84° 83° 82° 81° 80° 79° 78° 77° 76° 75°

84° 83° 82° 81° 80° 79° 78° 77° 76° 75°

36°

37°

38°

39°

40°

36°

37°

38°

39°

40°

RICHMOND

COLUMBUS

CHARLESTON

NORFOLK

WASHINGTON

BALTIMORE

PHILADELPHIA

DOVER

WEST

VIRGINIA

VIRGINIA

VIRGINIA

NORTH CAROLINA

VIRGINIA

VIRGINIA

TENNESSEE

KENTUCKY

WEST VIRGINIA

WEST VIRGINIA

KENTUCKY

KENTUCKY

OHIO

OHIO

WE

VIRGINIA

ST VIRGINIA

MARYLAND

MARYLAND

MARYLAND

PENNSYLVANIA

M

A

RY

LA

N

D

D

E

LAWA

R

E

VIRGINIA

MARYLAND

CHESAPEAKE

BA

Y

Potomac River

Delaware Ba

O

y

hio

R.

O hio R.

James R.

Rappahannaock R.

A

TLA

NTI

C

OCEAN

Albemarle Sound

Potomac R.

Lake Anna

James R.

York R.

Smith Mt.

Lake

John H. Kerr Res.

Lake Gaston

Bluestone

Lake

Cherokee Lake

Danville

Pittsylvania

Dare

Davidson Alexander

Sevier

Iredell Davie

Madison

Wake Martin Yancey

Caldwell

Edgecombe

Mitchell Cocke

Jefferson

Knox

Nash

Durham

Orange Bertie Guilford Alamance

Unicoi Forsyth

Franklin

Yadkin Avery

Anderson

Chowan

Hamblen

Perquimans

Greene Watauga

Grainger

Wilkes

Union

Washington Carter Pasquotank Halifax

Vance

Person

Granville

Rockingham

Stokes Caswell

Warren

Gates Camden

Hertford

Northampton

Currituck

Surry

Alleghany

Ashe

C Hawkins ampbell

Claiborne

Hancock

Johnson

Sullivan

Bristol

Franklin

City Galax Martinsville

Emporia

Grayson

Portsmouth

Henry Chesapeake Patrick

Lee Scott

Mecklenburg

Greensville

Suffolk

Washington

Carroll

Virginia

Beach

Norton

Bell

Norfolk

Whitley

Southampton

Smyth

Harlan

Brunswick

Halifax

Knox

Wythe

Hampton

Lunenburg Sussex Russell Floyd

Isle of Wight

Radford

Poquoson

Wise

Franklin

Newport

News

Pulaski

Petersburg

Surry

Charlotte

Letcher

Dinwiddie

Colonial

Heights

D Nottoway ickenson Bland

Salem

Leslie

Roanoke Hopewell

City Prince

George Laurel

Tazewell

Bedford

City

Clay

Montgomery

York

Prince

Edward

Roanoke

Campbell

Perry

James

City

Lynchburg

Giles

Charles

Amelia City

Mathews

Buchanan

Knott

Owsley

McDowell

Northampton

Appomattox Chesterfield

Jackson

Mercer

Gloucester

Richmond City

Bedford

New Kent

Craig

Breathitt Powhatan

Henrico

Lee

Monroe

Buena Vista

Cumberland Pike

Floyd

Middlesex

Buckingham

Botetourt

Wyoming

Covington Lexington

Amherst

Lancaster

Estill

Wolfe

Summers

Magoffin

Goochland

King

William

Powell

Martin Alleghany

King and Queen

Mingo

Raleigh

Johnson

Fluvanna

Hanover

Logan

Northumberland Accomack

Nelson

Menifee

Charlottesville

Rockbridge

Waynesboro

Richmond

Clark

Morgan

Louisa Essex

Staunton

Montgomery

Boone

Caroline

Fayette

Greenbrier

Bath

Elliott

Lawrence

Albemarle

Westmoreland

Somerset

Bath

Bourbon Fredericksburg

Lincoln

King

George

Spotsylvania

Rowan

Orange

Wayne

Worcester

Nicholas

Harrisonburg

Greene

Augusta

Boyd

Carter

St.

