Unreinforced Masonry

Buildings and Earthquakes

Developing Successful Risk

Reduction Programs

FEMA P-774 / October 2009

FEMA
Th e cover photos show signifi cant damage to unreinforced masonry 

buildings that resulted from earthquakes occurring over the last century, 

across the country.

Front Cover Photo Credits (clockwise from top left):

1886, Charleston, South Carolina: J. K. Hillers, U.S. Geological Survey

2003, San Simeon, California: Josh Marrow, Earthquake Engineering 

Research Institute Reconnaissance Team

2001, Nisqually, Washington: Oregon Department of Geology and Mineral 

Industries

1935, Helena, Montana: L. H. Jorud, courtesy of Montana Historical Society 

and Montana Bureau of Mines & Geology

1993, Klamath Falls, Oregon: Oregon Department of Geology and Mineral 

Industries

2008, Wells, Nevada: Craig dePolo, Wells Earthquake Portal, www.nbmg.unr.

edu/WellsEQ/.
Unreinforced Masonry Buildings 

and Earthquakes

Developing Successful Risk Reduction Programs

FEMA P-774/October 2009

Prepared for:

Federal Emergency Management Agency (FEMA)

Cathleen Carlisle, Project Monitor

Washington, D.C.

Prepared by:

Applied Technology Council (ATC)

201 Redwood Shores Parkway, Suite 240

Redwood City, California

Principal Author

Robert Reitherman

Contributing Author 

Sue C. Perry

Project Manager

Th omas R. McLane

Project Review Panel

Ronald P. Gallagher

Jon A. Heintz

William T. Holmes

Ugo Morelli

Lawrence D. Reaveley

Christopher Rojahn
Any opinions, fi ndings, conclusions, or recommendations expressed in this publication do not 

necessarily refl ect the views of FEMA. Additionally, 

neither FEMA or any of its employees makes any 

warrantee, expressed or implied, or assumes any 

legal liability or responsibility for the accuracy, 

completeness, or usefulness of any information, 

product, or process included in this publication. 

Users of information from this publication assume 

all liability arising from such use. 
Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Unreinforced Masonry Buildings and Earthquakes: Where in the 

United States are the Risks? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Types of Earthquake Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Earthquake Performance of Unreinforced Masonry Buildings . . . . . . . 7

What is Unreinforced Masonry? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Examples and Statistics from Past U.S. Earthquakes . . . . . . . . . . . . . . . . . . 10

3 Developing a Strategy for Implementing a URM Building Risk 

Reduction Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Occupancy and Ownership Factors: Th e People Who Own and Use the Buildings . 16

Historic and Architectural Character . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Cost Issues Related to Seismic Retrofi ts . . . . . . . . . . . . . . . . . . . . . . . . . 17

City Planning Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4 Examples of Successful Risk Reduction Programs . . . . . . . . . . . . . . 19

Compiling an Inventory of Unreinforced Masonry Buildings . . . . . . . . . . . . . 19

Successful Programs Require Sustained Support and Leadership . . . . . . . . . . . 20

Utah: Engineering Inspections Triggered by Re-roofi ng Projects . . . . . . . . . . . 20

Utah: Statewide Inventory of Unreinforced Masonry Buildings . . . . . . . . . . . . 21

State of California Unreinforced Masonry Building Law: Measuring 

the Problem and the Progress Toward Addressing It . . . . . . . . . . . . . . . 22

Seattle, Washington: Saving Historic Buildings . . . . . . . . . . . . . . . . . . . . . 23

Seattle, Washington: Combining Modernization with Seismic Retrofi tting . . . . . 23

Oregon: A Statewide Inventory and Funding Approach for Schools and 

Essential Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Berkeley and Other California Cities: Financial Incentives for Retrofi tting . . . . . 24

Public Schools in California: A Statewide Approach to a Special Kind of Facility . . 25

Long Beach, California: A Pioneering Accomplishment. . . . . . . . . . . . . . . . . 25

Los Angeles, California: Evidence of the Eff ectiveness of Retrofi ts . . . . . . . . . . 26

San Luis Obispo, California: Making the Eff ort to Communicate with 

Building Owners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5 Additional Technical Background on Unreinforced Masonry 

Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

How Do Unreinforced Masonry Buildings Behave in Earthquakes?. . . . . . . . . . 31

How Are Unreinforced Masonry Buildings Seismically Retrofi tted? . . . . . . . . . 34

6 Sources of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Publications for the General Public . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Historic Buildings and Seismic Retrofi ts . . . . . . . . . . . . . . . . . . . . . . . . . 40

Building Inventories and Evaluation of Existing Buildings . . . . . . . . . . . . . . . 40

Building Codes, Standards, Guidelines, and Laws Applicable to Existing Buildings. 41

Costs of Seismic Retrofi ts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

7 End Notes and Cited References . . . . . . . . . . . . . . . . . . . . . . . . . 43

8 Project Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 1

1 Introduction

This document provides guidance on how to develop programs to reduce the 

earthquake risks of existing unreinforced masonry buildings. As the following chapters will show, this building type is typically the most seismically 

vulnerable category of construction in a community, and it is by far the most 

common type of building to be singled out for voluntary or mandatory seismic 

risk reduction programs in the United States.

While the information presented here is based on extensive earthquake engineering knowledge, this guide has been written for use by a non-technical audience, 

including government offi cials, building owners, and the general public. It also 

contains relevant information for building offi cials, consulting structural engineers and building contractors. 

Unreinforced masonry walls 

do not have a grid of steel 

reinforcing bars embedded 

within them. See Chapters 2 

and 5 for further description.

Th e typical unreinforced masonry building in 

the United States has brick walls with no 

steel reinforcing bars embedded within them. 

A more precise defi nition of unreinforced 

masonry buildings or “URMs,” as they are 

known in many places, is contained in 

Chapter 2, “Earthquake Perfomance of 

Unreinforced Masonry Buildings.” Additional details about their construction are 

included in Chapter 5. Th e reader does not need to study all of this terminology, 

but he or she should clearly understand the basic diff erences between unreinforced 

and reinforced masonry. 

Chapter 3, “Developing a Strategy for Implementing a URM Risk Reduction 

Program,” describes how a number of factors unrelated to construction are 

involved in any eff orts to reduce unreinforced masonry seismic risks. Th ose factors 

include retrofi t costs and the economic viability of older existing buildings, the 

number of occupants and type of use of the buildings, and the historic or architectural character of the buildings. Each of these considerations involves an important segment of the community that should be included in active consideration of 

any risk reduction program.

Th is guide does not presume to prescribe a rigidly uniform sequence of steps that 

must be taken in order to reduce risk. As Chapter 4, “Examples of Successful Risk 

Reduction Programs,” clearly documents, a wide variety of approaches has been 

developed across the country.
2 Introduction

Chapter 5, “Additional Technical Background on Unreinforced Masonry Buildings,” 

provides simple explanations of some key earthquake engineering terminology 

and concepts for the non-engineer audience. Th is information is intended to help 

facilitate conversations between the non-technical audience, such as city offi cials 

and the general public, and the technical community that includes building inspectors, engineers, and architects.

Chapter 6, “Sources of Information,” provides a number of annotated references 

for both technical (engineering-oriented) and non-technical audiences.

Chapter 7, “End Notes and Cited References,” provides notes and cites references to 

document all of the information presented in this guide. Almost all of the Sources 

of Information and the Cited References are accessible on the internet free of 

charge.

Unreinforced Masonry Buildings and Earthquakes: 

Where in the United States are the Risks?

I

f the current building 

code in a locale does not 

allow unreinforced masonry 

construction, then existing 

buildings of that type can 

be considered a signifi cant 

earthquake risk that should 

be investigated further.

Current U.S. building codes (described further 

in Chapter 2) allow unreinforced masonry 

walls in new building construction only in 

those areas where the probability or chance of 

strong earthquake shaking is very low. In past 

decades, however, many thousands of unreinforced masonry buildings were constructed in 

all areas of the country, even in regions subject 

to the most frequent strong earthquakes. In 

the light of today’s knowledge, we recognize 

that this existing URM building stock presents a problem with respect to earthquake risk.

Th e URM problem in jurisdictions that are now eff ectively enforcing the current 

building code (essentially the latest edition of the International Building Code, the 

IBC) is due to those buildings that were built before recent model code seismic provisions were adopted and enforced. Th e jurisdiction’s building department can provide the benchmark date, when the locally enforced building code began to include 

seismic provisions that cover unreinforced masonry. Unreinforced masonry buildings can be found in every state. Because of its durability, fi re resistance, and architectural character, unreinforced masonry has often been the construction material 

of choice for schools, city halls, central business district buildings, factories, and 

apartment buildings. However, the probability of strong earthquake shaking is 

not equally distributed across the states, which raises the question: Where in the 

United States are unreinforced masonry buildings of concern?

Figure 1 provides a general view of those areas of the U.S. where unreinforced 

masonry is not permitted for current construction.1 Th is Figure serves as an initial 

guide to where some level of concern is warranted regarding the earthquake risks 

posed by these buildings. A local building department or a consulting structural 

engineer can provide more detailed guidance as to whether current seismic code 

provisions allow unreinforced masonry for a precise location, type of soil, and 

occupancy or use of a building. Even in regions where unreinforced masonry is currently allowed, older unreinforced masonry buildings may exist in a deteriorated 
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 3

 Figure 1. Approximate mapping of the areas of the United States where current building code regulations do 

not allow new construction with unreinforced masonry.

state much weaker than that required by code today. Assessing the earthquake 

vulnerabilities of older unreinforced masonry buildings appropriately in areas 

that still allow URM construction might take the form of requiring inspection of 

exterior materials, especially masonry materials like bricks or terra cotta, in order 

to ensure they are still attached fi rmly enough to prevent falling. Chicago, for 

example, has passed a local building condition assessment ordinance that requires 

periodic inspection of building facades, although the city is located in an area 

where the current International Building Code allows unreinforced masonry.

Types of Earthquake Risks

Poor building performance poses three basic types of risk in an earthquake: the 

risk of injury, property damage, and loss of use. Spending the time and eff ort, and 

imposing the new regulations and costs on building owners, to implement a risk 

reduction program for unreinforced masonry buildings makes sense when it is 

clearly based on reducing one or more of these types of risk.

INJURY: Promoting safety is the prime rationale for building code 

regulations in general, whether applied to earthquakes, fi res, or other 

hazards. Damage to unreinforced masonry buildings is dangerous. 

When masonry debris falls, it is potentially lethal. A single brick 

weighs from 6 to 12 pounds (21⁄2 to 5 kg), and just one square foot of a typical wall 

weighs 120 pounds or more (over 50 kg). Unreinforced masonry buildings are 

dangerous not only to their occupants but also to those in adjacent buildings and 

to pedestrians. Figure 2 illustrates the danger of falling masonry debris, even if 

the entire building does not collapse. Parapets, which are the short walls that often 

extend around the perimeter of a roof (as in the two buildings pictured in Figure 

2), are particularly vulnerable, as are chimneys and cornices (the decorative ledges 

that run around the top of the building). Figure 3 illustrates the level of danger 

posed by complete collapse of a URM building.
4 Introduction

PROPERTY DAMAGE: Experience from past earthquakes has shown 

that expensive repairs will be needed to an unreinforced masonry 

building, after an earthquake. More than for any other kind of damaged building, there is often no way to “put Humpty Dumpty back 

together again” for a URM building. Th is results in the demolition of the building. 

Some of the most architecturally prominent and historically valued buildings in 

the United States are made of unreinforced masonry. See Figure 4. Protecting 

these architectural and historic assets may be an important goal of risk reduction 

programs, in addition to preventing costly damage. Th e damage to the Pacifi c 

Avenue Historic District in the city of Santa Cruz that resulted from the 1989 

Loma Prieta earthquake was so extensive that the downtown area was removed 

from the National Register of Historic Places (see Figure 5). In that Historic 

District, 52% of the old brick buildings were so badly damaged that they were 

quickly demolished, and another 16% were “red-tagged” (closed because they were 

unsafe to enter2). 

LOSS OF USE: Even minor earthquake damage can require the closure 

of an unreinforced masonry building, until repairs are made. More 

often than for other kinds of construction, a damaged unreinforced 

masonry building may need to be upgraded to a higher level of safety 

than it possessed in its pre-earthquake state, before it can reopen. Closure of a 

building, while permits are obtained and a major re-construction project is carried 

out, often lasts for several years. Th e kind of damage shown in Figure 6, which 

causes the building to be “red tagged” as unsafe to enter, can present so many 

problems in bringing the building back into use that long-term vacancy or demolition of the building may result.

