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Dam Failure

Dam failure or levee breeches can occur with little warning. Intense storms may produce a flood in a few hours or even minutes for upstream locations. Flash floods occur within six hours of the beginning of heavy rainfall, and dam failure may occur within hours of the first signs of breaching.  Other failures and breaches can take much longer to occur, from days to weeks, as a result of debris jams.  Dam failures are not routine; two factors influence the potential severity of full or partial dam failure: (1) The amount of water impounded, and (2) the density, type, and value of development downstream.

Hawaii has over 100 dams, and the possibility of devastating floods resulting from dam failure is a concern.  Ka Loko is notable because its dam burst in 2006. The dam burst was preceded by unusually heavy rain. The flood from the dam failure raced downhill with a wall of water reported to be between 20 and 70 feet high, and 200 feet wide, resulting in the destruction of several homes and the deaths of 7 people.

Landslide

The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing.  Although landslides are primarily associated with mountainous regions, they can also occur in areas of generally low relief. In low-relief areas, landslides occur as cut-and-fill failures, river bluff failures, lateral spreading landslides, and a wide variety of slope failures associated with quarries and open-pit mines.  More than 15 giant landslides surround the Hawaiian Islands. The slides are among the largest known on Earth, and current evidence indicates that large blocks of land on the island of Hawai'i are beginning to slide, generating large earthquakes in the process.

To learn more about landslides in Hawai'i, click on the following link:  http://landslides.usgs.gov/

Coastal Erosion

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage.  Coastal erosion and beach loss in Hawai‘i are caused by numerous factors, most of which are poorly understood or poorly quantified. In general, these factors fall into three categories: (1) human impacts to sediment availability, (2) seasonal changes to waves and currents, and (3) long-term sea level rise.

Dramatic examples of coastal erosion, such as houses and roads falling into the sea, are rare in Hawai‘i; but the impact of erosion remains very serious. Coastal erosion is widespread and locally severe in Hawai‘i and other low-latitude areas.  Nearly one-quarter of the Hawaiian Islands' beaches have been significantly degraded over the last half-century, and all shorelines have been affected to some degree.

High Surf

High Surf is a condition of very dangerous and damaging waves ranging in height from 10 to 30 feet or more. These waves result from open ocean swell generated by storms passing far to the north of the islands, and conditions continue for a few days at a time.

In Hawai‘i, more injuries are caused by high surf than by any other coastal hazard.  Virtually all of Hawai'i's exposed coastal areas are vulnerable to high surf.  Typically, shorelines facing north, east, and west receive high surf during winter months. Shores facing southeast and southwest receive high surf during summer months.

Drought

Drought is defined as a deficiency of precipitation over an extended period of time, usually a season or more. Droughts are relative to the long-term average or normal balance between precipitation and evapo-transpiration (evaporation + transpiration) in a particular area. Drought is also related to the timing and the effectiveness of precipitation. Other climatic factors such as high temperatures, high wind, and low relative humidity are often associated with drought in many regions, including the Pacific basin.

Deficient rainfall amounts also reduce yields of crops such as sugar cane, which is one of the major economic bases for the region. Prolonged periods of drought also reduce soil moisture and deplete groundwater supplies.  Drought in Hawai'i has been a recurrent and troublesome problem, with rainfall totals reaching critically low levels. Severe droughts have occurred in Hawai'i in 1983-1984, 1996, and the winters of 1997-2001. Moreover, Maui County was designated a primary natural disaster area because of the drought from April-September in 2006.

Hazardous Materials (HAZMAT)

HAZMAT include hundreds of substances that pose a significant risk to humans. These substances may be highly toxic, reactive, corrosive, flammable, radioactive, or infectious.  Currently, over 380 chemicals are listed on the United States Environmental Protection Agency’s (EPA) list of Extremely Hazardous Substances (EHS).  HAZMAT in various forms can cause death, serious injury, long-lasting health effects, and damage to buildings, homes, and other property. Many products containing hazardous chemicals are used and stored in homes routinely. These products are also shipped daily via the nation's highways, railroads, waterways, and pipelines.

HAZMAT are most commonly defined as chemical substances that, if released or misused, can pose a threat to the environment or health. These chemicals are used over a broad range of industry, agriculture, medicine, research, and consumer goods; they come in many forms including explosives, flammable and combustible substances, poisons, and radioactive materials.

For more information on hazardous materials, click on the following link: http://www.epa.gov/oem/information.htm

Tsunami

A tsunami is a series of waves of extremely long wave length and long period, generated in a body of water by an impulsive disturbance that displaces the water such as an earthquake, landslide, or sub-marine volcanic eruption.  Tsunamis are primarily associated with the occurrence of earthquakes in oceanic and coastal regions. When an earthquake occurs, the energy generated travels outward in all directions from the source. 

Tsunamis potentially destructive to the State of Hawai'i may originate anywhere around the rim of the Pacific Ocean, or they may be locally generated by earthquakes on or near the islands. A tsunami produced by an earthquake on the coast of Chile will reach the Hawaiian Islands in about 15 hours, while one that originates in the Aleutian Islands will arrive in 4.5 to 5.5 hours. A locally generated tsunami gives much less warning; the waves may strike almost immediately after the earthquake occurs.

About 50 tsunamis have been reported in the Hawaiian Islands since the early 1800's. Seven caused major damage, and two of these were locally generated.  Because the speed of a tsunami depends entirely on the depth of the water, the arrival time of a wave from any point on the Pacific rim can be predicted.