Mary's

Fleming Wicomico

Nicholas

Highland

Cabell

Stafford

Robertson

Madison

Kanawha

Clay

Putnam

Culpeper

Dorchester

Lewis Charles

Pocahontas

Webster

Greenup

Mason

Calvert

Manassas Park

Bracken

Lawrence Page

Rockingham

Rappahannock

Braxton Prince

William

Roane

Talbot

Pendleton

Sussex

Fauquier

Scioto

Mason

Gallia

Warren

Calhoun

Adams

Fairfax Jackson

Shenandoah

Gilmer

Upshur Randolph

Prince

George's

Caroline

Lewis

Wirt

Pike Meigs

Jackson

Winchester

Anne

Arundel

Hardy

Brown

Clermont

Clarke Tucker

Queen

Barbour Anne's

Loudoun

Grant Montgomery

Howard

Kent

Highland

Kent

Vinton

Ritchie

Wood

Taylor

Doddridge

Frederick

Harrison

Pleasants

Jefferson

Ross

Hampshire

Athens

Clinton Cumberland

Warren

Tyler

Wa Marion Berkeley shington

Mineral

Hocking Morgan

Fayette

Frederick

Wetzel

Baltimore

Carroll

Preston

Monongalia Harford

Garrett

Cecil

Allegany

Washington Morgan

Pickaway Salem

New

Castle

Greene Monroe

Gloucester

Perry

Fairfield

Noble

Greene

Marshall

Clark

Adams

Madison

Philadelphia

Fayette

Franklin

Muskingum Fulton

Belmont

Guernsey

York

Chester

Licking

Somerset Franklin

Lancaster

Cumberland

Bedford

Washington

1993

1983

1987

1987

1984

1978

1984

1980

1979

1995 1982

1997 2001

1988

1983 1995

1978

1987

1999 1990

1990

1986

1985

1998

1986

1986

1987

2003

1981 1988

2001 1981 1991

2003

1987 1984

1977

1991

2001

1988

1988

1980

1980

1990 1980

1991

1983

1979

1989

1995

1990

1988

1984

1984

1978

1978

1978

1976

1976

1976

1975

1975

1974

1974

1973

1995

1989

1969

1969

1966

1959

1957

1956

1954

1952

1944

1929

1928

1926

1924

1918

1913

1907

1901

1899

1898

1897

1897

1889

1885

1875

1861

1853

1852

1852

1844

1833

1828

1824

1776

1774

Kill

Devil

Hills

Dandridge

Bakersville

Clemmons Youngsville

R Hobgood ed

Oak

Edenton

Mascot Kitty

Hawk

Greensboro Graham Hillsborough

Newland

Haw

River

Burlington Mebane Moravian Falls Louisburg WinstonSalem

Franklinton

New

Market

Whitakers

White

Pine

Askewville

Jefferson City

Kernersville Creedmoor

Banner Hill Scotland

Yadkinville Butner Neck

Blowing

Rock

Wilkesboro

Erwin

Blaine

Elk Park

North

Wilkesboro

Banner

Elk

Greeneville

Cricket Walkertown Centerville Enfield

Mosheim R Hertford oan

Mountain

Luttrell

Stem

Colerain

Stanleyville Summerfield

Morristown

Boone Ronda

Winfall

Kittrell

Powellsville Boonville Stokesdale Mulberry Jonesville

Rural

Hall

Elkin

Maynardville Bulls

Gap Rich

King Square

Rutledge

W Ahoskie alnut

Cove

Elizabeth City Harrellsville

Oxford

Johnson

City Halifax Henderson

Woodland

Baileyton Elizabethton

Reidsville

Cofield Watauga Madison Pilot

Mountain

Jackson Roxboro

Winton

Dobson Warrenton

Gatesville

West Jefferson Yanceyville

Rogersville

Danbury Mayodan

Fall

Branch Gray

Jefferson Weldon Littleton Conway Murfreesboro

New Tazewell

Stovall Norlina

Tazewell

Roanoke

Stoneville Rapids

Bluff

City Mountain

City

Colonial

Heights

Eden

Seaboard Mount

Airy

Como Sparta Toast Gaston

Severn

Church

Hill Sneedville

Blountville

Milton

Mount

Carmel

Virgilina

Kingsport Ridgeway

D Boykins Bristol anville Bristol

Independence Clarksville

D Newsoms amascus

Gate

City

Stuart

Galax Boydton

Clinchport

Franklin Emporia

Jonesville

Martinsville South

Boston La Crosse

Trout

Dale Brodnax

Abingdon

Collinsville

Courtland

Fries

South

Hill

Suffolk

Nickelsville

Scottsburg Lawrenceville Bassett

Pineville

Hillsville Halifax

Pennington

Gap

Glade

Spring Chilhowie Chase

City

Saint

Charles Windsor Jarratt Chesapeake

Chatham

Dungannon

Clover Marion Portsmouth

Harlan Norfolk

Virginia

Beach Alberta Saltville

Barbourville

Big Stone Gap Rural

Retreat

Lebanon Ivor Saint

Paul

Appalachia

Floyd Ferrum

Norton Coeburn Cleveland Stony

Wytheville Gretna Creek Kenbridge

Lynch Wakefield

Wise Cumberland Newport

News

Smithfield

Victoria McKenney Rocky

Mount

Honaker

Hampton Waverly Keysville

Dendron

Pulaski Brookneal

Charlotte

Court House

Rushmere

Phenix Blackstone Cedar

Bluff

Richlands

Dublin Altavista

Tazewell Boones

Mill

Whitesburg Pound

Christiansburg Radford Surry

Poquoson Clintwood

Manchester Hyden

Shawsville Crewe

Jenkins

Burkeville

Haysi McRoberts

Vicco

Petersburg Claremont

