Volcanoes
Volcanoes are a landform that we commonly see. They are formed
from eruption of hot magma, which is a kind of molten liquid
silicate, streaming deep beneath earth’s crust. The crust of some
places on the earth is thinner than other places. The magma will
erupt from certain places because of high temperature and pressure.
Volcanoes have different types, which can be divided into
“extinct volcanoes”, “dormant volcanoes” and “active volcanoes”.
Extinct volcanoes retains the shape and material of volcanoes.
However, they have never been active in human history. These
volcanoes are the most widely distributed in the world. Dormant
volcanoes indicate that volcanoes have been active during human
history. However, they are in “Dormant” states right now. They will
erupt with sudden movements in the crust. Active volcanoes are
volcanoes which still active today. Currently, there are about 500
active volcanoes in the world (Decker, 1991).
Volcanoes in the world are diverse and their outbreaks are
different. The Tambora volcano on the island of Son Bagua, Indonesia
is a “tempered” volcano. When it erupted on April 5, 1815, the
explosion shook the island of Sumatra, which was 1600 kilometers
away. Smog dust blocked the sunlight and among the 480 kilometers
range. This outbreak lasted for more than three months. It ejected
