Geologic hazards � Dates, Level of Events, Damage and Indirect Costs

Updated � August 2004

This page summarizes actual and estimated costs attributed to geologic hazards in North Carolina. It provides the date(s) and level of events also. The estimated damage and indirect costs have not been adjusted for inflation. These include events related to:

High hazard dam failure

Date Level of Event Damages Indirect Costs
August 13, 1916 50+ year event Tropical storm triggers catastrophic failure of Lake Toxaway Dam, Trysylvania County. No known fatalities; several home destroyed. Resort closes; local economy depressed until the dam was rebuilt in 1961. Resort closes; local economy depressed until the dam was rebuilt in 1961.
1976 10 year? Bearwallow Lake Dam failure caused four fatalities within one family. Dam repair costs.
May 26, 2003 10 year Hope Mills Dam fails after 6-9" of rain. Dam, roadway, and bridge replacement costs exceed $6 million. Rainfall from this event also triggered the failure of two other dams in the region. Emergency response; homeowner relief.

 

Abandoned mine collapse and subsidence

Date Level of Event Damages Indirect Costs
February 18, 2000 N/A Collapse of Phoenix Mine, Cabarrus Co. $100,000 home condemned. Extensive legal fees; state and county agency investigation (collapse and contaminant); costs exceed $100,000.
2000 - present N/A Subdivision built over North State Mine, Guilford County. Investigation and mitigation costs exceed $50,000. -

 

Landslides (regional events)

Date Level of Event Damages Indirect Costs
May 1901 100+ year event

Widespread floods and debris flows in Buncombe, Henderson and McDowell Counties. Railroad tracks covered by slides for hundreds of feet. Rail lines, bridges and roads destroyed. Exact damages unknown, but probably in excess of $0.5 million.

Rail, bridge and road transportation disrupted.
July 16, 1916 100+ year event Widespread floods and hundreds of debris flows in Transylvania, Henderson and Buncombe Counties. Scores of fatalities and destroyed structures. Rail, bridge and road transportation destroyed. Exact damages unknown, but probably exceeds $100 million. Transportation disrupted. Crop and private property damage.

August 10-17,1940 and August 28-31, 1940

100+ year event Two hurricanes caused widespread flooding though the southeastern U.S. Flooding and hundreds of debris flows caused 26 fatalities in N.C. — mainly in the Pigeon River basin (Avery, Watauga, Ashe, Buncombe, McDowell, Yancy and Wilkes Counties). Rail lines, bridges and roads destroyed. Exact damage unknown, but probably exceeded $20 million in N.C. alone. Private property and crop damage. Transportation disrupted.
November 6, 1977 10 year event Widespread flooding and scores of debris flows in Buncombe and McDowell Counties. Roads and bridges destroyed. Exact costs unknown but probably exceed $3 million. Private property damage. Emergency response.
February and March 1990 15 year event? Heavy rains during February and March triggered numerou debris flows in western N.C. Total road repair costs exceed $6.7 million. Transportation disruption. Private property damage. Damage to trout farms.
May 5-7, 2003 <10 year event Heavy rains (7-15") in western N.C. trigger scores of slope movements in Swain and Haywood Counties. Estimated damages: One debris flow goes into Bryson City Reservoir. Reservoir abandoned. Six major debris flows originate on slopes underlain by acid-producing rock. Costs exceed $2.5 million. Transportation disruption. Emergency response. Community water system destroyed.

 

Landslides (specific events)

Date Level of Event Damages Indirect Costs
December 13, 1990 <5 year event Swain County debris flow destroys chlorinator for Bryson City water system and mobile home. Direct costs in excess of $60,000. Municipal water system disabled for 2-3 days. Roads blocked, utility lines destroyed. Emergency response.
October 3, 1995 <25 year event Sedimentation from debris flow triggered by Hurricane Opel enters Franklin municipal watershed. Rehabilitation costs exceed $5,000. Indirect costs unknown.
July, 1997 <5 year event Rock slide closed I-40 in Pigeon Gorge. Direct costs exceed $10 million. I-40 blocked for over 20 days. Rerouted traffic, loss of business and tourism. Costs probably exceeded $5 million.
June 1999 - June 2001 N/A Cut slope failure along I-540 in Wake Co. in Triassic sedimentary rock near Jonesboro Fault. Direct costs of $3 million include purchase of private property right-of-way. Movement aggravated by Hurricanes Dennis and Floyd. Indirect costs include legal fees; investigation expenses probably exceeded $50,000.
December 11, 2003 <2 year event Occupant killed and home destroyed by debris flow in Maggie Valley, Haywood County. Home valued at $200,000. Road construction and community water system repairs required. Legal action pending. Emergency response and legal fees.

