Hurricanes and Tornadoes
A hurricane is a type of tropical cyclone, which is a generic term for a low‐pressure system that generally forms in the tropics. It is an intense tropical weather system of strong thunderstorms with a well‐defined surface circulation and maximum sustained winds of 74 miles per hour (119 km/h) or greater. Sustained winds are defined as a one‐minute average wind speed measured at about 33 feet above the surface. Hurricanes are categorized according to the strength of their winds. A category 1 hurricane has the lowest wind speeds, while a category 5 hurricane has the strongest. These are relative terms, though, because lower‐category storms can sometimes inflict greater damage than higher‐category storms, depending on where they strike and the particular hazards they create. Tropical storms can also produce significant damage and loss of life, typically due to flooding.
A tornado is a violently rotating column of air that is in contact with both a cloud base and the surface on the earth. Tornadoes come in many sizes, but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris. Most tornadoes have wind speeds of about 110 miles per hour, are approximately 250 feet (75 m) across, and travel a few miles before dissipating. Some attain wind speeds of more than 300 miles per hour (480 km/h), stretch more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 km).
The IMP is designed to provide immediate response measures for company facilities and personnel to reduce the risks and impacts presented by hurricanes and tornadoes. Facilities located in areas with a history of severe weather conditions may install permanent storm shutters to offer protection for windows. Alternatively, boarding up windows offers an emergency solution. Surrounding trees and shrubs should be well trimmed to prevent debris from damaging the property or personnel, and loose and clogged rain gutters and downspouts should be cleared. The company may designate a safe room and stock such a facility with a disaster supply kit—water, nonperishable food, medications, and lighting.
During a hurricane or tornado, personnel should avoid windows, skylights, and glass doors, as debris and strong winds may shatter such structures. Personnel should move to a safe area, such as an interior office, a closet, or a bathroom on the lower level of the facility. In case of flooding, electricity should be turned off at the main circuit breaker. If the facility loses power, major appliances should be turned off, such as the air conditioner and water heaters, to reduce damage. Personnel should not leave a safe location when in the eye of a hurricane, but must wait until the storm has passed over, since there will be a short period of calm, followed by a rapid increase in wind speed from the opposite direction.
Following a hurricane or tornado, personnel should remain indoors until official notifications have been issued indicating that it is safe to leave the property. Personnel should be advised not to touch fallen or low‐hanging wires and to stay away from puddles with wires in or near them. Many of the same conditions resulting from floods or earthquakes will be prevalent, with weakened structures, contaminated water, and a loss of social infrastructures. The IMP should provide guidelines to local managers and incident response groups so that they can prepare for pending hurricane and tornado events, limit the danger to personnel and facilities during the crisis, and recover safely once the storm has passed to safe areas or emergency muster points designated by government authorities.
A volcano is a mountain that opens downward to a reservoir of molten rock below the surface of the earth. When pressure from gases within the molten rock becomes too great, an eruption occurs. Eruptions can be either quiet or explosive; there may be lava flows, flattened landscapes, poisonous gases, and flying rock and ash. Because of their intense heat, lava flows create significant fire hazards and can destroy all structures in their paths. Typically, lava flows are slow moving, and personnel can move out of their way. Ash flows can occur on all sides of a volcano, and ash debris can fall hundreds of miles downwind of the volcano. Dangerous mudflows and floods can occur in valleys leading away from volcanoes, striking with little warning. Typically, mature crisis management plans are in place for projects operating within the shadow of a volcano. The IMP plays an important role in the first actions taken during an eruption, enabling personnel to deal with the common risks that accompany volcanic eruptions, including:
§ Earthquakes and tsunamis
§ Mudflows and flash floods
§ Landslides and rockfalls
§ Ashfall and acid rain
During a volcanic eruption, personnel should try to leave the affected area using an established evacuation plan (if advised by authorities), avoiding downwind areas and river valleys downstream of the volcano. If caught indoors, personnel should close all windows, doors, and dampers; put all machinery inside a garage or barn; and bring all animals and livestock into closed shelters. If personnel are outdoors, they should seek shelter indoors as quickly as possible. If subjected to ashfall, personnel should seek protection by wearing long‐sleeved shirts and long pants, goggles to protect vision, and a damp cloth to assist with breathing.
Following a volcanic eruption, personnel should stay out of an affected area, as the effects of a volcanic eruption can be experienced many miles from the main event, including mudflows, flash flooding, forest fires, and high‐temperature ash flows. When safe to do so, roofs should be cleared of ash, as it can result in structural collapse. The IMP should be designed to provide guidance if a volcanic eruption is imminent so as to enable managers to make the determination whether to evacuate or to remain in place, and help them reduce the possible risks associated with falling debris and other associated hazards. The employment of mature crisis response plans should quickly follow a volcanic eruption.
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