These earthquake scenarios represent the largest magnitude events estimated on the basis of a variety of geologic assumptions. The appropriateness of these assumptions depends on the intent of the analysis and the state of geologic knowledge. Therefore, the resulting estimates may not be appropriate for other purposes, such as the development of seismic design criteria for a specific site. The development of such criteria commonly requires detailed analyses of the site and its immediate geologic environment beyond the scope of this report. Consequently, detailed site analyses may require modification of the conclusions reached in this report, particularly fault systems other than the San Andreas and Hayward faults.
B. GEOLOGIC EVIDENCE
Some of the possible earthquakes listed are repeat occurrences of historical events, others are not, but geologic evidence indicates that earthquakes occurred on these faults before settlement of the region. Based on available data, the postulated earthquake magnitudes would be the largest events that could be expected at areasonable level of probability. They represent a selection of events useful for planning purposes, but are by no means the only such events likely to occur either on these or other fault systems.
The historic record of seismicity in California is too short to determine confidently how often large earthquakes reoccur. Information on past earthquakes must be gleaned from the geologic record and therefore, presents a picture of past seismicity that is incomplete and not yet fully deciphered. Current knowledge about the recurrence of large earthquakes on specific faults is rudimentary. The probabilities of occurrence shown above are order-of-magnitude estimates and subject to considerable uncertainty, especially for the less probable events.
C. DESCRIPTION OF EVENTS
Following are brief descriptions of postulated events. Figure 1 gives their geographic location.
1. Los Angeles-San Bernardino/Southern San Andreas Fault (Magnitude 8.3)
For the past several thousand years, great earthquakes have been occurring over a 300 km length of the San Andreas fault approximately every 100 to 200 years, 140 years on the average. The last such event took place in 1857. The probability of occurrence of this earthquake is estimated to be currently as large as 2 to 5 percent per year and greater than 50 percent in the next 30 years. The fault skirts the edge of the Los Angeles-San Bernardino metropolitan region, thus most of the urbanized area lies further than 20 miles from the source of strong shaking. Because of the distance, shaking would be more hazardous for large structures than for one- to two-story houses. The long duration of shaking could trigger numerous slides on steep slopes and cause liquefaction in isolated areas.
2. San Francisco Bay Area/Northern San Andreas Fault (Magnitude 8.3)
A repeat occurrence of the 1906 earthquake, in which the San Andreas fault broke over 400 km of its length, would cause severe damage to structures throughout the Bay Area and adjacent regions. The extensive urban development on lowlands and landfill around San Francisco Bay would be especially hard hit and liquefaction in many of these areas would intensify the damage to structures erected on them.
3. San Francisco Bay Area/Hayward Fault (Magnitude 7.4)
The last large events to occur on this fault were in 1836 and 1868. Should a major earthquake occur, severe ground shaking and liquefaction is expected to cause damage throughout the entire circum-bay area nearly as severe as that resulting from a 1906-type earthquake on the San Andreas fault. This earthquake would be of particular concern because of the many dams located along or near the fault.
4. Los Angeles/Newport-Inglewood Fault (Magnitude 7.5)
This earthquake would be a serious threat to the nearby, densely-populated areas of Los Angeles. Shaking would cause extensive structural damage throughout the Los Angeles Basin and liquefaction near the coast would add still more destruction.
5. San Diego Area/Rose Canyon Fault (Magnitude 7.0)
This fault—a segment of an active zone of faults extending from the Newport-Inglewood fault to Northern Mexico—would present the greatest earthquake risk to the San Diego area. Severe damage due to shaking and liquefaction could be expected in the coastal areas. Because of unstable sea-bed sediments in the offshore area, local tsunamis (tidal waves) are possible.
6. Los Angeles/Santa Monica Fault (Magnitude 6.7 and 7.0) and Riverside/San Bernardino/Cucamonga Fault (Magnitude 6.8)
These faults are part of a system of east-west tending faults bordering the northern edge of the Los Angeles basin. This fault system caused the 1971 San Fernando earthquake and is geologically similar to the system that generated the large 1952 Kern County earthquake. Although smaller in magnitude than the earthquakes previously described, these postulated events are potentially quite dangerous because of their vicinity to high population densities in Southern California.