 Figure 2. Diagram illustrating the dangers of unreinforced masonry. 

When unreinforced masonry buildings begin to come 

apart in earthquakes, heavy debris can fall on adjacent 

buildings or onto the exterior where pedestrians are 

located. This diagram illustrates the failure of parapets, 

one of the most common types of unreinforced masonry 

building damage. This level of damage can occur even 

in relatively light earthquake shaking. —Rutherford & 

Chekene

 Figure 3. Complete collapse of an unreinforced 

brick building. 

The most severe level of damage, with the greatest 

likelihood of fatalities, is complete collapse. After a 

few seconds of ground shaking in the 1933 Long Beach 

earthquake, the brick walls holding up the second 

fl oor and roof of this building broke apart. That not 

only caused the fall of hazardous brick debris—it also 

immediately led to complete collapse. —Los Angeles 

Public Library
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 5

 Figure 4. The Salt Lake City and County Building, 

an architectural and historic community asset that 

could be lost, if damaged.

The Salt Lake City and County Building was extensively 

seismically retrofi tted, not only to make it safer but 

also to provide long-term protection for a valued historic building. —U.S. Geological Survey

 Figure 5. Destruction of a historic building.

Complete collapse of one of the historic buildings in 

the former Pacifi c Avenue Historic District of the City of 

Santa Cruz, California. —James R. Blacklock, NISEE, U.C. 

Berkeley

 Figure 6. Damaged URM wall in a red-tagged building, fated to be torn down or to undergo a multi-year closure for repairs and upgrading.

Pre-earthquake retrofi tting usually looks quite modest, compared to the comprehensive upgrading that building codes 

will require to repair a damaged, non-code-conforming building after an earthquake. —Robert Reitherman
6 Introduction

All three kinds of risk—injury, property damage, and loss of use—are usually 

greater for unreinforced masonry buildings than for the other buildings in a city or 

region. While some communities, university systems, owners, and others have chosen to deal with the risks of other kinds of existing buildings or to upgrade utility 

and transportation systems,3 addressing unreinforced masonry building problems 

is usually the top priority in any serious eff ort to provide seismic protection.

Dealing with the earthquake risks of unreinforced masonry buildings is a challenging and diffi cult undertaking. However, many communities have developed successful risk reduction strategies. A number of examples are presented in Chapter 4.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 7

2 Earthquake Performance of 

Unreinforced Masonry Buildings

This chapter provides brief descriptions and illustrations of unreinforced 

masonry, along with explanations of why unreinforced masonry buildings 

are so susceptible to earthquake damage. When subjected to strong earthquake shaking in past U.S. earthquakes, fi ve out of six URM buildings have 

been damaged to the extent that potentially lethal amounts of brickwork fell. 

One-fi fth of those buildings either partially or completely collapsed.4

What is Unreinforced Masonry?

Unreinforced masonry can be defi ned generally as masonry that contains no reinforcing in it. Th e terms “unreinforced” and “masonry” are both more precisely 

described in this chapter. A shared understanding of these facts and defi nitions will 

be helpful to conversations between engineers and non-engineers, when discussing 

a risk reduction program.

Masonry is made of earthen materials and includes the sub-types listed below. 

Th e most common unreinforced masonry materials used for the walls of buildings 

are the fi rst two listed, brick and hollow concrete block, which are illustrated in 

Figure 7, Figure 8, and Figure 9.

• Brick: clay that is fi red to a hard consistency.

• Hollow concrete block: “concrete masonry unit” in the terminology of building 

codes, commonly known as “cinder block.”

• Hollow clay tile: similar to concrete block in shape, having hollow cells, but 

brick-colored.

• Stone: can be “dressed” or cut into rectangular blocks, or used in its natural 

shape.

• Adobe: mud poured into the form of walls or made into sun-dried bricks.
8 Earthquake Performance of Unreinforced Masonry Buildings

Bearing walls perform 

the essential job of 

resisting gravity and 

holding a building up. 

Destruction of bearing 

walls leads to collapse.

Th e most common type of unreinforced masonry 

building in the United States is constructed of brick 

walls, with wood-frame fl oors and roof, as shown in 

Figure 10 and Figure 11. From the outside, one can 

observe that the spans over windows are short, and 

the walls are thick. Th e masonry walls around the 

exterior, and sometimes similar walls in the interior, bear up under the weight that is delivered to 

them by fl oor or roof beams. For this reason, they are called bearing walls. When 

the masonry is built into the rectangular openings or bays of a concrete or steel 

frame, with the frame holding up the masonry, then they are called infi ll walls. Th at 

kind of building requires its own special analysis and is not in the subject of this 

booklet.

 Figure 8. “Header” versus “stretcher” courses.

The presence of header courses is usually the easiest 

way to tell if a brick wall is unreinforced. 

 Figure 9. Complete collapse of an unreinforced concrete block building, 1971 San Fernando 

earthquake. —Karl Steinbrugge, NISEE, U.C. Berkeley

Unreinforced concrete block 

walls do not have reinforcing 

steel bars placed vertically in 

the hollow cells or horizontally 

between the courses.

 Figure 7. Components of unreinforced brick (left) and unreinforced concrete block (right) walls. 

Header bricks extend into the 

wall, indicating that there is no 

cavity where reinforcing could 

have been placed.

Wythe (2-wythe-thick wall 

shown)
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 9

Masonry veneer is usually composed of one layer of ordinary brick or of thinner 

brick that is applied to a supporting wall behind it, as shown in Figure 12. Veneer 

is typically about four inches (100 mm) or less in thickness. It may also consist of 

stone facing. Th e veneer is adhered to and literally hangs onto a wall behind it for 

vertical and horizontal support. Terra cotta, a ceramic material similar to brick 

 Figure 12. Workers installing brick veneer.

The individual pieces of veneer are being adhered to the reinforced concrete wall behind 

them. The result looks like a brick wall. —Robert Reitherman

 Figure 10. Typical appearance of a multistory 

unreinforced brick building.

When buildings are much taller than this, there is often 

also a steel or concrete frame, making an infi ll structure. —Rutherford and Chekene

 Figure 11. Components of a URM building. 

Many larger unreinforced brick buildings have heavy 

timber columns and beams in the interior. The wooden 

posts and beams do not provide signifi cant horizontal 

(earthquake) force resistance. —FEMA 154, Rapid Visual 

Screening of Buildings for Potential Seismic Hazards: A 

Handbook
10 Earthquake Performance of Unreinforced Masonry Buildings

that has a smooth fi nish and is made in various forms and colors, was often used 

in older buildings for both decorations and veneer. Current code provisions in 

areas of seismic activity include requirements to prevent veneer from falling off in 

an earthquake. Older buildings with thick (one-brick thick) veneer that does not 

meet current seismic safety requirements can experience the veneer peeling off , 

when the building is shaken. Masonry veneer on houses is typically more of a property damage risk than a signifi cant safety risk. However, veneer on taller walls in 

public settings adjacent to areas where pedestrians may be presents a signifi cant 

risk that an unreinforced masonry risk reduction program should consider.

Further information on unreinforced masonry construction is provided in Chapter 5.

Examples and Statistics from Past U.S. Earthquakes

A number of earthquakes in the United States would have resulted in some property loss but no real disaster, if damage to unreinforced masonry buildings had not 

occurred. Th e following brief survey provides evidence in support of this conclusion. Magnitude (M) numbers are included for each earthquake below. While one 

may often hear references to the “Richter scale,” in many cases today, seismologists 

measure the overall size of an earthquake using one of the other magnitude scales 

that were developed after Charles Richter developed his in 1935. Th e diff erences in 

magnitude scales are not particularly relevant here. Th e symbol M below stands for 

generic earthquake magnitude.

1886 Charleston Earthquake, South Carolina, M 7.7: Eighty-two percent of 

the brick buildings suff ered more than minor damage, and 7% collapsed or were 

demolished.5 See Figure 13, illustrating the debris from collapsing second story 

masonry walls, which extends beyond the middle of the street.

 Figure 13. Debris resulting from the 1886 Charleston, 

South Carolina earthquake. 

—NISEE, U.C. Berkeley
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 11

1925 Santa Barbara Earthquake, Southern California, M 6.2: Th e most 

severe damage from this earthquake occurred among unreinforced brick commercial and residential construction and was a primary motivation for engineers 

in California to adapt seismic design ideas from Japan into the Uniform Building 

Code. Forty percent of the unreinforced masonry buildings were severely damaged 

or collapsed.6 See Figure 14, the Hotel Californian, in which extensive wood-frame 

and plaster partitions barely managed to hold the building up, after exterior brick 

walls failed.

 Figure 14. Heavily damaged Hotel 

Californian, 1925 Santa Barbara, 

California earthquake. —NISEE, U.C. 

Berkeley

1933 Long Beach Earthquake, Southern California, M 6.3: In the City of 

Long Beach (adjacent to the City of Los Angeles), 54% of the unreinforced masonry 

buildings ended up with damage that ranged from signifi cant wall destruction 

to complete collapse. In 20% of the cases, damage fell in the categories of either 

damage to more than half the wall area, partial collapse, or complete collapse.7 See 

Figure 15, showing parapet (the short walls that often extend around the perimeter of a roof) and top story failure and the eff ect of the falling masonry debris.

 Figure 15. URM building damage, 

1933 Long Beach, California earthquake. —Los Angeles County Public Library
12 Earthquake Performance of Unreinforced Masonry Buildings

1983 Coalinga Earthquake, Central California, M 6.2: Out of 37 unreinforced masonry buildings—the core of the Coalinga business district—only one 

escaped damage. Sixty percent were damaged to the extent of having more than 

half of their walls ruined, up to complete collapse.8 Th e entire downtown area was 

cordoned off , until badly damaged buildings could be demolished and the debris 

removed. See Figure 16, which illustrates a common form of damage, in which the 

gable (peaked roof) end wall falls.

 Figure 16. URM building 

with end-wall failure, 1983 

Coalinga, California earthquake. Robert Reitherman 

—NISEE, U.C. Berkeley

1983 Borah Peak Earthquake, Idaho, M 7.3: In the town of Challis, Idaho, the 

only earthquake-related fatalities occurred when an unreinforced masonry wall fell 

on two children on their way to school. In Mackay, the town’s main street buildings, built of unreinforced brick, concrete block, or stone, were all damaged, Eight 

required demolition. In relative terms, when compared to the size of the town (see 

Figure 17), this amount of damage constituted a large disaster.

 Figure 17. Aerial 

view of heavily damaged Mackay, Idaho. 

The unreinforced 

masonry buildings on 

the main commercial 

street of the small town 

were badly damaged in 

the 1983 Borah Peak, 

Idaho earthquake. 

—NISEE, U.C.Berkeley
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 13

1989 Loma Prieta Earthquake, Northern California, M 7.1: In this earthquake, 374 (16%) of the 2,400 unreinforced masonry buildings in the region experienced damage severe enough to require that they be vacated.9 Th e earthquake 

was centered 60 miles south of the San Francisco Bay Area, and the majority of 

these buildings were subjected to only light to moderate shaking. Figure 18 illustrates an upper-story failure of brickwork, which fell onto the sidewalk and cars 

below, killing fi ve people.

 Figure 18. Upper story wall collapse, with 

resulting fatalities. 

Five people were killed when the brick wall in the 

fourth story fell on top of cars and the sidewalk in 

the 1989 Loma Prieta earthquake. —James Blacklock, 

NISEE, U.C. Berkeley

2001 Nisqually Earthquake, Puget Sound Region, Washington, M 6.8:

“URM buildings built before 1950 exhibited the poorest behavior. Th e most common damage included shedding of brick from parapets and chimneys. Other URM 

buildings exhibited diagonal ‘stair-step’ cracking in walls and piers, damage to 

walls in the upper stories, vertical cracking in walls, damage to masonry arches, 

and damage to walls as a result of pounding. In many cases, fallen brick resulted 

in damage to objects, such as cars and canopies, outside the building.”10 See Figure 

19.

 Figure 19. URM building damage, 2001 Nisqually, Washington earthquake. 