 

Sink holes (karst) — subsidence

Date Level of Event Damages Indirect Costs
August 3, 2001 N/A Sinkhole develops on I-40 and creates a safety hazard at Interstate driving speeds. Repair costs exceed $50,000. Traffic disruption; investigation costs
2001 N/A Dewatering of Boiling Springs Lake. Repair cost unknown, but probably exceed $50,000. Property values decline.
1965 - present N/A Investigation and repair of rail and road transportation routes at Sunny Point Military Ocean terminal. Costs unknown but probably exceed $500,000. Unknown
1998 - present N/A Rocky Point Quarry - Investigations and mitigation for mine dewatering. Concern for sinkhole development near I-40. Exact costs unknown but probably exceed $100,000. Unknown regulatory agency and NC Department of Transportation (NCDOT) costs.
2003 - present N/A Onslow Quarry - Investigations and mitigation for mine dewatering. Concern for sinkhole development along transportation routes and private property. Costs unknown but probably exceed $20,000. Unknown regulatory agency and NCDOT costs.
1995 - present N/A Groundwater contamination remediation at Camp LeJeune military base complicated by influence of karst terrain on groundwater flow. Initial investigations undertaken without prior knowledge of karst features. Costs unknown, but probably exceed $1 million. Unknown state and federal regulatory agency costs.

 

Earthquakes

Date Level of Event Damages Indirect Costs
1811 - 1812   Damage in North Carolina from New Madrid (Magnitude 8.0) earthquakes. Cracked foundations and toppled chimneys.
1886   Damage in North Carolina from Charleston (Magnitude 6.0) earthquake. Cracked foundations and toppled chimneys.
February 21, 1916   Skyland earthquake (I VII) in North Carolina Damage in Waynesville, Tyron, Skyland, and Forest City, North Carolina.

 

Tropical cyclones / hurricanes (specific examples)

Damage estimates for these events are highly variable from one source to another. Hurricane damage is not always confined to the barrier island, so damage estimates for storms that inflicted damage to the mainland include the mainland damage. The storms in this list with the greatest mainland impacts relative to coastal impact were Fran and Floyd.

Further information about these storms are at:

Jarrell, J.D., Mayfield, Max, Rappaport, E.E., and Landsea, C.W., 2001, The Deadliest, Costliest, and Most Intense United States Hurricanes from 1900 to 2000, NOAA Technical Memorandum NWS TPC-1, web document at http://www.aoml.noaa.gov/hrd/Landsea/deadly/index.html

National Climatic Data Center — Storm Events Database, 19 July 2004, National Oceanic and Atmospheric Administration, 6 August 2004, http://www.nc-climate.ncsu.edu/monitoring/events.html

Date Level of Event Damages Indirect Costs
August 31, 1993 9 year Hurricane Emily (Category 3) — did not make landfall, and the center of the eye's closest approach as Lost Tourism about 20 nautical miles east of Hatteras Island. However, Emily caused widespread coastal flooding with wind speeds up to 98 mph. These strong winds produced the worst flooding on the Pamlico Sound sie of Hatteras Island this century. NC coastal damage was estimated at $50 million. Power outages, lost tourism, beach renourishment.
July 13, 1996 7 year Hurricane Bertha (Category 2) — made landfall midway between Wrightsville Beach and Topsail Beach. The primary effects in NC were to the coastal counties and included storm surge flooding and beach erosion, roof damage, piers washed away, fallen trees, and crop damage. Heaviest damage was in Topsail Beach and all of Onslow County up the coast to Emerald Isle in Carteret County, which was declared a Federal Disaster Area. This hurrican had an initial 8-10 foot storm surge, with maximum wind speeds of about 101 mph. Total NC damage estimate was about $310 million. Power outages, lost tourism, beach renourishment.
September 5, 1996 9 year

Hurricane Fran (Category 3) — made landfall at Cape Fear with widespread power outages, wind damage to trees and roofs as well as downed trees and power lines. Storm surges of 8-12 feet destroyed or seriously damaged numerous beachfront houses. On Topsail Island, a 12-foot-high storm surge caused 40 feet of beach erosion and wiped out dunes as overwash destroyed most of the first row of beach houses and heavily damaged the rest. Extensive flooding was responsible for additional damage as well as widespread power outages.

