Preparing for the "Big One" -- Saving Lives Through Earthquake Mitigation in Los Angeles, CA

HOUSING

I. Introduction

There are approximately 1.3 million dwelling units in the City of Los Angelesabout 791,000 multifamily units and 512,000 single-family homes. As of April 4, 1994, the damage tally from the Northridge earthquake included 65,300 residential buildings containing 308,846 units. Multifamily housing suffered disproportionately, comprising 84 percent of the damaged units.

Although the incidence of residential damage was greatest in the City of San Fernando, the City of Los Angeles incurred the most total damage. According to an April 1994 report from the Los Angeles Department of Building and Safety, estimated citywide damage to residential buildings totaled $1.15 billion-$599 million in multifamily buildings and $550 million in single-family buildings.

By October 1994, an updated estimate put the total damage to residential properties at over $1.3 billion. However, even this higher figure does not reflect the billions more that private insurance companies may have paid in claims.

Three common types of residential construction pose the greatest risk to life and safety in a seismic event. The vast majority of structures damaged in the earthquake were wood-frame buildingsthose with a "soft" first story were especially vulnerable. Unreinforced masonry buildings and hillside homes were also particularly susceptible to damage. Unexpected structural failure occurred in some steel-frame buildings. In addition to construction failure, gas-fed fires caused by unbraced water heaters and unanchored manufactured homes were a significant danger to life, safety, and property.

II. What Needs to Be Done?

Some measures of the nature and cost of mitigating the effects of future earthquakes on residential structures in Los Angeles are known. The City's Housing Department and Department of Building and Safety have identified mitigation priorities and estimated their costs. In addition, retrofitting measures and costs can be estimated for each construction type. However, other information critical to mitigation planning is not available. For example, the number of housing structures and units of each construction type is not known Los Angeles lacks an automated building inventory system that could provide such fundamental data.

Another impediment to retrofitting residential structures is the lack of State and municipal statutes that would require appropriate earthquake damage mitigation measures the associated cost to property owners would make such legislation extremely difficult to pass. Nor is the technical basis for mandatory mitigation necessarily in place. For example, no accepted standard for steel-frame buildings currently exists. A standard for cripple-wall retrofit has been developed, but is not officially accepted.

A great deal of information is available on retrofitting and repairing single-family homes, which make up the bulk of Los Angeles' residential structures. In contrast, research on multifamily housing particularly wood-frame structures is quite limited, although more studies are currently underway. Unreinforced masonry residential buildings are an exceptionextensive research on this structural type has already been completed.

The failure of steel-frame buildings in the Northridge earthquake was unexpected and requires further research. Although the majority of steel-frame buildings are used for commercial purposes, there are 140 steel-frame multifamily buildings in the City of Los Angeles.

Wood-Frame Homes

The vast majority of buildings affected by the Northridge earthquake are wood-frame structures. In the urban areas of Los Angeles, three- or four-story buildings of this type make up most of the multifamily stock. Under seismic stress, multi- story structures with a soft first story (usually in the form of wood-framed parking facilities) performed poorly. The three- story Northridge Meadows apartment building, which collapsed and killed 16 people, was one such wood-frame building.

The most common structural weaknesses of light, wood-frame residential structures are:

• Discontinuous or non-existent foundations below the exterior walls.

• The absence of proper connections between the exterior walls and the foundation. Inadequate bracing of cripple walls, which extend from the top of the foundation to the underside of the lowest floor framing (see Exhibit 9).

Incentives are needed to encourage property owners to retrofit their wood-frame buildings. The cost of retrofitting an undamaged wood-frame, single-family home ranges from $2,000 to $4,000, including the installation of sill bolts and cripple-wall bracing. However, the cost of repairing a damaged unit of this type is about $30,000. The total cost of retrofitting 100,000 undamaged wood-frame, cripple-wall homes would range from $200 million to $400 million, although the actual number of such buildings may be higher.

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EXHIBIT 7 Structural damage at Northridge Meadows Apartments, where the top two floors collapsed, killing 16 people.

