Order Code RL33861
Earthquakes: Risk, Monitoring,
Notification, and Research
February 2, 2007
Peter Folger
Specialist in Energy Policy
Resources, Science, and Industry Division
Earthquakes: Risk, Monitoring,
Notification, and Research
Summary
Close to 75 million people in 39 states face some risk from earthquakes.
Seismic hazards are greatest in the western United States, particularly California,
Alaska, Washington, Oregon, and Hawaii. The Rocky Mountain region, a portion
of the central United States known as the New Madrid Seismic Zone, and portions
of the eastern seaboard, particularly South Carolina, also have a relatively high
earthquake hazard. Compared to citizens of other countries, relatively few Americans
have died as a result of earthquakes over the past 100 years, but the country faces the
possibility of large economic losses from earthquake-damaged buildings and
infrastructure. Until Hurricane Katrina in 2005, the 1994 Northridge (CA) earthquake
was the costliest natural catastrophe to strike the United States; some damage
estimates were $26 billion (in today’s dollars). Estimates of total loss from a
hypothetical earthquake of magnitude more than 7.0 range as high as $500 billion for
the Los Angeles area.
Given the potentially huge costs associated with a severe earthquake, an ongoing
issue for Congress is whether the federally supported programs aimed at reducing
U.S. vulnerability to earthquakes are an appropriate response to the earthquake
hazard. Under the National Earthquake Hazards Reduction Program (NEHRP), four
federal agencies have responsibility for long-term earthquake risk reduction: the U.S.
Geological Survey (USGS), the National Science Foundation (NSF), the Federal
Emergency Management Agency (FEMA), and the National Institute of Standards
and Technology (NIST). They variously assess U.S. earthquake hazards, send
notifications of seismic events, develop measures to reduce earthquake hazards, and
conduct research to help reduce overall U.S. vulnerability to earthquakes.
Congress established NEHRP in 1977, and its early focus was on research that
would lead to an improved understanding of why earthquakes occur and to an ability
to predict them accurately. Congress most recently reauthorized NEHRP in 2004
(P.L. 108-360), and designated NIST as the lead agency, to create better synergy
among the agencies and improve the program. Understanding has improved about
why and where earthquakes occur; however, reliably predicting the precise date and
time an earthquake will occur is not yet possible. Research may eventually lead to
an ability to predict earthquakes, but the focus of NEHRP now has shifted towards
improving the nation’s ability to prepare for earthquakes and to minimize losses
when an earthquake occurs.
Under NEHRP, the USGS has responsibility for conducting targeted research
to improve the basic scientific understanding of earthquake processes. USGS
research has produced, for example, a relatively new product called ShakeMap.
ShakeMap provides a near real-time map of ground motion and shaking intensity and
portrays the extent of damage following an earthquake. NSF supports more
fundamental research — it distributes research grants and coordinates programs —
that leads to a better understanding of crustal processes that cause earthquakes around
the globe. NSF recently initiated a major project called EarthScope to study the
structure and evolution of the North American Continent.
Contents
Earthquake Hazards and Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Advanced National Seismic System (ANSS) . . . . . . . . . . . . . . . . . . . . 9
National Strong-Motion Project (NSMP) . . . . . . . . . . . . . . . . . . . . . . . 9
Global Seismic Network (GSN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Detection, Notification, and Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
National Earthquake Information Center (NEIC) . . . . . . . . . . . . . . . . 11
ShakeMap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
National Earthquake Hazards Reduction Program (NEHRP) . . . . . . . . . . . 13
Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Research — Understanding Earthquakes . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
U.S. Geological Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
National Science Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
List of Figures
Figure 1. Earthquake Hazard in the United States . . . . . . . . . . . . . . . . . . . . . . . . 2
Figure 2. Histogram Showing the Number of Earthquakes from 2000-2006
Plotted Against Their Magnitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
List of Tables
Table 1. 26 Urban Areas Facing Significant Seismic Risk . . . . . . . . . . . . . . . . . . 3
Table 2. Earthquakes Responsible for Most United States Fatalities
Since 1970 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Table 3. The 10 Most Damaging Earthquakes in the United States . . . . . . . . . . . 6
Table 4. U.S. Cities With Estimated Annualized Earthquake Losses
More Than $10 Million . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 5. Authorization Levels for NEHRP by Agency . . . . . . . . . . . . . . . . . . . . 15
Table 6. Authorization Levels for ANSS and NEES . . . . . . . . . . . . . . . . . . . . . 15
Earthquakes: Risk, Monitoring,
Notification, and Research
The 1994 Northridge (CA) earthquake caused as much as $26 billion in damage,
according to one estimate, and was one of the costliest natural disasters to strike the
United States. The U.S. Federal Emergency Management Administration (FEMA)
has estimated that earthquakes cost the United States, on an annualized basis, over
$4 billion per year. Some damage estimates of a single, large earthquake striking the
Los Angeles area range as high as $500 billion.
Under the National Earthquake Hazards Reduction Program (NEHRP), the
federal government supports efforts to assess and monitor earthquake hazards and
risk in the United States. Four federal agencies, responsible for long-term earthquake
risk reduction, coordinate their activities under NEHRP: the U.S. Geological Survey
(USGS), the National Science Foundation (NSF), FEMA, and the National Institute
of Standards and Technology (NIST). Congress reauthorized NEHRP in 2004 (P.L.
108-360).
Given the potentially huge costs associated with a large, damaging earthquake
in the United States, an ongoing issue for Congress is whether the federally supported
earthquake programs are appropriate for the earthquake risk. This report describes
estimates of earthquake hazards and risk in the United States, the current federal
programs that support earthquake monitoring and that provide notification after a
seismic event, and the programs that support mitigation and research aimed at
reducing U.S. vulnerability to earthquakes.
