344 Lightning-caused Deaths and Injuries in the Vicinity of Trees

Monday, 7 January 2013
Exhibit Hall 3 (Austin Convention Center)
Ronald L. Holle, Vaisala, Inc., Tucson, AZ
Manuscript (114.2 kB)

A number of case studies have described the impacts of lightning on trees. The present study appears to be the first to summarize the impacts of lightning on people in the vicinity of trees for a large sample. Among the 444 events, single-person events were most common. Some events had up to 60 injuries; multiple injuries were more common outside the U.S. Most victims were male, and the most frequent age range was between 11 and 20. There was a dominance of afternoon events between noon and 1800 local time.

The activity of people who became lightning casualties in the vicinity of trees was divided into two groups: 1)The first group occurred when people stopped their activity and sought shelter in the vicinity of trees. In this group, non-U.S. casualties were most often engaged in agriculture, while the U.S. group was dominated by people in team sports and on a golf course. 2)The second group occurred when people had not stopped their activity while in the vicinity of trees. People standing or walking comprised most of these events.

The location of people was determined to be dominated by those under and near trees. Quite a few reports included a description of the probable path by which lightning reached the person. The most common situation was for one object to be in the path from a tree to a person, such as a tent, hammock, or shed. Nearly as many events involved two objects in the path, such as a pump house being hit, then the lightning's effects went through pipes to the person. In a few cases, lightning first hit an object such as a utility pole, then hit a tree, then reached the casualty.

The distance from trees was found from reports when they were explicitly provided. The three fatalities with clearly-identified distances involved trees between one and seven meters away from the person. Injuries ranged up to 100 meters away, but most were between 1.5 and 10 meters away. The mechanism of injury was often difficult to identify, but ground current appeared to be evident most often, followed by side flash and blunt trauma, and occasionally from direct contact with a tree.

Several narratives described precautions taken by people which were thought to provide safety in a forest. A general conclusion is that any configuration of trees may result in a path from lightning to a tree to a person, including under or near a single tree, as well as in a forest or woods.

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