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EXHIBIT 8 The result of cripple-wall failure in a wood-frame house.

Unreinforced Masonry Buildings

Unreinforced masonry buildings are the construction type considered most vulnerable to earthquake damage. Los Angeles' estimated 46,000 multifamily unreinforced masonry buildings are concentrated in four downtown neighborhoods: Hollywood, Boyle Heights, Wilshire/Westlake, and South Central.

Observations after the earthquake confirmed that retrofitted unreinforced masonry buildings performed better than unretrofitted ones. No properly retrofitted unreinforced masonry building sustained significant structural damage. Retrofitted buildings that were damaged were found, upon inspection, to have improperly designed or constructed systems. Correctly retrofitted masonry buildings were not immune to quake damage, but unretrofitted structures generally had more extensive damage, and a significant number of partial or complete collapses were observed. Typical damage included falling walls and parapets, shear cracks in walls, and partial collapse because of the loss of corner piers. Masonry fireplaces, common in single-family structures, also performed poorly: many complete and partial failures of fireplaces and chimneys occurred in areas of seismic damage.

Unreinforced masonry buildings no longer pose as great a threat as in earlier years because many have been retrofitted through a local seismic safety program, which began in 1981. According to city officials, the program has successfully retrofitted 5,800 unreinforced masonry buildings in Los Angeles, but 500 are still in need of retrofit and another 300 should be demolished. Included in this inventory are mostly commercial and mixed use buildings with some residential.

The average per-unit cost of retrofitting an unreinforced masonry building is between $5,000 and $15,000. The lower boundary of this estimate applies to the addition of plywood to the walls, while the more extensive and expensive retrofit includes installing grade beams and steel columns. Other retrofit measures include bracing the parapet and tying the floor and walls together. An upper bound cost estimate of completing retrofit of the 15,000 units in unimproved masonry buildings in the City of Los Angeles would range from $75 million to $225 million.

Hillside Homes

Homes built on steep slopes of 20 degrees or greater are quite vulnerable to damage in a seismic event. The Northridge earthquake damaged 400 hillside homesin two instances, collapsing homes killed the occupants.

Because the City of Los Angeles does not have a building inventory system, the total number of homes constructed on hillsides is unknownone guess places the figure at 10,000 units. Retrofitting an undamaged hillside home costs an estimated $6,000-$25,000, which includes adding plywood walls and anchor bolts. Thus the total cost of retrofitting the estimated 10,000 undamaged hillside homes in the City of Los Angeles would be between $60 million and $250 million. Repairs to damaged homes can exceed $70,000.

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EXHIBIT 9 A damaged shear wall in an unreinforced masonry building undergoes repair and retrofit.

Due to the risk of seismic damage and high cost, owners of hillside homes should be offered incentives to retrofit their homes.

Gas-Fed Residential Fires: Water Heaters

Both the Los Angeles Department of Housing and the Southern California Gas Company (SoCal Gas) reported that gas-fed fires were a major concern during the Northridge earthquake. According to SoCal Gas, 40 percent of all structure fires were caused by water heaters whose gas lines had ruptured. Even braced water heaters were found to be inadequateplumbing tape and staples, while commonly used, are not sufficient to safely secure a water heater and its gas pipes during a seismic shock. Another factor contributing to the potential for gas-fed fires was the buckling of the legs and/or plywood shelves used to support water heaters. Manufacturers should strengthen or eliminate water heater legs.

The cost of bracing and strapping a water heater is approximately $100.22 Since 1984, any new water heater installed required strapping. Based on an upper bound estimate, providing all of the approximately 512,000 single-family detached units in the City of Los Angeles with proper water heater bracing would cost $51.2 million.

Additional mitigation activities need to be undertaken as well. For example, local building codes should adopt the Division of State Architect bracing standard for new homes, replacement homes, and replacement water heaters. There is no requirement addressing the need for adequate bracing. To ease the expense of mitigation, cash incentives, similar to those offered for buying energy-efficient appliances or lighting fixtures, should be provided for homeowners who implement a seismic mitigation measure, such as properly bracing their water heater.