At left, hollow clay tile debris from a collapsed wall; at right, diagonal “stair-step” cracking of a brick wall (the crack following mortar horizontal bed joint and vertical head joint 

lines), a sign of the wall’s inability to resist shear stress from in-plane forces. —André 

Filiatraut
14 Earthquake Performance of Unreinforced Masonry Buildings

2003 San Simeon Earthquake, Central California, M 6.5: Of 53 unreinforced 

masonry buildings in Paso Robles, the nearest aff ected city, none of the nine that 

had been retrofi tted experienced major damage. Many of the others were damaged 

so extensively that they were subsequently demolished. “During earthquakes unreinforced masonry buildings that have not been retrofi tted continue to be the most 

dangerous buildings in California.” One building owner commented afterward: 

“I’m confi dent the building would have come down in the quake if we hadn’t done 

the retrofi tting. Th ere were times when we were bleeding so badly in paying for it, 

we wondered what in the heck we were doing. Now we know.”11 See Figure 20. Th e 

two fatalities in the town were due to the collapse of an unretrofi tted, unreinforced 

brick building. 

 Figure 20. Retrofi tted 

URM building, 2003 

San Simeon, California 

earthquake. 

Retrofi tted prior to the 

earthquake, this unreinforced brick building 

experienced no damage.

—Janise E. Rodgers, NISEE, 

U.C. Berkeley.

Putting together the statistics on 4,457 unreinforced masonry buildings from several U.S. earthquakes4, we see the following profi le of how unreinforced masonry 

buildings perform, when strong earthquake shaking occurs:

• Five out of six are damaged enough for brickwork to fall;

• One-fi fth are damaged to the point of partial or complete collapse.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 15

3 Developing a Strategy for 

Implementing a URM Building Risk 

Reduction Program

A number of considerations should be taken into account when developing a 

strategy for implementing an unreinforced masonry building risk reduction 

program. Each consideration involves key individuals and groups who will formulate, carry out, and be affected by the program. For that reason, it is important 

to involve them as early in the process as possible.

Many considerations must be taken into account when developing a program to 

reduce the earthquake risks of unreinforced masonry buildings. Each consideration 

involves key individuals and groups, who should become involved at an early stage in 

the development process. For example, a planning department maintains information on the inhabitants and people who use the buildings in a community. Th e local 

building department is the agency that maintains data on the construction characteristics of buildings. Th is department is centrally involved in enforcing building 

code ordinances or voluntary construction standards and in issuing permits for any 

retrofi t construction projects. Economic factors in a risk reduction program obviously aff ect building owners (and retrofi t costs often “fl ow down” to tenants); in 

addition, fi nancial and real estate institutions may have relevant insights and interests regarding the program. Agencies or non-profi t organizations with architectural 

or historical preservation interests have a stake in how buildings of that character 

may be changed by any seismic retrofi ts. Finally, when unreinforced masonry buildings are clustered together, as they often are in older central business districts, then 

risk reduction programs raise city planning issues with regard to zoning, parking, 

redevelopment eff orts, and other city concerns.

Retrofi tting is 

the process of 

adding earthquake 

resistance to an 

existing building. It 

is generally synonymous with the terms 

‘seismic strengthening’ or ‘seismic 

rehabilitation.’

Th e principal means of reducing the seismic risks of 

unreinforced masonry buildings is retrofi tting, although 

changing a building’s use in order to reduce its occupant 

load (number of occupants) also reduces risk. 

Retrofi tting an unreinforced masonry building can take 

several diff erent forms (see Chapter 5), but it must be 

kept in mind that a retrofi t is a signifi cant construction 

project, which may aff ect owners, occupants, and the 

community at large.
16 Developing a Strategy for Implementing a URM Building Risk Reduction Program

Occupancy and Ownership Factors: 

The People Who Own and Use the Buildings 

Th e usage or occupancy of a building is an important consideration, when planning 

a risk reduction program. Occupancies are defi ned by building codes in terms of the 

number of people who occupy a building and what the building’s functions are. More 

intensive uses, which bring more people to a building, increase risk exposure to 

earthquake-caused injuries. Current building code regulations require that essential facilities such as fi re stations be designed to higher earthquake safety standards 

than ordinary buildings. Th is suggests that existing buildings with many occupants 

or essential facilities should have a higher priority for retrofi ts. Ownership patterns 

are also important. Twenty buildings on a school or college campus have one owner 

and ultimately, one decision-making process (for example, the setting of policies 

by a school board). Twenty buildings along a commercial street may be owned by 

twenty diff erent owners, with twenty distinct sets of decision-making variables 

involved, leading to greater variety of outcomes. 

A retrofi t project in an apartment building that displaces residents for weeks or 

months presents the problem of where those residents will fi nd temporary housing. 

Are apartment buildings providing low-rent housing, so that passing along retrofi t 

costs to tenants in the form of higher rents will be a major economic burden? Are 

unreinforced masonry buildings located where few residents speak English? Such 

demographic factors must be taken into account, when planning how to craft a risk 

reduction program and how to involve the public. In San Francisco, a study was conducted to lay the groundwork for San Francisco’s unreinforced masonry building 

retrofi t program that specifi cally estimated what kinds of retrofi ts would be needed 

for residential buildings.

Historic and Architectural Character

Protecting people from the earthquake dangers of unreinforced masonry buildings 

must be a community’s highest priority. However, protecting the property value of 

buildings by preventing damage is also important. In addition, some buildings have 

historic or architectural signifi cance, which is itself a value to be preserved. Because 

masonry is a durable material and was often the fi rst choice for important buildings constructed in the past, many communities’ most historic and architecturally 

valued buildings are of this structural type, as in the case illustrated in Figure 21.

Retrofi tting these buildings to increase their earthquake resistance is necessary in 

order to prevent irreparable damage from occurring to the buildings in an earthquake. Yet the retrofi t itself can alter the building’s appearance and change its historic materials in an undesirable way, if not carried out sensitively. Fortunately, 

today’s earthquake engineering methods provide options for dealing with the earthquake vulnerabilities of a building, while leaving its appearance largely unchanged. 

As Chapter 5 discusses, the technique of seismic isolation has been used for some 

monumental public buildings with extensive unreinforced masonry components. 

Th ese isolators can reduce the seismic forces on the building to only one third of 

what they would otherwise be, and the isolators are usually installed unobtrusively 

at the foundation or basement level.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 17

Cost Issues Related to Seismic Retrofi ts

Groups like a downtown business owners association or chamber of commerce, an 

apartment owners or renters association, or a historic preservation league, may 

have concerns about retrofi t costs. Structurally strengthening an unreinforced 

masonry building is not an inexpensive remodeling project, and the cost implications must be considered. As part of developing a risk reduction plan, it is important to collect information on the economic viability of the unreinforced masonry 

buildings at issue. Are the buildings high in value, generating strong income 

streams, because they form the heart of the “old town” tourist district that is common in many cities? Or are they in a declining area that used to be the central business district but which has been supplanted by shopping centers and offi ce parks 

located elsewhere? Do the properties provide enough collateral for their owners to 

obtain construction loans to fi nance the upgrading work?

FEMA provides an on-line retrofi t cost estimating feature on its website,12 and 

FEMA documents provide further information.13 Costs can vary greatly, however, 

so locally-based estimates should be carried out prior to instituting a risk reduction program.

City Planning Factors

An inventory of unreinforced masonry buildings can be presented in table format, to 

display the buildings’ square footage and number of stories, construction dates, and 

occupancy. Building location is also signifi cant. Are buildings dispersed throughout 

an area, or are they clustered? How are they located with respect to current zoning 

districts? Th e community may have a long-range plan for streets, parking, plazas 

and pedestrian areas. Any economic redevelopment plans should include a list of the 

locations of unreinforced masonry buildings. Aside from an individual building’s 

architectural or historic merits, it is important to consider the collective eff ect for a 

town or city of having a number of well-preserved, economically vital, older buildings that defi ne the overall community character. Th ere may also be environmental 

 Figure 21. Pioneer Square 

Historic District, Seattle, 

Washington. 

The historic buildings in this 

city district are unreinforced 

masonry buildings. This is often 

the case.

Arena
18 Developing a Strategy for Implementing a URM Building Risk Reduction Program

impact reporting requirements that a retrofi t program would trigger; city planning 

departments should be familiar with any such requirements. Figure 22 illustrates 

how an inventory of unreinforced masonry buildings can be overlaid with political 

and economic (building value) data.

As the examples in Chapter 4 make clear, a variety of risk reduction approaches that 

address these factors have been successfully adopted. Developing these successful 

approaches has almost always required involving the key individuals and groups 

associated with each consideration in the planning and decision-making process.

 Figure 22. The distribution of unreinforced masonry 

buildings in the greater New 

York City region. 

Maps such as this one, 

published by the New York 

City Area Consortium for 

Earthquake Loss Mitigation, 

relate seismic information to 

geographic and land use planning data.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 19

Rapid Visual Screening of Buildings for Potential Seismic Hazards 

FEMA-154 Data Collection Form HIGH Seismicity

Address: __________________________________________________ 

 _________________________________Zip _______________ 

Other Identifiers _____________________________________________ 

No. Stories ________________________________ Year Built ________ 

Screener _____________________________ Date _________________ 

Total Floor Area (sq. ft.) _______________________________________ 

Building Name ______________________________________________ 

Use _______________________________________________________

 

PHOTOGRAPH 

OCCUPANCY TYPE FALLING HAZARDS

Assembly Govt. Office 

Commercial Historic Residential 

Emer. Services Industrial School 

Number of Persons 

0 – 10 11 – 100 

101-1000 1000+ 

 A B C D E F 

Hard Avg. Dense Stiff Soft Poor 

 Rock Rock Soil Soil Soil Soil 

 

Unreinforced Parapets Cladding Other: 

 Chimneys _____________

BASIC SCORE, MODIFIERS, AND FINAL SCORE, S

BUILDING TYPE W1 W2 S1 (MRF) S2 

(BR) 

S3 

(LM) 

S4 

(RC SW) 

S5 (URM INF) C1 

(MRF) 

C2 

(SW) 

C3 (URM INF) PC1 

(TU) 

PC2 RM1 (FD) RM2 

(RD) 

URM 

Basic Score 

Mid Rise (4 to 7 stories)

High Rise (> 7 stories) 

Vertical Irregularity

Pre-Code 

Post-Benchmark 

4.4 

N/A 

N/A 

-2.5 

0.0

+2.4 

3.8 

N/A 

N/A 

-2.0 

-1.0 

+2.4

2.8 

+0.2 

+0.6 

-1.0 

-1.0 

+1.4 

3.0

+0.4 

+0.8 

-1.5 

-0.8 

+1.4 

3.2

N/A 

N/A 

N/A 

-0.6 

N/A 

2.8 

+0.4 

+0.8 

-1.0 

-0.8 

+1.6 

2.0

+0.4 

+0.8 

-1.0 

-0.2 

N/A 

2.5

+0.4 

+0.6 

-1.5

-1.2

+1.4 

2.8 

+0.4 

+0.8 

-1.0 

-1.0 

+2.4 

1.6

+0.2

+0.3 

-1.0 

-0.2 

N/A 

2.6 

N/A 

N/A 

N/A 

-0.8 

+2.4 

2.4 

+0.2 

+0.4 

-1.0 

-0.8

N/A

2.8 

+0.4 

N/A 

-1.0

-1.0 

+2.8 

2.8

+0.4 

+0.6 

-1.0 

-0.8 

+2.6 

1.8

0.0 

N/A 

-1.0 

-0.2 

N/A 

Soil Type C 

Soil Type D 

Soil Type E 

0.0 

0.0 

0.0 

-0.4 

-0.8 

-0.8 

-0.4 

-0.6 

-1.2 

-0.4 

-0.6 

-1.2 

-0.4 

-0.6 

-1.0 

-0.4 

-0.6 

-1.2 

-0.4 

-0.4 

-0.8 

-0.4 

-0.6

-1.2 

-0.4 

-0.6 

-0.8 

-0.4 

-0.4 

-0.8 

-0.4 

-0.6 

-0.4 

-0.4 

-0.6 

-1.2 

-0.4 

-0.6 

-0.4 

-0.4 

-0.6 

-0.6 

-0.4 

-0.6 

-0.8 

FINAL SCORE, S

COMMENTS Detailed 

Evaluation 

Required 

YES NO

* = Estimated, subjective, or unreliable data 

DNK = Do Not Know

Plan Irregularity -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 -0.5 

BR = Braced frame

FD = Flexible diaphragm

LM = Light metal 

MRF = Moment-resisting frame

RC = Reinforced concrete

RD = Rigid diaphragm

SW = Shear wall

TU = Tilt up

URM INF = Unreinforced masonry infill

SOIL

4 Examples of Successful Risk 

Reduction Programs

A large number of unreinforced masonry building risk reduction programs have 

been implemented across the United States. A sample of representative programs is included here, to illustrate the variety of possible approaches.

