PLATE TECTONICS CASE STUDIES

VOILCANIC ERUPTION CASE STUDIES

NEVADO DEL RUIZ - Columbia

 Context - On a subductive plate boundary at the subduction zone where the Nazca plate subducts beneath the South American plate. The volcano had been dormant for 69 years. Ash was ejected 30km into the atmosphere. The closest town was Armero

PREDICTION The authorities didn't believe the scientists, Hazard maps were produced by funding from the UN, showing that there was a 100% probability of mudflows and a great chance they would damage Armero. - Colombia couldnt afford their own investigation - outside aid Geologists in the area had been monitoring an increased frequency of earthquakes and minor gas explosions for over a year

IMPACTS  23,000 deaths 8000 injured, costed £700 million, loss of livelihood 30% croploss % livelistock loss, everything was covered in thick mud, 4th deadliest eruption on record

PROTECTION Before - no attempts to provide defences for local people, Red Cross ordered an evacuation at 7pm but it was called off after ash stopped falling After - limited supplies - Lahar channels are now built but due to a lack of funding 100,000 people are still at risk, Helicopters airlifted people to safety, US gave $1 million, Red Cross sent $4,650.

The lahars had a direct path to the town, by the channel formed by valleys. The volcano was covered by a glacier which was melted quickly by pyroclastic flows cuasing the rivers to be swollen

EYJAFJALLAJOKULL ERUPTION - Iceland

Iceland is located on the Mid Atlantic ridge which is constructive plate boundar. Second phase Eruption was explosive on 14th April 2010 - Ash was ejected over 8km into the atmosphere - VEI 4 - Eruption wasnt that explosive because of the basaltic lava

PREDICTION - It had a well thought out hazard management plan as Iceland has several eruptions every year

IMPACTS A thick layer of ash fell on the farm pastures which caused crops to fail in the short term, river levels rose as pasrt of the icecap melted, for 6 days flights in the airspace had to be stopped which coincided with the Easter Holiday period Costed airlines £2.5 billion,

RESPONSES - 800 people evacuated overnight, local people issued with face masks, resevoir used to hold meltwater, Met Office…