Gas-Fed Residential Fires: Manufactured Housing

Inadequate bracing also leaves manufactured homes extremely vulnerable to seismic damage. Eight separate fires started in one mobile home parkduring the Northridge earthquake. The earthquake shook manufactured homes off their 30-inch-high bases, damaging gas pipes and sparking fires that would then spread to several other homes. Water shortages caused by broken water mains and pipes exacerbated the crisis and complicated firefighting efforts. Manufactured housing developments, often located in hilly areas, were also sometimes difficult for firefighters to reach.

To prevent manufactured homes from slipping off their foundations in the next earthquake, units should be braced and anchored. In the Northridge area, there are currently about 9,000 mobile homes. The cost of anchoring a manufactured home ranges from $2,500 to $5,000. However, this cost may be out of reach to many owners of manufactured homes, who are disproportionately elderly and often have lower (or fixed) incomes.

Other mitigation measures that need to be implemented include developing construction standards that require manufactured homes to have seismic bracing and adequate anchorage; requiring that gas meters in new construction be located at least 4 feet from the home; and creating financial incentives for manufacturers and owners to anchor their mobile homes.

III. What Is Being Done?

Multifamily buildings are a vital housing resource, particularly for low-income families and elderly households. In Los Angeles, 54 percent of all housing units are in multifamily buildings. Multifamily housing-especially low-rent property is concentrated in the neighborhoods of downtown Los Angeles.

Such neighborhoods of largely multifamily properties were among those most devastated in the Northridge earthquake. More than a dozen "ghost towns" have sprung up in areas where property owners and residents have abandoned damaged buildings and homes because the cost of repair seems to outweigh the benefits of rebuilding. These ghost towns are single blocks or entire neighborhoods awaiting demolition or repair, populated primarily by squatters, drug addicts, and gangs.

However, apartment owners are perhaps least well-served by the existing response and recovery programs. Rebuilding and mitigation activities for multifamily housing are highly dependent upon Federal funds from FEMA, SBA, and HUD. Privately owned multifamily developments do not qualify for most FEMA funding the small amount of funding available under its Minimum Home Repair program is unlikely to be sufficient. Many landlords face serious obstacles to obtaining adequate, timely SBA loans. And direct HUD assistance for multifamily housing is available only to owners of HUD-insured properties, although in recent months additional funds were allocated to address the multifamily rebuilding crisis. Most recovery resources are targeted at middle-class owners of single- family homes.

Small Business Administration

Although the Small Business Administration (SBA) offers low- interest loans for rebuilding damaged residential properties, vulnerable groups, such as owners of affordable multifamily housing, have had difficulty in using this resource. Restrictive, narrowly defined loan criteria can sometimes exclude even qualified borrowers with damaged homes. For example, a home that has twisted may not qualify for an SBA loan if it has no cripple-wall damage. SBA's loan cap of $1.5 million is not sufficient to repair large apartment buildings. Loan approvals can take months, and loan proceeds often arrive up to 7 months after the earthquake. Moreover, because SBA loans are based on the project's credit worthiness instead of the level of financial need or damage, financially marginal housing is less likely to qualify for sufficient loan amounts. Nonetheless, SBA has approved over 87,000 loans for $2.7 billion in repairs related to the Northridge earthquake.

At the applicant's request, loans may be increased by up to 20 percent of the amount of the loan for necessary or appropriate hazard mitigation measures. Although encouraging applicants for SBA loans to apply for mitigation funding would promote measures that improve safety and help structures better withstand future earthquakes, SBA does not publicize this component because it increases the debt load for the borrower.

U.S. Department of Housing and Urban Development

HUD's Earthquake Loan Program (HELP) authorized up to $100 million in loans to owners of HUD-insured multifamily properties for appropriate mitigation activities. HUD-insured single-family properties, including condominiums, are not eligible under the HELP program. The Northridge earthquake damaged approximately 3,500 condo units and fewer than 1,000 FHA-insured homes in the City of Los Angeles. In the early fall of 1994, an additional $255 million from the President's Discretionary Fund were allocated to rebuild "ghost towns" and repair multifamily buildings, including condominiums and non- HUD insured residential multifamily properties.

