Southern Californians would love to find some way of knowing a month in advance whether a 11 earthquake will likely strike. One meteorologist suggests atmospheric pressure patterns might provide some 12 . Jerome Namias of the Scripps Institution of Oceanography in La Jolla, Calif. , proposed this 13 in 1988 when he reported that an unusually strong high-pressure system developed in the North Pacific before quakes struck southern California in 1986 and 1987. Now Namias has 14 expanded his analysis by studying the summers between 1947 and 1987. From a 15 of all southern California earthquakes with magnitudes of 4- 5 or greater during that period, Namias 16 out the summers with many quakes and those with no quakes. His analysis of the meteorology during these summers shows that quakes were more 17 under a particular set of conditions; a stronger-than-normal North Pacific high pressure, a low-pressure ridge over the 18 interior. Summers with no quakes usually had a weak Pacific high and a poorly developed continental high, he reports in the Dec. 10 JOURNAL OF GEOPHYSICAL RESEARCH. Namias cannot 19 the apparent correlation between pressure and seismicity, but he 20 that variations in seafloor pressure or in sea-surface temperature might influence both the atmospheric pressure and the ground stress in California.
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发表于 2012-8-14 10:00:37
