Primary and secondary impacts of volcanoes

Primary impacts:

• Buildings and roads are destroyed by lava flows and pyroclastic flows - buildings also collapse if enough ash falls on them. 
• People and animals are injured or killed, mainly by pyroclastic flows but also by lava flows and falling rocks.
• crops are damaged and water supplies are contaminated when ash falls on them.
• People, animals and plants are suffocated by carbon dioxide.

Secondary impacts:

• Mudflows…