1. Management of volcanoes
Management strategies generally fall into 3 categories:
Prediction
Prevention / Protection
Preparation
The 3 Ps

2. Prediction

3. Prediction worked in the Philippines
Aggressive monitoring and public information campaigns did their job according to the director of PHIVOLCS.
A big part of the success in this instance was due to timing – there was a steady escalation and build up which gave people enough time to react (this isn’t always the case) – if the eruption is very drawn out people will become impatient and then less likely to listen to final warnings.
20 years on, monitoring of the volcano is much more simple due to technological advances- the internet allow scientists in the Philippines to consult scientists in the US, GPS and radar satellites make it possible to measure changes in the ground.

4. Prevention / Protection

5. Building design to prevent damage
After studying building affected by ash after the Pinatubo eruption it was found that:
Wet ash remained on roofs with up to a 25° pitch
Buildings tended to suffer worse damage if they had a roof span of over 5 metres
Wooden framed building were affected worse than concrete structures
New buildings have therefore been designed with narrower span roofs with steep pitches using materials such as metal for the roof as this will allow ash to shed more easily
In Mt Sakurajima in Japan, 10,000 people live around this popular tourist island.
Volcano shelters have been built that will withstand a direct hit from a 50kg volcanic bomb

6. Eldfel volcano – Heimaey (Iceland) 1973
In Jan 1973 the volcano erupted, after the inhabitants of the island were evacuated the authorities turned their attention to protecting the houses and the harbour (essential to the economy of the island).
Firefighters used sea water to spray the front of the lava flow - 32 pumps (each spraying up to 1000 litres per second) were used which after 3 months saved 2/3 of buildings in the main town and stopped the lava 100 metres from the harbour entrance.
In some causes, prevention is possible but is very reliant on the nature of the eruption.

7. Lahar protection in the Philippines
For the protection and rehabilitation of lahar-threatened areas in Central Luzon, a 24-kilometer “Megadike”was constructed in 4 months to protect Bacolor. The megadike served as a defence of the vulnerable areas against rampaging lahars during the 1996 rainy season.
Mt Pinatubo

8. Lahar warning systems
USGS scientist installing a lahar warning system on the flanks of Mt Pinatubo - Radiotelemetered rain gauges provide data on rainfall in lahar source regions, acoustic flow monitors on stream banks detect ground vibration as lahars pass, and manned watchpoints further confirm that lahars are rushing down Pinatubo’s slopes. This system has enabled warnings to be sounded for most but not all major lahars at Pinatubo, saving hundreds of lives.
Warnings are announced over the radio, through local authorities, or, in symbolic form, through the sound of gunshots and the pealing of church bells.
This warning sign is from New Zealand.

9. Preparation

10. Public preparedness
Around Mt Sakurajima in Japan, school children have to wear hard hats as part of their school uniform due to the frequent risk of volcanic debris

11. More reading…

12. To what extent can prediction, protection and preparation mitigate volcanic hazards?