1. Volcanic Eruptions have primary and secondary impacts
The primary impacts of a volcanic eruption are the immediate effects of a volcano
spewing out lava, ash, rocks and gas (e.g. carbon dioxide and sulphur dioxide) as well as
pyroclastic flows. The secondary impacts are the effects that happen later on.
Primary impacts Secondary impacts
1) Buildings and roads are destroyed 1) Mudflows (also called lahars) form
by lava flows and pyroclastic flows when volcanic materials mixes with
– buildings also collapse if enough water, e.g. from heavy rainfall or
ash falls on them. snow melt. Mudflows cause loads
2) People and animals are injured or more destruction, deaths and
killed, mainly by pyroclastic flows injuries.
but also by lava flows and falling 2) Fires are started by lava flows and
rocks. pyroclastic flows, which then
3) Crops are damaged and water spread
supplies are contaminated when 3) People may suffer psychological
ash falls on them. problems if they knew people who
4) People, animals and plants are died or if they lose their home
suffocated by carbon dioxide. etc.
4) People are left homeless
5) There’s a shortage of food
because crops are damaged.
6) There’s a shortage of clean water
7) Roads are blocked or destroyed so
aid and emergency vehicles can’t
get through.
8) Businesses are damaged or
destroyed, causing unemployment.
9) Sulphur dioxide released into the
atmosphere causes acid rain.
This was the city of Plymouth in
Montserrat (a poorer country) – it was
buried under ash and mud after a
volcanic eruption