Blacksburg

Vansant Hampden

Sydney

Hazard

Bluefield

Gloucester

Point Pamplin

Cape Charles

Bluefield Williamsburg Roanoke

Grundy

Cheriton

Salem

Farmville Elkhorn War

City

Hopewell

Annville

Bramwell

Pearisburg Narrows

Wheelwright

Bedford

Hindman

Montcalm Bradshaw

Eastville

Chester F Appomattox orest Gary Princeton Blue

Ridge Rich

Creek

Peterstown

Matoaka Lynchburg Troutville

Kimball

McKee

Madison

Heights

Welch

Wayland Iaeger

Nassawadox

Booneville

Pikeville Davy Fincastle New

Castle

Bon

Air

Buchanan

Exmore West

D Point illwyn

Jackson

Richmond

Beattyville

Pineville Mullens Amherst Union

Wachapreague

Lakeside Mechanicsville

Gilbert Matewan

Glasgow

Urbanna

White

Stone

Prestonsburg Melfa Glen Hinton Allen

Williamson

Onley

Oceana

Irvine

Shady

Spring

Kilmarnock Delbarton

Onancock Accomac

Alderson

Campton

Buena Vista Lester

Man

Ronceverte

Salyersville

Ashland Beckley

Parksley

Lewisburg Covington Lexington Scottsville

White

Sulphur

Springs

Paintsville

Clifton

Forge

Bloxom

Stanton

Logan Meadow

Bridge

Clay

City Inez Hallwood Mount

Hope

West

Liberty Tappahannock

Chincoteague Frenchburg

Warsaw Rupert Rainelle

Jeffersonville

Chapmanville Whitesville

Crisfield

Goshen

Oak

Hill

Mineral Louisa Stuarts

Draft

Charlottesville

Bowling

Green Fayetteville

Mount

Sterling

Quinwood

Madison

Waynesboro Crozet

Pocomoke

City

Craigsville

Danville

Sandy

Hook Montross

Fishersville

Louisa

Salt

Lick Fort

Gay Ansted Hillsboro Gordonsville

Owingsville

Staunton Crimora Gauley

Bridge

Port Royal

Snow Hill

Montgomery

Morehead

Spotsylvania Verona

Princess

Wayne C Anne edar

Grove Richwood Marlinton

Belle Orange

Colonial

Beach

Lexington

Park

Grottoes Summersville

Hamlin

West

Hamlin

Leonardtown

Stanardsville

Olive

Hill

Fredericksburg

Fruitland Berlin

C Falmouth raigsville

Grayson

Ocean

City

Dunbar

Salisbury

South Charleston Bridgewater Madison

Saint

Albans

Willards

Kenova

Catlettsburg Barboursville

C Elkton owen Monterey Dayton

Nitro Huntington

Hebron Flemingsburg Ewing

Proctorville Milton Elkview Harrisonburg

Selbyville Delmar

Fairview

Clay

Poca Culpeper

Ashland Vienna

Shenandoah Clendenin

Coal

Grove

Athalia

Frankford

Flatwoods

LaPlata Sissonville Hughesville

Winfield Remington

Ironton Eleanor

Raceland Prince

Triangle Frederick

Lewisburg

Durbin

C Laurel ambridge Greenup

Stanley

Millsboro

Crown

City

Vanceburg

Broadway

Buffalo

Washington

Waldorf

Hurlock Dale

City Timberville

Maysville Franklin

Furnace

Franklin

Seaford

New

Market

Aberdeen

Woodbridge

Trappe

Sutton Luray

Accokeek

Gassaway

Occoquan Chesapeake

Beach

Concord Oxford

Manchester Georgetown Federalsburg Dewey

Beach Lorton Brandywine

North

Beach

Preston

Rehoboth

Beach

Washington Warrenton

Huttonsville

Flatwoods

Wheelersburg

Mill

Creek

Bridgeville

Hybla Valley

Ripley

Mount

Jackson

Portsmouth

Manassas

New

Boston Clinton Rosaryville Groveton

Milton Lewes

Easton Deale

Rose Hill Farms

Franconia Manassas

Park

Saint

Michaels Springfield

Higginsport

Burke

West

Union

Spencer Camp Springs

Alexandria

Ellendale

Forest

Heights

Haymarket

South

Webster Upper

Marlboro Gallipolis Ripley Edinburg A Morningside nnandale Hillcrest

Heights

Centreville

Shady

Side

Beverly

Forestville Fairfax Suitland

Point

Pleasant Baileys Crossroads District Heights Burnsville

The

Plains

Georgetown

Russellville

Otway

Merrifield Arlington

Lucasville

Oakton Woodstock

Falls

Church Rio Denton

Grande Chantilly Dunn Loring Mayo

Oak

Hill Reedy Vienna

Milford

Sand

Fork

Queen

Anne

Hamersville

Front

Royal

Tysons Corner Palmer Park

Harman Grantsville

R Harrington arden

Elkins

Cheverly

Highland

Beach Glenville McLean Mount Rainier

Seaman

C Landover Hills heshire Toms

Brook

Peebles Ridgely

Ravenswood

Grasonville C Riverdale Reston hillum Middleburg Glen

Herndon Echo

Chevy Chase

Greensboro

Vinton

Junior

Takoma Park Annapolis

College

Park Stevensville New Haven Glenn Dale

Strasburg

Silver Spring

Buckhannon Petersburg Middleport

Greenbelt Crofton Sterling

Bowie

Sardinia Felton Frederica

Mason Potomac Belington

Kensington

Mount

Orab

Pomeroy

Middletown Crownsville Arnold Beaver Beltsville

Weston

Mowrystown

Centreville

Ashburn Rutland WheatonGlenmont