Earthquake Hazards and Risk
All 50 states are vulnerable to earthquake hazards, although risks vary greatly
across the country. Seismic hazards are greatest in the western United States,
particularly California, Alaska, Washington, Oregon, and Hawaii (see Figure 1).
Alaska is the most earthquake-prone state, experiencing a magnitude 7 earthquake1
1 Magnitude is a number that characterizes the relative size of an earthquake. Earthquake
magnitude is often reported using the Richter scale (magnitudes in this report are generally
consistent with the Richter scale). Richter magnitude is calculated from the strongest
seismic wave recorded from the earthquake, and is based on a logarithmic (base 10) scale:
for each whole number increase in the Richter scale, the ground motion increases by ten
times. The amount of energy released per whole number increase, however, goes up by a
factor of 32. The moment magnitude scale is another expression of earthquake size, or
energy released during an earthquake, that roughly corresponds to the Richter magnitude
and is used by most seismologists because it more accurately describes the size of very large
earthquakes. Intensity is a measure of how much shaking occurred at a site based on
observations and amount of damage. Intensity is usually reported on the Modified Mercalli
(continued...)
CRS-2
almost every year and a magnitude 8 earthquake every 14 years on average.
California has more citizens at risk than any other state because of the state’s
frequent seismic activity combined with its high population.
Figure 1. Earthquake Hazard in the United States
Source: USGS, “Conterminous States Probabilistic Maps & Data” (modified by CRS),
at [http://earthquake.usgs.gov/research/hazmaps/products_data/images/nshm_us02.gif].
Note: The hazard levels indicate the potential ground motion — expressed as a percentage
of the acceleration due to gravity (g) — with up to a 1 in 10 chance of being exceeded
over a 50-year period.
Figure 1 also shows relatively high earthquake hazard in the Rocky Mountain
region, portions of the eastern seaboard — particularly South Carolina — and a part
of the central United States known as the New Madrid Seismic Zone (discussed
below). Other portions of the eastern and northeastern United States are also
vulnerable to moderate seismic hazard. According to the USGS, 75 million people
in 39 states are subject to significant risk. During the period 1975-1995, only four
states did not experience detectable earthquakes: Florida, Iowa, North Dakota, and
Wisconsin.
Precisely when an earthquake will occur cannot be reliably predicted yet;
however, good information exists on where earthquakes are likely to occur and how
severe the earthquake magnitude and resulting ground shaking are likely to be. The
1 (...continued)
Intensity Scale as a roman numeral ranging from I (not felt) to XII (total destruction).
CRS-3
map in Figure 1 depicts the potential shaking hazard from future earthquakes. It is
based on the frequency at which earthquakes occur in different areas and how far the
strong shaking extends from the source of the earthquake.
Shaking-hazards maps, such as the one in Figure 1, are often combined with
other data, such as the strength of existing buildings, to estimate possible damage in
an area following an earthquake. The combination of seismic risk, population, and
vulnerable infrastructure can help improve the understanding of which urban areas
across the United States face risks from earthquake hazards that may not be
immediately obvious from the probability maps of shaking hazards alone. The USGS
has identified 26 urban areas that face a significant seismic risk from the combination
of population and severity of shaking. Table 1 lists those areas at risk.
Table 1. 26 Urban Areas Facing Significant Seismic Risk
(alphabetically by state for cities with at least 300,000 people)
State
City
State
City
Alaska
Anchorage
Nevada
Las Vegas
California
Fresno
Nevada
Reno
California
Los Angeles
New Mexico
Albuquerque
California
Sacramento
New York
New York
California
Salinas
Oregon
Eugene-Springfield
California
San Diego
Oregon
Portland
California
San Francisco-Oakland
Puerto Rico
San Juan
California
Santa Barbara
South Carolina
Charleston
California
Stockton-Lodi
Tennessee
Chattanooga-Knoxville
Idaho
Boise
Tennessee
Memphis
Indiana
Evansville
Utah
Provo-Orem
Massachusetts
Boston
Utah
Salt Lake City
Missouri
St. Louis
Washington
Seattle
Sources: USGS Fact Sheet 2006-3016 (March 2006); USGS Circular 1188, Table 3.
Note: These areas are identified using a population-based risk factor based on 1999
population data. (William Leith, ANSS Coordinater, USGS, Reston, VA, telephone
conversation, Nov. 15, 2006).
The USGS estimates that several million earthquakes occur worldwide each
year, but the majority have very small magnitudes or occur in remote areas, and are
not detectable. More earthquakes are detected each year as more seismometers2 are
installed in the world, but the number of large earthquakes (magnitude greater than
6.0) has remained relatively constant. Between 2000 and 2006, the National
Earthquake Information Center (NEIC) reported as few as 2,261 and as many as
3,683 earthquakes each year in the United States, ranging in magnitude from less
than 2.0 to greater than 7.0. Figure 2 shows the number of earthquakes plotted
against magnitude over the 2000-2006 time span in the United States.
2 Seismometers are instruments that measure and record the size and force of seismic waves,
essentially sound waves radiated from the earthquake as it ruptures. Seismometers generally
consist of a mass attached to a fixed base. During an earthquake, the base moves and the
mass does not, and the relative motion is commonly transformed into an electrical voltage
that is recorded. A seismograph usually refers to the seismometer and the recording device,
but the two terms are often used interchangeably.
