86°30´ 86°00´ 85°30´ 85°00´ 84°30´

86°30´ 86°00´ 85°30´ 85°00´ 84°30´

33°30´

34°00´

34°30´

35°00´

35°30´

33°30´

34°00´

34°30´

35°00´

35°30´

TENNESSEE

ALABAMA GEORGIA

TENNESSEE

ALA

BA

MA

GE

OR

GIA

Gun

ters

ville

Lak

e

Tenn

esse

e Ri

ver

Weiss Lake

Allatoona Lake

Chickamauga Lake

Coos

a Rive

r

Coos

a Ri

ver

Epicentral Area

JACKSON

DE KALB

FLOYD

ST CLAIR

CALHOUN

ETOWAH

MARION

POLK

CHEROKEE

FRANKLIN

BARTOW

HAMILTON

WALKER

MARSHALL

CLEBURNE

COBB

POLK

CARROLL

GORDON

MURRAY

GRUNDY

BRADLEY

MADISON

MCMINN

DADE

COFFEE

BLOUNT

PAULDING

FULTON

HARALSON

CHATTOOGA

WHITFIELD

GILMER

DOUGLAS

CHEROKEE

SEQUATCHIE

LINCOLN

CATOOSA

MOORE

TALLADEGA

MEIGSBEDFORD

RHEA

PICKENS

BLEDSOE

FANNIN

FAYETTE

CULLMAN

SHELBY

ROME

Soddy

Heflin

Bremen

Centre

Dalton

Etowah

Athens

Dayton

Oneonta

GADSDEN

Calhoun

Decherd

Fairburn

ANNISTON

PiedmontMARIETTA

Rockmart

Whitwell

Pell City

Cedartown

TULLAHOMA

Carrollton

Tallapoosa

Fort Payne

Rainsville

SCOTTSBORO

La Fayette

Chatsworth

Bridgeport

Winchester

Tracy City

Manchester

Springville

ALBERTVILLE

Adairsville

CHATTANOOGA

SHELBYVILLE

Cartersville

South Pittsburg

2003

1984

19842001

2001

19861994

19971993

1985

1995

GENERAL INTEREST PRODUCT XXXU.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY

DISCLAIMER

Base map data, such as place names and politicalboundaries, are the best available but may not be current or may contain inaccuracies and thereforeshould not be regarded as having official significance.

M4.6 Fort Payne, Alabama Earthquake of 29 April 2003

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

29°

30°

31°

32°

33°

34°

35°

36°

37°

29°

30°

31°

32°

33°

34°

35°

36°

37°

Earthquake History of the Southeastern U.S.

G E O R G I A

F L O R I D A

M I S S I S S I P P I A L A B A M A

T E N N E S S E E N O R T H C A R O L I N A

S O U T HC A R O L I N A

K E N T U C K Y V I R G I N I AM I S S O U R I

A R K A N S A S

L O U I S I A N A

A T L A N T I CO C E A N

G u l f o f M e x i c o

M i

s s

i s s

i p

p i

R i

v e

r

C u m

b e

r l a

n d

P

l a t

e a

u

A P P

A L A

C H

I A N

M T

S.

P i e

d m o

n t

T e n n e s e e R.

Nashville

Charleston

New Orleans

Memphis

BirminghamAtlanta

Charlotte

Jacksonville

MAIN MAP

C o a s t a l P l

a i n

1972

1970

19631962

1959

1957

1956

1956

1955

1954

1945

1938

1934

1931

1930

1927

1924

1923

1918

1916 1914

1911

1909

19031903

1903

1899

1898

1895

1886

1883

1878

1878

1875

1861

1852

1850

1843

1843

1817

1811

2002

19991997

1997

1991

1991

1990

1986

1981

1976

19751975

1974

1974

1974

2003

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

29°

30°

31°

32°

33°

34°

35°

36°

37°

29°

30°

31°

32°

33°

34°

35°

36°

37°

Seismic Hazard of the Southeastern U.S.

