Chemical releases associated with cyclones

Overview

Cyclones can be hundreds of kilometres wide and can bring destructive high winds, storm surges, inland flooding, lightning and, occasionally, tornadoes. A storm surge is the abnormal rise of water generated by strong winds. Storm surges and battering waves can cause extensive damage along the affected coastline. In addition, a storm surge can travel several kilometres inland along rivers and estuaries.

Cyclones can result in a chemical release in a variety of ways. High winds and tornadoes can directly damage buildings and structures at chemical installations by tipping over storage tanks and dislocating piping and connections between storage and processing units. Such high-force winds may also launch objects such as tree branches and rooftops into the air and into storage vessels and pipework. Gaseous toxic chemicals released from punctured or ruptured storage tanks can be blown over populated areas or can dissolve in rainwater to produce toxic or corrosive rain. Flooding of internal plant drainage systems may release waste oil or other chemical waste if not segregated from surface water drainage systems.

The released chemicals can mix and react with the water, potentially generating toxic reaction products or a fire or explosion hazard. When flammable hydrocarbons are released into the floodwaters, ignition can result in pool fires. These are buoyant flames above a horizontal pool of vaporizing hydrocarbon fuel and can carry a fire to new sources of flammable materials or into residential areas. They are a particular risk at storage depots or refineries for petroleum products.