The most dangerous part of a volcano is the eruption of debris
and lava. The main hazards are: causing casualties; destroying
houses, farmland, roads and bridges; blocking rivers and flooding
them; may cause disasters such as earthquakes, tsunamis, landslides
and debris flows; affect the global climate; destroy the environment.
Volcanic ash, lava flow, pyroclastic flow and volcanic debris flow,
earthquake and tsunami associated with volcanic eruption can cause
huge disasters, even long-term disaster consequences, cause global
climate change, and lead to large-scale regional famines. According
to statistics, about 50 to 65 volcanoes erupt every year in the world,
posing a serious threat to human life. Since the 1920s, in order to
prevent and mitigate volcanic disasters, many countries have carried
out monitoring and research on volcanic activities, predicted volcanic
disasters and adopted corresponding countermeasures for disaster
prevention and mitigation.
The main hazards of volcanic eruption are as follows:
Volcanic eruptions present a wild side of nature. An erupting volcano
may spew hot red lava streams or emit large quantities of ash and
volcanic gases. Such a natural catastrophe could cause thousands
of casualties. Volcanic eruptions are often accompanied by massive
gas ejections. Some volcanoes give out enough toxic gases to kill
people. In August 1986, when the Nyworth volcano erupted in Cameroon,
more than 1700 people died fromlarge quantities of harmful gases
such as carbon dioxide emitted by the volcano.
The combination of volcanic ash and torrential rain from volcanic
eruptions can destroy roads and Bridges, inundate nearby villages
and cities, and leave millions homeless. Mud from debris of soil
and rock can flood the whole city.
Iceland's Eyjafjallajokull volcano erupted on a massive scale in
April 2010, ash forced many European airports to close and the
aviation industry was badly hit. European Airlines suffered a 7% drop
in traffic in April as a result of volcanic ash. Iceland's volcanic
ash crisis has cost the global aviation industry $1.7 billion.
Indonesia's Mount Merapi has erupted several times since October 26, 2010,
tens of millions of cubic meters of gas, gravel and ash plume washed up
thousands of meters into the air, affected by volcanic ash, many aviation
operations were affected.
Volcanic ash can drill into parts of aircraft engines block the engine,
causing all sorts of damage.