U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3028

March 2012

Real-Time Seismic Monitoring of Instrumented Hospital Buildings

The Veterans Affairs Medical Center in Memphis has been recently instrumented for real-time seismic monitoring

 The U.S. Geological Survey’s 

(USGS) National Strong Motion Project 

(NSMP), a part of the Advanced National 

Seismic System (ANSS), has instrumented 

more than 250 structures in the continental 

United States, Alaska, Hawaii, and Puerto 

Rico for seismic monitoring. Installation 

of seismic monitoring systems in 

structures is part of the research program 

conducted under the National Earthquake 

Hazards Reduction Program (NEHRP) to 

improve understanding of the seismic 

loads that structures are likely to 

experience and help engineers design 

earthquake-resistant structures.

The NSMP works closely with VA to 

monitor earthquake shaking in more than 

70 VA medical centers across the country. 

This effort not only helps the VA safeguard its building inventory from future 

earthquake losses but also ensures timely 

response to damaging earthquakes.

Earthquake Risk in the New 

Madrid Seismic Zone 

The New Madrid Seismic Zone 

(NMSZ), which lies mainly in 

southeastern Missouri and northwestern 

Arkansas, is the most active seismic zone 

in the eastern United States. Today, the 

The 1971 San Fernando, California, earthquake (magnitude 6.7) collapsed four buildings at the San 

Fernando VA Hospital, killing 49 people. The buildings had been built in 1925, before building codes 

were in effect. Real-time seismic monitoring of such buildings can provide critical information about 

their structural integrity and help save lives in future earthquakes.

dense urbanization in the area increases 

earthquake risk—Memphis, Tenn. and St. 

Louis, Mo., are the largest vulnerable 

urban centers and sit well within range of 

damaging earthquakes in the NMSZ. This 

zone is well known for a series of major 

earthquakes during 1811–12. The 

geological record of pre-1811 earthquakes 

also reveals that the NMSZ has repeatedly 

produced sequences of major quakes, 

including several of magnitude 7 to 8, over 

the past 4,500 years. These shocks caused 

severe and widespread ground failures in 

the New Madrid region, much like those 

caused by the 1811–12 earthquake 

sequence. A continuing concern exists for 

future major destructive earthquakes in the 

NMSZ. Many structures in Memphis, St. 

Louis, and other communities in the 

central Mississippi River Valley region are 

vulnerable and at risk from severe ground 

shaking. Such high hazard requires 

prudent measures to protect public safety 

and ensure the social and economic 

resilience of the region in future 

earthquakes. Seismic monitoring of 

structures is one of the urgent measures in 

preparing for those quakes. 

USGS Structural Health 

Monitoring

The Nation’s critical infrastructure 

includes hospitals, fire stations, emergency 

operation centers, major bridges, nuclear 

power plants, offshore platforms, and 

airports. It is imperative to monitor the 

condition of these structures in near-real 

time in order to be able to assess their 

structural integrity immediately after a 

major catastrophic event. Such efforts 

can help protect human lives and prevent 

I

 n collaboration with the 

 Department of Veterans Affairs 

(VA), the U.S. Geological Survey’s 

National Strong Motion Project has 

recently installed sophisticated 

seismic monitoring systems to 

monitor the structural health of 

two hospital buildings at the 

Memphis VA Medical Center in 

Tennessee. The monitoring systems 

in the Bed Tower and Spinal Cord 

Injury buildings combine sensing 

technologies with an on-site 

computer to capture and analyze 

seismic performance of buildings 

 in near-real time.

Department of

Veterans Affairs

Department of

Veterans Affairs

Map showing earthquakes greater than magnitude 2.5 

in the New Madrid Seismic Zone and its surroundings. 

Red dots are earthquakes that occurred after 1972, 

blue dots are earthquakes before 1972. Magnitudes of 

earthquakes are proportional to size of dots—largest 

dots are magnitude 7–8.
injuries, minimize economic losses 

(structural and nonstructural damage), 

maintain vital services, minimize 

operation/production interruptions, and 

protect the environment.

For these purposes, the USGS’s 

NSMP has recently instrumented two 

buildings in the Memphis VA Medical 

Center. The monitoring system installed in 

the 5-story Bed Tower consists of a seismic 

array of 24 sensors. The 3-story Spinal 

Cord Injury building has 12 sensors. These 

sensors are deployed permanently in critical 

locations at each level of the buildings to 

detect building motion along the reference 

east-west and north-south directions; 

vertical motion is monitored at the ground 

level. Specifically, the instrumentation 

within these buildings is designed to 

record lateral swaying, twisting (torsion), 

traveltime of transmitted seismic waves 

from foundation to roof, and drift (relative 

displacement) between pairs of adjacent 

floors, as well as overall building offset. 

The extent of swaying, twisting, and drift 

can be compared to what the building was 

designed to withstand. 

The building sensors are complemented by three-component seismic 

sensors located at a reference site distant 

from the buildings to monitor ground 

shaking without interference from the 

The USGS National Strong Motion Project Monitors Seismic 

Performance of Buildings at the Memphis VA Medical Center

Erol Kalkan1, Jon Peter B. Fletcher1,

William S. Leith2, Jill McCarthy3,

and Krishna Banga4

Edited by Peter H. Stauffer

Graphic design by Jeanne S. DiLeo

COOPERATING ORGANIZATIONS

Advanced National Seismic System

U.S. Department of Veterans Affairs

1

U.S. Geological Survey, Menlo Park, CA

2

U.S. Geological Survey, Reston, VA

3

U.S. Geological Survey, Golden, CO

4

U.S. Department of Veternas Affairs, Washington, DC

response of buildings. The sensors at the 

reference site measure the input seismic 

waves and feed USGS ShakeMaps, an 

online product that provides near-real-time 

maps of ground motion and shaking 

intensity following significant earthquakes. This dense array of seismic 

sensors in buildings and reference site is 

the main component of a sophisticated 

structural-health monitoring system at the 

Memphis VA Medical Center. 

Recordings from such USGS 

structural-health monitoring systems are 

critical both to designing safer hospitals 

and other buildings and to preventing 

loss of life. In particular they will help 

engineers to: 

• Understand how damage to structural 

and nonstructural components (such 

as equipment and pipes) occurs from 

strong shaking,

• Evaluate and improve earthquakeresistant design techniques and also 

methods for predicting the seismic 

performance of structures,

• Improve earthquake resistant design 

provisions of building codes, and

• Assess building safety immediately 

following a damaging quake.

In the Memphis, Tennessee, VA Medical 

Center, the Spinal Cord Injury (top) and Bed 

Tower (above) buildings now have the most 

sophisticated structural-health monitoring 

systems in the country.

As shown in the schematic (left), motion 

sensors have been deployed permanently 

on each floor of the Bed Tower building. 

Red arrows indicate the locations of 

sensors from ground level to roof. These 

sensors are connected to the central 

data-acquisition and transmission system. 

For more information, contact:

Earthquake Science Center

U.S. Geological Survey

Menlo Park, CA 94025

http://earthquake.usgs.gov/

Earthquake Information Hotline: (650) 329–4085

Advanced National Seismic System

http://www.anss.org/

This Fact Sheet and any updates to it are 

available online at:

http://pubs.usgs.gov/fs/2012/3028/