Jackson

Bowers

Beach

Elizabeth Moorefield

Piketon

Montrose

Severna Park

Sinking

Spring Wilkesville Colesville

Hambleton Wardensville

Stephens

City

Auburn Parsons Boyce Rockville Odenton

Lake Shore Pasadena Burtonsville Jane

Lew

Leesburg

Coalton Wyoming

Wellston Waverly

Davis

Round

Hill Purcellville Severn

Rock

Green Haven Hall

Washington

Grove

Church

Hill

Gaithersburg

Barclay

Poolesville

Thomas

Jessup

Philippi Berryville Lost Olney

Creek

Glen

Burnie

Riviera

Germantown Beach Brookeville Ferndale Winchester

Sudlersville

Mineralwells West Milford

Hillsboro

Linthicum

Heights

Kingstown

Cairo

Chestertown

Harrisville Laytonsville

Elkridge

Barnesville

Albany

Bainbridge

Lubeck Brooklyn Park

Halethorpe Columbia

Lynchburg

Edgemere

Port

Norris

McArthur Dundalk

Millington

Anmoore Ellenboro Flemington

Ellicott

City

Bayard Catonsville Belpre Clarksburg

Zaleski Parkersburg Pennsboro Salem

Damascus Charles

Town

Baltimore

Clayton

Blanchester

West

Union

Capon

Bridge

Essex Smyrna

Brunswick

Rosedale Woodlawn

New

Vienna Harpers A Ferry thens

Chillicothe Middle

River

Grafton Vienna

Galena

Romney

Leesburg

Rowlesburg

Greenfield

Inwood Boaz Overlea

Betterton

Randallstown

Mount Sykesville Pikesville Airy

Parkville White Marsh

Newburg Tunnelton

Saint

Marys Shinnston

Chauncey Mountain

Lake Park Amesville

Clarksville

Frankfort

Williamstown

Towson

Millville

Perry Cecilton Hall Marietta Frederick

Owings Edgewood

Mills

Bridgeton

Keyser Middletown

Wilmington

Terra

Alta

Kingsville Middletown

Martinsburg Sharpsburg

Shiloh

Monongah

Adelphi Reisterstown Perryman

Kingwood

Kingston

Jacksonville Laurelville

Cockeysville Fairmont Westernport

Vineland

C Walkersville hesterhill

Sabina

Middlebourne Albright

Fort

Ashby Barrackville Boonsboro

Murray Aberdeen

City Reedsville

Fallston

Mannington

Chesapeake

City

Rivesville Paw

Paw

Bel Air Logan Stockport

Havre de Grace

Masontown Hedgesville

Tarlton

Sistersville

Perryville

Alloway

Pine

Grove

Union

Bridge

Salem

Charlestown

Delaware

City New Westminster Straitsville

Bowersville

Fairview

Milledgeville Elmer North

East Circleville

Corning Jarrettsville Shawnee

Port

H Deposit ampstead

Bloomingburg Stoutsville Elkton

Halfway Thurmont

Berkeley

Springs

Sugar

Grove

Morgan Accident town

New

Martinsville Hagerstown McConnelsville

Amanda

Woodstown

Cumberland

Jeffersonville Pennsville

Clear Spring Smithsburg Osage

D Taneytown exter

City Frostburg

Jamestown

Bruceton

Mills

La Vale

Clayton

Manchester Brookside

Friendsville

New

Castle

Brandonville

Hundred

Xenia

Wilmington

Manor

Rising Newark

Sun Hancock Bremen

Glassboro

Emmitsburg Littleton

Carneys

Point

Newport

Lancaster New

Lexington

Stanton South

Bloomfield

Mount

Sterling Delta

Penns Grove Pitman

Markleysburg

South

Solon New

Freedom Point

Marion

Elsmere

Mullica

Hill

Cedarville

Littlestown

Wilmington Swedesboro

Caldwell Salisbury

Stewartstown Waynesboro Woodsfield

Rushville

Lewisville Clarington

Bellefonte

Crooksville

Oxford Turnersville

Greencastle Fairfield Belle

Valley

Glen

Rock

Wenonah

Summerfield Carroll Hanover

Claymont Blackwood Ardencroft Yellow

Springs

Somerset Roseville

Talleyville

Arden

Harrisburg Lockbourne Pleasantville

Confluence Meyersdale

Marcus Hook Laurel

West Springs

Grove Hyndman

Avondale

Cameron Fairchance

South

Charleston

Linwood Gibbstown Stratford

Mercersburg

Trainer Paulsboro

Gettysburg

Toughkenamon Woodbury Glendora

Thurston Canal

Winchester

Somerdale

Mont

Alto

Baltimore

Masontown

Kennett

Square

Beallsville

Chester

Runnemede

Cumberland

Groveport

Upland

Magnolia

Seven Felton Powhatan Valleys

Point

New

Oxford

Parkside

Bellmawr Village Green

Nemacolin

Grove

City

London

Prospect Park

Woodlyn

Audubon Haddonfield

Rainsburg

Rose Valley

Waynesburg Thornville Uniontown

Quarryville South

Zanesville

Glenolden

Millersport Red

Lion

Morton

Fayetteville Rockwood

Brice

Darby

Moundsville Berlin

Springfield Camden Springfield

Biglerville McConnellsburg

East

Berlin

Cherry Hill

Chambersburg Zanesville

Drexel Hill Philadelphia

West

York

Parkesburg West

Chester York

Republic

Modena Byesville East

Prospect Shadyside Dunbar

Broomall Coatesville Strasburg Lore

City New

Baltimore