G E O R G I A

F L O R I D A

M I S S I S S I P P I A L A B A M A

T E N N E S S E E N O R T H C A R O L I N A

S O U T HC A R O L I N A

K E N T U C K Y V I R G I N I AM I S S O U R I

A R K A N S A S

L O U I S I A N A

A T L A N T I CO C E A N

G u l f o f M e x i c o

Nashville

Charleston

New Orleans

Memphis

BirminghamAtlanta

Charlotte

Jacksonville

MAIN MAP

New MadridSeismic Zone

Eastern TennesseeSeismic Zone

South CarolinaSeismic Zone

2003

2002

19991997

1997

1996

1992

1991

19911990

1989

19871987

1986

1984

1981

1976

19751975

1975

1974

1974

1973

1972

1967

1963

1957

1957

1956

1956

1956

1954

1945

1934

1931 1931

1930

19281918

1916

1916

1914

1913

1913

1911

1903

1903

1899

1898

1886

1883

1878

1875

1861

1858 1852

1850

1817

0 100 200 300 40050

Kilometers

SCALE 1:5,000,000Albers Equal-Area Projection

0 100 200 300 40050

Kilometers

SCALE 1:5,000,000Albers Equal-Area Projection

0 10 20 30 405

Kilometers

SCALE 1:1,000,000Albers Equal-Area Projection

DISCUSSION

TECTONIC SETTING AND SEISMICITY CONTEXT

The Eastern Tennessee seismic zone, which extends from southwest Virginia to northeast Alabama, is one of the most active earthquake areas in the Southeast. Although the zone has not had a large earthquake in historic times, a few earthquakes have caused slight damage. The largest recorded earthquake in this seismic zone was a magnitude 4.6 that occurred in 1973 near Knoxville. Sensitive seismo-graphs have recorded hundreds of earthquakes too small to be felt in this seismic zone. Small, non-damaging, felt earthquakes occur about once a year.

Earthquakes in the central and eastern U.S., although less frequent, are typically felt over a much broader region than the western U.S. East of the Rockies, an earthquake can be felt in an area as much as ten times greater than a similar magnitude earthquake in the western U.S. For example, a magnitude 4.0 eastern U.S. earthquake typically can be felt at many locations as far as 100 km (60 mi) from where it occurred, and it might or might not cause damage near its source. A magnitude 5.5 eastern US earthquake usually can be felt as far as 500 km (300 mi) in most directions and can cause damage out to 40 km (25 mi).

FAULTS

At plate boundaries, earthquakes can commonly be related to specific faults or fault systems. In contrast, in the eastern Tennessee seismic zone the relation between faults and earthquakes is more enigmatic. The Eastern U.S. is far from the plate boundaries, the nearest of which are in the center of the Atlantic Ocean and in the Caribbean Sea. No active faults are known to reach the surface in the region, although the area is laced with ancient faults that developed as the Appalachian Mountains formed several hundred million years ago. The larger faults, particularly those that have been exposed at the Earth's surface by erosion, are likely to have been mapped by geologists. Unknown but probably numerous smaller or more deeply buried faults remain undetected. Even those faults that are mapped at the surface are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the eastern Tennessee seismic zone can be linked to known faults, and it is difficult to determine if a specific fault could still slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the seismic zone is the earthquakes themselves.

DISCUSSION (continued)

PAST EARTHQUAKES IN ALABAMA

The documented history of small earthquakes in Alabama spans about 100 years and includes about a half dozen small- to moderate-sized damaging events. The largest recent earthquake recorded in the State was a magnitude 4.9, which occurred south of the Eastern Tennessee seismic zone near Atmore, Alabama, on October 24, 1997. For an in-depth summary of historical earthquake activity in the State, see theEarthquake History of Alabama (see Online Resources at bottom of map).

SEISMIC MONITORING IN ALABAMA

The U.S. Geological Survey works in cooperation with the Center for Earthquake Research and Information (CERI) at the University of Mem-phis to monitor seismicity in the Alabama region. In response to the 1997 magnitude 4.9 Atmore, Alabama earthquake, the U.S. Geological Surveyin cooperation with the State Survey of Alabama installed a seismic monitoring station near Birmingham, Alabama in 2001. This station is a key part of an upgraded seismic monitoring network being implemented by the USGS as part of its Advanced National Seismic System (ANSS). Additional stations are planned for the southeastern U.S., pending the allocation of Federal funds.

IMPACT OF THE 29 APRIL 2003 EARTHQUAKE

This earthquake produced very limited damage. Cracked foundations and bricks fallen from chimneys were reported at Fort Payne. The water system at Valley Head also reported muddy water. Some schools in the region were closed as a precaution.

PUBLIC RESPONSE TO THE 29 APRIL 2003 EARTHQUAKE

Thousands of web surfers recorded their observations of thisearthquake on a USGS internet site designed to compile public observations into an integrated shaking map for the epicentral region. This "Did You Feel It" web site not only provides a concise summary of the distribution of perceived shaking, but it also provides researchers with data they need to supplement limited seismic recordings. The public is encouraged to visit the "Did You Feel It" site and record their own observations.

ALABAMA

29 April 2003 08:59:38.59 UTC34.508°N., 85.612°W.Depth 15 kmMagnitude = 4.6

This earthquake was felt widely over the southeastern United States.Slight damage (intensity VI) at Fort Payne, Graylesville and Valley Head. Felt (intensity V) at Flat Rock, Henagar, Higdon, Leesburg, Mentone, Rainsville and Sylvania. Felt in parts of Alabama, Georgia, Kentucky, Mississippi, North Carolina, South Carolina and Tennessee.

