- Environmental impact of a  volcanic eruption

- Mt. St. Helens  5/18/80

- precursors = bulge and numerous small earthquakes
- earthquake and landslide triggered the eruption

Elements of the Eruption

- lateral blast

- tephra
 a) ash fall

 b) pyroclastic flow

- mud flows
 lahars

 - environmental risk for
 those not in the immediate
 vicinity of the volcano = MUD FLOWS
 

Stratovolcanoes

=> the geologic hazard…...

Direct Effects = property damage, loss of human life, etc.....=> from lahars

Indirect Effects = Climate Change

- Global climate change as a result of small volcanic events

- larger eruptions could be global catastrophes  - calderas