Primary and Secondary Effects
- Lahars killed 70% of Armero’s population 45km away.
- Lahars were as much as 40m thick and travelled at 50km per hour.
- Most killed by suffocation as lahars up to 8m buried them.
- Lahars killed 1,800 people in Chinchina.
- 3400 ha of agricultural land was lost.
- Infrastructure destroyed.
- Hot pyroclastic flows and surges caused rapid melting of snow and ice creating hot lahars.
- Region was isolated.
- Fifty schools and two hospitals damaged and destroyed.
- $7.7billion cost of the damage.
- Clean water in short supply.
- Mobility in the valley was limited.
Earthquakes
- Primary waves (P) – are body waves that pass through the earth along paths. P waves are compressional longitudinal waves similar to sound waves in which particles vibrate parallel to the direction of movement.
- P waves pass through solids, liquids and gases, and the velocity of P waves depend on density and resistance to compression of the medium it passes through.
- While, P waves will pass through the centre of the Earth, they will be refracted by the changing density of the mantle, outer core and inner core.
- This causes the wave to bend and helps explain the formation of the shadow zone. Shadow zones happen between P waves that have been refracted and a wave that hasn’t. S waves don’t have shadow zones as these are absorbed by the outer core.
Primary Effects of an Earthquake
- Buildings and bridges collapse.
- Infrastructure is destroyed.
- People are injured or killed.
- Damage to cables, water pipes etc.
Secondary Effects
- Businesses are destroyed leading to unemployment.
- Exposed gas pipes could cause potential fire.
- Lack of clean water.
- Spread of disease.
- People left homeless.
- Earthquakes can trigger landslides and tsunamis.