Los Angeles Task Force

To enhance the seismic safety of Los Angeles' building stock, committees of engineers and contractors from the City's Task Force on Evaluating Damage from the Northridge Earthquake are assessing building failures and plan to recommend the expansion and revision of local residential building codes and standards. Committee reports are expected to be available beginning in August 1994.

Low-Income Housing Mitigation

For the past 14 years, Southern California Gas Company has provided weatherization training through community-based organizations, Job Training Partnership Act (JTPA) programs, and others. Through ratepayer funds established by the Public Utilities Commission, the gas company contracts with community-based organizations to do one of three things: perform outreach to identify low-income candidates for job training and homes in need of weatherization, perform the weatherization, or inspect work performed by another organization.

More than 14,000 workers have been trained and well over 300,000 low-income homes have been weatherized through this program. FEMA has been so impressed with the program that it is considering modeling a mitigation program on it. One possibility would be to combine mitigation with weatherization measures. A related option has been suggested by North Valley Occupational Center, a regional vocational school located close to the Northridge epicenter, which has expressed interest in adding retrofitting techniques to its curriculum of carpentry courses.

Limitations on Repair and Mitigation

Governments at all levels are encountering a number of challenges in their efforts to facilitate earthquake repair and mitigation activities, particularly among owners of multifamily properties. Many apartment owners, operating with minimal repair reserves and without earthquake or disaster insurance, cannot afford mitigation or even basic repairs without financial assistance. Ironically, however, buildings owned by these uninsuredand often undercapitalizedlandlords tend to be the most vulnerable to earthquake and fire damage. For those unable to qualify for loans, the only way to pay for repairs to damaged units is to raise rentsan option that is not always feasible.

This combination of problems can seriously reduce the local stock of affordable multifamily housing and result in the displacement of lower income renters. In addition, owners of damaged single-room occupancy (SRO) properties may be tempted to demolish them and rebuild as condominiums, commercial or industrial buildings. The market value of an SRO is typically less than the highest use of the land. Preserving this vital part of the affordable multifamily housing stock may require incentives to persuade owners to keep SRO properties from demolition, as well as to repair and mitigate damage.

For relief and recovery programs to be truly equitable across the spectrum of needs, resources and programs must be targeted not only to homeowners, but also to residents of affordable multifamily housing. Before the next earthquake, State and Federal agencies need to formally revise their policies on temporary shelter in a disaster, so that all victims have some access to assistance.

Simply recognizing that disaster victims are not primarily homeowners would be an important first step in reconceptualizing the recovery process. One way to encourage a more equitable distribution of recovery funds would be to channel Federal and State housing assistance through local governments, rather than aiding building owners directly. This would allow funding providers to allocate resources in a way that was sensitive to patterns of actual damage, such as the number and type of units affected. It would also give local governments the flexibility to target areas of need and/or to combine various funding sources to meet specific problems.

IV. Conclusion

Numerous challenges confront efforts to save lives by making Los Angeles area housing more resistant to earthquakes. The first is a problem of information. The City of Los Angeles lacks fundamental data on the size, composition, location, and condition of its housing stock that is indispensable to effective mitigation planning. In addition, although Los Angeles building codes have been significantly strengthened in the past to encourage seismically safe construction, the Northridge experience indicates several types of construction such as wood-frame homes, hillside homes, and steel-frame structureson which more technical research and evaluation is needed as a basis for further code reforms.

However, building codes primarily affect new construction. In the absence of laws that would require property owners to upgrade their units to a seismically safe standard, it is vitally important to find mechanisms that will encourage retrofitting of existing housing. Currently, few such incentives exist that can overcome property owners' reluctance to voluntarily take on the expense of preventive measures to protect homes that may or may not have been damaged in previous quakes.

