I was wondering why the wood did not burn when Mt. St. Helens eurpted? and if it did why does it not look like it did?

Carol Rushmore

There was certainly some wood that burned during the eruption, but much of the damage that you see from most of the visitor centers is not burned (as you observed). A lot of the damage that you see was caused by horizontally-directed pyroclastic surges and flows, and some of these passed through so quickly that they didn't have a chance to ignite the trees. They certainly were strong enough to blow down the trees though. The eruption occurred in May so the trees were probably pretty moist, having had plenty of snow the winter before. In order to cause a big tree to catch fire you need to expose it to heat for a long time (especially if it isn't dried out). These pyroclastic blasts and surges whipped through in only a few minutes in places, and therefore couldn't ignite the trees.

Sincerely,
Scott Rowland

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