D. EARTHQUAKE EFFECTS
Detailed maps were prepared for each event showing qualitative estimates of ground shaking intensity resulting from each earthquake. These estimates are indicative of the general severity of damage to ordinary structures. Empirical formulae providing quantitative estimates of peak ground motion at various distances from the postulated earthquakes were developed for use in the effects of severeground shaking on individual structures or critical facilities. No estimates were made of localized effects, such as ground failures related to liquefaction (the complete failure or loss of strength, of a saturated soil due to shaking), landslides, and fault rupture. These effects can be far more destructive than ground shaking alone.
Figure 1. Geographic Locations of Selected Regional EventsFigure 1. Geographic Locations of Selected Regional Events
Figure 1. Geographic Locations of Selected Regional Events
A. INTRODUCTION
As part of a program that FEMA and its predecessor agencies have had underway for a number of years, property loss and casualty estimates were prepared in 1972 and 1973 for a number of potential maximum credible earthquakes that could impact on the San Francisco and the Los Angeles areas—North San Andreas (Richter magnitude 8.3), Hayward (Richter magnitude 7.4), South San Andreas (Richter magnitude 8.3), and Newport-Inglewood (Richter magnitude 7.5). These estimates have now been updated as part of the current assessment.
Estimates of property loss and casualties are based on the expected type and distribution of damage for each postulated earthquake as determined by the size and location of the earthquake and the distribution and character of the buildings and structures within the affected area. Methodologies for estimates of this type are approximate at best. Consequently, the figures shown below may vary upward or downward by as much as a factor of two or three. This degree of uncertainty does not affect the validity of the conclusions of this report, however, since there are greater uncertainties in all other aspects of emergency response planning.
B. PROPERTY LOSS ESTIMATES
The property loss estimates were obtained by first estimating the total replacement dollar value of buildings and their contents, multiplying them by percentage loss factors (inferred from the anticipated strength of shaking in each county), and then summing to obtain the aggregate loss. Included in the estimates are private as well as Federal, State, and local government buildings, insured and uninsured. Excluded from consideration is the replacement value of transportation and communication facilities, dams, utility installations, and special purpose structures (e.g., convention centers and sports arenas). Also excluded is the potential damage resulting from a major dam failure or the indirect dollar losses due to such factors as higher unemployment, lower tax revenue, reduced productivity, and stoppage of industrial production. Experience indicates that indirect losses could be approximately equal to the dollar amounts lost in buildings and their contents. The property loss estimates for four postulated earthquakes on the faults listed below are as follows.
FaultLoss to Building($ in Billions)Loss of Contents($ in Billions)Total Loss($ in Billions)Northern San Andreas251338Hayward291544Newport-Inglewood452469Southern San Andreas11617[1]Uncertain by a possible factor of two to three.
[1]Uncertain by a possible factor of two to three.
[1]Uncertain by a possible factor of two to three.
C. CASUALTY ESTIMATES
Deaths and injuries in these earthquakes principally would occur from failures of man-made structures, particularly older, multistory, and unreinforced brick masonry buildings built before the institution of earthquake-resistant building codes. Experience has shown that some modern multistory buildings—constructed as recently as the late 1960's, but not adequately designed or constructed to meet the current understanding of requirements for seismic resistance—are also subject to failure. Consequently, the number of fatalities will be strongly influenced by the number of persons within high-occupancy buildings, capable of collapsing, or by failure of other critical facilities such as dams. Additional imponderables are the degree of saturation of the ground at the time of the event and the possibility of weather conditions conducive to the spread of fire. A conflagration such as occurred in the 1906 San Francisco earthquake, is not considered likely to occur in any of the analyzed events, however, because of improvements in fire resistance of construction and firefighting techniques. Nonetheless, numerous smaller fires must be anticipated in any of the analyzed events and a "Santa Ana type" wind could cause serious problems.
An additional element of uncertainty in estimating casualties from earthquake stems from not knowing where most of the population will be at the time of the earthquake. In the early morning (i.e., 2:30 a.m.) most people are at home, by far the safest environment during a seismic emergency. At 2:00 in the afternoon, onthe other hand, the majority of people are at their places of employment and therefore vulnerable to collapse of office buildings. Around 4:30 p.m. many more people are in the streets and thus subject to injury due to falling debris or failures of transportation systems. Consequently, depending on the time of day, wide variations in the number of casualties can be expected.