The effects of each new tsunami, and the effects on different coasts of the same tsunami, vary greatly. The size and destructiveness of the waves at any particular site are largely determined by the local topography, both onshore and offshore, and the direction from which the wave approaches.

Volcano

There are several kinds of events caused by volcanic activity that can be harmful to life and property. These include lava flows, ash falls and debris avalanches.

Magma, which is molten rock that flows from the interior of the Earth to the surface is called lava. The higher the silica content of the lava, the thicker and stickier it becomes. Low-silica basalt lava usually flows faster because it is more liquid. It can flow as fast as 10-30 miles per hour (16-48 kmh) or spread out and cover vast areas of land up to a few miles wide.

Such basalt lava flows erupted at Kilauea Volcano on Hawai'i’s Big Island between 1983 and 1993, destroying almost 200 nearby homes and covering the coast highway on the island’s southeastern shore. As the lava flows down the volcano, it burns and buries everything in its path.

As they erupt, volcanoes also emit gases, of which the most common ones are water vapor, sulfur dioxide, carbon dioxide, hydrogen and hydrogen sulfide. Sulfur dioxide can react with water in the atmosphere and come down as acid rain, which causes corrosion and has a damaging effect on vegetation. Carbon dioxide can also be dangerous because it tends to collect in valleys where it can accumulate in toxic concentrations and cause people and animals to suffocate.

Hurricane

A hurricane is a type of tropical cyclone or severe tropical storm that forms in the southern Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern Pacific Ocean. Hurricanes can cause catastrophic damage to coastlines and several hundred miles inland. Hurricanes can also produce winds exceeding 155 miles per hour as well as tornadoes and mircrobursts. Hawai'i’s hurricane season runs from June 1 to November 30.

The potential for property damage in Hawai'i is increased because of the numerous lightly constructed buildings and dwellings.  Flying debris from these structures and airborne vegetation increases the possibility of serious damage to neighboring properties and utility lines. Hawai'i's topography funnels and amplifies the tropical cyclone winds across ridges and through island channels. The terrain in Hawai'i also focuses torrential rains on mountain slopes, resulting in destructive flash floods and landslides.

Earthquake

Earthquakes are sudden, rapid shaking of earth caused by breaking and shifting subterranean rock and release of strain that has accumulated over long periods of time.  Forty-five states and territories throughout the United States are at moderate to high risk for earthquakes.  Some areas of Hawai'i, particularly the Big Island, are more prone to earthquakes; others not as much.

If you find yourself in an earthquake, experts say you should drop to the ground, cover yourself with a strong supported object or structure (as in a doorway or under a strong table) and hold on until the shaking stops.

More information about earthquakes is accessible at the U.S. Geological Survey’s (USGS) Earthquake Hazards, Program website: http://earthquake.usgs.gov/earthquakes/?source=sitenav

Pandemic

Pandemics are illnesses that pose a threat to the health of living organisms, primarily that of humans and domesticated animals, including livestock. In humans, these can include seasonal illnesses, such as colds or influenza viruses, or more specific outbreaks, such as H1N1 or bird flu. In animals, this can
include a variety of illnesses, some of which are transmittable to humans.  Communicable disease outbreaks and pandemics will have the most immediate impact on life and health safety.

The extent of the impact will be contingent on the type of infection or contagion, the severity of the outbreak, and the speed at which it is transmitted. Property and infrastructure could be affected if large portions of the population were affected and unable to perform maintenance and operations tasks.

Flash Flooding

Hawai’i is at risk of flash flooding. Some floods develop slowly, while others such as flash floods can develop in just a few minutes and without visible signs of rain. Flash floods can occur within a few minutes or hours of excessive rainfall, or a dam or levee failure. Many flash floods have a dangerous wall of roaring water carrying rocks, mud, and other debris. These can also occur when rainfall exceeds the capacity of underground pipes or the capacity of streets and drains designed to carry flood water away from urban areas.

Do not enter or swim in flood water. The speed of the moving flood water is not the only danger. It is impossible to know with certainty what is in or under the surface of flood water. Any number of hidden risks from debris to chemical or sewage pollution may be present.  Even boating in flood waters should be avoided if at all possible.

Much information about flooding is accessible at the Pacific Disaster Center’s website:  http://www.pdc.org/iweb/flood.jsp?subg=1

Fire

Fire conditions arise from a combination of hot weather, accumulation of vegetation, and low moisture content in air and fuel. These conditions, especially when combined with high winds and years of drought, increase the potential for wildfires to occur. Three major factors sustain wildfires and indicate a given area’s potential to burn:  fuel, topography, and weather.

In Hawai'i, wildfires occur on all six major islands:  Kauai, Oahu, Molokai, Lanai, Maui, and Hawai'i (otherwise known as the Big Island).  Unlike the mainland United States, Hawai'i's ecosystem—like that of other Pacific islands—is not adaptive to wildfire. Humans are the number one cause of wildfires in the State of Hawai'i, and the number of wildfires is increasing. You can help improve the fire-fighting effort by making your property a place to effectively battle a blaze, and rendering your structure more easily saved.

Firewise offers a variety of brochures, checklists, and videos to educate homeowners, landscapers, designers, and builders on how to build and maintain a Firewise home. To learn more about protecting your home from wildfire, visit the following website: http://www.firewise.org/