Plate Tectonics

At a plate boundary:

• divergent/ constructive margins where the crust is pulled apart and a magma 'plugs' up the gap, forming underwater volcanoes
• after serval eruptions, the volcanoes can break the ocean surface to form islands

At a plate boundary:

• Covergent/ destuctive margins where slabs of crust move towards each other
• the denser oceanis crust subducts
• as it is forced into the mantle, friction and increasing heat causes the rock to melt
• as it is hotter, the magma is forced upwards from a magma chamber, exploiting a weakness in the rock and erupts as a volcano

Volcano: Formed by material from the mantle being forced through an opening in the earths crust called a vent.

Prediction of Volcanic Eruptions

• GPS- bulging volcano
• Gas sampling- sulphur!
• Geothermal monitoring- form space
• Seismic monitoring- tremors proir to eruption
• Historical records- can you predict when the next is likely to go
• EG... Popacatapetl, Mexico 2000- successfully predicted due to detecting small tremours

Preventing Volcanic Eruptions

• Spraying lava to cool it down
• Concrete blocks or barriers to divert the flow of lava
• Setting off explosions to divert lava flow
• Digging Ditches
• EG... The Village of Zafferana, Sicily was saved in 1991-1993

Prediction of Earthquakes

• Noting animal behaviour
• Increased electrical dischange prior to a quake
• Recording/ monitoring foreshocks
• BUT USUALLY LITTLE WARNING

Prevention of Earthquakes

• Providing education to the population about what to do in an emergancy
• Have an emergancy kit ready
• Designing 'earthquake' proof building ( eg counter balances; rubberised foundations; fexible steel frames)
• Planning regulations

• Natural resources (tin, silver, copper, gold -> mining=jobs)
• Geothermal energy (eg Iceland)
• Fertile soils for farming
• Low ricks of eruption
• Tourism
• Family and friend are there
• Earthquake proof building
• Evacuation/Disaster Plans 
• Low chance
• Wortht the risk
• Well-established (eg San Franciso)