A Proposal to Review How Geophysical Precursors

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A Proposal to Review How Geophysical Precursors
Can Help Predict Earthquakes
Christopher Gray
February 1995

Introduction
Throughout the world, devastating earthquakes occur with little or no advance warning. Some of these earthquakes kill hundreds of people. If the times, magnitudes, and locations of these earthquakes could be accurately predicted, many lives could be saved. This document proposes a review of how monitoring geophysical precursors can help in the short-term prediction of earthquakes. The proposed review will discuss the physical principles behind the monitoring of three common precursors and evaluate how accurate each monitoring is in predicting earthquakes. Included in this proposal are my methods for gathering information, a schedule for completing the review, and my qualifications.

Justification of Proposed Review
On the morning of April 18, 1906, the population of San Francisco was awakened by violent shaking and by the roar caused by the writhing and collapsing of buildings [Hodgson, 1964]. The ground appeared to be thrown into waves that twisted railways and broke the pavement into great cracks. Many buildings collapsed, while others were severely damaged. The earthquake caused fires in fifty or more points throughout the city. Fire stations were destroyed, alarms were put out of commission, and water mains were broken. As a result, the fires quickly spread throughout the city and continued for three days. The fires destroyed a 5 square-mile section at the heart of the city [Mileti and Fitzpatrick, 1993]. Even more disastrous was the Kwanto earthquake in Japan that devastated the cities of Yokohama and Tokyo on September 1, 1923 [Hodgson, 1993]. In Yokohama, over 50 percent of the buildings were destroyed [Bolt, 1993], and as many as 208 fires broke out and spread through the city [Hodgson, 1964]. When the disaster was over, 33,000 people were dead [Bolt, 1993]. In Tokyo, the damage from the earthquake was less, but the resulting fires were more devastating. The fires lasted three days and destroyed 40 percent of the city [Hodgson, 1964]. After the fire, 68,000 people were dead and 1 million people were homeless [Bolt, 1993]. The 1906 San Francisco earthquake and the Kwanto earthquake were two of the most famous and devastating earthquakes of this century. These earthquakes struck without warning and with disastrous results. If earthquakes could be predicted, people would be able to evacuate from buildings, bridges, and overpasses, where most deaths occur. Some earthquakes have been successfully predicted. One of the most famous predictions was the Haicheng Prediction in China. In 1970, Chinese scientists targeted the Liaoning Province as a site with potential for a large earthquake. These scientists felt that an earthquake would occur there in 1974 or 1975. On December 20, 1974, an earthquake warning was issued. Two days later, a magnitude 4.8 earthquake struck the Liaoning Province; however, further monitoring suggested a larger earthquake was imminent [Mileti and others, 1981]. On February 4, 1975, the Chinese issued a warning that an earthquake would strike Haicheng within 24 hours [Bolt, 1993]. The people in Haicheng were evacuated, and about 5.5 hours later, a magnitude 7.3 earthquake shook the city of Haicheng. If the people hadn't been evacuated, the death toll could have exceeded 100,000. Using geophysical precursors, the Chinese have predicted more than ten earthquakes with magnitudes greater than 5.0 [Meyer, 1977]. For example, the Chinese predicted a pair of earthquakes of magnitude 6.9 that occurred 97 minutes apart in Yunnan on May 19, 1976 [Bolt, 1993]. Despite these successes, the Chinese failed to predict the earthquake that struck the city of Tangshan on July 27, 1976; this earthquake killed 250,000 people and injured 500,000 more [Bolt, 1988]. This earthquake wasn't completely unexpected, but the Chinese believed it to be a few years away. Other earthquakes have been...
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