Barnesville

North

Hampton

New

Concord

Pataskala Millersville Upper Arlington

Earthquakes in Virginia and Vicinity 1774 - 2004

0 10 20 40 60 80

Miles

SCALE 1:1,000,000

0 25 50 100 150 200

Kilometers

EXPLANATION

Magnitude Classes By Color

M < 3.0

3.0 - 3.9

4.0 - 4.9

5.0 - 5.9

Earthquake Catalog Source

SIGUS

SEUSSN

PDE

County Name Prince George

Urbanized Area

Populated Place

Warrenton

OPEN- FILE REPORT 2006-1017

Version 1.0

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

84° 83° 82° 81° 80° 79° 78° 77° 76° 75°

84° 83° 82° 81° 80° 79° 78° 77° 76° 75°

36°

37°

38°

39°

40°

36°

37°

38°

39°

40°

Generalized Seismic Hazard

GILES COUNTY

SEISMIC ZONE

CENTRAL VIRGINIA

SEISMIC ZONE

VIRGINIA

NORTH CAROLINA

WEST VIRGINIA

TENNESSEE

KENTUCKY

PENNSYLVANIA

D

E

LAWA

RE

OHIO

MARYLAND

NEW

JERSEY

DISTRICT OF

COLUMBIA

PHILADELPHIA

BALTIMORE

WASHINGTON

RICHMOND

ROANOKE

COLUMBUS

WINSTON-SALEM

EASTERN TENNESSEE

SEISMIC ZONE

APPALACHIAN MOUNTAINS

AlleghenyMountains

Blue Ridge

Allegheny Plateau

CHARLESTON

NORFOLK

CHARLOTTESVILLE

NEWPORT NEWS/

HAMPTON

EXPLANATION

Seismic Hazard

30 - 40% g

20 - 30

18 - 20

16 - 18

14 - 16

12 - 14

10 -12

8 - 10

6 - 8

4 - 6

2 - 4% g

0 25 50 100 150 200

Kilometers

0 25 50 100 150 200

Miles

85 SCALE 1:2,000,000 ° 80°

75°

85° 80°

75°

35°

40°

35°

40°

May 31, 1897, Giles County, Virginia Earthquake

PHILADELPHIA

PITTSBURGH

COLUMBUS

INDIANAPOLIS

ATLANTA

RICHMOND

WASHINGTON

BALTIMORE

NASHVILLE

CLEVELAND

CINCINATTI

CHARLOTTE RALEIGH

COLUMBIA

CHICAGO

NEWARK/

NEW YORK

ATLANTIC OCEAN

BIRMINGHAM

WINSTON-SALEM

SIGNIFICANT SEISMIC EVENTS 1774-2004

VIRGINIA AND VICINITY

YR MO DY LAT(°N) LON(°W) MAG

1774 2 21 37.2 77.4 4.5

1776 39.6 81.9 4.0

1824 7 15 39.7 80.5 4.1

1828 3 10 37.0 80.0 4.6

1833 8 27 37.7 78.0 4.5

1844 11 28 36.0 84.0 4.2

1852 4 29 36.6 81.6 4.8

1852 11 2 37.6 78.6 4.3

1853 5 2 38.5 79.5 4.6

1861 8 31 36.1 81.1 5.0

1875 12 23 37.8 78.0 4.8

1885 10 10 37.7 78.8 4.4

1889 3 8 40.0 76.6 4.1

1897 5 3 37.1 80.7 4.3FS

1897 5 31 37.3 80.7 5.6

1898 2 5 37.0 81.0 4.4

1898 11 25 37.0 81.0 4.5

1899 2 13 37.0 81.0 4.5

1901 5 17 38.75 83.00 4.2

1907 2 11 37.70 78.30 4.0

1913 3 28 36.20 83.70 4.1

1918 4 10 38.70 78.40 4.6

1924 11 13 36.60 82.20 4.0

1928 11 3 36.112 82.828 4.5

1944 1 8 39.800 75.500 4.2

1952 6 20 39.640 82.023 4.0

1954 1 2 36.600 83.700 4.3

1956 9 7 36.445 83.787 4.1

1957 1 25 36.600 83.700 4.0

1966 5 31 37.660 78.130 4.3

1969 7 13 36.120 83.890 4.1

1969 11 20 37.449 80.932 4.6

1975 2 16 39.050 82.422 4.4

1976 1 19 36.866 83.861 4.0

1976 6 19 37.362 81.624 4.7

1976 9 13 36.624 80.768 4.3

1980 7 27 38.193 83.891 5.2

1984 4 23 39.921 76.355 4.1

1984 8 17 37.868 78.324 4.2

1988 4 14 37.238 81.987 4.1

1988 9 7 38.142 83.834 4.6

1989 4 10 37.136 82.068 4.3ME

1990 8 17 36.934 83.384 4.0

1995 10 26 37.053 83.121 4.0ME

1996 6 29 37.187 81.950 4.1

2003 12 9 37.774 78.100 4.5

FS: Foreshock

ME: Mine event

85° 80°

75°

85° 80°

75°

35°

40°

35°

40°

December 9, 2003, Central Virginia Earthquake

PHILADELPHIA

PITTSBURGH

COLUMBUS

INDIANAPOLIS

ATLANTA

RICHMOND

WASHINGTON

BALTIMORE

NASHVILLE

CLEVELAND

CINCINATTI

CHARLOTTE RALEIGH

COLUMBIA

CHICAGO

NEWARK/

NEW YORK

ATLANTIC OCEAN

BIRMINGHAM

WINSTON-SALEM

EXPLANATION

Main Shock

May 31, 1897

Generalized MMI

II - IV

V

VI

VII

VIII

MMI Observations

Not Felt

Felt

II

III

IV

V

VI

VII

VIII

Urbanized Area

EXPLANATION

Main Shock

December 9, 2003

CIIM Intensity

I

II

III

IV

V

VI

Urbanized Area

0 50 100 200 300 400

Kilometers

0 20 40 80 120 160

Miles

SCALE 1:5,000,000

0 50 100 200 300 400

Kilometers

0 20 40 80 120 160

Miles

SCALE 1:5,000,000

By Arthur C. Tarr and Russell L. Wheeler

2006

This map summarizes two and a third centuries of earthquake activity. The seismic history

consists of letters, journals, diaries, and newspaper and scholarly articles that supplement

seismograph recordings (seismograms) dating from the early twentieth century to the

present. All of the pre- instrumental (historical) earthquakes were large enough to be felt

by people or to cause shaking damage to buildings and their contents. Later, widespread

use of seismographs meant that tremors too small or distant to be felt could be detected

and accurately located.