“If the shoe doesn’t fi t, then don’t wear it” is a good caveat to add, when giving 

advice. While one of the following programs may provide an ideal model for a 

given community, it is likely that a new risk reduction program will require some 

unique features based on the particular situation in that community. Th e examples 

presented in this chapter illustrate key components of risk reduction programs, 

which communities can then synthesize in a variety of ways, in order to suit their 

particular circumstances.

Compiling an Inventory of Unreinforced Masonry 

Buildings

Most programs to reduce unreinforced masonry seismic risks share certain characteristics. First, they all need to include an inventory of buildings, which should be 

carried out early in the planning process. Conducting an inventory is not diffi cult, 

because unreinforced masonry buildings are among the easiest of construction 

types to identify. Building department, insurance industry, and tax assessor fi les 

can sometimes provide useful information. “Sidewalk surveys” that observe buildings from the outside are often suffi cient. Th e FEMA 154 Handbook provides a 

“rapid visual screening” method that is applicable to a wide variety of buildings14

(see Figure 23). Section E.13 of Appendix E of the FEMA 154 Handbook provides 

Rapid

FEMA

Assemb

Comme

Emer. S

BUI

Basic Sc

Mid Rise

High Ris

Vertical 

Pre Cod

Plan Irre

 Figure 23. FEMA 154, a technical 

resource containing forms and standardized guidance on compiling an inventory. —FEMA 154, Rapid Visual Screening 

of Buildings for Potential Seismic Hazards: A 

Handbook
20 Examples of Successful Risk Reduction Programs

relevant information for a screening program restricted to unreinforced masonry 

buildings. Any inventory needs to include not only the overall quantity of unreinforced masonry buildings, but also their locations, ownership and physical characteristics, as well as social or city planning factors. Typically, a building department 

and planning department of the jurisdiction are key actors in carrying out that 

inventory. Local structural engineers and architects can also be a valuable source 

of expertise and knowledge.

Successful Programs Require Sustained Support 

and Leadership

More broadly, successful programs share another trait: they benefi t from the sustained support and eff orts of individuals and organizations that recognize the value 

of earthquake protection and are willing to work for it. Th e following conclusion, 

from a review of successful seismic safety programs in the United States,15 outlines concisely some of the challenges that arise when addressing the unreinforced 

masonry building problem (Note: interested readers can fi nd more information on 

social aspects of seismic safety eff orts in the references cited in the passage below):

Promoting seismic safety is diffi cult. Earthquakes are not high on the 

political agenda because they occur infrequently and are overshadowed 

by more immediate, visible issues. Even where citizens are aware of 

seismic risks, taking action to improve seismic safety is diffi cult because 

costs are immediate and benefi ts uncertain, public safety is not visible, 

benefi ts may not occur during the tenure of current elected offi cials, and 

seismic safety lacks a signifi cant public constituency (Olshansky and 

Kartez, 1998; Lambright, 1984; May, 1991; Drabek et al., 1983; Rossi 

et al., 1982; Wyner and Mann, 1986; Alesch and Petak, 1986; Berke and 

Beatley, 1992). Many factors are critical to the successful advancement of 

seismic safety at local and state levels. Th ese include public advancement 

of the problem; persistent, skillful, and credible advocates; repeated 

interaction and communication among participants; availability of staff 

resources; linkage to other issues; occurrence of a disaster that leads to a 

‘‘window of opportunity’’ for change; community wealth and resources; 

assistance from higher levels of government; and previous experience 

with hazards (Berke and Beatley, 1992; Olshansky and Kartez, 1998). Of 

these, advocacy stands out because it represents a way that individuals 

can make a diff erence. 15

Utah: Engineering Inspections 

Triggered by Re-roofi ng Projects

This program, implemented 

in a variety of ways by 

local governments across 

Utah, has the virtue of 

setting a deadline almost 

automatically.

Th e Utah Uniform Building Standard Act Rules 

have been amended to add a way to upgrade 

the earthquake resistance and general structural safety of buildings, especially unreinforced masonry ones, incrementally. When 

embarking on a re-roofi ng project, the building 

owner must retain an engineer to inspect the 
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 21

adequacy of the building’s roof-to-wall connections and the ability of its parapet 

walls and cornices to withstand horizontal earthquake forces. Th e logic behind this 

incremental approach is that the removal of old roofi ng presents an opportune 

time for an engineer to inspect these conditions, and that any strengthening 

measures would be carried out prior to re-roofi ng, as part of that construction 

project. Section R156-56-801, Statewide Amendments to the IBC (International 

Building Code), Section 58, requires that these appendages be able to withstand 

75% of the force levels that are stipulated for new buildings. Portions of the 

building that don’t perform up to that standard must be either reinforced or 

removed. Buildings built after 1975, when codes for new buildings began to 

address this seismic vulnerability in Utah, are exempt.16

Roofi ng materials will typically need to be replaced within a time period of twenty 

to forty years, and that replacement work will then trigger this retroactive seismic 

requirement. It is common for building codes to require retroactive upgrading of 

safety features, if a building is to be signifi cantly remodeled. Th e reasoning is that 

the remodel will extend the life of the building and that in the context of a major 

renovation project, the safety improvements will represent only a minor cost.

Utah: Statewide Inventory 

of Unreinforced Masonry Buildings

The evolving Utah program 

demonstrates the need 

to conduct an inventory of 

buildings as a fi rst step in 

evaluating their seismic risks 

and the costs and methods 

that could best be used to 

retrofi t them.

In 2008, the Utah legislature passed a resolution urging “the Utah Seismic Safety 

Commission to compile an inventory of 

unreinforced masonry buildings so that the 

quantity and extent of the problem in Utah 

can be determined. Be it further resolved that 

the Legislature urges the Utah Seismic Safety 

Commission to recommend priorities to 

address the problem in a manner that will 

most eff ectively protect the lives, property, 

and economy of the state.”17 Similar in some respects to the California case 

described below, the strategy here is fi rst, to identify the location and size of the 

problem and then, to devise appropriate solutions. Utah is unique among the most 

highly seismic states of the United States, in that it has many single-family 

dwellings of unreinforced masonry construction. Th ese smaller buildings present 

diff erent (usually lesser) risks of collapse or injury, but they also could have a very 

high impact on the population after an earthquake, if many such housing units 

were unsafe to occupy, and if homeowners’ investments in their homes were wiped 

out. In the Salt Lake Valley alone, there are over 185,000 unreinforced masonry 

buildings, many of them single-family residences, typically built with hollow walls 

that do not comply with model codes and retrofi t provisions such as the Uniform 

Code for Building Conservation.

18
22 Examples of Successful Risk Reduction Programs

State of California Unreinforced Masonry Building 

Law: Measuring the Problem and the Progress 

Toward Addressing It

The California program 

provides one example of a 

state government imposing 

a basic requirement on local 

governments to identify their 

unreinforced masonry buildings, while leaving open a 

range of ways in which they 

can deal with that risk.

In 1986, California passed a state law requiring all local governments situated in the 

highest seismicity zone of the currently 

enforced building code to inventory their 

unreinforced masonry buildings, to establish a 

risk reduction program, and to report results 

to the state. At that time, that highest zone of 

seismicity was Zone 4 of the Uniform Building 

Code, which was used in the West and 

Midwest, until the nationwide International 

Building Code took eff ect in 2000. Th e geographic scope of Zone 4 in California encompasses a population of approximately 

28 million people. Th e state sought to balance its compelling interest in seismic 

safety against the cost of retrofi tting buildings by leaving its criteria for these new 

risk reduction programs loosely defi ned: a program could consist of as little as 

publishing a list of the unreinforced masonry buildings in a local jurisdiction and 

encouraging owners to renovate them, while posting warning signs at unretrofi tted buildings. Th us, a recent review of the law concluded, “On the surface, the level 

of compliance with this law has been quite high with over 98 percent of the 25,900 

URM buildings now in loss reduction programs. But so far, only about 70 percent 

of the owners have reduced earthquake risk by retrofi tting in accordance with a 

recognized building code or by other means. Signifi cant progress has occurred, yet 

many URM programs are ineff ective in reducing future earthquake losses.”19

Relatively few of the 25,945 URM buildings addressed by the loss reduction 

programs were demolished. While demolition is sometimes desirable in order to 

renew the building stock, it is generally wise to minimize it to avoid abruptly 

changing the architectural and socio-economic fabric of a city.

Th e local programs with the strictest requirements require actual retrofi tting or 

demolition of the hazardous buildings. Next strictest are those programs that 

require owners to retain an engineer to produce an evaluation report, with actual 

retrofi tting remaining voluntary, perhaps encouraged by incentives. Th e California 

Seismic Safety Commission has found that voluntary strengthening programs 

have not been eff ective. One can conclude either that the incentives in voluntary 

programs have not been great enough, or that the absence of the “stick” to go along 

with the “carrot” is the weakness. Th e lowest level of compliance with the state law, 

and the least eff ective at reducing risks, is when local governments send a letter to 

the building owners informing them that the local building inventory conducted 

under state law found their building to be of unreinforced masonry construction. 

Th ese simple notices do not impose any requirement to have the building either 

evaluated by an engineer or upgraded. Th e Commission’s 2006 survey of local governments found that 52% had mandatory programs, 15% voluntary, 18% notifi cation of owner only, with another 15% in a miscellaneous category. Th e Commission 

provides a suggested model ordinance. Once a local government makes that decision and sets time tables, the actual engineering measures required are already set 

in model code provisions for existing buildings.20
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 23

Seattle, Washington: Saving Historic Buildings

This case illustrates the valuable support that an 

organization knowledgeable 

about grants and loans can 

provide to retrofi t programs, 

by making funds available to 

bridge any funding gaps.

In the 2001 Nisqually earthquake, two-thirds of 

the 31 buildings that were posted as unsafe for 

occupancy (“red tagged”) were built of unreinforced masonry, and many were a century old. 

“Historic” and “unreinforced masonry” are often 

synonymous. After that earthquake, Historic 

Seattle, a non-profi t advocacy organization, 

quickly launched a program of grants of approximately $10,000 each to historic building owners: 

the grants provided fi nancial support for initial engineering studies, with the goal 

being to have owners investigate repair and upgrading alternatives in lieu of 

demolition. While this initiative was a reaction to an earthquake rather than a 

preventive program in place prior to the earthquake, it still had the eff ect of 

promoting retrofi t measures to reduce earthquake risks from future earthquakes. 

In this case, those risks include both the risk of injury to occupants or pedestrians 

and the risk of irreparable damage to the buildings. Any Seattle resident who 

appreciates historic architecture will recognize many of the buildings that Historic 

Seattle helped through that program: Steil Building, McCoy’s Firehouse, Slugger 

Sports, Compass Center, Bread of Life Mission, Milwaukee Hotel and Alps Hotel, 

Hong Kong Building, Hip Sing Building, Panama Hotel, Bush Hotel, Bing Kung 

Building, Seattle Hebrew Academy, Trinity Parish Episcopal Church, Assay Offi ce, 

Mount Baker Park Presbyterian Church, and the Cadillac Hotel.21

Seattle, Washington: Combining Modernization 

with Seismic Retrofi tting

The voters who were 

asked to fund seismic 

retrofi ts were supportive 

partly because the money 

was to be applied to 

essential facilities.

Th irty-two fi re stations in Seattle were identifi ed 

as needing modernization work that included 

energy conservation measures, general remodeling 

and in some cases, seismic upgrading. A ballot 

measure to approve a tax for that purpose was 

passed by a 69% majority of voters in 2003. Th e 

measure was introduced only two years after the 

Nisqually earthquake, when memories of damage 

from that earthquake were fresh in the voters’ minds. Known as the Fire Facilities 

and Emergency Response Levy, the program integrates seismic retrofi ts with 

historic preservation requirements and with upgrading the stations to modern fi re 

safety and other standards. Th e $197 million in taxes average out to about $73 a 

year in additional property tax for the owner of a median-value house.22

Th is program provides more than one possible lesson for other local programs. 