CRS-4
Figure 2. Histogram Showing the Number of Earthquakes from
2000-2006 Plotted Against Their Magnitude
2000
1800
1600
s
e 1400
uak 1200
rthq
a
E 1000
r of
800
be
um
N
600
400
200
0
1.0 to 1.9
2.0 to 2.9
3.0 to 3.9
4.0 to 4.9
5.0 to 5.9
6.0 to 6.9
Magnitude
2000
2001
2002
2003
2004
2005
2006
Source: USGS, “Earthquake Facts and Statistics,” at [http://neic.usgs.gov/neis/eqlists/eqstats.html];
data as of Nov. 6, 2006.
As Figure 2 shows, about 97% of earthquakes detected each year by the NEIC
are smaller than magnitude 5.0; only 45 earthquakes exceeded magnitude 6.0 for the
five-year period (less than 0.2% of the total earthquakes detected) for an average of
six earthquakes per year of at least 6.0 magnitude.
Although infrequent, large earthquakes cause the most damage and are
responsible for the most earthquake-related deaths in the United States and around
the world. Over the past 100 years, relatively few Americans have died as a result
of earthquakes, compared to citizens in other countries. The great San Francisco
earthquake of 1906 claimed an estimated 3,000 lives, as a result of both the
earthquake and subsequent fires. Since 1970, three major earthquakes in the United
States were responsible for 188 of the 212 total earthquake-related fatalities (see
Table 2).
Since 2000, only two deaths directly caused by earthquakes have occurred in the
United States, both associated with falling debris in Paso Robles (CA) during the
December 22, 2003, San Simeon earthquake of magnitude 6.5. In contrast,
earthquakes are directly or indirectly responsible for more than 430,000 fatalities in
other countries since 2000. More than half of those estimated deaths resulted from
the December 2004 Indonesian earthquake of magnitude 9.1 and the resulting
tsunami.
CRS-5
Table 2. Earthquakes Responsible for
Most United States Fatalities Since 1970
Date
Location
Magnitude
Deaths
February 9, 1971
San Fernando Valley, CA
6.6
65
October 18, 1989
Loma Prieta, CA
6.9
63
January 17, 1994
Northridge, CA
6.7
60
Source: USGS Earthquakes Hazards Program.
Note: Other sources report different numbers of fatalities associated with the Northridge
earthquake.
The 1994 Northridge earthquake was the nation’s most damaging earthquake
in the past 100 years, preceded five years earlier by the second most costly
earthquake — Loma Prieta. Table 3 shows the 10 costliest U.S. earthquakes
according to one estimate of insured and uninsured losses. Comparing losses
between different earthquakes, and between earthquakes and other disasters such as
hurricanes, can be difficult because of the different ways losses are calculated.
Calculations may include a combination of insured losses, uninsured losses, and
estimates of lost economic activity. For example, insured losses — mainly property
— from Hurricane Katrina in 2005 may be $41 billion, according to one estimate.3
Including damage to uninsured property would add to the sum of total property
damage. Including interrupted economic activity in the calculation could bring the
total loss for Hurricane Katrina to $100 billion, according to another estimate.4
The United States faces potentially large total losses due to earthquake-caused
damage to buildings and infrastructure, and potential lost economic activity. As
urban development continues in earthquake-prone regions in the United States,
concerns are increasing about the exposure of the built environment, including
utilities and transportation systems, to potential earthquake damage.5 One estimate
of loss from a severe earthquake in the Los Angeles area is over $500 billion. An
even higher estimate — approximately $900 billion — includes damage to the
heavily populated central New Jersey-Philadelphia corridor if a 6.5 magnitude
earthquake occurred along a fault lying between New York City and Philadelphia.6
3 Insurance Information Institute, [http://www.iii.org/media/facts/statsbyissue/hurricanes/].
4 Risk Management Solutions (RMS), Newark, CA, press release (Sept. 2, 2005), at
[http://www.rms.com/NewsPress/PR_090205_HUKatrina.asp].
5 FEMA Publication 366, HAZUS 99 Estimated Annualized Earthquake Losses for the
United States (Feb. 2001). Hereafter referred to as FEMA 366.
6 A. M. Best Company Inc., 2006 Annual Earthquake Study: $100 Billion of Insured Loss
in 40 Seconds (Oldwick, NJ: A.M. Best Company, 2006), p. 12. The A. M. Best report
includes estimates from catastrophe-modeling companies of predicted damage from
hypothetical earthquakes in Los Angeles, the Midwest, the Northeast, and Japan. The report
cites an estimate by one such company, Risk Management Solutions, that a hypothetical 7.4
(continued...)
CRS-6
Table 3. The 10 Most Damaging Earthquakes
in the United States
Year
Location
Magnitude
2005 constant $
1994
Northridge, CA
6.7
$26 billion
1989
Loma Prieta, CA
6.9
$11 billion
1964
Anchorage, AK
9.2
$3.1 billion
1971
San Fernando, CA
6.5
$2.7 billion
2001
Nisqually, WA
6.8
$2.5 billion
1987
Whittier Narrows, CA
5.9
$615 million
1933
Long Beach, CA
6.3
$600 million
1953
Kern County, CA
7.5
$440 million
1992
Landers, CA
7.6
$130 million
1992
Cape Mendocino, CA
7.1
$92 million
Source: Insurance Information Institute, at [http://www.iii.org/media/facts/statsbyissue/
earthquakes/].
Note: Includes insured and uninsured losses.
Some studies and techniques combine seismic risk with the value of the building
inventory7 in cities, counties, or regions across the country to provide estimations of
economic losses from earthquakes. One report calculates that the annualized loss
from earthquakes nationwide is $4.4 billion per year, with California, Oregon, and
Washington accounting for $3.7 billion (84%) of the U.S. total estimated loss each
year.8 Table 4 shows cities with estimated annualized U.S. earthquake losses over
$10 million.
