Скачать или смотреть FORMATION OF A MAAR

A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow crater lake, which may also be called a maar. Lake Simbi is an example of such a lake.

1. Magma rises to the surface.
2. It intrudes water-saturated rocks beneath the surface.
3. Water is abruptly converted to steam - an explosion
4. The explosion pulverizes the surrounding rocks and shoots them upwards.
5. A funnel-shaped crater is formed.
6. Fine ash and steam produce an eruption plume.
7. The material falls back into the crater and its surroundings.
8. The falling material forms a ring lining the crater.
9. The crater fills with water - a lake is formed