Following are estimates of dead and injured (requiring hospitalization) for each of the four representative faults and for the three time periods just discussed.
FaultTimeDeadHospitalized[2]Northern San Andreas2:30 a.m.2:00 p.m.4:30 p.m.3,00010,00011,00012,00037,00044,000Hayward2:30 a.m.2:00 p.m.4:30 p.m.3,0008,0007,00013,00030,00027,000Southern San Andreas2:30 a.m.2:00 p.m.4:30 p.m.3,00012,00014,00012,00050,00055,000Newport-Inglewood2:30 a.m.2:00 p.m.4:30 p.m.4,00021,00023,00018,00083,00091,000[1]Uncertain by a possible factor of two to three.[2]Injuries not requiring hospitalization are estimated to be from 15 to 30 times the number of deaths.
[1]Uncertain by a possible factor of two to three.
[1]Uncertain by a possible factor of two to three.
[2]Injuries not requiring hospitalization are estimated to be from 15 to 30 times the number of deaths.
[2]Injuries not requiring hospitalization are estimated to be from 15 to 30 times the number of deaths.
D. OVERVIEW OF OTHER TYPES OF DAMAGE
For this assessment, estimates of damage to substantial numbers of different type facilities essential to the immediate response capability were updated.Earthquakes associated with the same four major fault systems identified earlier in this chapter were used as a basis for these estimates. The types of facilities analyzed includedhospitals,medical supply storages,blood banks, andcustodial care homes, together with their essential services and personnel resources. Although newer hospitals in California are being built according to substantially improved seismic safety standards and practices, older hospital facilities can be expected to be poorly resistant to earthquakes.
Among residential buildings, single family homes are expected to suffer structural damage and loss of contents. Damage to multifamily dwellings—particularly older buildings—would, in all likelihood, be more extensive. Analysis of expected damage indicates that temporary housing for as many as 200,000 families might be needed—a requirement calling for careful planning and exceptional management skills.
Schools are judged to be among the safest facilities exposed to the earthquakes. Since passage of the Field Act in 1933, after the Long Beach earthquake, school buildings in California have been continuously improved to withstand seismic hazards.
As a result of continuing and substantial upgrading of design and construction practices in the past 10 years, dams and reservoirs can be expected to show an improved performance in an earthquake. Nonetheless, on a contingency basis, one dam failure might be assumed for each planning effort.
Realizing the fact that 84 key communications facilities, earth stations, Department of Defense voice and data switches, commercial transoceanic cable heads, Federal Telecommunications System switches, and major direct distance dial switches are located within 55 miles of either Los Angeles or San Francisco, damage must be expected to occur. With this realization, priorities have been assigned to all critical circuits transiting the key facilities, based on established criteria of criticality of service continuity.National warning systems circuitry, command and control circuits, and circuits supporting diplomatic negotiations(of which a high concentration exists in California) are examples of those circuits carrying high-restoration priority.
In the civil sector there would be 24 to 72 hours of minimal communications, with a possible blackout of telephonic communications in the area immediately following an earthquake. The commercial carriers would institute network control procedures to regain control of the situation as fast as possible.
The impact on transportation facilities in any of the four hypothesized earthquakes could be massive. Since the magnitude and severity is unprecedented inrecent years, conclusions regarding losses must be accepted as tentative. As in the case of hospitals, however, the lessons learned in earthquakes during the past 10 years are being incorporated in the design and construction of new facilities.
In general, all major transportation modes would be affected—highways,streets,overpasses and bridges,mass transit systems,railroads,airports,pipelines, andocean terminals, although major variances in losses are expected among the modes. From a purely structural standpoint, the more rigid or elevated systems (such as railroads and pipelines) which cross major faults on an east-west axis would incur the heaviest damage, with initial losses approaching 100 percent. Other major systems (such as highways, airports, and pile-supported piers at water terminals) have better survivability characteristics and therefore would fare much better, with damage generally in the moderate range of 15 to 30 percent. These transportation facility loss estimates are stated in terms of immediate post-quake effects. They do not reflect the impact of priority emergency recovery efforts and expedient alternatives that are available, some within hours, to aid in restoration of transportation capacity. In addition, transportation systems generally have an inherently significant degree of redundancy and flexibility. Consequently, an unquantified but significant movement capability in all transport modes is expected to survive. Finally, these loss estimates do not take into account the question of availability of essential supporting resources, particularly petroleum fuels, electricity, and communications. In the initial response phase, these could prove to be the most limiting factors in the capability of the transportation system.