Selecting an obviously high priority public safety category of facilities likely 

increased voter support, as did the recency of an earthquake (although a nonearthquake disaster might also be an impetus for multi-hazard upgrades). Rather 

than fi rst imposing requirements on private property owners, the local government also provided leadership by example, by dealing with vulnerabilities in its 

own buildings. And in packaging a variety of renovation measures along with 

seismic retrofi tting, more cost-eff ective construction projects resulted.
24 Examples of Successful Risk Reduction Programs

Oregon: A Statewide Inventory and Funding 

Approach for Schools and Essential Facilities

This example illustrates 

the value of assembling 

a committee or task force 

comprised of a variety 

of important community 

organizations. 

In 2002, Oregon voters approved two seismic 

safety measures. One allowed the use of general 

obligation bonds to fi nance seismic upgrades of 

educational facilities owned by the State government (including State universities and community 

colleges) and local governments (local public 

school districts). A companion measure applied to 

fi re, police, and hospital buildings. Th e educational measure followed up on a state law passed by the legislature in 2001 that 

required seismic evaluations of schools, using a standardized method published by 

FEMA.23 While these laws launched Oregon on the path toward reducing seismic 

risks from existing buildings—URM buildings being prominent among them—no 

funding was provided to implement the initiatives. Th e Oregon Seismic Safety 

Policy Advisory Committee and the Division of Geology and Mineral Industries 

subsequently worked to obtain funding to conduct a statewide seismic evaluation 

of educational and emergency services buildings, and to put bonds on the ballot as 

needed to correct the seismic defi ciencies found.24

Berkeley and Other California Cities: 

Financial Incentives for Retrofi tting

A “carrot and stick” 

approach can be more 

effective than using an 

incentive or penalty alone. 

Because the City of Berkeley levies a tax of 1.5% 

of the selling price of real estate, it has the 

leverage to refund a portion of that tax, if the 

new owner carries out seismic retrofi t work. Th e 

City will refund retrofi t expenses up to one-third 

of that tax amount (up to 1/2% of the property 

value transferred) for qualifying residential 

properties, when the new owner completes seismic retrofi t work within one year of 

purchase, up to a maximum refund of $2,000. While most of the properties 

included in the program have been wood-frame dwellings, unreinforced masonry 

buildings also qualify.25 In its fi rst decade of implementation, 12,000 properties 

were retrofi tted and rebates were issued totaling $6 million.

A number of other California cities off er incentives, and their programs are summarized by the Association of Bay Area Governments.26 Th ese programs include 

tax breaks, as in the Berkeley case; waiving of building permit fees for seismic 

upgrades; conferring zoning benefi ts such as an increase in density or exemption 

from non-conforming parking or other conditions; low-interest or no-interest 

fi nancing from publicly issued bonds or redevelopment district revenue, and; 

acquiring federal grant money for subsidizing retrofi ts. Th e Association of Bay 

Area Governments report includes information specifi c to unreinforced masonry 

buildings. A number of cities are included in that survey: Arroyo Grande, Berkeley, 

Fullerton, Inglewood, La Verne, Long Beach, Palo Alto, San Diego, San Jose, San 

Mateo, Sonoma, Torrance, Upland, Vacaville, and West Hollywood. Th e report also 

includes sample ordinances, state legislation, and other reference material.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 25

One possible lesson to be drawn from the examples of these cities is the value 

of off ering both a carrot and a stick, both incentives and requirements. As the 

California Seismic Safety Commission report19 noted, incentives by themselves 

have not led to signifi cant retrofi tting.

Public Schools in California: A Statewide Approach 

to a Special Kind of Facility

California legislation singled 

out schools as a high-priority 

type of facility. The legislation 

set long-term but defi nitive deadlines for retrofi tting buildings or 

taking them out of service.

Th e Long Beach earthquake in Southern 

California occurred at 5:54 p.m. on Friday, 

March 10, 1933. Th e fact that it barely 

missed occurring while children were in 

school and that the public saw numerous 

scenes of unreinforced masonry rubble on 

school campuses supplied graphic proof 

that new earthquake regulations in the 

building code were needed. Prior to this time, there were no statewide earthquake 

regulations in the United States, and only a handful of California cities, such as 

Santa Barbara, which had gone through its own earthquake disaster in 1925, had 

any such provisions. Precisely one month after the Long Beach earthquake, the 

California legislature passed the Field Act, which eff ectively made the State into 

the building department for every school constructed by local governments (local 

school districts). Th e act prevented construction of new unreinforced masonry 

buildings and in 1939, the Garrison Act required school districts to inventory and 

to design a program for reducing the hazards of all pre-Field Act buildings. Th ese 

were essentially the unreinforced masonry buildings remaining on their campuses. 

However, this legislation did not lead to immediate retrofi t eff orts, and the law 

gave school board members immunity from liability, if they made an eff ort to 

secure funds for retrofi t eff orts via bond elections. One key reason for the lack of 

action was that there was no deadline in the Garrison Act. In 1967 and 1968, the 

legislature passed the Greene Acts. Th is action “put teeth” in the retroactive 

seismic safety requirements for schools by setting a 1970 deadline for producing 

structural evaluations of pre-1933 buildings and by prohibiting their use by 

students, as of 1975.27

Possible lessons for unreinforced masonry seismic safety programs include the 

singling out of a key public concern, such as safe schools, and the need to consider 

the possibility that deadlines and compliance may slip over time.

Long Beach, California: 

A Pioneering Accomplishment

The persistent and skillful 

efforts of just one person 

can have a lasting effect.

Long Beach, California, where the 1933 earthquake had been centered, was the fi rst city to 

enforce retroactive requirements to seismically 

upgrade unreinforced masonry buildings. In 

1959, Edward O’Connor was the chief building 

offi cial of the city, and he took upon himself the duty to identify the most hazardous of these buildings, including high-occupancy buildings like theaters, and to 

deliver the notice personally to the owners that they must either structurally 
26 Examples of Successful Risk Reduction Programs

strengthen them or tear them down. Th is case-by-case approach withstood 

resistance, based on a California Supreme Court case that justifi ed retroactive fi re 

safety requirements when high risk to public safety was present (retroactive 

“hazard abatement”). It later developed into a long-term, systematic law and 

program enacted and updated by the Long Beach City Council.28 Over time, as 

engineering developments occurred, technical details of the program evolved, but 

the essence of what one person began endured. By 1989, the unreinforced masonry 

buildings that had been rated as being in the most dangerous and intermediate 

dangerous categories had all been retrofi tted or demolished, although there 

remained 560 buildings in the third category of hazard. 

In addition to the mandatory regulation, the city introduced an incentive by 

establishing an assessment district composed of the aff ected properties. Th e establishment of the assessment district enabled the city to issue bonds, the proceeds 

of which would provide loans to the property owners and cover the city’s cost of 

implementing the fi nancial program and the building department’s monitoring 

of the retrofi t work. Th e repayment of the bonds came from assessments on the 

owners in the district. While owners paid the going rate for the loans, they would 

otherwise have been largely unavailable. Owners who defaulted on their loans 

could have their property foreclosed, with the city verifying in advance that there 

was enough value in the property to cover the loan value.29

Edward O’Connor had to go it alone, without other models of mandatory programs 

to refer to and without adopted engineering standards for the evaluation and retrofi t of unreinforced masonry buildings. Today, those resources are available. Still 

applicable as a lesson of this story, however, is the need for a dedicated lead individual to push steadily for the goal of seismic safety. It is also true that the local 

building department will usually be the key agency implementing such eff orts.

Los Angeles, California: Evidence of the 

Effectiveness of Retrofi ts

Successful local programs 

vary in their sources of 

support, but three kinds are 

usually essential: a state or 

local structural engineering association or supportive 

individual engineers, the local 

building department, and key 

local government offi cials and 

legislators.

Th e City of Los Angeles, adjacent to the City 

of Long Beach and with a population over 

three million, launched the largest mandatory local government retroactive seismic 

safety program in the United States, when 

the City Council passed an ordinance in 

1981. Th e law required structural upgrading, 

or demolition, of 14,000 unreinforced 

masonry buildings, excepting residential 

buildings that had four or fewer dwelling 

units.30 Th e 1985 Mexico City earthquake 

that caused over 10,000 deaths motivated 

the Los Angeles City Council to accelerate the time table for compliance, and by the 

time of the 1994 Northridge earthquake in Los Angeles, most URM buildings 

subject to the ordinance had been retrofi tted.

Th e 1994 earthquake caused strong ground motion over Los Angeles and other 

cities of the region and “provided one of the fi rst major tests of the performance of 

retrofi tted unreinforced masonry (URM) buildings, and once again pointed out the 

vulnerability of URMs that have not been strengthened.... As would be expected, 
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 27

unretrofi tted URM buildings performed worse, in general, than both reinforced 

masonry buildings and retrofi tted URM buildings. As observed in previous earthquakes, many of these buildings suff ered signifi cant structural damage and posed 

serious risks to life safety.”31 Th ese statements pertain to unreinforced brick buildings. Th e region also had some very old and historic adobe buildings, and the same 

engineering report just cited noted: “Historic adobe buildings in the Los Angeles 

area suff ered a tragic loss.” Th ese buildings, which are present in other Western 

and Southwestern states, have unique structural features, including the diff erent 

material properties of the adobe walls and their usually larger thickness, and they 

require their own engineering retrofi t approaches, diff erent from those used on 

the more common brick building.

Th e large-scale program enacted by the Los Angeles ordinance catalyzed the 

involvement of a wide spectrum of the community, many of whom initially 

opposed the idea because of cost. Th e key to its eventual success may lie with three 

sets of proponents. Th ese include its earliest advocates, the structural engineers 

of the region, who knew how great the risks were. With funding from the National 

Science Foundation, tests and analyses were conducted to develop a hazard reduction package of retrofi t measures. Th e goal was not to bring these old buildings 

up to current code standards—which would be virtually an impossible task and 

prohibitively expensive—but to bring them up to a reasonable level of safety. Th e 

performance of buildings retrofi tted to that standard in the 1994 Northridge 

earthquake was generally in line with that criterion, although building owners 

often did not understand that “hazard reduction” could be compatible with a level 

of damage that required expensive repairs.

Th e Los Angeles Department of Building and Safety also played an essential role in 

this program. Th is agency reviewed a large volume of building evaluation reports 

submitted by consulting engineers and approved retrofi t design documents, 

once the program was underway. It was also responsible for reporting to the City 

Council on costs and progress and for initiating any legal actions against noncompliant owners.

Th e third source of crucial support was the Los Angeles City Council, which 

remained determined in passing an unpopular law. One legislator in particular, 

Howard Berman, maintained progress on the eff ort over a span of decades.

San Luis Obispo, California: Making the Effort to 

Communicate with Building Owners

The goal of working 

toward seismic safety 

was combined with efforts 

by local agencies to support 

the economic development 

of the affected businesses.

Th is central California city passed its unreinforced masonry law in 1992, taking the 

approach of setting deadlines for mandatory 

retrofi tting. Buildings were put into two 

categories, with the higher occupancy buildings 

having closer deadlines. Partial upgrades could 

be implemented, in order to extend the time 

permitted to come into full compliance. After 

the nearby 2003 San Simeon earthquake, the city decided to accelerate retrofi ts of 

the remaining 40 unreinforced masonry buildings, which were clustered in the 

central business district. In the meantime, the state’s unreinforced masonry law 

required posting a standard hazard warning on unretrofi tted unreinforced 
28 Examples of Successful Risk Reduction Programs

masonry buildings. As the deadlines approached, the downtown business association and individual owners became more opposed to and concerned about mandatory retrofi ts. Rather than wait until confl icts fl ared, the city retained an Economic 

Development Manager, who met individually with building owners to explain 

requirements and to inform them of technical assistance and fi nancial incentives 

available.32 Th e original deadline for all of the buildings to be in full compliance 

was 2018; it has since been moved to 2012. Twenty years would seem like a reasonable timetable for compliance but in fact, many business owners ignored the 

program in its fi rst decade and only seriously considered the law’s requirements 

when the time remaining had grown short. 

Th e City’s eff ort to incorporate an economic development perspective into its program, rather than a building safety enforcement approach alone, is a lesson that 

may well be applicable elsewhere. Another lesson is that allowing a long lead time 

before the fi rst deadline for compliance comes due can result in a program getting 

off to a slow start. 
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 29

5 Additional Technical Background 

on Unreinforced Masonry 

Construction

Unreinforced masonry buildings have design and construction characteristics 

that make them perform poorly in earthquakes. Various retrofi t techniques 

are available to reduce their risk, ranging from low-cost solutions like anchoring masonry parapets to highly engineered solutions involving seismic isolation. 