Hurricane Fran was the worst natural economic disaster to occur in North Carolina to date. The total damage estimate for NC was about $3.2 billion. Damage to crops, livestock, and farm equipment / buildings was $400 million.

The greatest agricultural damage was in Sampson, Johnston and Wayne Counties. Tens of thousands of homes were damaged by falling trees. The copious rainfall produced many severe flash and river floods. A full twelve days after the event, 150 secondary roads were still closed. This hurricane was responsible for 24 deaths statewide.

Power outages, lost tourism, beach renourishment.
August 26, 1998 9 year

Hurricane Bonnie (Category 3) — made landfall near Cape Fear and caused widespread flooding and property loss with a 6-8 foot storm surge. This storm resulted in numerous reports of downed trees, roof damage and widespread power outages. This hurricane had wind speeds of up to 115 mph and resulted in one death in NC.

Carteret County appeared to sustain the most damage from the storm. Along the Outer Banks, soundside flooding form the Pamlico Sound produced water levels 4-6 feet above normal in Manteo on Roanoke Island and over portions of Hatteras Island where Route 12 was briefly closed due to high water.

Storm surge at the beaches of Onslow and Carteret counties was generally 3-5 feet above normal with moderate beach erosion. North Topsail Beach lost most of the protective dunes constructed after the hurricanes of 1996. Total NC damage estimates exceeded $720 million. A Federal Disaster was declared.

Power outages, lost tourism, beach renourishment.
September 4, 1999 7 year

Hurricane Dennis (Category 2) — Meandered off the NC coast for about one week, resulting in storm tides of 3-5 feet at the coast and higher tides reported in the sounds. After being downgraded to a tropical storm, Dennis made landfall on Core Banks just north of Cape Lookout. Beach erosion and the storm tide effects were extreme on the Outer Banks.

Unfortunately the hurricane approached eastern NC during one of the highest astronomical tides of the month. The dune structure on Hatteras Island was breeched in numerous locations. Just north of Buxton, a 3,000-foot-long section of Highway 12 was completely lost and a new inlet along the Core Banks was formed.

The town of Nags Head estimated their dune loss at $16.5 million. Ocean storm surges were 3-4 feet above normal. Total NC damage estimates of property and crops was about $67 million.

Power outages, lost tourism, beach renourishment.
September 16, 1999 7 year

Hurricane Floyd (Category 2) — made landfall near Topsail Island with wind speeds of about 100mph. This hurricane was the third costliest U.S. hurricane (1999-2000) and produced more human misery and environmental impact in NC than any disaster in memory. The 15-20 inches of rain that fell across the eastern half of the state caused every river and stream to flood.

Ocean storm surge was 9-10 feet, inundating barrier islands and causing extensive dune erosion. Floyd was responsible for coastal damage, however, much of the real damage was by severe flooding of more inland areas. This flooding was responsible for extensive livestock deaths with more than 3,000 hogs, 90,000 turkeys, and 200 cows lost to drowninging. Animal waste and septic tanks added pollution to the flooding.

Floyd was the deadliest hurricane since Hurricane Agnes in 1972, and resulted in 35 deaths in NC. Total NC damage estimates were about $4.5 billion. A Federal Disaster was declared.

Power outages, lost tourism, beach renourishment.
September 18, 2003 7 year

Hurricane Isabel (Category 2) — made landfall near Drum Inlet with wind speeds of about 100 mph. Major ocean overwash and beach erosion occurred along the North Carolina Outer Banks where waves up to 20 feet in height accompanied by a 6-8 foot storm surge.

In Dare County alone, several thousand homes and businesses, several piers, and sections of Highway 12 were damaged or washed away. A new inlet was opened near Hatteras Village. Widespread wind and storm surge (6-10 feet) damage occurred in coastal NC. Damage estimates for NC totaled about $500 million.

Power outages, lost tourism, beach renourishment, isolation of Hatteras Village.

 

For additional information

The contact for additional information about geologic hazards in North Carolina is Mr. Richard Wooten, P.G.; his e-mail is Rick.Wooten@ncmail.net. He is located in the Swannanoa, North Carolina office (western North Carolina) and can be reached by telephone at 828.296.4500. His mailing address is: 2090 U. S. Highway 70, Swannanoa, North Carolina 28778. An alternate North Carolina Survey staff geologist contact is Dr. Jeff Reid, P.G., 512 North Salisbury Street, Raleigh, North Carolina, 27699-1612. His telephone number is 919.733.2423 x403. His e-mail is Jeff.Reid@ncmail.net.