Business and industry would be affected by damage to office buildings, plants, and other support facilities. Although the 1971 San Fernando earthquake occurred on the margin of a largely suburban area, industrial facilities incurred significant damage. For example, several buildings of the kind commonly used for light industry or warehouses suffered from collapsed roofs or walls. Generally, building codes do not apply to special industrial facilities, and the ability of these structures to resist earthquake shaking will depend largely on the foresight of the design engineer. For example, a major electrical power switching yard and a water filtration plant were seriously damaged in the 1971 San Fernando earthquake.
About 10 percent of the population and industrial resources of the Nation are located in California. Over 85 percent of these resources (or about 8.5 percent of the Nation's total) are located in the 21 California counties that are subject to the possibility of damage from a major earthquake. Much of the aerospace and electronics industry is centered in California. For example, about 56 percent of the guided missiles and space vehicles, 40 percent of the semiconductors, 25 percent of the electronic computer equipment, and approximately 21 percent of the opticalinstruments and lenses manufactured in the Nation are manufactured in these 21 counties. The probability that all these counties would be affected by one earthquake is extremely remote; yet the significant concentration of key industries remains a concern. For example, about 25 percent of the Nation's semiconductors are manufactured in Santa Clara County, an area along the Northern San Andres fault that suffered very heavy damage in the 1906 San Francisco earthquake. Estimates of damage to these industrial facilities and the resulting loss of production have not been made. Similarly, the resulting impact of possible damage to national production has not been adequately analyzed.
Federally regulated financial institutions were generically analyzed to determine their ability to continue to promote essential services in the event of a major earthquake like those that have been postulated for this assessment. The conclusion reached thus far is that large-magnitude earthquakes pose no significant or unanticipated problems of solvency and liquidity for such institutions. The Federal Reserve System and other regulatory entities have procedures in place that are designed—and have been tested—specifically to provide for the continued operation of financial institutions immediately following an earthquake or other emergency.
A. INTRODUCTION
An earthquake of catastrophic magnitude, with or without credible warning, happens suddenly. The potential for disaster, however, does not occur suddenly. The degree of preparedness and commitment to comprehensive planning and mitigation programs for the inevitable event will largely determine the degree of hardship to be experienced through loss of life, human suffering, property destruction, and the other related economic, social, and psychological aspects of disruption to day-to-day community activities. The impacts can be reduced substantially from current expected levels through the development and implementation of improved and more widely practiced earthquake hazards reduction measures. These includecoordinated emergency preparedness plans and procedures,earthquake prediction and warning systems,improved construction techniques, andeffective public education and information programs.
The State of California Office of Emergency Services (OES) and FEMA conducted an analysis of the readiness capability for potential catastrophic earthquakes in California at the Federal, State, and local government levels. The planning of 22 counties and 38 cities, of 34 State agencies, and of 17 Federal organizations were reviewed with the following objectives: (a) identify opportunities for improvement; (b) provide a basis for making decisions that would strengthen program direction and planning efforts; and (c) specify resource needs and potential legislative initiatives. Annex 2 summarizes current Federal and California earthquake planning.
The environment in which preparedness planning in California occurs is characterized by the following observations of public expectations and attitudes:
There is widespread public support for government action.Most people have some ideas as to what government should be doing.There is understanding of the need for hazard reduction as well as emergency response planning.People are willing, in the abstract, to have government funds spent for hazard mitigation.The public is not very satisfied with what government officials have done.Public officials perceive that current preparedness plans and response are inadequate at best.
As discussed below, the review indicates that all is not well in earthquake plans and preparedness. Current plans and preparedness are judged to be adequate for the "moderate" earthquakes most likely to occur frequently in California. By moderate it is meant an event causing property damage on the order of $1 to $2 billion. Such an event, however, will severely tax existing resources and provide a major test of management relationship among different governmental jurisdictions and levels. For a catastrophic earthquake, current plans and preparedness are clearly inadequate, leading to a high likelihood that Federal, State, and local response activities would become disorganized and largely fail to perform effectively for an extended period of time.
