In order to assess the influence of volcanic eruptions upon the atmosphere, the volcanic explosivity index is used (VEI). This index defines the eruption force of the volcano on the assumption of volume of the erupted products (tephra) and the height of ash column.
Range of changes: from zero - for the eruptions, with the emission volume of less than 10 thousand m³ (104 m³), to eight - for the eruptions, emitting into the atmosphere more than 1,000 cubic kilometers (1,012 cubic meters) of ash and ash column of more than 25 km in height.
The eruptions with VEI magnitude of 6 and more can cause the effect of volcanic winter - marked fall in temperature on a planetary scale.
Figure 1 - Connection of VEI with the emission volume into the atmosphere.
Table 1 - Activity of supervolcanoes.
|Name||VEI||Continent||Country||Location||Last eruption||Last activity||Status|