[填空题]Earthquakes can be devastating (1) disasters. The infamous San Francisco earthquake of 1906 caused over $ 200 million worth of damage, (2) almost 30,000 buildings, and (3) about 450 persons. In Japan, the cities of Tokyo and Yokohama were leveled by the earthquake of 1923 in which more than 140, 000 persons were killed by falling buildings and fires, and over a million people were left (4) — all in 30 seconds.
Hundreds (5) earthquakes occur every year (6) the world. Fortunately, (7) are as destructive as those described above. The development of (8) accurate system for predicting earthquakes would (9) the loss of life and (10) , but at present scientists can only study these phenomena. The study of earthquakes is called seismology. Seismographs, instruments sensitive (11) ground movement, are used to chart each motion, and the Richter Scale is commonly used