The largest earthquakes occur where oceanic plates move beneath continents. Obviously, water trapped in the boundary between both plates has a dominant1（占优势的） influence on the earthquake rupture2 process. Analyzing3 the great Chile earthquake of February, 27th, 2010, a group of scientists from the GFZ German Research Centre for Geosciences and from Liverpool University found that the water pressure in the pores of the rocks making up the plate boundary zone takes the key role. The stress build-up before an earthquake and the magnitude of subsequent seismic4 energy release are substantially controlled by the mechanical coupling between both plates. Studies of recent great earthquakes have revealed that the lateral5 extent of the rupture and magnitude of these events are fundamentally controlled by the stress build-up along the subduction plate interface6. Stress build-up and its lateral distribution in turn are dependent on the distribution and pressure of fluids along the plate interface.We combined observations of several geoscience（地球科学） disciplines -- geodesy（测地学）, seismology, petrology（岩石学）. In addition, we have a unique opportunity in Chile that our natural observatory7 there provides us with long time series of data, says onno Oncken, director of the GFZ-Department Geodynamics and Geomaterials. Earth observation using GPS technology and radar8 interferometry today allows a detailed9 mapping of mechanical coupling at the plate boundary from the Earths surface. A complementary image of the rock properties at depth is provided by seismology. Earthquake data yield a high resolution three-dimensional image of seismic wave speeds and their variations in the plate interface region. Data on fluid pressure and rock properties, on the other hand, are available from laboratory measurements. All these data had been acquired shortly before the great Chile earthquake of February 2010 struck with a magnitude of 8.8.For the first time, our results allow us to map the spatial10 distribution of the fluid pressure with unprecedented11 resolution showing how they control mechanical locking and subsequent seismic energy release, explains Professor Oncken. Zones of changed seismic wave speeds reflect zones of reduced mechanical coupling between plates. This state supports creep along the plate interface. In turn, high mechanical locking is promoted in lower pore fluid pressure domains12. It is these locked domains that subsequently ruptured13 during the Chile earthquake releasing most seismic energy causing destruction at Earths surface and tsunami14 waves. The authors suggest the spatial pore fluid pressure variations to be related to oceanic water accumulated in an altered oceanic fracture zone within the Pacific oceanic plate. Upon subduction of the latter beneath South America the fluid volumes are released and trapped along the overlying plate interface, leading to increasing pore fluid pressures. This study provides a powerful tool to monitor the physical state of a plate interface and to forecast its seismic potential.
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1 dominant adj.支配的，统治的；占优势的；显性的；n.主因，要点，主要的人；显性基因 参考例句： The British were formerly dominant in India.英国人以前统治印度。 She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。
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