Overview

The State of Ohio is prone to many natural and manmade hazards. Ohio has experienced thousands of hazard events, resulting in millions of dollars in losses and casualties, and 44 Presidential disaster declarations. A Hazard Identification/Risk Analysis (HIRA) is a systematic way to identify and analyze hazards to determine their scope, impact and the vulnerability of the built environment to such hazards. Requirements of the 44 CFR 201.4 include identifying hazards, profiling hazard events, assessing vulnerability by jurisdiction, estimating potential losses by jurisdiction, assessing vulnerability of state facilities, and estimating potential losses of state facilities.

For more information, see the Hazard Identification/Risk Analysis (HIRA) Overview and Hazard Identification Summary - Section 2.1

Flooding

Tornadoes

Winter Storms

Landslide

Dam / Levee Failure

Wildfire

Seiche / Coastal Flooding

Earthquake

Coastal Erosion

Drought

Severe Summer Storm

Invasive Species

Land Subsidence

Flooding

Flooding is the most frequently occurring natural disaster in Ohio as well as in the United States. Floods in Ohio occur in rivers and streams when flow exceeds the capacity of the channel in to the floodplain. Although this is a natural process, humans continue to inhabit areas where flooding is eminent in flood hazard areas. Development in flood hazard areas often leads to loss of life and property – floods damage property and infrastructure in Ohio every year.

For more information, see the section on flooding in the State Hazard Mitigation Plan: Section 2.2

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Tornado

Ohio ranks within the top 20 states in the nation for fatalities, injuries, and dollar losses, indicating that it has a relatively high likelihood for damages resulting from tornado. Tornadoes are vigorously rotating columns of air that are in contact with both the surface and storm clouds. Typically, they are in the shape of a funnel surrounded by a cloud of debris and dust which makes them extremely dangerous in populated areas. Most tornadoes have wind speeds less than 110 miles per hour (177 km/h), are approximately 250 feet (80 m) across, and travel a few miles (several kilometers) before dissipating. It is difficult to predict the exact location of tornadoes therefore risk assessments are done using historical information and past declarations.

For more information, see the section on tornadoes in the State Hazard Mitigation Plan: Section 2.3

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Winter Storm

Severe winter weather affects all parts of Ohio. A winter storm occurs when precipitation (snow or sleet) forms at cold temperatures or when the ground temperature is cold enough where ice forms (freezing rain). Accumulations of snow and ice often make conditions hazardous to motorists and pedestrians. Ice storms and heavy snow fall may cause power and telecommunication outages, disrupting activities for days. While Ohio residents and governments are accustomed to handling winter storm events, occasional extreme events can make conditions dangerous and disruptive.

For more information, see the section on winter storms in the State Hazard Mitigation Plan: Section 2.4

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Landslide

In Ohio, there are three main types of landslides that occur, Rotational Slump, Earthflow and Rockfall (see link to Hazard Mitigation Plan below for more information) Landslides are wide ranges of ground movement (soil and rock material) which can occur in offshore, coastal and onshore environments. Factors in Ohio that may impact slope stability and contribute to landslides include: groundwater pressure, soil structure, stream erosion, saturation (snow melt, heavy rains) and earthquakes.

For more information, see the section on landslides in the State Hazard Mitigation Plan: Section 2.5

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Dam/Levee Failure

Ohio has a dam safety program that provides inspections and promotes maintenance to prevent dam/levee failure throughout the state. Dam/levee failure is often the result of design error, geologic instability, poor maintenance, extreme rainfall and/or structure failure. Dam/levee failures are generally rare but have major consequences when they occur. Significant flooding downstream can cause major destruction of life and property.

For more information, see the section on dam/levee failures in the State Hazard Mitigation Plan: Section 2.6

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Wildfire

Each year in Ohio, an average of 800 wildfires burn 4,000 to 5,000 acres of forest and grassland within ODNR Division of Forestry’s forest fire protection district. The protection district includes all 185,000 acres of Ohio’s 20 State Forests, as well as all privately owned lands within the district boundaries. A wildfire is any uncontrolled fire with extensive size and speed in a combustible vegetative area. The danger of wildfires is that they are unpredictable, especially when weather conditions are warm, dry, and windy and the topography of the area is uneven.

