A hybrid disaster occurs when a natural or man-made hazard causes increased damages as a byproduct of anthropogenic actions. For example, clear cutting in a rain forest increases the vulnerability of nearby villages to flood by removing the vegetation that previously helped absorb rain water. Dr. Igor Boyarsky and Dr. Amiram Shneiderman identified two main causal types of hybrid disasters in their 2002 paper, "Natural and Hybrid Disasters—Causes, Effects, and Management": technical failure and sabotage.
The obvious cause of a hybrid disaster due to technical failure stems from a failure or fault in construction or design, but the root causes are often political and social choices that increase societal vulnerability. A sub-type of technical failure, the na-tech disaster, occurs when a natural hazard causes the release of a hazardous material into the environment.
Technological Failure Examples
If a tornado upturns a mobile home, resulting in deaths, then the technological fault lies in the lack of foundation and tie downs, but the root cause stems from the municipality's lack of ordinance requiring each mobile home have a foundation and tie downs, and further, zoning to allow mobile homes in a tornado prone area. The 1994 Northridge, CA earthquake provides a good example of a na-tech disaster. The earthquake caused ruptures to petroleum pipelines, natural gas line breaks and the release of sulfuric acid when a train derailed.
A hybrid disaster caused by sabotage may be serendipitous or deliberate, but ultimately equates to a weapon of war, according to Dr. Ilan Kelman, Senior Research Fellow at the Center for International Climate and Environmental Research, Oslo. Besides violent conflict, sabotage may also be used to damage a business or government operation or project.
According to Kelman, in the past Russia has used serendipitous sabotage by incorporating its winter weather into defense strategies when invaded. The Dutch have used deliberate sabotage as a defense strategy by breaching their own dikes to flood the invading force. More modern examples include induced earthquakes and biological warfare.