A single large earthquake can cause far more damage than the average annual
estimate (see Table 3.) However, annualized estimates help provide comparisons of
infrequent, high impact events like damaging earthquakes, with more frequently
occurring hazards like floods, hurricanes, or other types of severe weather.
6 (...continued)
magnitude event along the Newport-Inglewood Fault near Los Angeles would cause $549
billion in total property damage. A hypothetical 6.5 magnitude earthquake along a fault
between Philadelphia and New York City would produce $901 billion in total loss,
according to an RMS estimate.
7 Building inventory refers to four main inventory groups: (1) general building stock, (2)
essential and high potential loss facilities, (3) transportation systems, and (4) utility systems
(FEMA 366).
8 FEMA 366.
CRS-7
Table 4. U.S. Cities With Estimated Annualized
Earthquake Losses More Than $10 Million
(in millions)
Rank
Metro area
AEL
Rank
Metro area
AEL
1
Los Angeles, CA
$1,069
21
Bakersfield, CA
$31
2
Riverside, CA
$357
22
Tacoma, WA
$28
3
Oakland, CA
$349
23
Las Vegas, NV
$28
4
San Francisco, CA
$346
24
Anchorage, AK
$25
5
San Jose, CA
$243
25
Boston, MA
$23
6
Orange, CA
$214
26
Hilo, HI
$20
7
Seattle, WA
$128
27
Stockton, CA
$19
8
San Diego, CA
$128
28
Reno, NV
$18
9
Portland, OR
$98
29
Memphis, TN
$17
10
Ventura, CA
$89
30
Philadelphia, PA
$17
11
New York, NY
$56
31
San Luis Obispo, CA
$16
12
Vellejo, CA
$53
32
Salem, OR
$15
13
Santa Rosa, CA
$51
33
Fresno, CA
$14
14
Salt Lake City, UT
$40
34
Charleston, SC
$13
15
Sacramento, CA
$39
35
Albuquerque, NM
$13
16
St. Louis, MO
$34
36
Newark, NJ
$12
17
Eureka, CA
$34
37
Honolulu, HI
$12
18
Salinas, CA
$33
38
Atlanta, GA
$11
19
Santa Barbara, CA
$33
39
Modesto, CA
$11
20
Santa Cruz, CA
$33
40
Redding, CA
$10
Source: FEMA Publication 366, HAZUS 99 Estimated Annualized Earthquake Losses
for the United States (Feb. 2001). Annualized earthquake losses (AEL) calculated in
2001.
Estimating earthquake damage is not an exact science and depends on many
factors. Primarily, these are the probability of ground motion occurring in a
particular area (see Figure 1), and the consequences of that ground motion, which
are largely a function of building construction type and quality, and of the level of
ground motion and shaking during the actual event. Some researchers have
questioned whether the probability of ground motion estimates for regions of the
country that experience infrequent earthquakes, such as the New Madrid Seismic
CRS-8
Zone, are too high.9 These researchers bring into question whether the benefits of
building structures to conform with the earthquake probability estimates merit the
costs, in light of the uncertainty in making those probability estimates.10
The New Madrid Seismic Zone in the central United States is vulnerable to
large but infrequent earthquakes. A series of large (magnitude greater than 7.0)
earthquakes struck the Mississippi Valley over the winter of 1811-1812, centered
close to the town of New Madrid, MO. Some of the tremors were felt as far away as
Charleston, SC, and Washington, DC. The mechanism for the earthquakes in the
New Madrid zone is poorly understood,11 and no earthquakes of comparable
magnitude have occurred in the area since these events. Such factors contribute to
the difficulty of making a reasonable damage estimate for a low-frequency, high-
impact event in the region based on the probability of an earthquake of similar
magnitude occurring. This uncertainty has implications for policy decisions to
ameliorate risk, such as setting building codes, and for designing and building
structures to withstand a level of shaking commensurate with the risk. Developers
of building codes tend to err on the side of caution.
Table 4 also shows annualized earthquake losses for the cities of New York,
Boston, and Newark, where no destructive earthquakes have struck for generations.12
Those cities represent areas of relatively low seismic hazard, but have high
populations and dense infrastructure, which produces a significant risk according to
some estimates.13 In the absence of any significant or damaging earthquakes for those
cities in recent memory, however, the actual risk is difficult to grasp intuitively.
Monitoring
Congress authorized the USGS to monitor seismic activity in the United States
in the 1990 reauthorization of the National Earthquake Hazards Reduction Act (P.L.
101-614). The USGS operates two nationwide networks of seismographic stations:
the Advanced National Seismic System (ANSS) and the National Strong-Motion
Project (NSMP). Globally, the USGS and the Incorporated Research Institutions for
Seismology (IRIS) operate 140 seismic stations of the Global Seismic Network
9 Andrew Newman, Seth Stein, John Weber, Joseph Engeln, Ailin Mao, and Timothy
Dixon, “Slow Deformation and Lower Seismic Hazard in the New Madrid Seismic Zone,”
Science, v. 284 (April 23, 1999), pp. 619-621.
10 Seth Stein, Joseph Tomasello, and Andrew Newman, “Should Memphis Build for
California’s Earthquakes?”, Eos, v. 84, no. 19, (May 13, 2003), pp. 177, 184-185.
11 In contrast to California, where earthquakes occur on the active margin of the North
American tectonic plate, the New Madrid seismic zone is not on a plate boundary but may
be related to old faults in the interior of the plate, marking a zone of tectonic weakness.
12 The largest earthquakes in New York, New Jersey, and Massachusetts were, respectively,
1944 Massena, NY, magnitude 5.8, felt from Canada south to Maryland; 1783 New Jersey,
magnitude 5.3, felt from New Hampshire to Pennsylvania; 1755 Cape Ann and Boston, MA,
intensity of VIII on the Modified Mercalli Scale, felt from Nova Scotia to Chesapeake Bay
(USGS Earthquake Hazards Program).