Perhaps most urgent is the fundamental disparity between housing mitigation needs and available assistance. Most forms of disaster assistance, to the extent that they support residential repair and mitigation activities, are best suited to the needs and circumstances of middle-class owners of single-family homes. However, the vast majority of housing units damaged in the Northridge earthquake were in multifamily structures, and in many cases were by housing type, age of structure, or locationparticularly likely to be occupied by low- and moderate-income households. Owners of such housing are usually less able to afford needed repair and mitigation. Moreover, Federal assistance for owners of private, affordable multifamily housing is quite limited and remains difficult to obtain and use. The consequences of this imbalance in assistance may be seen in the deterioration, abandonment, and disinvestment of the "ghost towns" that have sprung up in some of the neighborhoods most affected by the Northridge earthquake.

Footnotes

1. City of Los Angeles Housing Department, "Current Status of Damage to the Housing Stock of the City of Los Angeles from the Northridge Earthquake", Los Angeles, CA, April 4, 1994, p. 5.

2. Joseph Carreras, "Impact of the Northridge Earthquake on the Regional Housing Market", Southern California Association of Governments, Los Angeles, California, January 28, 1994, p. 2.

3. City of Los Angeles Housing Department, "Current Status of Damage to the Housing Stock".

4. Nicolino Delli Quadri, Senior Structural Engineer, City of Los Angeles Department of Building and Safety, phone conversation, October 11, 1994.

5. Mary Comerio, phone interview, October 3, 1994.

6. Barbara Zeidman, Deputy Manager, City of Los Angeles Housing Department, phone interview, July 1994.

7. Mary Comerio, "Design Lessons in Residential Rehabilitation". Earthquake Spectra 10/1, 1994, p. 47.

8. Seismic Safety Commission, "Performance of Wood Frame Buildings", Interim Background Report B13, Draft Report, June 1994, p. 6.

9. "Findings and Recommendations of the Residential Buildings-Cripple Wall Subcommittee of the City of Los Angeles Department of Building and Safety and Structural Engineers Association of Southern California", Task Force on Evaluating Damage from the Northridge Earthquake, Final Report, Attachment C, June 16, 1994, p. 1.

10. "Findings and Recommendations of the Residential Buildings-Cripple Wall Subcommittee", Final Report, p. 12.

11. However, for more complex retrofits, such as providing an independent new concrete foundation instead of strengthening an existing foundation, the cost could range from $8,000 to $12,000.

12. Ibid, p. 10.

13. Mary Comerio, "Design Lessons...", p. 47.

14. Earthquake Engineering Research Institute, "Northridge Earthquake January 17, 1994. Preliminary Reconnaissance Report", Oakland, CA, March 1994, p. 43.

15. Ibid.

16. Nicolino Delli Quadri, October 11, 1994.

17. Nicolino Delli Quadri, August 1994.

18. Mary Comerio, "Design Lessons...", p. 47.

19. Nicolino Delli Quadri, August 1994.

20. Ibid.

21. Nicolino Delli Quadri, October 11, 1994.

22. Nicolino Delli Quadri, August 1994.

23. 1980 and 1990 census tabulations, in Chamun Koo, "Selected Demographic and Housing Data for the City of Los Angeles", prepared for the Los Angeles Housing Department, July 11, 1994.

24. National Conference of States on Building Codes and Standards, "Northridge Earthquake Effect on Manufactured Housing in California", U.S. Department of Housing and Urban Development, Washington, DC, June 17, 1994, p. 2.

25. Barbara Zeidman, July 1994.

26. Mary Comerio, "Design Lessons in Residential Rehabilitation", p. 47.

27. Barbara Zeidman, July 1994.

28. Ibid, p. 37.

29. Office of Management and Budget, "Six Months after the Northridge Earthquake: A Look Back at the Federal Response", Washington, DC, July 27, 1994, p. 2.

30. FEMA office memo, Los Angeles, CA, July 11, 1994.

31. Similar problems were encountered in rebuilding after the Loma Prieta earthquake. See Mary Comerio, John Landis, and Yodan Rofe, "Post-Disaster Residential Rebuildings", Institute of Urban and Regional Development, University of California at Berkeley, January 1994, p. 37.

32. Ibid, p. 69.