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Greenville County Hazards

Naturally Occurring Events

According to NOAA's Storm Events Database, from 2008 through 2018, Greenville County has experienced 10 drought events.

While far less common than in other parts of the world, South Carolina has experienced more than 200 minimal earthquakes since 2001. The Brevard Fault Zone and the Pax Mountain fault system cross into the northern part of Greenville County. In addition to these faults, the county is susceptible to earthquakes in other locations, especially near dams. According to the USGS, three earthquakes ranging from magnitude 2.2 to 2.5 have occurred in Greenville County since 1997.

According to the South Carolina State Hazard Mitigation Plan, historically Greenville County has the highest number of annualized losses and the highest number of flood-loss causing events. Greenville County is affected by four types of flooding: 1) Dam/Levee Failure; 2) Local Drainage Problems; 3) Flash Flooding; and 4) Riverine Flooding.

Flash flooding occurs when heavy rainfall in a short period of time accumulates in areas faster than the ground is able to absorb it. According to the National Oceanic and Atmospheric Administration’s (NOAA) Storm Events Database, from 2008 through 2018, 22 flash flooding events have been reported in Greenville County, resulting in two deaths and over $2.3 million in damage.  

Riverine flooding occurs when an increase of water volume within a river channel causes an overflow onto the surrounding flood plain. Greenville County's topography, combined with its humid, subtropical climate, makes it highly vulnerable to riverine flooding.

Greenville County has experienced over 110 flooding events since 1970 – three significant flooding events occurred between 2003-2005, resulting in more than $11 million in crop and property damage.

Hurricane / Tropical Storm
Although hurricanes are primarily thought of as a coastal phenomenon, inland counties may be directly affected by these storms. Inland flooding poses the greatest threat to life and property for Greenville County. Tornadoes, high winds, and heavy rain also accompany these storms.

In 1995, Tropical Storm Jerry dropped over 15" of rain in some portions of Greenville County.

Infectious Disease Outbreak or Other Public Health Emergency
Infectious disease outbreaks or other public health emergencies may occur in Greenville County with little or no notice. Infectious disease can present special requirements for disease surveillance, rapid delivery of vaccines, antibiotics, or antiviral drugs, allocation of limited medical resources, and expansion of health care services to meet a surge in demand for care.

Severe Thunderstorms, Tornadoes, and Lightning
According to NOAA’s Storm Events Database, from 2008 through 2018, Greenville County experienced 191 thunderstorm wind events resulting in one injury and $750,000 in damage, three lightning events resulting in one injury and $225,000 in damage, and 192 hail events.

Tornadoes in Greenville County occur most often in March, April, and September, but can happen at any time. Though they are relatively weak compared to tornadoes in other regions, damage can be extensive from strong winds and large hail.

Severe Winter Weather
Snow, ice storms, and extremely cold temperatures periodically threaten Greenville County. Winter storms can damage property, create safety risks, destroy crops and valuable timber, damage infrastructure components, such as power lines, and have enormous economic impacts.

According to NOAA’s Storm Events Database, from 2008 through 2018, Greenville County experienced eight heavy snow events, nine winter storm events, and 26 winter weather events.

In December 2005, a winter storm producing ice and snow across the Upstate of South Carolina, including Greenville County, caused almost $1.5 million in property damage due to power outages and housing unit damage from falling limbs and trees. The winter storm resulted in a Presidential Disaster Declaration in January 2006. 

As the population of Greenville County grows and residential developments continue to expand into forested areas, wildland urban interface issues increase and more wildfires threaten homes. According to the South Carolina Forestry Commission (SCFC), 98% of the wildfires are caused by human activities. The leading causes are careless outdoor burning and woods arson. Wildfires can occur any time of the year, but the height of the wildfire season usually occurs from late winter through spring.

Technological Events

Communications Failure 
The severe interruption or loss of private and or public communications systems, including but not limited to transmission lines, broadcast, relay, switching and repeater stations as well as communications satellites, electrical generation capabilities, and associated hardware and software applications necessary to operate communications equipment.  These disruptions may result from equipment failure, human acts, (deliberate or accidental) or the results of natural or human made disasters.

Mass Power Failure 
The loss of commercial power from a public utility company substation, subsidiaries or electric cooperative that effects 1,000 customers for a 24-hour period.

Human Related Events

Active Shooter/Hostile Action
An active shooter is an individual(s) actively engaged in killing or attempting to continuously harm people. In most cases, active shooters use firearms, and there is generally no pattern or method to the selection of victims. Active shooter/hostile action situations are unpredictable and evolve quickly. An active shooter/hostile action situation could occur anywhere at any time with little or no warning and may result in mass casualties.

Civil Disturbance
Civil disturbances may occur at any time in Greenville County and are often preceded by periods of increased tension cause by questionable social and/or political events, such as controversial jury trials or law enforcement actions.

Terrorism and Cyber Terrorism
There are many critical and high-profile facilities, high concentrations of population, and other potentially attractive venues for terrorist activity that make Greenville County vulnerable to a variety of terrorist methods.

Cyber terrorism is a risk for all organizations, including Greenville County government. Though the county uses technology that consists of firewalls, proxy servers, and virus walls to provide a secure perimeter around the network, these can be ineffective when users fail to heed security requirements

Hazardous Materials (HazMat) Events

Hazardous Materials Spill or Release
Greenville County has the largest concentration of facilities reporting Extremely Hazardous Substances (EHS) in South Carolina. The county’s industrial capacity and the network of interstate highways and railways result in vulnerabilities to hazardous material releases from both stationary sites and transportation sources.

According to the South Carolina State Hazard Mitigation Plan, Greenville County has the most Toxic Release Inventory (TRI) and Superfund sites in the State.

Nuclear Accident (Fixed)
A fixed nuclear accident is an incident that produces significant amounts of radioactive gases and or particles which can be released from the facility. Effects can range from a minor release to a radioactive release that would force the evacuation of the general population within a ten mile radius of the facility.  Radioactivity from a release may enter the food chain through crops or dairy products out to a fifty mile radius of the facility.  Meteorological conditions can have significant influence on the size of the contaminated area.

Greenville County is within the 50-mile emergency planning zone of the Oconee Nuclear Station and is a host county for evacuees from Pickens County.

Pipeline Accident
A pipeline accident is the spillage or release, either intentionally or accidently, of Hazardous Waste, Toxic Materials, or Natural Gas which may cause death and injury to the public and damage or destruction to property and the environment.

Both Colonial Pipeline Company and Kinder Morgan have gas/petroleum pipelines that run through the southern end of Greenville County.  

In June of 1996, Greenville County experienced one of the largest inland oil spills in U.S. history when 957,600 gallons of fuel oil spilled into the Reedy River.