13 FEMA 366 and USGS Circular 1188, Table 3.
CRS-9
(GSN) in more than 80 countries. The GSN provides worldwide coverage of
earthquakes, including reporting and research, and also monitors nuclear explosions.
Advanced National Seismic System (ANSS). “The mission of ANSS is
to provide accurate and timely data and information products for seismic events,
including their effects on buildings and structures, employing modern monitoring
methods and technologies.”14 If fully implemented, ANSS would encompass more
than 7,000 earthquake sensor systems covering parts of the nation vulnerable to
earthquake hazards. Currently, the system includes 696 stations that comprise its
backbone stations, dense urban networks, and existing regional networks.15
Approximately 6,000 of the planned stations will be installed in 26 high-risk urban
areas to monitor strong ground shaking and how buildings and other structures
respond. Currently, five high-risk urban areas have instruments deployed in
sufficient density to generate the data to produce near real-time maps, called
ShakeMaps,16 which can be used in emergency response during and after an
earthquake.
Approximately 1,000 new instruments will replace aging and obsolete stations
in the networks that now monitor the nation’s most seismically active regions. The
current regional networks contain a mix of modern, digital, broadband, and high-
resolution instruments that can provide real-time data together with older instruments
that may require manual downloading of data. Universities in the region typically
operate the regional networks and will continue to do so as ANSS is implemented.
Lastly, approximately 100 instruments comprise the existing “backbone” of
ANSS, with a roughly uniform distribution across the United States, including
Alaska and Hawaii. These instruments provide a broad and uniform minimum
threshold of coverage across the country. The backbone network consists of USGS-
deployed instruments and other instruments that serve both ANSS and the
EarthScope project (described below, under “Research — Understanding
Earthquakes”).
In 2004, Congress passed the National Earthquake Hazards Reduction Program
Reauthorization Act of 2004 (P.L. 108-360), which authorized $30 million for ANSS
in FY2005 and $36 million per year through FY2009. Congress first authorized the
program with P.L. 106-503 at a level of $38 million for FY2002 and $44 million
FY2003. Total expenditures for ANSS from FY2002 to FY2006 are slightly more
than $28 million, or approximately 15% of authorized levels. Overall, ANSS is
about 10% completed.
National Strong-Motion Project (NSMP). The USGS operates the NSMP
to record seismic data from damaging earthquakes in the United States on the ground
14 USGS Earthquake Hazards Program, at [http://earthquake.usgs.gov/research/monitoring/
anss/].
15 William Leith, USGS, telephone conversation Oct. 30, 2006.
16 ShakeMap is a product of the USGS Earthquake Hazards Program in conjunction with
regional seismic network operators, and is discussed in more detail below.
CRS-10
and in buildings and other structures in densely urbanized areas. The program
currently has 900 strong-motion17 instruments in 701 permanent stations across the
United States and in the Caribbean. The NSMP has three components: data
acquisition, data management, and research. The near real-time measurements
collected by the NSMP are used by other government agencies for emergency
response and real-time warnings. If fully implemented, the ANSS program would
deploy about 3,000 strong-motion instruments, and the NSMP program would
operate those strong-motion instruments located in buildings and other structures.
Many of the NSMP instruments currently deployed are older designs and are being
upgraded with modern seismometers.
Global Seismic Network (GSN). The GSN is a system of broadband digital
seismographs arrayed around the globe and designed to collect high-quality data that
are readily accessible to users worldwide, typically via computer modems. Currently,
140 stations in 80 countries have been installed and the system is nearly complete,
although the spacing and location of stations has not fully met the original goal of
uniform spacing of approximately 2,000 kilometers. The system is currently
providing data to the United States and other countries and institutions for earthquake
reporting and research, and for monitoring nuclear explosions to assess compliance
with the Comprehensive Test Ban Treaty. The Emergency Supplemental
Appropriations Act for Defense, the Global War on Terror, and Tsunami Relief, 2005
(P.L. 109-13) provided more than $8 million to the USGS to help make the GSN
capable of real-time communications.18
The Incorporated Research Institutions for Seismology (IRIS)19 coordinates the
GSN and manages and makes available the large amounts of data that are generated
from the network. The actual network of seismographs is organized into two main
components, each managed separately. The USGS operates two-thirds of the stations
from its Albuquerque Seismological Laboratory, and the University of California-San
Diego manages the other third via its Project IDA (International Deployment of
Accelerometers). Other universities and affiliated agencies and institutions operate
a small number of additional stations. IRIS, with funding from the NSF, supports all
of the stations not funded through the USGS appropriations.
Detection, Notification, and Warning
Unlike other natural hazards, such as hurricanes, where predicting the location
and timing of landfall is becoming increasingly accurate, the scientific understanding
of earthquakes does not yet allow for precise advance warnings to vulnerable
populations. Instead, notification and warning typically involves communicating the
17 Strong motion seismometers, or accelerometers, are special sensors that measure the
acceleration of the ground during large (>6.0 magnitude) earthquakes.
18 See also CRS Report RL32739, Tsunamis: Monitoring, Detection, and Early Warning
Systems, by Wayne A. Morrissey.
19 IRIS is a university research consortium, primarily funded by NSF, that collects and
distributes seismographic data.
CRS-11
location and magnitude of an earthquake as soon as possible after the event to
emergency response providers and others who need the information.
