VEI 5 - Mount Pinatubo 0.0 / 5 ? GeographyCase studiesASNone Created by: Pho3b301Created on: 10-03-17 21:12 VEI 5 - Mount Pinatubo Luzon Island, Philippines Philippines plate subducting under Eurasian plate USA has huge military presence in the area - 2 big US airbases close by June 15th 1991 Eruption: Triggered by Rizal City Earthquake (6.8) in 1990 Not many died, mostly local tribesmen USGS predicted eruption & managed eruption USGS evacuated everyone Pyroclastic flows Explosions rocked volcano - many tribes fled 3 explosion craters, 4 columns of steam Seismometer - 400 earthquakes in 2 days Early may - 7 sites of studying volcano 5 miles below surface, Measure SO2 levels (5000 tonnes per day) suggesting rising magma June 7th - Level 4 alert after frequent earthquakes - everyone within 12 miles evacuated, 120,000 left for temp homes 1 of 4 VEI 5 - Mount Pinatubo Visible molten rock Early June - summit gave way, resulting in pyroclastics Pyroclastics changed direction & killed 43 people Lava dome observed Eruption occured 48 hours after air base was evacuated Lahars carried on for years after 2 of 4 VEI 5 - Mount Pinatubo Lahars: 40mph/65kmh Travel 50 miles + Contain as much as 90% of debris Annual rainfall at Pinatubo is 80inches to 160 inches Destroyed vegetation that was on the volcano Transported & deposited tens of millions of cubic yards of mud in a single day / 35,000cubic ft of debris & mud per second 30 feet deep Damming of stream channels & tributary valleys by 1991 ash deposits or by subsequent lahars, creating temporary lakes Civil engineers tried to trap sediment behind small damns & confine it between levees (too small to contain lahars) Base of volcano - lahars erode city blocks Lowlands - inundated & buried entire towns Destroyed 100,000 homes 3 of 4 VEI 5 - Mount Pinatubo By 1995 - volume of material carried by Pinatubo's lahars had decreased to less than 1/4 New towns built on high ground Near system warning to monitor activity has been put in place Preliminary hazard map 4 of 4
Comments
No comments have yet been made