How much time have we got to evacuate the city after sighting the first
sign of eruption?
Dear Reader,
You ask a very general question. So, I'll give you a very general
answer. Local authorities might have hours to months to evacuate a
city. It depends on many different events and factors. Some of these
include distance from the volcano to the city, steepness of the volcano,
type of eruption (Strombolian, Plinian, etc...), type of volcanic
material (lava or pyroclastic), composition of material (basalt or
rhyolite), conditions as the volcano starts to erupt (many changes in a
short time period or slow a gradual changes), atmospheric conditions
(wind speed and direction), availability of geologists to assess the
volcano, ability of geologists to convey information to local
authorities, ability of local authorities to react to the crisis and
convey information to public, ability of the public to react to the
crisis and evacuate the city, and infrastructure of the city (number and
size of highway, etc...).
If you have a specific city in mind you might write us again.
Steve Mattox, University of North Dakota