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Deadly Shadow of Vesuvius
Site Map

Volcanic Explosivity Index (VEI)
Description Volume of
Ejected
Material
Plume
Height
Eruption
Type
Duration Total
Eruptions
Given
this VEI
Example VEI
Non-
Explosive
variable <100m Hawaiian variable 699 Kilauea
(1983 to
present)
0
Small <.001 km3 100-
1000m
Hawaiian/
Strombolian
<1 hr 845 Nyiragongo
(1982)
1
Moderate .001-.01 km3 1-5km Strombolian/
Vulcanian
1-6 hrs 3477 Colima
(1991)
2
Moderate/
Large
.01-.1 km3 3-15km Vulcanian/
Plinian
1-12 hrs. 869 Galeras
(1924)
3
Large .1-1 km3 10-25km Vulcanian/
Plinian
1-12 hrs. 278 Sakura-Jima
(1914)
4
Very
Large
1-10 km3 >25 km Plinian/
Ultra-Plinian
6-12 hrs. 84 Villarrica
(1810)
5
Very
Large
10-100 km3 >25 km Plinian/
Ultra-Plinian
>12 hrs. 39 Vesuvius
(79 AD)
6
Very
Large
100-1000 km3 >25 km Ultra-Plinian >12 hrs. 4 Tambora
(1812)
7
Very
Large
>1,000 km3 >25 km Ultra-Plinian >12 hrs. 0 Yellowstone
Caldera
(2 million
years ago)
8


Rate the Eruption
  1. Read the description below.

  2. Click on each category and select an entry that's closest to the description.

  3. When you're ready to select a VEI number, scroll up to review the VEI Chart above. Then select a VEI and click to see if you're right.

Description:
Volume of Ejected Material:
Plume Height:
Eruption Type:
Duration:
When you're ready, select a VEI: 0  |   1  |   2  |   3  |   4  |   5  |   6  |   7  |   8



Eruption Observations
What began as a quiet morning suddenly took a violent turn. At 8:32 a.m. a strong earthquake shook the Earth, triggering an avalanche and tearing the volcano apart. The volcano's bulge and summit suddenly began to slide and collapse, setting off powerful explosions. Rocks, ash, volcanic gas, and steam were blasted outward. The blast flattened whole forests.

This lateral blast continued for two minutes and then stopped. Moments later the volcano began to erupt upwards. An eruptive plume of ash rose more than 25 kilometers into the sky. Winds blew the ash eastward. Lightning, generated by the swirling ash, set off forest fires. The Plinian eruption continued until about 5 p.m. During that time, nearly 540 million tons of ash fell over an area of over 57,000 square kilometers. The total volume of uncompacted ash was about 1.25 cubic kilometers—enough to fill a football field about 240 kilometers high with fluffy ash.

Around noon, the volcano began giving off flows of pumice and ash, like a "pot of oatmeal boiling over." These flows lasted for the next five hours. Mudflows also started, sweeping down the volcano slopes, surging over hills, and causing destruction to the areas below.

By early the next morning, most activity of this very large eruption ceased. The sun rose to reveal a volcano that had changed in many ways—most dramatically, it was 1,313 feet (400 meters) shorter than it had been the morning before.



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