EXPLANATIONMain Shock 29 April 2003

2003

Aftershocks 29 April 2003

Recent Earthquakes

1986

Magnitude Classes

M1.0 - 1.9

2.0 - 2.9

3.0 - 3.9

4.0 - 4.9

Urbanized Areas

EXPLANATIONMain Shock 29 April 2003

2003

Recent Earthquakes 1973 - 2003

1975

Historic Earthquakes Pre-1973

1914

Magnitude Classes

M3.0 - 3.9

4.0 - 4.9

5.0 - 5.9

6.0 - 6.9

7.0 - 7.9

8.0 - 8.9

Urbanized Areas

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

92° 91° 90° 89° 88° 87° 86° 85° 84° 83° 82° 81° 80° 79°

78°

29°

30°

31°

32°

33°

34°

35°

36°

37°

29°

30°

31°

32°

33°

34°

35°

36°

37°

ANSS Backbone Stations in the Southeastern U.S.

G E O R G I A

F L O R I D A

M I S S I S S I P P I A L A B A M A

T E N N E S S E E N O R T H C A R O L I N A

S O U T HC A R O L I N A

K E N T U C K Y V I R G I N I AM I S S O U R I

A R K A N S A S

L O U I S I A N A

A T L A N T I CO C E A N

G u l f o f M e x i c o

Nashville

Charleston

New Orleans

Memphis

BirminghamAtlanta

Charlotte

Jacksonville

MAIN MAP

2003OXF

WVT

ATAL

ENGA

VBMS

LRAL NHSCGOGA

PLALCBSC

MONCSWET

SEKY

DATA SOURCES

EARTHQUAKES AND SEISMIC HAZARD USGS, National Earthquake Information Center CERI, University of Memphis SLUEC, Saint Louis University IASPEI, Centennial Catalog (1900 - 1999) Handbook of Seismology and Earthquake Engineering Global Seismic Hazard Assessment Program

BASE MAP NIMA and ESRI, Digital Chart of the World USGS, EROS Data Center

SCALE 1:5,000,000Albers Equal-Area Projection

0 100 200 300 40050

Kilometers

Internet Intensities

EXPLANATIONANSS Seismic Stations

Cooperating

Planned

USNSN

Map prepared by U.S. Geological SurveyNational Earthquake Information Center23 June 2003Map not approved for release by Director USGS

Representative Digital

Seismograms

Lakeview Retreat, AL (LRAL)

Pickwick Lake, AL (PLAL)

0 20 sec

P

P

S

S

COMMUNITY INTERNET INTENSITY MAP

The Community Internet Intensity Map (CIIM) summarizes the online questionnaire responses provided by Internet users. An intensity number is assigned to each community from which a filled-out CIIM questionnaire was received; each intensity value reflects the effects of earthquake shaking on the people and structures in the community.The color-coded ZIP Code zone on the map represents the average of the individual intensity values in thatZIP Code zone.

This map is found at: http://pasadena.wr.usgs.gov/shake/cus/STORE/Xteak/ ciim_display.html

ADVANCED NATIONAL SEISMIC SYSTEM

The Advanced National Seismic System (ANSS) will be a nation-wide network of at least 7000 shaking measurement systems, both on the ground and in buildings that will make it possible to provide emergency response personnel with real-time earthquake informa-tion, provide engineers with information about building and site re-sponse, and provide scientists with high-quality data to understand earthquake processes and solid earth structure and dynamics.

ONLINE RESOURCES

USGS Earthquake Program http://earthquake.usgs.govCommunity Internet Intensity Map (CIIM) http://pasadena.wr.usgs.gov/shake/cus/html/background.htmlAdvanced National Seismic System (ANSS) http://www.anss.orgCenter for Earthquake Research and Information http://www.ceri.memphis.eduSaint Louis University Earthquake Center http://www.eas.slu.edu/Earthquake_CenterEarthquake History of Alabama http://neic.usgs.gov/neis/states/alabama/alabama_history.htmlGeological Survey of Alabama http://www.gsa.state.al.us/

Seismic hazard is expressed as peak ground acceleration (PGA) on firm rock, in percent g, expect-ed to be exceeded with a proba-bility of two percent in a 50- year period

EXPLANATION

Seismic Hazard

170 - 180 %g Highest Hazard

160 - 170

150 - 160

140 - 150

130 - 140

120 - 130

110 - 120

100 - 110

90 - 100

80 - 90

70 - 80

60 - 70

50 - 60

40 - 50

30 - 40

20 - 30

10 - 20

2 - 10 %g Lowest Hazard

Prepared in cooperation with theUniversity of Memphis Center for Earthquake Research and Information

and the Saint Louis University Earthquake Center