| Loma Prieta Earthquake |
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This was a major earthquake which caused severe damage as far as 70 miles (110 km) away; most notably in San Francisco , Oakland , the San Francisco Peninsula , and in areas closer to the epicenter in the communities of Santa Cruz , the Monterey Bay , Watsonville , and Los Gatos . Most of the major property damage in the more distant areas resulted from Liquefaction of soil used over the years to fill in the waterfront and then built upon. SCIENCE, EFFECTS AND RESPONSE The magnitude and distance of the earthquake from the severe damage to the north were surprising to geotechnologists. Subsequent analysis indicates that the damage was likely due to reflected Seismic Wave s - the reflection from well-known deep (about 15 miles) discontinuities in the Earth's gross structure. There were at least 63 deaths (some say 66) and 3,757 injuries as a result of this earthquake. The highest concentration of fatalities, 42, occurred in the collapse of the Cypress Street Viaduct on the Nimitz Freeway ( Interstate 880 ), where a double-decker portion of the freeway collapsed, crushing the cars on the lower deck. One 50-foot (15 m) section of the San Francisco-Oakland Bay Bridge also collapsed, causing two cars to fall to the deck below, leading to the single fatality on the bridge. The bridge was closed for repairs for a month and one day, reopening on November 18 . While the bridge was closed, ridership on Bay Area Rapid Transit and ferry services soared. After the 1906 earthquake much of the rubble was bulldozed into San Francisco Bay. This reclaimed land was built upon and was extremely unstable. In the Loma Prieta 'quake many buildings on this reclaimed land were destroyed. Because this quake occurred during the evening Rush Hour , there could have been a large number of cars on the freeways at the time, which on the Cypress Street Viaduct could have endangered many hundreds of commuters. Very fortunately, and in an unusual convergence of events, the two local Major League Baseball teams (the Oakland Athletics and the San Francisco Giants ) were about to start their third game of the World Series (the game was scheduled to start shortly after 5:30 pm). Many people had left work early or were participating in early after-work group viewings and parties. As a consequence, the usually crowded highways were experiencing exceptionally light traffic at the time. Not taking this into account, initial media reports pegged the death toll at 300, a number that was corrected in the days after the earthquake. {Link without Title} Extensive damage also occurred in San Francisco's Marina District, where many expensive homes built on filled ground collapsed. Fires raged in some sections of the city as water mains broke. San Francisco's Fireboat (the ''Phoenix'') was used to pump salt water from San Francisco Bay through hoses dragged through streets by citizen volunteers. Power was cut to most of San Francisco and was not fully restored for several days. Deaths in Santa Cruz occurred when brick storefronts and sidewalls in the historic downtown (what was then called the Pacific Garden Mall ) tumbled down on people exiting the buildings. The quake also caused an estimated $6 billion in property damage, the costliest natural disaster in U.S. history at the time. It was the largest earthquake to occur on the San Andreas Fault since the great 1906 San Francisco Earthquake . Private donations poured in to aid relief efforts and on October 26 , President Bush signed a $3.45 billion earthquake relief package for California. . Note that the high intensity areas skipped likely mid-peninsula and lower east-bay locations while strong in the San Francisco and Oakland - Richmond areas]] TRANSPORTATION EFFECTS The Loma Prieta earthquake irrevocably changed the San Francisco Bay Area's transportation landscape. Not only did the quake force Seismic Retrofitting of all San Francisco Bay Area bridges, it caused enough damage that some parts of the region's freeway system had to be demolished. In some cases, the freeways in question had never been completed, terminating in mid-air; in that regard, the quake provided the impetus to deal with regional transportation problems that had gone largely unsolved for decades.
1989 WORLD SERIES The earthquake had been "predicted" in the morning edition of ''. KGO-TV was the first to cover the earthquake after the game was canceled Fortunately, less than half of the 65,000+ fans had reached their seats, lessening the load on the structure of the stadium. There had also been a seismic strengthening project previously completed on the upper deck concrete windscreen. Fans reported that the stadium moved in an articulated manner as the earthquake wave passed through it, that the light standards swayed by many feet, and that the concrete upper deck windscreen moved in a wave-like manner over a distance of several feet. As soon as the shaking stopped, the assembled crowd roared as loud as if a game-winning double had been hit. A few minutes later they yelled "Play Ball, Play Ball!" However, the game was called and the Series was postponed for 10 days. ABC sportscaster Al Michaels was nominated for an Emmy award for his News Broadcasts about the earthquake. PRECEDING MAGNETIC DISTURBANCES The Loma Prieta earthquake was preceded by significant disturbances in the background Magnetic Field strength nearby. Large increases in Extremely Low Frequency field strength were observed about 7 kilometers from the epicenter, up to two weeks in advance of the actual event. The measurement instrument was a single-axis search-coil Magnetometer that was being used for research on radio communications with Submarines by Prof. Antony C. Fraser-Smith of Stanford University . Signal strengths 20 times higher than normal were observed on October 3rd, rising to 60 times normal about three hours before the earthquake. EXTERNAL LINKS Seismology
Transportation
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