Short-term probabilistic earthquake forecasts are being made available now that
give, for example, a 24-hour probability of strong earthquake shaking for a particular
region, such as California. These forecasts are not predictions, and are currently
intended to increase public awareness of the seismic hazard, improve emergency
response, and increase scientific understanding of the short-term hazard.20 In the
California example, a time-dependent map is created and updated every hour by a
system that considers all earthquakes, large and small, detected by the California
Integrated Seismic Network21 and that calculates a probability that each earthquake
will be followed by an aftershock22 that can cause strong shaking. The probabilities
are calculated from known behavior of aftershocks and the possible shaking pattern
based on historical data.
When a destructive earthquake occurs in the United States or in other countries,
the first reports of its location, or epicenter,23 and magnitude often originate from the
National Earthquake Information Center in Golden, CO, or from one of the regional
seismic networks that are part of ANSS. Other organizations, such as universities,
consortia, and individual seismologists may also contribute information about the
earthquake after the event. Products, such as ShakeMap, are assembled as rapidly as
possible to assist in emergency response and damage estimation following a
destructive earthquake.
National Earthquake Information Center (NEIC). The NEIC, part of the
USGS, is currently located in Golden, CO. Originally established as part of the
National Ocean Survey (Department of Commerce) in 1966, the NEIC was made part
of the USGS in 1973 and moved to Golden from Boulder (CO) in 1974. With data
gathered from the networks described above and from other sources, the NEIC
determines the location and size of all destructive earthquakes that occur worldwide
and disseminates the information to the appropriate national or international
agencies, government public information channels, news media, scientists and
scientific groups, and the general public.
The NEIC has long-standing agreements with key emergency response groups,
federal, state, and local authorities, and other key organizations in earthquake-prone
20 USGS Open-File Report 2004-1390, and California 24-hour Aftershock Forecast Map,
at [http://pasadena.wr.usgs.gov/step/].
21 The California Integrated Seismic Network is the California region of ANSS; see
[http://www.cisn.org/].
22 Earthquakes typically occur in clusters, in which the earthquake with the largest
magnitude is called the main shock, events before the main shock are called foreshocks, and
those after are called aftershocks. See also [http://pasadena.wr.usgs.gov/step/aftershocks.
html].
23 The epicenter of an earthquake is the point on the earth’s surface directly above the
hypocenter. The hypocenter is the location beneath the earth’s surface where the fault
rupture begins.
CRS-12
regions who receive automated alerts — typically location and magnitude of an
earthquake — within a few minutes of an event in the United States. The NEIC
sends these preliminary alerts by email and pager immediately after an earthquake is
detected and its magnitude and epicenter are automatically determined by computer.24
This initial determination is then checked by around-the-clock staff who confirm and
update the magnitude and location data.25 After the confirmation, a second set of
notifications and confirmations are triggered to key recipients by email, pager, fax,
and telephone.
For earthquakes outside the United States, the NEIC notifies the State
Department Operations Center, and often sends alerts directly to staff at American
embassies and consulates in the affected countries, to the International Red Cross, the
U.N. Department of Humanitarian Affairs, and other recipients who have made
arrangements to receive alerts.
With the advent of the USGS Earthquake Notification Service (ENS),
notifications of earthquakes detected by the ANSS/NEIC are provided free to
interested parties in a customizable format. Users of the service can specify the
regions of interest, establish notification thresholds of earthquake magnitude,
designate whether they wish to receive notification of aftershocks, and even set
different magnitude thresholds for daytime or nighttime to trigger a notification.
ShakeMap. Traditionally, the information commonly available following a
destructive earthquake has been epicenter and magnitude, as in the data provided by
the NEIC described above. Those two parameters by themselves, however, do not
always indicate the intensity of shaking and extent of damage following a major
earthquake. Recently, the USGS developed a product called ShakeMap that provides
a near real-time map of ground motion and shaking intensity following a major
earthquake in areas of the United States where the ShakeMap system is in place.
Currently, ShakeMaps are available for northern California, southern California, the
Pacific Northwest, Nevada, Utah, and Alaska.26
With improvements to the regional seismographic networks in the areas where
ShakeMap is available, new real-time data telemetry from the instruments deployed
in the region, and advances in digital communication and computation, ShakeMaps
are now triggered automatically and made available within minutes of the event via
the Web. In addition, better maps are now available because of recent improvements
in understanding the relationship between the ground motions recorded during the
earthquake and the intensity of resulting damage. The maps produced portray the
extent of damaging shaking and can be used by emergency response and for
estimating loss following a major earthquake. If databases containing inventories of
24 Stuart Simkin, NEIC, Golden, CO, telephone conversation, Nov. 4, 2006.
25 In early 2006, the NEIC implemented an around-the-clock operation center and seismic
event processing center in response to the Indonesian earthquake and resulting tsunami of
December 2004. Funding to implement 24/7 operations was provided by P.L. 109-13.
26 See [http://earthquake.usgs.gov/eqcenter/shakemap/].
CRS-13
buildings and lifelines are available, they can be combined with shaking intensity
data to produce maps of estimated damage.
The ShakeMaps have limitations, especially during the first few minutes
following an earthquake before more data arrive from distributed sources. Because
they are generated automatically, the initial maps are preliminary, and may not have
been checked by human oversight when first made available. They are considered
a work in progress, but are deemed to be very promising, especially as more modern
seismic instruments are added to the regional networks under ANSS and the
computational and telecommunication ability improves.
National Earthquake Hazards Reduction Program (NEHRP)
In 1977 Congress passed the Earthquake Hazards Reduction Act (P.L. 95-124)
establishing NEHRP as a long-term earthquake risk reduction program for the United
States. The program initially focused on research, led by USGS and NSF, toward
understanding and ultimately predicting earthquakes. Earthquake prediction has
proved to be intractable thus far and the NEHRP program shifted its focus to
minimizing losses from earthquakes after they occur. FEMA was created in 1979
and President Carter designated it as the lead agency for NEHRP. In 1980, Congress
reauthorized the Earthquake Hazards Reduction Act (P.L. 96-472), defining FEMA
as the lead agency and authorizing additional funding for earthquake hazard
preparedness and mitigation to FEMA and the National Bureau of Standards (now
NIST).