This chapter details typical construction characteristics, conceptual information 

about the earthquake response of URM buildings, and possible retrofi t solutions.

Out-of-plane forces act 

on a wall both inwardly 

and outwardly, primarily 

causing bending (fl exural) 

stresses. In-plane forces, 

oriented parallel with the 

wall, cause sliding or shear 

stresses.

Masonry materials are intrinsically strong when 

compressed under the usual gravity loads but are 

weak in resisting earthquake forces, which make 

materials fl ex and also shear; ‘shear’ describes the 

tendency for a portion of the wall to slide vis-àvis the rest. When an earthquake shakes an 

unreinforced masonry building, it causes the 

building’s walls to fl ex out-of-plane (see Figure 24) 

and to shear in-plane (see Figure 25). Unreinforced 

masonry is weak in resisting both of those types 

of forces. Mortar is the “glue” that holds the masonry units together; however, 

when it eventually cracks, it does so in a brittle manner, similar to the way that the 

bricks crack. Generally speaking, older masonry construction was built using 

much weaker mortar than current building codes require. Mortar also tends to 

deteriorate in strength over time more than the masonry units themselves do. 

Th us, earthquake engineers sometimes say that in old masonry buildings, “the 

mortar holds the bricks apart, not together.”

 Figure 25. In-plane failure of unreinforced 

masonry walls. —Rutherford and Chekene

 Figure 24. Out-of-plane failure of unreinforced 

masonry walls. —Rutherford and Chekene

Shaking 

parallel to 

wall

Shaking perpendicular 

to wall
30 Additional Technical Background on Unreinforced Masonry Construction

A common type of unreinforced masonry wall in one- or two-story buildings is 

approximately a foot thick and uses a pattern of brickwork called “American bond.” 

In this pattern, most of the bricks are laid running parallel with the wall (these are 

known as stretchers). Approximately every sixth horizontal row, there will be a row 

of bricks with their ends rather than their sides visible (these are known as headers), 

as illustrated in Figure 7 and Figure 8. Th e header courses extend into the cross-section or thickness of the wall, and they provide a strong clue that the wall is unreinforced (because there is no empty space in the middle of the wall, where reinforcing and grout could have been placed). A form of hollow cavity unreinforced brick 

wall also exists, which has no bricks connecting outer and inner layers. Th is type 

of masonry work is done to provide some insulation and to keep rainwater from 

seeping through from the outside to inside of a building. Th ere are many patterns of 

brickwork, although American bond is the most common one. While engineers and 

building departments evaluate the strengths of unreinforced masonry walls on their 

individual merits, all unreinforced masonry walls are essentially “guilty until proven 

innocent,” when it comes to earthquake resistance. Simple fi eld testing methods can 

be used to measure existing masonry strength without damaging the wall.

Unreinforced masonry, as the name implies, is masonry without reinforcing. 

“Reinforcing” (see Figure 26) has a very specifi c meaning in this context. It refers 

to steel reinforcing bars (rebar), which vary in diameter from approximately 3/8 

inch in diameter (9.5 mm, called a #3 bar) to an inch (25 mm) or more in diameter. A bar 4/8 inch in diameter is called a #4 bar, and so on. Th e bars have knobs 

or ridges along their length to increase their adhesion or bond with concrete or 

grout. Grout is essentially a very fl uid form of concrete, with small pea-sized gravel 

instead of the larger aggregate in concrete. 

A reinforced masonry wall has a grid of horizontal and vertical steel reinforcing 

bars within the wall cross-section (see Figure 27). In reinforced brick construction, 

a hollow cavity is formed between an outer stack or wythe of bricks and an inner 

wythe, and the reinforcing is placed in this space. Grout is poured into the cavity, 

and when it sets, a monolithic structural sandwich forms, which is strong in resisting horizontal earthquake forces, both those forces perpendicular to and those 

parallel to the wall.

 Figure 26. A piece of #4 bar (a steel reinforcing 

bar that is 4/8 inch in diameter). 

A nickname for reinforcing bar is rebar.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 31

Ductility is the toughness of 

a material—its ability to 

crack or permanently bend out 

of shape, while still maintaining its structural integrity.

Reinforced masonry walls are not only much 

stronger than unreinforced ones: they also 

remain intact and stable, even if they are 

shaken to the point at which cracking occurs. 

Th at desirable property of ductility is one of 

the most important seismic requirements for 

all kinds of construction. Unreinforced 

masonry, which lacks ductility, often comes apart in a brittle manner and collapses, when it is shaken severely and begins to crack.

How Do Unreinforced Masonry Buildings 

Behave in Earthquakes?

Th e short answer to this question is that unreinforced masonry buildings, on average, perform very poorly in earthquakes. More than any other kind of construction, they can be singled out as being seismically vulnerable. Th e following points 

clarify why this is so.

I

nertial forces are caused by 

rapid movements—the quick 

speeding up, slowing down, or 

turning of a car, for example—

or the rapid and erratic shaking of the ground to which the 

building is connected.

When shaken in an earthquake, the heavy 

mass of masonry walls contributes to high 

earthquake forces. If you hold an empty 

cardboard box and shake it, then you don’t 

feel much eff ect. Fill it with groceries, 

though, and shake it, and you experience 

large inertial forces, because the mass is now 

greater. Inertial forces are the product of the 

mass of an object and the acceleration of its 

motions; thus, heavier (more massive) buildings generate higher forces when they 

are shaken. Acceleration indicates how much an object speeds up, slows down, or 

changes direction. Drop an object here on Earth, and it falls with an acceleration of 

1 unit of gravity, 1 g. Shake the ground horizontally with an acceleration of 1 g, 

and an object that is rigidly mounted to it experiences a sideways force that is 

equal to its own weight. Accelerations of 1⁄2  g up to 1 g or more have been measured 

in earthquakes. It is easy to understand why people 

can’t stand up during strong earthquake shaking, 

when you imagine yourself subjected to horizontal, 

erratic pulls equal to half or more of your body 

weight.

Acceleration is a common measure of the 

severity of earthquake 

shaking.

 Figure 27. Reinforced brick wall. —FEMA 154, 

Rapid Visual Screening of Buildings for Potential 

Seismic Hazards: A Handbook
32 Additional Technical Background on Unreinforced Masonry Construction

As a rough guide, when strong-motion seismographic instruments measure accelerations of ground shaking to be about one to two tenths of that of gravity (0.1 g 

to 0.2 g), then earthquake-resistant construction may suff er cracking but no serious damage. However, unreinforced masonry buildings can experience signifi cant 

damage and may drop debris, such as parapets. As shaking severities approach 1⁄2  g 

or even exceed 1 g, then damage to all kinds of construction is common, but it is 

especially severe for unreinforced masonry buildings. Th e building code allows the 

structure to deform so much in a severe earthquake that it no longer elastically 

returns to its pre-earthquake position and condition. Keeping it “earthquakeproof”—that is, able to undergo strong shaking without experiencing even minor 

damage—would require prohibitively expensive protection for the structure and 

for nonstructural components such as ceilings, partitions, piping, etc. Modern 

buildings designed to recent building codes have successfully resisted the most 

severe earthquake ground motions with only repairable damage. For most kinds 

of modern, code-conforming construction, less than 5% is severely damaged or 

performs in a hazardous manner in a strong earthquake, whereas more than half 

of unreinforced masonry buildings typically receive that level of damage (see 

Chapter 2).

A cardboard box with a lid can resist much higher sideways or lateral forces than 

the same box without the top can resist. Building walls also need that “lid on 

the box,” in order to stabilize them. Th at role is provided by the roof and any 

fl oors above ground level. Floor and roof diaphragms hold the walls of a building 

together. 

Diaphragm is the term structural engineers use to refer 

to fl oors or roofs in their roles of 

resisting horizontal, rather than 

the usual vertical, forces.

Th e most common kind of fl oor and roof 

in an unreinforced masonry building is 

wood frame, typically “two-by” lumber 

such as 2 × 10 small beams (joists), which 

are usually sheathed with “one-by” boards 

(the use of plywood not being common 

until after World War II in building 

construction). Th e wood fl oor or roof diaphragm of a building is, unfortunately, 

very fl exible when compared to the stiff er masonry walls. Th is fl exible wooden 

diaphragm can allow building walls to lean or bow excessively either inwardly or 

outwardly (out-of-plane). As the diaphragm bends sideways and vibrates back and 

forth, it dynamically pushes and pulls on the brick walls, increasing their motions 

and damage.

Individual structural elements, such as a wall and the roof, only perform adequately in earthquakes when these elements are strongly connected. Th e typical 

connection of the wood beams or joists to the unreinforced masonry walls, however, is very weak. A common construction detail used over the decades was to 

rest the end of a beam in a pocket or niche in the brick wall, with little or no steel 

hardware providing a strong, positive connection. When an unreinforced masonry 

building is shaken, the roof or fl oor framing can pull away from the walls. Th e 

walls need the roof to keep them from leaning too far and collapsing, while the 

roof needs the walls to support it, in order to keep from falling. Typical unreinforced masonry damage includes both the collapse of heavy masonry wall areas 

and the collapse of part or all of the roof or upper fl oors (see Figure 28).
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 33

Chapter 2 previously mentioned the common presence of parapets, chimneys, and 

cornices or other decorative features on unreinforced masonry buildings. Th ese 

elements do not play a structural role, but their failure can be very hazardous.

Th e fact that unreinforced masonry buildings often have multiple seismic weaknesses is not surprising—they were not designed to be seismically safe in the 

fi rst place. By the time when American building codes started to include seismic 

requirements, fi rst in California in the 1930s and slowly spreading nationwide, 

reinforced masonry construction techniques became increasingly standard. Strong 

steel connections, analysis of the overall load path that the structural elements 

needed to provide, and an emphasis on ductility also became increasingly standard.

Th us, unreinforced masonry buildings not only have three strikes against them 

from an earthquake engineering point of view—they are vulnerable for at least 

twice as many reasons:

1. Th e walls are weak in resisting horizontal forces (and they lack ductility or 

toughness);

2. Th e walls are heavy (they have high mass, leading to high inertial forces);

3. Diaphragms are excessively fl exible (insuffi cient lateral support for the walls);

4. Diaphragm-to-wall connections are either absent or weak;

5. Parapets and ornamentation are common (and made of masonry), and;

6. Th e buildings were not seismically designed by an engineer (because they were 

built prior to the time when seismic regulations pertaining to masonry began 

to be enforced in that particular region).

 Figure 28. Failure of roof-towall connection, with resulting 

collapse. —Rutherford and Chekene
34 Additional Technical Background on Unreinforced Masonry Construction

How Are Unreinforced Masonry Buildings 

Seismically Retrofi tted?

Retrofi tting or seismically upgrading a building, which means reconstructing 

portions of it, in order to improve its earthquake resistance, is not the only way 

to reduce risks. A building that is demolished obviously poses no further risk. 

One that has its occupancy changed to a lower level—for example, from a theater 

to a warehouse—also reduces the risk of injury. Th e risk of economic loss might 

be reduced by purchasing earthquake insurance (although it is often unavailable 

or very expensive for this kind of construction). In this document, however, risk 

reduction through structural seismic retrofi t (also referred to as rehabilitation) is 

the focus. 

A variety of retrofi t measures have been included in unreinforced masonry 

building risk reduction programs, and one or more of those measures may be 

appropriate in a given case. Th e FEMA book, Techniques for Seismic Rehabilitation 

of Existing Buildings (FEMA 547), provides examples that relate to several kinds 

of construction, including unreinforced masonry bearing wall buildings.33 Th e 

general standard for such retrofi t measures in the United States is the International 

Existing Building Code.

34 Th e International Code Council (ICC) was formed in 2000 

through the merger of the three previous model building code organizations: 

the Building Offi cials and Code Administrators (BOCA), which promulgated the 

National Building Code; the International Conference of Building Offi cials (ICBO), 

which promulgated the Uniform Building Code (UBC), and; the Southern Building 

Code Congress International (SBCCI), which promulgated the Standard Building 

Code. Prior to the establishment of the ICC code for existing buildings, the model 

code available with specifi c application to seismic retrofi t projects was “Seismic 

Strengthening Provisions for Unreinforced Masonry Bearing Wall Buildings,” the 

Uniform Code for Building Conservation (UCBC) Appendix Chapter 1, 1997 edition, 

which was cross-referenced with the 1997 Uniform Building Code. In some cases, a 

local program may still use the Uniform Code for Building Conservation rather than 

the newer ICC document. Over time, it is expected that adopted versions of building codes will standardize around the ICC codes and the standards that it incorporates by reference.

