It is much more difficult to predict the end of an eruption than to predict its beginning. The table below gives the length of time that volcanoes erupt.
Explosive eruptions end when sufficient decompression is attained to cause magma chamber collapse and restoration of the initial pressure conditions.
Length of Eruption |
% of Eruptions |
Cumulative Total % |
< 1 day |
10 |
10 |
1 day to 1 week |
14 |
24 |
1 week to 1 month |
20 |
44 |
1 to 6 months |
28 |
72 |
6 months to 1 year |
12 |
84 |
1 to 2 years |
7 |
91 |
2 to 5 years |
5 |
96 |
5 to 10 years |
2 |
98 |
10 to 20 years |
1 |
99 |
> 20 years |
1 |
100 |