B. STATE AND LOCAL RESPONSE
Although there are widely differing approaches, local emergency planning in California generally consists of a basic plan and a series of contingency plans. The basic plan establishes the authority, sets forth references, addresses hazard vulnerability, states the planning assumptions, establishes an emergency services organization, assigns tasks, formulates a mutual aid system, and directs the development of specific support annexes. For those hazards identified in the basic plan, a separate contingency plan is then developed to address the unique nature of the hazardous event. The contingency plan contains service support plans for each of the functional operations, including detailed standard operating procedures. The planning efforts of local jurisdictions are coordinated with adjacent jurisdictions and the California OES for consistency.
A plan is not considered complete without the support annexes which make the plan operational. The survey undertaken for this assessment disclosed that approximately 93 percent of the jurisdictions examined have existing, basic plans; 50 percent have completed annexes; 28 percent of the basic plans addressed an earthquake hazard vulnerability; 35 percent have planned for earthquake contingency; and only 1 percent (one city) has a plan to respond to an earthquake prediction.
At the State level, the California OES, as an integral part of the Governor's Office, functions as his immediate staff and coordinating organization in carrying out the State's emergency responsibilities. Specific emergency assignments have been made to 34 State agencies by the OES Director through a series of Administrative Orders. During emergencies the activities of these agencies and departments are coordinated by the California OES.
The State OES is also responsible for maintaining and updating the California Emergency Plan (CEP) and associated readiness plans. As in the case of local plans, the basic document is supported by operational annexes as listed below:
CONTINGENCYMUTUAL AIDEarthquakeFire and RescueEarthquake PredictionLaw EnforcementOil SpillMedicalNuclear BlackmailUtilitiesReactor AccidentMilitary SupportRadioactive Material IncidentFloodSUPPORTING SYSTEMSEMERGENCY RESOURCES MANAGEMENTWarningConstruction and HousingEmergency Broadcast SystemEconomic StabilizationEmergency Public InformationFoodIntelligence OperationsHealthRadiological DefenseIndustrial ProductionManpowerPetroleumTelecommunicationsTransportationUtilities
Based on this planning concept, the review assessed quantitatively the preparedness activities of the 34 State agencies that have preparedness responsibilities in accordance with the CEP. The quantitative data are listed in the following table.
Preparedness ElementNumber of AgenciesPercent of 34 AgenciesExistence of Plan2265Conduct of Exercises2779Public Education Activities1029Public Information Activities926Operational Capability3294
The quality of the plans, activities, and operational capabilities were then evaluated on a scale of 1 (expected to fail/inadequate) to 5 (expected to succeed well/adequate). The qualitative results are shown below.
Preparedness ElementCapability RatingPlanning2.67Exercises2.64Public Education1.44Public Information1.50Operational Capability2.91
It should be emphasized that these ratings apply to the State'spresentlevel of planning and preparedness for response to a major destructive earthquake (magnitude 8), not a moderate (San Fernando-type) event.
C. FEDERAL RESPONSE
At the Federal level the principal capability to respond to a catastrophic earthquake in California resides in FEMA, the agency responsible by law tocoordinate Federal activities in all emergencies. FEMA has developed a basic plan for supplemental Federal assistance for a major earthquake in the San Francisco Bay area. This plan, however, covers only the emergency phase of response (first few days of efforts to save lives and protect property). In addition, FEMA is participating in a broader effort concentrating in Southern California. This cooperative effort is getting under way with State and local governments, other Federal departments, voluntary agencies, practicing professions, business and commercial interests, labor, educators, and researchers. It is expected to develop an effective program to respond to an earthquake or a credible earthquake prediction in that part of the State. The emphasis is being placed onpublic safety, reduction of property damage, self-help on the part of individuals, socioeconomic impacts, improved response and long-range recovery planning, mitigation activities, and public participation for both the post-prediction and immediate post-earthquake periods. This pilot effort is expected to be usable in other highly seismic areas of California as well as in other States.