Usually retrofi t that off ers the biggest benefi t relative to its costs is the anchorage 

of masonry parapets, those short walls that extend a few feet above a building’s 

roofl ine. Bracing or removing these parts of the building, along with other exterior 

masonry appendages such as cornices, eff ectively addresses the type of damage 

that can happen even in very light shaking. Th e most common type of bracing used 

is to bolt diagonal steel struts to the top of the parapet, with the bottom end of the 

struts anchored with bolts into the roof structure. Usually this does not change 

the building’s appearance from the street (see Figure 29).

Parapet safety programs do not provide protection, however, against the collapse 

of the building itself. Th e fi rst additional increment of seismic protection, beyond 

parapet and appendage bracing, is provided by bolting the walls to the roof and to 

any fl oors above the ground fl oor level. Long steel bolts are typically inserted into 

holes drilled in the wall and attached to a steel angle, which in turn is bolted to 

the side of a wooden joist. Th e end of the bolt on the outside of the wall requires a 

large washer (the size of a teacup saucer) to prevent it from pulling through in an 

earthquake (see Figure 30). In many communities that have enacted seismic ret-
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 35

rofi t ordinances, the row of these washers running along the roofl ine indicates the 

presence of this kind of retrofi t. Similar-looking steel washers may be part of an 

older building’s construction. In general, old, pre-seismic-code wall-joist anchors 

are not found to be adequate.

Th e next additional increment of earthquake protection is provided by conducting 

a more thorough engineering examination of the entire building structure. Th is 

examination might reveal the need to increase the horizontal stiff ness of fl oors 

and the roof, which is typically accomplished by adding a layer of sheathing (sheets 

of plywood or oriented-strand board). New columns (posts) may be added that can 

hold up the fl oors and roof, even if portions of the bearing wall fail. Th e brick or 

concrete block walls themselves cannot be transformed into modern reinforced 

masonry construction. However, walls can be strengthened by several techniques, 

making them stronger, even if not as strong as new, reinforced masonry walls. One 

available technique is to add a layer of reinforced concrete to the inside or outside 

of the wall, as shown in Figure 31.

Strongbacks are vertical 

“splints” that retrofi t 

a wall to increase its 

out-of-plane resistance to 

horizontal forces.

Another approach is to install columns attached to 

the walls, which act like splints or strongbacks that 

brace the wall against excessively bowing outward 

or inward (see Figure 32). Yet another wall 

strengthening method is to drill holes down 

through the wall from top to bottom, using 

machinery adapted from the oil well industry to 

insert a steel bar and grout. Interior partitions can also help to stiff en the overall 

box structure and can damp out or absorb its vibrations. Each retrofi t brings its 

 Figure 29. Retrofi t 

bracing of an unreinforced masonry 

parapet. 

Typically, diagonal 

bracing struts are 

installed behind the 

wall and anchored to 

the roof, as shown 

here, which makes 

them unobtrusive. 

—Federal Emergency 

Management Agency

 Figure 30. Generic 

wall-diaphragm connection 

retrofi t detail. —FEMA 547, 

Techniques for the Seismic 

Rehabilitation of Existing 

Buildings
36 Additional Technical Background on Unreinforced Masonry Construction

own challenges. For example, a church with an unreinforced masonry spire may 

need to insert steel trusswork inside the tower to brace it adequately.

Seismic isolation devices can be employed in combination with any of the above 

techniques. Th ese devices are “shock absorbers” manufactured for the specifi c 

purpose of being installed between a building’s superstructure and foundation; 

they soften and reduce the motion of the ground, as it comes up into the building 

structure. Prominent examples of this kind of retrofi t being applied to prominent 

historic buildings that contain unreinforced masonry include the Salt Lake City 

and County Building and San Francisco City Hall (see Figure 33).

One can’t simply take the building code regulations for new buildings and extract 

particular features to guide the retrofi tting of existing buildings. In fact, these 

kinds of retrofi ts require design criteria developed specifi cally for existing buildings. Th e Uniform Code for Building Conservation and the ICC International Existing 

Building Code evolved to meet that need. Local communities have also adopted a 

number of diff erent code rules for unreinforced masonry retrofi ts; some of these 

are described in Chapter 4. Codes also typically have “triggers” that require much 

more signifi cant overall building upgrading if a building remodel exceeds a particular threshold. For example, code requirements might be triggered if the cost 

of the new work exceeds some percentage of the value of the existing building. 

 Figure 31. California Capitol 

Retrofi t.

An exhibit shows a cut-away view 

of the reinforced concrete that is 

anchored into the brickwork with 

epoxied reinforcing bars. —Robert 

Reitherman

 Figure 32. A retrofi tted 

lateral-force-resisting post 

(strongback). 

The strongback column spans 

from foundation to roof, 

serving to brace a brick wall 

against out-of-plane forces. 

—Consortium of Universities 

for Research in Earthquake 

Engineering
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 37

Th ese requirements may address concerns beyond the seismic safety concern that 

motivated an earthquake retrofi t. Issues such as handicapped access, exits, energy 

conservation, removal of hazardous materials such as asbestos, and so on can 

come into play. Deciding on the level of required seismic retrofi tting that is appropriate relative to its associated costs is a big part of developing any risk reduction 

program.

Retrofi ts require an engineer’s expertise to design the changes to the construction. Th ere are many kinds of engineer; in this instance, we are referring to civil 

engineers with structural engineering expertise. In some states, “structural 

engineer” is a license or professional registration category, while in other states, 

the term is used more generically. Seismic retrofi ts are signifi cant remodels that 

require building permits, and thus building departments must review plans and 

issue permits. Th e technical community—the consulting structural engineers, 

building departments, architects, and contractors—are essential to any successful 

unreinforced masonry building risk reduction program, but they can’t implement 

such measures by themselves. Th e guidance in Chapter 3, “Developing a Strategy 

for Implementing a URM Risk Reduction Program,” and in Chapter 4, “Examples of 

Successful Risk Reduction Programs,” makes it clear that key non-technical sectors 

of the community must be involved and exert leadership.

 Figure 33. The San Francisco 

City Hall seismic retrofi t, which 

includes seismic isolators. —Robert 

Reitherman
38 Additional Technical Background on Unreinforced Masonry Construction
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 39

6 Sources of Information

I

n addition to the cited references, the following sources of information may 

be useful to consult for further information.

Note that all of the documents published by FEMA listed here are available as 

downloads and can often be mailed in printed form, upon request. A much larger 

number of earthquake publications than are listed here are available from FEMA. 

See: http://www.fema.gov/plan/prevent/earthquake/. 

Publications for the General Public

California Seismic Safety Commission, “Status of the Unreinforced Masonry 

Building Law: 2006 Progress Report to the Legislature,” California Seismic 

Safety Commission, Sacramento, California; http://www.seismic.ca.gov/pub.

html.

In concise form, this report indicates the types of programs being used 

in California and their success rates.

Oregon Department of Land Conservation and Development, Natural Hazard 

Technical Resource Guide, Salem, Oregon, July 2000; http://oregon.gov/LCD/

HAZ/docs/earthquakes/08_seismic.pdf.

Th is booklet explains to the public the nature of the various natural 

hazards in Oregon and what is being done about them. Examples of 

programs to reduce the earthquake hazards of existing buildings are 

included, along with a review of legislative bills that were drafted to 

require seismic inventories of buildings. It points the reader toward further sources of information. 

Utah Seismic Safety Commission, “The Utah Guide for the Seismic 

Improvement of Unreinforced Masonry Dwellings” (n.d.); http://ussc.utah.

gov/utahseismic.

Th is booklet exists as a web-based document for the general public. It 

promotes the idea of producing web-accessible public information products as part of a seismic risk reduction program, with the twin advantages of lowering costs (eliminating printing and distribution costs once 

the document is produced) and appealing to the increasing number of 

people who turn to the web as their fi rst source of information. It may 

also be advisable to have printed versions of such documents available, 

for example, to hand out at meetings, to reach those who do not usually 

use the web, and to reach additional audiences such as those who pick up 

a copy when waiting at the counter of a building or planning department.
40 Sources of Information

Utah Seismic Safety Commission, “Putting Down Roots in Earthquake 

Country: Your Handbook for Earthquakes in Utah,” 2008; http://ussc.utah.gov.

Th is booklet is a customized version of a publication developed for 

California residents by the Southern California Earthquake Center, the 

U.S. Geological Survey, and the Federal Emergency Management Agency. 

It includes an explanation of the hazard of earthquake shaking and fault 

rupture in Utah and information on unreinforced masonry.

Historic Buildings and Seismic Retrofi ts

California Historical Building Code (Part 8, Title 24 of California law), 

California Building Standards Commission, 2007; http://www.dsa.dgs.ca.

gov/SHBSB/default.htm.

Th is is the generally prevailing code used for historical buildings in 

California, though not required statewide, and is now correlated with the 

provisions of the 2006 International Building Code. It allows more latitude 

in seismic retrofi tting of historic buildings than apply to non-historic 

building projects.

Rachel Cox, Controlling Disaster: Earthquake-Hazard Reduction for Historic 

Buildings, National Trust for Historic Buildings, Washington, DC 2001;

http://www.preservationbooks.org.

An introduction to the topic and guide to further resources.

Building Inventories and Evaluation of Existing 

Buildings

American Society of Civil Engineers, Seismic Evaluation of Existing Buildings—

ASCE 31-03, Reston, Virginia, 2002; ordering information: http://pubs.asce.

org/books/standards/.

Th is standard was developed for the use of structural engineers and 

building departments in applying consistent criteria and calculation 

methods to the seismic evaluation of existing buildings, that is, the 

process of deciding whether an existing building is defi cient in particular 

ways and requires strengthening. It covers all kinds of buildings.

Applied Technology Council, Rapid Visual Screening of Buildings for Potential 

Seismic Hazards: A Handbook—FEMA 154, second edition, Federal Emergency 

Management Agency, Washington, DC, 2002; http://www.fema.gov/plan/

prevent/earthquake/.

A guide to the subject concerning all types of buildings, but with a chapter specifi c to unreinforced masonry bearing wall buildings. Includes 

sample data collection forms and guidance on fi eld methods to identify 

unreinforced masonry buildings.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 41

Building Codes, Standards, Guidelines, and Laws 

Applicable to Existing Buildings

American Society of Civil Engineers, Seismic Rehabilitation of Existing 

Buildings—ASCE/SEI 41/06, Reston, Virginia, 2007; ordering information: 

http://pubs.asce.org/books/standards/.

Th is standard was developed for use by structural engineers and building departments after the decision is made to strengthen (rehabilitate) a 

building, and it is not limited to unreinforced masonry. It includes guidance to the engineer on how to give appropriate earthquake engineering 

“credit” to older kinds of structural components that are not included 

in modern building codes and how to analyze them. Forerunner publications to this standard include documents known as FEMA 273, and 

FEMA 356.

Association of Bay Area Governments, Seismic Retrofi t Incentive Programs,

Oakland, California; http://www.abag.ca.gov/bayarea/eqmaps/incentives

Th is report focuses on incentives, but it also includes summaries of several local government ordinances.

California Seismic Safety Commission, “Status of the Unreinforced Masonry 

Building Law: 2006 Progress Report to the Legislature,” California Seismic 

Safety Commission, Sacramento, California; http://www.seismic.ca.gov/pub.

html.

Includes a summary of this state law, passed in 1986. Also mentioned 

above, under Publications for the General Public.

International Code Council, International Existing Building Code, 2006 

edition, Washington, DC; ordering information: http://www.iccsafe.org/

Th is is derived from the earlier Uniform Code for Building Conservation, 

which may still be the locally applicable standard, depending upon the 

jurisdiction.

Rutherford & Chekene, Techniques for the Seismic Rehabilitation of Existing 

Buildings—FEMA 547, Federal Emergency Management Agency, October 2006;

http://www.fema.gov/plan/prevent/earthquake/.

Written for engineers and building department personnel, this manual 

deals in Chapter 21 with specifi c retrofi t measures for unreinforced 

masonry buildings, ranging from bracing parapets and veneer to reinforced 

concrete and fi ber-reinforced polymer methods of strengthening walls. 