Earthquakes are a legitimate concern in Virginia and parts of adjacent States. Moderate earthquakes cause slight local damage somewhere in the map area about twice a decade on the

average. Additionally, many buildings in the map area were constructed before earthquake

protection was added to local building codes. The large map shows all historical and instrumentally located earthquakes from 1774 through 2004.

EARTHQUAKES

Plate tectonics cause most of the Earth's earthquakes at boundaries between moving plates.

However, the map area is in the middle of the North American plate, far from plate boundaries.

Eastern U.S. earthquakes occur on faults, typically kilometers underground, but usually we

cannot tell which fault slips to cause an individual earthquake. Accordingly, the best guides

to earthquake hazards in the map area are the earthquakes themselves, not faults or plate

motions.

Our estimate of the location of an earthquake within the Earth is uncertain, typically by several

kilometers or more, except where dense monitoring networks exist, such as in the urban areas

of California. Uncertainties are larger where seismographs are spaced far apart, and for preinstrumental earthquakes. Despite the uncertain locations of some earthquakes, the map shows

that people in most parts of the map area have felt earthquakes over at least the last century

or two.

The most common measure of earthquake size is itsmagnitude (M), which reflects the total

energy released as seismic waves. There are several ways to measure magnitude. The frequently cited “Richter scale” was the first, although the name is too often applied indiscriminately. Use of different magnitude types can give slightly different values for the same earthquake. Differences of several tenths of a magnitude unit are common.

While the size of an earthquake is characterized by a single number (magnitude), the effect

of seismic shaking on people, buildings, and the landscape is characterized by a quantity

called intensity that varies spatially. Intensity on the Modified Mercalli Intensity (MMI)

scale ranges from I (barely felt or not felt) to XII (total destruction) (see box at far right).

MMI VI marks the onset of slight damage to poorly built structures, whereas MMI VIII or

higher generally involves considerable damage to some buildings, even collapse. Maps of

intensity values, such as the small maps (below and far right) of the 1897 and 2003 earthquakes, demonstrate that the intensity, highest at the place above where the earthquake

occurred underground, falls off with distance. As the maps illustrate, intensity also varies

with local ground conditions.

EASTERN U.S. EARTHQUAKES

Earthquakes are less common east of the Rocky Mountains than in California, but because of

differences in crustal properties, an eastern earthquake affects an area about ten times as large

as a California earthquake of the same magnitude. A M4.0 eastern U.S. earthquake typically

can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A M5.5 eastern U.S. earthquake usually can be felt as far

as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as

40 km (25 mi).

EARTHQUAKES IN AND NEAR VIRGINIA

A pattern of Virginia and nearby seismicity (see large map) has emerged from the collection

of historical records and instrumental detection and location of small earthquakes. Three loose

clusters of earthquakes (seismic zones) and a small component of scattered, background seismicity contribute to the seismic hazard of Virginia and adjoining States (see Generalized Seismic Hazard map). The color and size of each earthquake symbol designates the magnitude

on the large map.

The Eastern Tennessee seismic zone extends southwestward beyond the map area. The largest

known damaging earthquake in the zone (M4.6) occurred on April 29, 2003, near Fort Payne,

Alabama, and was felt in westernmost Virginia. Earthquakes too small to cause damage are

felt about once a year in the seismic zone, although most of them are outside the map area.

Since at least 1828, earthquakes have been reported in the Giles County seismic zone.

The largest known damaging earthquake (M5.6) in the zone occurred in 1897. Smaller

earthquakes are felt or cause light damage once or twice a decade.

Since at least 1774, people in the Central Virginia seismic zone have felt small earthquakes and suffered damage from infrequent larger ones. The largest known damaging

earthquake in the zone (M4.8) occurred in 1875. Smaller earthquakes that cause little or

no damage are felt each year or two. The February 21, 1774, Petersburg earthquake recorded by Thomas Jefferson in his memorandum book was located in this zone.

SEISMIC HAZARD

Engineers who design buildings, bridges, and other structures with earthquake resistance

in mind, need to estimate the vertical and horizontal shaking from an earthquake that a

structure is likely to undergo. The Generalized Seismic Hazard map (below center) portrays

seismic hazard (calculated by the USGS) as bands of color (cooler for lower hazard, warmer

colors for higher hazard). Hazard is expressed as percentage of the acceleration of gravity

(%g). In addition, the hazard value is computed for sites on firm rock for particular time

intervals (here, 50 years) and probability of exceedance (here, 2%). For example, the hazard

value at Roanoke is between 16%g and 18%g. That means that a structure built on firm rock

has 1 in 50 odds (2% probability) of undergoing ground shaking of 16% – 18%g (the threshold for structural damage in poorly constructed buildings) or higher in the next 50 years.

