This is a drawing of the 1631 eruption of Mt. Vesuvius.
Click on image for full size
Image courtesy of: Dr. Boris Behncke. Artist: Giovan Batista Passaro This account of the eruption of Mt. Vesuvius was modified from the Vesuvio website.
The ad79 Eruption of Mt. Vesuvius
Around 1:00 pm on 24 August a tall cloud of steam and ash rose above Mt. Vesuvius and debris began to fall. In the area around Pompeii the thickness of falling debris increased by 6 to 8 inches per hour.
The rocks which comprised the debris were up to 3 inches in diameter, and fell with a speed of up to 100 miles/hour. They may have caused injuries and isolated deaths, and should have, after a few hours, caused the collapse of roofs.
The city was soon covered in complete darkness, a phenomenon which is familiar to other populations involved in eruptions such as those at Mount St. Helens, and Mt. Pinatubo. The residents probably did not even know what kind of event was striking them, and waited in their homes, hoping that the shower of rock would sooner or later come to an end.
After 12 hours of continuous explosive activity, a change in the eruptive dynamics occurred. The mouth of the volcano widened such that local gas pressure could no longer push up the tall ash column. The mixture of gas and ash no longer rose up into the sky, but immediately fell back
onto the slopes of the volcano, forming glowing avalanches of hot flowing material (perhaps 800 degrees) which rushed rapidly down slope, destroying everything in their paths. This change in the eruption proved fatal to the thousands of people around the volcano. The Roman towns of Pompeii and Herculaneum were destroyed in a matter of minutes.
Pompeii and Herculaneum were rediscovered in the 18th century with many treasures intact. The reconstruction of these cities gives a vivid idea of what Mt. Vesuvius is able to do.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, as well as books
on science education!
You might also be interested in:
Ash is made of millions of tiny fragments of rock and glass formed during a volcanic eruption. Volcanic ash particles are less than 2 mm in size and can be much smaller. Volcanic ash forms in several ways...more
Cinder cones are simple volcanoes which have a bowl-shaped crater at the summit and only grow to about a thousand feet, the size of a hill. They usually are created of eruptions from a single opening,...more
Lava can move in broad flat lava flows, or it can move through tight channels or tubes. Lava flows tend to cool quickly and flow slowly. The fastest lava outside of channels moves at about 6 mi/hr an easy...more
Plates at our planetís surface move because of the intense heat in the Earthís core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when...more
Many kinds of surface features are clues that our lithosphere is sliding. Two types of features can form when plates move apart. At mid ocean ridges, the bottom of the sea splits apart and new crust is...more
Magma consists of remelted material from Earth's crust and fresh material from other regions near the Earth's surface. When magma is erupted onto the surface in the form of lava, it becomes silicate rock....more
As the Earth cools, hot material from the deep interior rises to the surface. Hot material is depicted in red in this drawing, under an ocean shown in blue green. The hotter material elevates the nearby...more