Includes generic engineering details of the various retrofi t alternatives.
42 Sources of Information

Uniform Code for Building Conservation, Appendix Chapter 1, International 

Code Conference, Washington, DC, 1997; ordering information: http://www.

iccsafe.org/

Originally published by the International Conference of Building 

Offi cials, the organization promulgating the Uniform Building Code, prior 

to the merger of model code organizations into the International Code 

Council. Th e Uniform Code for Building Conservation is formatted to be 

compatible with the 1997 Uniform Building Code.

Costs of Seismic Retrofi ts

Federal Emergency Management Agency, “FEMA Seismic Rehabilitation Cost 

Estimator,” FEMA Seismic Rehabilitation Cost Estimator; http://www.fema.

gov/srce/index.jsp

Th e user of this web-based calculator can either use a simplifi ed method 

requiring little input information or a more advanced method that 

requires selections among more variables.

Hart Consultant Group, Inc., Typical Costs for Seismic Rehabilitation of 

Buildings, Volume 1, Summary—FEMA 156, and Volume 2, Supporting 

Documentation—FEMA 157, Federal Emergency Management Agency, 

Washington DC, 1994-1995, second edition; http://www.fema.gov/plan/

prevent/earthquake/.

A study of completed seismic upgrade projects to derive cost statistics.

Rutherford & Chekene, Seismic Retrofi tting Alternatives for San Francisco’s 

Unreinforced Masonry Buildings: Estimates of Construction Cost and Seismic 

Damage, San Francisco Department of City Planning, 1990.

A study which grouped the city’s 2,000 unreinforced masonry buildings 

into categories based on occupancy, size, and confi guration, in order to 

estimate what kinds of retrofi ts would be needed to meet alternative 

proposed strengthening criteria, listed with associated costs.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 43

7 End Notes and Cited References

1. Th e International Building Code, promulgated by the International Code Council, 

obtains its seismic criteria for where particular types of structural systems 

can be used from ASCE 7-05, Minimum Design Loads for Buildings and Other 

Structures (ASCE/SEI 7-05 including Supplement No. 1), American Society of 

Civil Engineers, Reston, Virginia, 2006. Th e map in Figure 1 of this document 

is based on several assumptions, including: (1) Occupancies up through III in 

Table 1-1 of ASCE 7-05, which does not include fi re stations, hospitals, or other 

essential facilities; (2) a short-period site coeffi cient, Fa, of 1.75 (Table 11.4-1), 

based on the mapped short-period Maximum Considered Earthquake (SS); 

and (3) the design spectral short-period accelerations (SDS) must be less than 

0.33 for Seismic Design Category B to apply (Table 11.6-1), and with the above 

assumptions, the maximum SS of 0.33 is rounded here to 0.3 for mapping purposes. For essential occupancies or for very soft soil, the red areas on the map 

would expand.

2. Architectural Resources Group, An Assessment of Damage Caused to Historic 

Resources by the Loma Prieta Earthquake, National Trust for Historic 

Preservation, Washington, DC, August 1990, p. 40.

3. Th e Federal Emergency Management Agency has published a number of publications that deal with a variety of kinds of buildings, and also for utility and 

transportation systems. See http://www.fema.gov/plan/prevent/earthquake/. 

FEMA publication number 736, “Catalog of FEMA Earthquake Resources,” 

available at that website, provides the complete list.

4. Statistics are compiled from the 1886 Charleston, 1906 San Francisco, 1925 

Santa Barbara, 1933 Long Beach, 1971 San Fernando, and 1983 Coalinga 

earthquakes, in districts where the Modifi ed Mercalli Intensity was approximately VII or greater. Data for the 1886 Charleston earthquake from H.C. 

Stockdell, H. C. et al., Record of Earthquake Damages, Winham & Lester 

Publishers, Atlanta, Georgia, 1886. Data for the 1925 Santa Barbara earthquake in Karl V. Steinbrugge, Earthquakes, Volcanoes, and Tsunamis: An Anatomy 

of Hazards, Skandia America, New York, New York, 1982, p. 306. Data for 

the other earthquakes from the compilation in Robert Reitherman, “Seismic 

Damage to Unreinforced Masonry Buildings,” Final Report to the National 

Science Foundation, Scientifi c Service, Inc., Redwood City, California, 1984, p. 

23.

5. H.C. Stockdell, et al., Record of Earthquake Damages, Winham & Lester 

Publishers, Atlanta, Georgia, 1886; fi gure for the demolitions from John R. 

Freeman, Earthquake Damage, McGraw-Hill, New York, New York, 1932, p. 284.

6. Karl Steinbrugge, Earthquakes, Volcanoes, and Tsunamis: An Anatomy of Hazards, 

Skandia America Group, New York, 1982, p. 306.
44 End Notes and Cited References

7. C. D. Wailes and A. C. Horner, “Earthquake Damage Analyzed by Long Beach 

Offi cials,” Engineering News-Record, May 25, 1933.

8. Robert Reitherman, Gregor Cuzner, T.C. Zsutty, and Gretchen Smith, 

“Performance of Unreinforced Masonry Buildings,” Coalinga, California, 

Earthquake of May 2, 1983, Earthquake Engineering Research Institute, 

Oakland, California, 1984, p. 132.

9. Architectural Resources Group, An Assessment of Damage Caused to Historic 

Resources by the Loma Prieta Earthquake, National Trust for Historic 

Preservation, Washington, DC, 1990, p. 29.

10. Nisqually Earthquake Clearinghouse Group, Th e Nisqually Earthquake of 28 

February 2001: Preliminary Reconnaissance Report, p. 11.

11. California Seismic Safety Commission, “Findings and Recommendations from 

the San Simeon Earthquake of December 22, 2003,” California Seismic Safety 

Commission, Sacramento, California; http://www.seismic.ca.gov/pub.html.

12. Federal Emergency Management Agency, “FEMA Seismic Rehabilitation Cost 

Estimator,” http://www.fema.gov/srce/index.jsp.

13. Hart Consultant Group, Inc., Typical Costs for Seismic Rehabilitation of Buildings, 

Volume 1, Summary—FEMA 156, and Volume 2—FEMA 157, Supporting 

Documentation, Federal Emergency Management Agency, Washington DC, 

1994-1995, second edition; http://www.fema.gov/plan/prevent/earthquake/.

14. Applied Technology Council, Rapid Visual Screening of Buildings for Potential 

Seismic Hazards: A Handbook—FEMA 154, second edition, Federal Emergency 

Management Agency, Washington, DC, 2002; http://www.fema.gov/plan/prevent/earthquake/.

15. Robert Olshansky, “Making a Diff erence: Stories of Successful Seismic Safety 

Advocates,” Earthquake Spectra, Volume 21, No. 2, May 2005; http://www.

urban.illinois.edu/faculty/olshansky/index.html.

16. Th e Utah law; http://www.dopl.utah.gov/laws/R156-56.pdf.

17. Th e Utah resolution H.J.R. 7; http://le.utah.gov/~2008/bills/hbillenr/hjr007.pdf.

18. Personal communication from Barry Welliver, former Chair, Utah Seismic 

Safety Commission, June 23, 2009.

19. California Seismic Safety Commission, “Status of the Unreinforced Masonry 

Building Law: 2006 Progress Report to the Legislature,” California Seismic 

Safety Commission, Sacramento, California; http://www.seismic.ca.gov/pub.html.

20. Th e original referenced standard was the Uniform Code for Building 

Conservation, Appendix Chapter 1, published by the International Conference 

of Building Offi cials. After the three U.S. model code groups merged in 2000 to 

form the International Code Council and to promulgate the International Building 

Code, the relevant existing building code became the International Existing 

Building Code of 2006.

21. Historic Architecture, Seattle, Washington; http://www.historicseattle.org/advocacy/nisqually.aspx.
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 45

22. Levy Oversight Committee, “Status Report, July 17 2008,” Fleets and Facilities 

Department, City of Seattle, Washington; http://www.seattle.gov/fl eetsfacilities/

fi relevy/about.htm.

23. Robert Olshansky, “Making a Diff erence: Stories of Successful Seismic Safety 

Advocates,” Earthquake Spectra, Volume 21, No. 2, May 2005; http://www.

urban.illinois.edu/faculty/olshansky/index.html.

24. Yumei Wang and Bill Burns, “Case History on the Oregon GO Bond Task 

Force: Promoting Earthquake Safety in Public Schools and Emergency 

Facilities,” Proceedings of the 8th National US Earthquake Conference, Earthquake 

Engineering Research Institute, Oakland, California, 2006; http://www.oregongeology.org/sub/projects/rvs/EERI-GO-Bond-text.pdf.

25. Real Property Transfer Tax—Seismic Retrofi t Fund, City of Berkeley; http://

www.ci.berkeley.ca.us/ContentDisplay.aspx?id=6282.

26. Association of Bay Area Governments, Seismic Retrofi t Incentive Programs, 

Oakland, California; http://www.abag.ca.gov/bayarea/eqmaps/incentives.

27. Daniel Barclay, “Assessing Seismic Safety Policy,” Massachusetts Institute of 

Technology Undergraduate Research Journal, Volume 10, Spring 2004; http://web.

mit.edu/murj/www/v10/v10-Features/v10-f2.pdf.

28. Edward M. O’Connor, ““An Interview With Edward M. O’Connor: Retroactive 

Regulations in Long Beach,” Robert Reitherman, interviewer, Building 

Standards, International Conference of Building Offi cials, September-October, 

1984. 

29. Association of Bay Area Governments, Seismic Retrofi t Incentive Programs, 

Oakland, California; http://www.abag.ca.gov/bayarea/eqmaps/incentives/. See 

pages 25-34.

30. Daniel Alesch and William Petak, Th e Politics and Economics of Earthquake 

Hazard Mitigation: Unreinforced Masonry Buildings in Southern California, Natural 

Hazards Center, University of Colorado, Boulder, 1986; http://www.colorado.

edu/hazards/publications/monographs/monopubs.html - 1980.

31. William T. Holmes and Peter Somers, editors, Northridge Earthquake of January 

17, 1994 Reconnaissance Report—Volume 2, Earthquake Spectra, supplement C to 

Volume 11, January 1996, p. 195-217.

32. City of San Luis Obispo, “Unreinforced Masonry Hazard Mitigation Program,” 

http://www.ci.san-luis-obispo.ca.us/economicdevelopment/seismiccoord.asp; City 

Manager, City of San Luis Obispo, “Draft Outline of Seismic Safety Ordinance 

Update,” http://www.prcity.com/government/citycouncil/agenda-items/2004/

March/2004 03-16 CC ITM 17.pdf.

33. Rutherford & Chekene, Techniques for the Seismic Rehabilitation of Existing 

Buildings—FEMA 547, Federal Emergency Management Agency, October 2006; 

http://www.fema.gov/plan/prevent/earthquake/.

34. International Code Council, International Existing Building Code, 2006 edition, 

Washington, DC; ordering information: http://www.iccsafe.org/.
46 End Notes and Cited References
FEMA P-774: Unreinforced Masonry Buildings and Earthquakes 47

8 Project Participants

FEMA Project Monitor

Cathleen M. Carlisle

Federal Emergency Management Agency

500 C Street, SW

Washington, DC 24072

Project Manager

Th omas R. McLane 

Applied Technology Council

2111 Wilson Blvd., Suite 700

Arlington, Virginia 22201

Principal Authors

Robert K. Reitherman

Consortium of Universities for Research in 

Earthquake Engineering

1301 South 46th St., Building 420

Richmond, California 94804

Sue C. Perry

U.S. Geological Survey

525 So. Wilson Avenue

Pasadena, California 91106

Project Review Panel

Ronald P. Gallagher

R P Gallagher Associates, Inc.

519 17th Street, Suite 220

Oakland, California 94612

Jon A. Heintz

Applied Technology Council

201 Redwood Shores Parkway, Suite 240

Redwood City, California 94065

William T. Holmes

Rutherford & Chekene

55 Second Street, Suite 600

San Francisco, California 94105

Ugo Morelli

2700 Calvert Street, NW, #314

Washington, DC 20008

Lawrence D. Reaveley

University of Utah

Dept. of Civil and Environmental Eng’g

160 S. Central Campus Drive, Room 104

Salt Lake City, Utah 84112-0561

Christopher Rojahn

Applied Technology Council

201 Redwood Shores Parkway, Suite 240

Redwood City, California 94065

Editor

Kristen Yawitz

1923 Lyon Avenue

Belmont, California 94002