An Assessment of the Consequences and Preparations for a Catastrophic California Earthquake: Findin | Page 3

earthquakes, casualties could surpass the previous single greatest loss of life in the United States due to a natural disaster, which was about 6,000 persons killed when a hurricane and storm surge struck the Galveston area of the Texas coast in 1900. The highest loss of life due to earthquakes in the United States occurred in San Francisco in 1906, when 700 people were killed. By way of comparison (in spite of the vast differences in building design and practices and socioeconomic systems) the devastating 1976 Tangshan earthquake in China caused fatalities ranging from the official Chinese Government figure of 242,000 to unofficial estimates as high as 700,000. Fortunately, building practices in the United States preclude such a massive loss of life.
Property losses are expected to be higher than in any past earthquake in the United States. For example, San Francisco in 1906, and Anchorage in 1964, were both much less developed than today when they were hit by earthquakes. And the San Fernando earthquake in 1971, was only a moderate shock that struck on the fringe of a large urban area. Each of these three earthquakes caused damage estimated at about $0.5 billion in the then current dollars. Estimates of property damage for the most probable catastrophic earthquake on the Southern San Andreas (Richter magnitude 8+) and for the less probable but more damaging one (Richter magnitude 7.5) on the Newport-Inglewood fault, are about $15 billion and $70 billion respectively. By comparison, tropical storm Agnes caused the largest economic loss due to a natural disaster in the United States to date but it amounted to only $3.5 billion (in 1972 dollars).
It should be noted, however, that substantial uncertainty exists in casualty and property damage estimates because they are based on experience with only moderate earthquakes in the United States (such as the 1971 San Fernando earthquake) and experience in other countries where buildings are generally less resistant to damage. The uncertainty is so large that the estimated impacts could be off by a factor of two or three, either too high or too low. Even if these lowest estimates prevail, however, the assessment about preparedness and the capability to respond to the disasters discussed in this report would be substantially unchanged.
Assuming a catastrophic earthquake, a variety of secondary problems could also be expected. Search and rescue operations--requiring heavy equipment to move debris--would be needed to free people trapped in collapsed buildings. It is likely that injuries, particularly those immediately after the event, could overwhelm medical capabilities, necessitating a system of allocating medical resources to those who could be helped the most. Numerous local fires must be expected; nevertheless, a conflagration such as that which followed the Tokyo earthquake of 1923, or the San Francisco earthquake of 1906, is improbable, unless a "Santa Ana type" wind pattern is in effect. Since the near failure of a dam in the San Fernando, California, earthquake of 1971 (which was a moderate event), substantial progress has been made in California to reduce the hazard from dams, in some cases through reconstruction. For planning purposes, however, experts believe that the failure of at least one dam should be anticipated during a catastrophic earthquake in either the Los Angeles or San Francisco regions.
Experience in past earthquakes, particularly the 1971 San Fernando earthquake, has demonstrated the potential vulnerability of commercial telephone service to earthquakes, including the possibility of damage to switching facilities from ground shaking and rupture of underground cables that cross faults. This is especially serious because immediately following earthquakes, public demand for telephone services increases drastically. This increased demand overloads the capability of the system, even if it had not been damaged, and therefore management action to reduce the availability of service to non-priority users and to accommodate emergency calls is mandatory. Radio-based communication systems, particularly those not requiring commercial power, are relatively safe from damage, although some must be anticipated. The redundancy of existing communication systems, including those designed for emergency use, means that some capability for communicating with the affected region from the outside would almost surely exist. Restoration of service by the commercial carriers should begin within 24 to 72 hours as a result of maintenance and management actions; however, total restoration of service would take significantly longer.
While numerous agencies have the capability for emergency communication within themselves, non-telephonic communication among entities and agencies in the affected area is minimal. This is true for Federal, State, and local agencies. This weakness has been pointed out repeatedly by earthquake response exercises, and the problem is raised by almost every emergency preparedness official at every level of government. Consequently, a major problem for resolution is the operational integration of communications systems and networks among the relevant Federal, State, and local agencies.
Because of their network-like character, most systems for transportation and water and power