Mitigation. In 1990, Congress reauthorized NEHRP (P.L. 101-614) and made
substantive changes, to decrease the emphasis on earthquake prediction, clarify the
role of FEMA, clarify and expand the program objectives, and require federal
agencies to adopt seismic safety standards for new and existing federal buildings. In
2004, Congress reauthorized NEHRP through FY2009 (P.L. 108-360) and shifted
primary responsibility for planning and coordinating NEHRP from FEMA to NIST.
It also established a new interagency coordinating committee and a new advisory
committee, both focused on earthquake hazards reduction.
The current program activities are focused on four broad areas:
! developing effective measures to reduce earthquake hazards;
! promoting the adoption of earthquake hazards reduction measures
by federal, state, and local governments, national building standards
and model building code organizations, engineers, architects,
building owners, and others who play a role in planning and
constructing buildings, bridges, structures, and critical infrastructure
or lifelines;27
! improving the basic understanding of earthquakes and their effects
on people and infrastructure, through interdisciplinary research
involving engineering, natural sciences, and social, economic, and
decision sciences; and
27 Lifelines are essential utility and transportation systems.
CRS-14
! developing and maintaining ANSS, the George R. Brown Jr.
Network for Earthquake Engineering Simulation (NEES),28 and the
GSN.
The House Science Committee report on the bill noted that NEHRP has
produced a wealth of useful information since 1977, but it also stated that the
program’s potential has been limited by the inability of the NEHRP agencies to
create synergy through coordinated efforts.29 The committee felt that restructuring
the program with NIST as the lead agency, directing funding towards appropriate
priorities, and implementing it as a true interagency program would lead to
improvement.
Under the reauthorization, the Director of NIST chairs the Interagency
Coordinating Committee, which is composed of the directors of FEMA, USGS, NSF,
the Office of Science and Technology Policy, and the Office of Management and
Budget. The Interagency Coordinating Committee is charged with overseeing the
planning, management, and coordination of the program. Primary responsibilities for
the NEHRP agencies break down as follows:
! NIST supports the development of performance-based seismic
engineering tools and works with other groups to promote the
commercial application of the tools through building codes,
standards, and construction practices.
! FEMA assists other agencies and private-sector groups to prepare
and disseminate building codes and practices for structures and
lifelines, and aid development of performance-based codes for
buildings and other structures.
! USGS conducts research and other activities to characterize and
assess earthquake risks, and (1) operates a forum, using the NEIC,
for the international exchange of earthquake information, (2) works
with other NEHRP agencies to coordinate activities with earthquake
reduction efforts in other countries, and (3) maintains seismic hazard
maps in support of building codes for structures and lifelines, and
other maps needed for performance-based design approaches.
! NSF supports research to improve safety and performance of
buildings, structures, and lifelines using the large-scale experimental
and computational facilities of NEES and other institutions engaged
in research and implementation of NEHRP.
Table 5 shows authorization of appropriations for NEHRP. The funding
authorization for ANSS and NEES are broken out separately in P.L. 108-360 and are
shown in Table 6.
28 NEES is an NSF-funded project that consists of 15 experimental facilities and an IT
infrastructure with a goal of mitigating earthquake damage by the use of improved materials,
designs, construction techniques, and monitoring tools.
29 U.S. House, Committee on Science, National Earthquake Hazards Reduction Program
Reauthorization Act of 2003, H.Rept. 108-246 (Aug. 14, 2003), p. 13.
CRS-15
Table 5. Authorization Levels for NEHRP by Agency
($ millions)
FY2005
FY2006
FY2007
FY2008
FY2009
NIST
10.00
11.00
12.1o
13.31
14.64
FEMA
21.00
21.63
22.28
22.95
23.64
USGS
47.00
48.41
49.86
51.36
52.90
NSF
38.00
39.14
40.31
41.52
42.77
Total
116.00
120.18
124.55
129.14
133.95
Table 6. Authorization Levels for ANSS and NEES
($ millions)
FY2005
FY2006
FY2007
FY2008
FY2009
ANSS
30.00
36.00
36.00
36.00
36.00
NEES
20.00
20.40
20.87
21.39
21.93
Total
50.00
56.40
56.87
57.39
57.93
HAZUS-MH. FEMA, under contract with the National Institute of Building
Sciences,30 developed a methodology and software program called the Hazards U.S.
Multi-Hazard (HAZUS-MH).31 The program allows a user to estimate losses from
damaging earthquakes, hurricane winds, and floods before a disaster occurs. The
pre-disaster estimates could provide a basis for developing mitigation plans and
policies, preparing for emergencies, and planning response and recovery. HAZUS-
MH combines existing scientific knowledge about earthquakes (for example,
ShakeMaps, described above), engineering information that includes data on how
structures respond to shaking, and geographic information system (GIS) software to
produce maps and display hazards data including economic loss estimates. The loss
estimates produced by HAZUS-MH include the following:
! physical damage to residential and commercial buildings, schools,
critical facilities, and infrastructure;
! economic loss, including lost jobs, business interruptions, repair and
reconstruction costs; and
30 The National Institute of Building Sciences (NIBS) is a non-profit non-governmental
organization established by Congress in the Housing and Community Development Act of
1974 (PL 99-383). NIBS is funded through dues from its membership, private sector
contributions, and contracts with federal and state agencies. The mission of NIBS is to
improve the building regulatory environment, facilitate introducing new products and
technologies into the building process, and disseminate technical and regulatory
information. See [http://www.nibs.org/].