REFERENCES CITED AND ADDITIONAL SCIENTIFIC ARTICLES

Bollinger, G.A., Johnston, A.C., Talwani, Pradeep, Long, L.T., Shedlock, K.M., Sibol, M.S., and Chapman,

M.C., 1991, Seismicity of the southeastern United States, 1698 to 1986, in Slemmons, D.B., Engdahl, E.R.,

Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Boulder, Colorado, Geological

Society of America Decade Map Volume 1, p. 291- 308.

Bollinger, G.A., and Sibol, M.S., 1985, Seismicity, seismic reflection studies, gravity and geology of the

central Virginia seismic zone -- Part I. Seismicity: Geological Society of America Bulletin, v. 96, p. 49- 57.

Bollinger, G.A., and Wheeler, R.L., 1988, The Giles County, Virginia, seismic zone -- Seismological results

and geological interpretations: U.S. Geological Survey Professional Paper 1355, 85 p.

Chapman, M.C., Powell, C.A., Vlahovic, Gordana, and Sibol, M.S., 1997, A statistical analysis of earthquake

focal mechanisms and epicenter locations in the Eastern Tennessee seismic zone: Bulletin of the

Seismological Society of America, v. 87, p. 1522- 1536.

ESRI, 1993, Digital Chart of the World: Data Dictionary and CD-ROMs (4), Environmental Systems

Research Institute, Inc., Redlands, Calif., USA.

Kim, W.- Y., and Chapman, M., 2005, The 9 December 2003, Central Virginia earthquake sequence: A compound earthquake in the Central Virginia Seismic Zone: Bulletin of the Seismological Society of America,

v. 95, p. 2428 - 2445.

Stover, C.W., and Coffman, J.L., 1993, Seismicity of the United States, 1568 - 1989 (Revised): U.S. Geologcal Survey Professional Paper 1527, p. 375 - 378.

Street, R.L., Bollinger, G.A., and Woolery, E., 2002, Blasting and other mining- related activities in Kentucky:

A source of earthquake misidentification: Seismological Research Letters, v.73, p. 739- 750.

INFORMATION SOURCES ON THE WEB:

(If you lack access to the World- Wide Web, your public library may have it.)

U.S. Geological Survey Earthquake Hazards Program: http://earthquake.usgs.gov/ or

toll- free 1- 888- ASK- USGS. The site contains regional, national, and global earthquake

information and links to other sites.

Earthquake Information Network: http://www.eqnet.org/. The site consists of many links

to all sorts of information about earthquakes and their hazards.

Virginia Tech Seismological Observatory: http://www.geol.vt.edu/outreach/vtso/ . The

site concentrates on earthquakes of Virginia and the rest of the Southeast.

ABBREVIATED MODIFIED MERCALLI INTENSITY SCALE

I. Not felt except by a very few under especially favorable conditions.

II. Felt only by a few persons at rest, especially on upper floors

of buildings.

III. Felt quite noticeably by persons indoors, especially on upper floors

of buildings. Many people do not recognize it as an earthquake.

Standing motor cars may rock slightly. Vibrations similar to the passing

of a truck. Duration estimated.

IV. Felt indoors by many, outdoors by few during the day. At night,

some awakened. Dishes, windows, doors disturbed; walls make

cracking sound. Sensation like heavy truck striking building.

Standing motor cars rocked noticeably.

V. Felt by nearly everyone; many awakened. Some dishes,

windows broken. Unstable objects overturned. Pendulum

clocks may stop.

VI. Felt by all, many frightened. Some heavy furniture moved;

a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures;

considerable damage in poorly built or badly designed structures;

some chimneys broken.

VIII. Damage slight in specially designed structures; considerable

damage in ordinary substantial buildings with partial collapse.

Damage great in poorly built structures. Fall of chimneys, factory

stacks, columns, monuments, walls. Heavy furniture overturned.

IX. Damage considerable in specially designed structures; welldesigned frame structures thrown out of plumb. Damage great

in substantial buildings, with partial collapse. Buildings shifted

off foundations.

X. Some well-built wooden structures destroyed; most masonry

and frame structures destroyed with foundations. Rails bent.

XI. Few, if any (masonry) structures remain standing. Bridges

destroyed. Rails bent greatly.

XII. Damage total. Lines of sight and level are distorted. Objects

thrown into the air.

TECHNICAL NOTES

The earthquakes shown on the maps were drawn

from three catalogs: SIGUS; PDE; and SEUSSN.

SIGUS, the Significant Earthquakes in the U.S.

catalog (Stover and Coffman, 1993), lists earthquakes from the historical period (1754 is the earliest earthquake in Virginia) through 1989. The

PDE (Preliminary Determination of Epicenters)

catalog covers the overlapping period 1973- 2004.

Both catalogs are maintained by the USGS (see

DATA SOURCES list at the bottom left of the map).

The SEUSSN (Southeastern U.S. Seismic Networks)

catalog covers the southeastern U.S. for the period

1977 - 2003. While considered authoritative, the

SEUSSN catalog is less accurate at the edges of its

coverage area, especially for small magnitude shocks.

In addition, all the catalogs may contain mining- related seismic events, such as blasts and roof collapses.

Mining events are typically small magnitude, however, and may not be differentiated from small earthquakes (see Street and others, 2002). Two of the

largest mining events are found in the SIGNIFICANT

SEISMIC EVENTS listing at top right.