In the event of a catastrophic earthquake, a substantial number of Federal agencies would provide support to and be coordinated by FEMA. Illustrative are the following:
1. Department of Defense (DOD)
Initially, local military commanders may provide necessary support to save lives, alleviate suffering, or mitigate property damage. Normally, additional DOD resources would not be committed until a presidential declaration of an emergency or major disaster. When this occurs, the Secretary of the Army is DOD Executive Agent for military support. The Commander, Sixth U.S. Army, at the Presidio, San Francisco, has been further delegated authority to coordinate disaster relief operations in the western portion of the United States. Extensive planning and coordination have taken place between the Sixth U.S. Army and FEMA Region IX. DOD emergency functions include:damage survey,search and rescue,emergency medical care,identification and disposition of dead,emergency debris clearance,emergency roads and bridge construction,airfield repair, andidentification and demolition of unsafe structures. Specific units have been identified to respond to an earthquake in any of the major population centers of California. For example, at this time the following units would be prepared for commitment within 8 hours after a disaster is declared by the President:
Six medical units with a 1,320 bed capacitySeven helicopter units with 90 utility helicopters and 36 medium helicoptersOne Infantry brigade of 1,500 personnelTwo engineer units with 78 pieces of heavy equipmentTwo transportation units with 124 cargo trucks and trailers
These as well as additional DOD assets could be made available, contingent on defense priorities.
2. The National Communication System
This Agency's plan, the "National Plan for Communications Support in Emergencies and Major Disasters," provides for planning and using national telecommunications assets and resources during presidentially declared emergencies and major disasters. The plan, which has been exercised repeatedly in past disasters, provides the management structure and the communications staff to support FEMA. Restoration priorities have been assigned to all critical circuits.
3. Department of Transportation (DOT)
DOT has established an Office of Emergency Transportation. This office has developed and maintains comprehensive emergency plans and procedural manuals for natural disasters and other civil crises. It constantly monitors the civil transportation system for indications of potential adverse impacts from all hazards. It conducts scheduled periodic training and readiness exercises for DOT emergency personnel and maintains quick response cells and emergency operating facilities at DOT headquarters and in the field to provide an immediate reaction capability. The system has been activated several times in the recent past (e.g., Three Mile Island, 1979 Energy/Fuel Crisis, Independent Truckers' Strike, and the Mt. St. Helens eruption).
D. CONSIDERATIONS FOR IMPROVING RESPONSE CAPABILITY
Earthquake prediction has not been incorporated into existing plans. Response to predictions in the current environment, if given, would bead hoc. The State of California has only a rudimentary plan and the Federal Government none. The City of Los Angeles has examined the problem extensively, but only considers its own jurisdiction and has not produced an actionable plan. Current planning for the recovery period is incomplete, uncoordinated, and not functional. State and local governments have done little to plan for the recovery period when, following the emergency lifesaving phase, efforts and resources are concentrated on restoring thefunctioning of the community. They presume that the Federal Government will "step in" after a presidential declaration. The Federal Government has an untested draft plan for the San Francisco area that is not fully coordinated with the State plans. Current Federal plans are geared to the provision of assistance on the order of a few hundred million dollars. Thus, there is little confidence that they would function under the requirements for tens-of-billions-of-dollars and concomitant service demands.
Both Federal and State agencies need to commit the financial resources and assignment of personnel to maintain and enhance earthquake plans and preparedness. Earthquake preparedness, although responding to high damage expectation, is still based upon a relatively low probability occurrence. When it is in competition with pressing social needs for a portion of limited resources, social needs tend to prevail at all levels of government. Without a clear commitment, future development of earthquake preparedness, as in the past, is problematic and its implementation is in considerable doubt. The Federal earthquake preparedness effort needs to focus on a high state of readiness.
History in the area of natural hazard mitigation suggests that assignment of responsibility, even by the President, when not followed by leadership and regular oversight over the allocation of financial resources, seldom leads to programs which can be expected to function. The same weakness is evidenced at the State and local government levels with few exceptions. The stresses likely to occur in emergency response programs after a catastrophic earthquake will be such that effective response will require a cooperative, integrated effort among different jurisdictions and levels of government.
Experience in other areas of planning and preparedness, particularly for civil defense, indicates that damage to existing programs occurs when the Federal Government raises expectations of the public and of other levels of government and then fails to follow through with implementation and funding. It is better to maintain thestatus quowith minor changes at the margin than to announce substantial program initiatives and not meet their requirements.