tectonics" paper, suggests that the mapped faults are very steep with dominantly lateral or strike- slip displacements taking place over time scales of thousands to hundreds of thousands of years. This contrasts with shorter-term measurements using Global Positioning Systems which suggest a greater proportion of thrust or shortening displacement than lateral displacement. The observations of seismologists at the British Geological Survey suggest both things - more thrust in the southwest, nearer the epicenter of the quake, and more strike-slip toward its direction of propagation, the northeast. To read the paper, "Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau," click here. http://www.geography.dur.ac.uk/documents/densmore/densmore_etal07.pdf --

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