Selected events from the USGS National Seismic

Hazard Maps (NSHM) project earthquake catalog

were added when these events were not listed in

either the SIGUS or the PDE catalog.

The following selection rules were used to minimize

duplicate events during periods of overlap:

1754 - 1972 SIGUS + NSHM (selected)

1973 - 1976 PDE + NSHM (selected)

1977 - 2003 SEUSSN (36° - 39° N.); PDE otherwise

2004 PDE

In cases of duplication, the NSHM event parameters

were favored above the SIGUS or PDE determinations.

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 questionnaire received and

reflects the effects of earthquake shaking on the

people and structures in the community. The average of the individual intensity values in each

ZIP Code zone is plotted on the map in a colorS coded format. eismic hazard is expressed as

peak ground acceleration (PGA)

on firm rock, in percent g, expected to be exceeded in a 50-year

period with a probability of two

percent.

A NOTE ON THE INTENSITIES OF THE

1897 GILES COUNTY EARTHQUAKE

The May 31, 1897, Giles County earthquake

is one of the most important to have occurred in the eastern United States principally

because of the large area over which it was

felt (blue area in the map at right). This

M5.6 shock (the largest earthquake on the

large map) was located in the heart of the Appalachian Mountains. Contemporary accounts,

culled from newspapers, journals, and diaries,

are the sources of the intensity observations,

plotted on the map as color- coded circles. Each

observation is assigned a Modified Mercalli

Intensity (MMI) and the results are contoured.

An observation is coded "F" if the earthquake

was felt but no MMI was assigned and "N" if

a source document indicated that the event

was not felt.

Although the contours are approximate, the

pronounced asymmetry of the pattern of

higher intensity values (roughly parallel with

the trend of the Appalachians) is similar to

that of the December 9, 2003, central Virginia

earthquake (see map at far right).

DISCLAIMER

Any use of trade names is for descriptive purposes only and

does not imply endorsement by the U.S. Government. Base

map data, such as place names and political boundaries, are

the best available but may not be current or may contain inaccuracies and therefore should not be regarded as having

official significance.

GIS files and a PDF file are online at http://pubs.usgs.gov/of/2006/1017

INTENSITY AND MAGNITUDE

Intensity is a measure of the effects of shaking upon people,

buildings, and in extreme cases, the landscape (see table above).

For a given earthquake, the intensity ranges from a maximum

value, usually observed near the epicenter of the earthquake,

to increasingly smaller values at greater distances. The intensity

distributions for the notable 1897 and 2003 earthquakes are

portrayed on two small maps below. As noted elsewhere on

this map, the magnitude of an earthquake is single- valued, representing the total energy released by the earthquake. Thus, an

earthquake can have many intensity values but only one maximum intensity and one magnitude. The symbols plotted on the

large map represent the best estimates of time, location, and

magnitude that are tabulated in several earthquake catalogs

(see TECHNICAL NOTES at right).

Authorities differ on the magnitude inferred from intensity patterns of pre- instrumental earthquakes, and some degree of uncertainty accompanies the computation of instrumental magnitudes. In both cases, this uncertainty may be several tenths of

a magnitude unit or even larger, depending upon the method,

quality of available data, and assumptions made during the

determination.

DATA SOURCES

SIGUS and PDE earthquake catalogs: http://neic.usgs.gov/neis/epic.html.

Search engine for all earthquake catalogs managed by the USGS National Earthquake Information Center.

SEUSSN earthquake catalog: http://www.geol.vt.edu/outreach/vtso/anonftp/catalog/susn2003cat.html.

USGS National Seismic Hazard Maps (NSHM) project: http://earthquake.usgs.gov/hazards/hazmaps/.

Overview of the NSHM project and its products.

USGS NSHM seismic hazard data: ftp://hazards.cr.usgs.gov/hazmaps/data2003/ascii/USpga2500v6.asc.

USGS NSHM earthquake catalog: http://earthquake.usgs.gov/hazmaps/products_data/2002/catdoc- 2202/emb2001.cc.

Base from U.S. Geological Survey National Elevation Dataset,

National Hydrologic Database, and Digital Chart of the World

(ESRI, 1993)

Albers equal- area conic projection, standard parallels 36° 40' 00 ́ ́

and 39° 20 ́ 00, ́ ́ central meridian 79° 30 ́ 00, ́ ́ latitude of origin

0° 00 ́ 00 ́ ́

Base from ETOPO2 digital elevation model and Digital Chart of

the World (ESRI, 1993)

Albers equal-area conic projection, standard parallels 34° 30' 00 ́ ́

and 40° 30 ́ 00, ́ ́ central meridian 81° 00 ́ 00, ́ ́ latitude of origin

0° 00 ́ 00 ́ ́

Base from ETOPO2 digital elevation model and Digital Chart of

the World (ESRI, 1993)

Albers equal-area conic projection, standard parallels 34° 30' 00 ́ ́

and 40° 30 ́ 00, ́ ́ central meridian 81° 00 ́ 00, ́ ́ latitude of origin

0° 00 ́ 00 ́ ́

Base from U.S. Geological Survey National Elevation Dataset

and Digital Chart of the World (ESRI, 1993)

Albers equal-area conic projection, standard parallels 36° 40' 00 ́ ́

and 39° 20 ́ 00, ́ ́ central meridian 79° 30 ́ 00, ́ ́ latitude of origin

0° 00 ́ 00 ́ ́