For more information, see the section on wildfires failures in the State Hazard Mitigation Plan: Section 2.7

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Seiche/Coastal Flooding

The most common cause of seiches in Ohio is a strong, constant wind blowing over the surface of the water forcing it to accumulate at the down-wind shore. A seiche is a standing wave in an enclosed or partially enclosed body of water that can cause coastal flooding. Small rhythmic seiches are almost always present on the Great Lakes but are usually unnoticeable except during periods of unusual calm. Wind speed and barometric pressure are the most obvious contributors to the size of an event. Because of the shallowness and elongated shape of Lake Erie, it is more prone to wind seiches similar to a storm surge like that caused by hurricanes.

For more information, see the section on seiche/coastal flooding failures in the State Hazard Mitigation Plan: Section 2.8

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Earthquake

Although most earthquakes are unnoticeable in Ohio, there have been numerous quakes with a magnitude of 2.0 or higher over the last several years. Earthquakes in Ohio are primarily located the northeast and far west-central portions of the state and historically have not exceeded 5.4 magnitude. An earthquake results from a release of energy from the Earth creating seismic waves. Earthquakes are caused mostly by tectonic plate movement known as geologic faults, but also by volcanic activity and landslides. The seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. The magnitude of an earthquake is measured by the Richter scale while the intensity is measured on the Mercalli scale. The most substantial known earthquake in Ohio history was the Anna (Shelby County) earthquake, (see here) which occurred on March 9, 1937. It was centered in western Ohi and had a magnitude of 5.4, and was of intensity VIII ( USGS historic description).

For more information, see the section on earthquakes in the State Hazard Mitigation Plan: Section 2.9

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Coastal Erosion

The excessive erosion of the Lake Erie shoreline can be considered a hazard due to properties located on or near the shoreline. Coastal erosion is defined as the gradual wearing away of the earth’s surface by the natural forces of wind and water. The geologic settings vary throughout the length of Ohio’s coast causing significant coastal erosion in this area.

For more information, see the section on coastal erosion in the State Hazard Mitigation Plan: Section 2.10

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Drought

Within the State of Ohio, the potential for drought to occur is equal in all sections of the state. However, the effects of drought vary from farming difficulties to water consumption in different parts of Ohio. A drought is extended period of time when an area has a deficiency in its water supply due to a lack of precipitation. The four primary types of drought: meteorological, hydrological, agricultural and socioeconomic.

For more information, see the section on drought in the State Hazard Mitigation Plan: Section 2.11

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Severe Summer Storms

Severe summer storms and associated high wind / hail events are common throughout Ohio and reported hundreds of times each year. Severe summer storms traditionally precede an approaching cold air mass. Key components to the formation of storms are a low pressure zone, high pressure zone and the jet stream. Lightning is another main concern throughout Ohio damaging trees, utilities, structures and sometimes loss of life.

For more information, see the section on drought in the State Hazard Mitigation Plan: Section 2.12

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Invasive Species

According to the Ohio Department of Natural Resources, Division of Natural Areas and Preserves, approximately 75 percent of plant species are native to Ohio. The remaining species were introduced by other states or countries and have become invasive and destructive to natural areas.

For more information, see the section on drought in the State Hazard Mitigation Plan: Section 2.13

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Land Subsidence

In Ohio the two primary causes are abandoned underground mines (AUMs) and karst (glacial deposits). Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to several factors. Mining techniques create voids in the earth that cause instability throughout the surface. Much like in areas of excessive mining, in areas of karst deposits, groundwater dissolves away the limestone or dolomite creating voids under the Earth’s surface. Soil type throughout the state also plays a role in land subsidence since some types expand when wet and contract when dry.

For more information, see the section on drought in the State Hazard Mitigation Plan: Section 2.14

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Disasters

Disaster History

Click here for a listing (Declaration number, declaration date, and brief description) of each declared disaster and emergency declaration within the State of Ohio. Information includes: the counties involved, the event type(s), what happened, casualties, damage amounts, etc.

Disaster Declaration

This map shows the Presidential Disaster Declarations for each county in Ohio between 1964 and April 24, 2009.

County Hazard Identification/Risk Analysis (HIRA)