Word: occurs
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Dates: during 1970-1979
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...last large-scale killers occurred in Asia. One, last December in northern Pakistan, ravaged nine towns and took nearly 5,000 lives. The other, a February tremor in China, is believed to have killed hundreds. Indeed, not a day passes without earth tremors somewhere on the globe. Some of those quakes are too weak to be felt by humans; they can be detected only by sensitive seismographs. Others are more violent but occur on the ocean floor or in remote areas and do no harm. Some add to the long catalogue of destruction. Last week, for example, a 4.7 earthquake...
When quake centers are marked on a map of the world, it becomes clear that many earthquakes do indeed occur along plate boundaries. The earthquake-marked "ring of fire" around the Pacific Ocean, for example, neatly outlines the Pacific plate. But earthquakes can also occur well within a plate, possibly because the plate structure has been weakened in those places during periods of ancient volcanism. Charleston, S.C., for instance, is more than 1,000 miles away from the edge of the North American plate; yet it lies in a seismically active area (see map page...
Long before the plate-tectonics theory was conceived, scientists were aware that rocks fracture only under extreme stress. As early as 1910, Johns Hopkins Geologist Harry Reid suggested that it should be possible to tell when and where quakes were likely to occur by keeping close tab on the buildup of stresses along a fault. But the knowledge, instruments and funds necessary to monitor many miles of fault line and interpret any findings simply did not exist. Earthquake prediction did not draw much attention until 1949, when a devastating quake struck the Garm region of Siberia, causing an avalanche that...
...Doherty Geological Observatory, urged one of his students, a young Indian doctoral candidate named Yash Aggarwal, to look for similar velocity shifts in records from Lamont-Doherty's network of seismographs in the Blue Mountain Lake region of the Adirondacks, in upper New York State, where tiny tremors occur frequently...
...strike-slip fault, along which the adjoining sides are sliding past each other. Because most upheavals along the San Andreas Fault involve strike-slip quakes, Whitcomb's forecast raised hopes that seismologists could use their new techniques to predict the major earthquakes that are bound to occur along the San Andreas...