Good morning class, today I will be doing my presentation on volcanoes.
So, what is a volcano
A volcano is an opening on the surface of a planet that allows material warmer than its surroundings to escape from its interior. When this material escapes, it causes an eruption. An eruption can be explosive, sending material high into the sky. Or it can be calmer, with gentle flows of material.
These volcanic areas usually form mountains built from the many layers of rock, ash or other material that collect around them. Volcanoes can be active, dormant, or extinct. Active volcanoes are volcanoes that have had recent eruptions or are expected to have eruptions in the future. Dormant volcanoes no longer produce eruptions, but might again sometime in the future. Extinct volcanoes will likely never erupt again.
How is a volcano formed?
On Earth, the erupted material can be lava, ash, cinders, and/or gas. There are three reasons why magma might rise and cause eruptions onto Earth’s surface.
Magma can rise when tectonic plates slowly move away from each other. The magma rises up to fill in the space. When this happens underwater volcanoes can form.
Magma also rises when these tectonic plates move toward each other. When this happens, part of Earth's crust can be forced deep into its interior. The high heat and pressure cause the crust to melt and rise as magma.
The final way that magma rises is over hot spots. Hot spots are hot areas inside of Earth. These areas heat up magma. The magma becomes less dense. When it is less dense it rises.
Pros and cons of volcanoes on the environment and humans:
Create new islands and land.
Provide habitat to pioneer species.
Create economic mineral deposits.
Create beautiful landscapes.
Destroy old habitat and crops.
Destroy cities, towns, communities.
Kill people and other animals.
Krakatoa (Gunung Krakatau) is a volcanic island between Java and Sumatra. The eruption of mount Krakatoa in August 26-27 in 1883 was among the most violent volcanic events in modern and recorded history. The eruption was equivalent to 200 megatons of TNT—about 13,000 ti...