31 See [http://www.fema.gov/plan/prevent/hazus/].
CRS-16
! social impacts, including estimates of shelter requirements,
displaced households, and the number of people exposed to the
disaster.
In addition to furnishing information as part of earthquake mitigation efforts,
HAZUS-MH can also be used to support real-time emergency response activities by
state and federal agencies after a disaster. Twenty-seven HAZUS-MH user groups32
— cooperative ventures among private, public, and academic organizations that use
the HAZUS-MH software — have formed across the United States to help foster
better-informed risk management for earthquakes and other natural hazards.
HAZUS-MH software was first released to the public in 1997 and the first user
group, the Bay Area HAZUS-MH User Group, was formed the same year.
Research — Understanding Earthquakes
U.S. Geological Survey. Under NEHRP, the USGS has responsibility for
conducting targeted research into improving the basic scientific understanding of
earthquake processes. The current earthquake research program at the USGS covers
six broad categories:33
! Borehole geophysics and rock mechanics: studies to understand heat
flow, stress, fluid pressure, and the mechanical behavior of fault-
zone materials at seismogenic34 depths to yield improved models of
the earthquake cycle.
! Crustal deformation: studies of the distortion or deformation of the
earth’s surface near active faults as a result of the motion of tectonic
plates.
! Earthquake geology and paleoseismology: studies of the history,
effects, and mechanics of earthquakes.
! Earthquake hazards: studies of where, why, when, and how
earthquakes occur.
! Regional and whole-earth structure: studies using seismic waves
from earthquakes and man-made sources to determine the structure
of the planet ranging from the local scale, to the whole crust, mantle,
and even the earth’s core.
! Strong-motion seismology, site response, and ground motion:
studies of large-amplitude ground motions and the response of
engineered structures to those motions using accelerometers.
National Science Foundation. NSF supports fundamental research into
understanding the earth’s dynamic crust. Through its Earth Sciences Division35 (part
of the Geosciences Directorate), NSF distributes research grants and coordinates
programs investigating the crustal processes that lead to earthquakes around the
32 See [http://www.hazus.org/].
33 See [http://earthquake.usgs.gov/research/].
34 Seismogenic means capable of generating earthquakes.
35 See [http://www.nsf.gov/div/index.jsp?div=EAR].
CRS-17
globe. Recently, NSF initiated a Major Research Equipment and Facilities
Construction (MREFC) project called EarthScope.36 EarthScope is deploying
instruments across the United States to study the structure and evolution of the North
American Continent, and to investigate the physical processes that cause earthquakes
and volcanic eruptions. EarthScope, a five-year, $200 million project, began in 2003,
is funded by NSF, and is conducted in partnership with the USGS and NASA.
EarthScope instruments will form a framework for broad, integrated studies of
the four-dimensional (three spatial dimensions, plus time) structure of North
America. The project is divided into three main programs:
! The San Andreas Fault Observatory at Depth (SAFOD): a deep
borehole observatory drilled through the San Andreas fault zone
close to the hypocenter of the 1966 Parkfield, CA, magnitude 6
earthquake.
! The Plate Boundary Observatory (PBO): a system of GPS arrays and
strainmeters37 that measure the active boundary zone between the
Pacific and North American tectonic plates in the western United
States.
! USArray: four hundred transportable seismometers that will be
deployed systematically across the United States on a uniform grid
to provide a complete image of North America from continuous
seismic measurements.
Through its Engineering Directorate, NSF funds NEES,38 a project intended to
operate until 2014, aimed at understanding the effects of earthquakes on structures
and materials. To achieve the program’s goal, the facilities conduct experiments and
computer simulations of how buildings, bridges, utilities, coastal regions, and
materials behave during an earthquake. Table 6 (above) shows authorization levels
for NEES through 2009.
Additional Reading
Aspects of the federal role in the aftermath of a damaging earthquake or other
natural catastrophes — the response and recovery phase — are covered in the
following CRS reports.
36 See [http://www.earthscope.org/].
37 A strainmeter is a tool used by seismologists to measure the motion of one point relative
to another.
38 A non-profit NEES consortium (NEESinc.) has operated the facilities for the 10-year
operating lifespan at the following institutions: Cornell University; Lehigh University;
Oregon State University; Renssalaer Polytechnical Institute; University of Buffalo-State
University of New York; University of California-Berkeley; University of California-Davis;
University of California-Los Angeles; University of California-San Diego; University of
California-Santa Barbara; University of Colorado-Boulder; University of Illinois at Urbana-
Champaign; University of Minnesota; University of Nevada-Reno; University of Texas at
Austin. See [http://www.nees.org/].
CRS-18
CRS Report RL33330, Community Development Block Grant Funds in Disaster
Relief and Recovery, by Eugene Boyd.
CRS Report RL32847, Tsunamis and Earthquakes: Is Federal Disaster Insurance
in Our Future?, by Rawle O. King.
CRS Report RL33060, Tax Deductions for Catastrophic Risk Insurance Reserves:
Explanation and Economic Risk Analysis, by David L. Brumbaugh and Rawle
O. King.
CRS Report RS22268, Repairing and Reconstructing Disaster-Damaged Roads and
Bridges: The Role of Federal-Aid Highway Assistance, by Robert S. Kirk.
CRS Report RS22248, Federal Disaster and Emergency Assistance for Water
Infrastructure Facilities and Supplies, by Claudia Copeland, Mary Tiemann,
and Nicole T. Carter.
CRS Report RL33206, Vulnerability of Concentrated Critical Infrastructure:
Background and Policy Options, by Paul W. Parfomak.
CRS Report RS22273, Emergency Contracting Authorities, by John R. Luckey.