Volcanoes Flashcards
Where is Mount Pinatubo located?
Luzon, The Philippines
Which kind of plate boundary does Mount Pinatubo lie on?
Destructive, where the dense oceanic crust of the Philippines plate is subducted below the less dense continental crust of the Eurasian plate
How many active volcanoes are there in The Philippines?
Over 30
When was Mount Pinatubo’s last eruption (before case study)?
1380
What were the slopes of Pinatubo used for?
An indigenous group called the Aeta use the land for subsistence farming as the soil is fertile
What points of interest are there near Pinatubo?
The rapidly growing city of Angeles, a US air base and a US naval station
How close is the US naval station to Pinatubo?
The station is 50 miles south of the volcano
When did Pinatubo first show signs of erupting?
Early June, giving authorities time to evacuate thousands from Angeles and 15,000 personnel from the US air base
What happened to Pinatubo’s eruptions after June 9th?
They increased in size and number
On what date did Pinatubo erupt majorly?
12th June 1991
What was the main characteristic of Pinatubo’s eruption?
A 30km cloud of ash and steam
Which eruption was the third largest of the 20th century?
Pinatubo
After one month Pinatubo’s ash cloud had circled the Earth, causing…
Increased ozone destruction and lowering of global temperatures; it may have delayed global warming by several years
After the eruption of Pinatubo, over 10 cm of ash fell over what distance?
600 km radius
What affect did the ash have on communities in the Philippines?
All nearby crops were destroyed, 200,000 homes collapsed under the weight (as well as a hospital)
How many people died as a result of the Pinatubo eruption, and what were the main causes?
Around 700; over 600 from disease, 70 from suffocation, six as a direct result of the eruption
Why did disease spread so quickly after the Pinatubo eruption?
Farmers and their families had to take refuge in shanty-type refugee camps
Define pyroclastic flow/surge?
A high density mixture of hot, dry rock fragments and hot gases that move away from the volcano at high speeds
How do pyroclastic flows move?
As a basal flow of coarse material that moves along the ground, destroying everything it its path, and a turbulent cloud of ash that may leave a layer of ash for miles around
What are lahars?
Mass movements of rock fragments and water that flow down slopes and river valleys after a volcanic eruption
How many people were displaced due to lahars after the eruption of Pinatubo?
50,000; sediment was deposited by rain induced lahars
What was the name of the volcano that erupted on Montserrat in 1997?
Soufriere Hills
What kind of plate boundary does Montserrat lie on?
Destructive; where the oceanic crust of the North American plate is subduction below the Caribbean plate
When did Soufriere Hills become active?
1995, after 300 years
In what ways was/wasn’t Montserrat prepared for a volcanic eruption?
There was no activity on record so most people were unprepared, the economy relies on tourism and farming, no monitoring of the volcano; however people in the capital Plymouth were evacuated in 1995 due to pyroclastic flows and mudflows
When was the major eruption of Soufriere Hills?
June 25th 1997
What were the main characteristics of the Soufriere Hills eruption?
9km eruption column, pyroclastic flows killing 19 people
What effe to did pyroclastic flows have on Montserrat?
Plymouth and other settlements destroyed (covered in ash and abandoned), island’s only airport destroyed,
What were the immediate responses after the Soufriere Hills eruption?
£41 million in aid, 7,000 people evacuated by HMS Liverpool to neighbouring islands or UK
What were the long term responses to the Soufriere Hills eruption?
Southern two thirds of island became exclusion zone, Montserrat Volcano Observatory set up, services expanded in north of island, new airport in 2005, tourism focused on scientists
How many people were evacuated from the area around Pinatubo?
200,000
What were the immediate responses to the Pinatubo eruption?
Manila airport closed, refugee camps, disaster relief from NGOs
What were the long term responses to the eruption of Pinatubo?
New houses built on stilts to protect from lahars, monitoring of volcano
Where is the Nevado del Ruiz volcano located?
Colombia
What plate boundary does Nevado del Ruiz lie on?
Destructive; oceanic Nazca plate subducting under continental South American plate
When did the Nevado del Ruiz volcano erupt?
13th November 1985
When was the last eruption of Nevado del Ruiz (before case study)?
1916, there was very little pre activity to warn of the 1985 eruption as well
Why were the people of Armero not prepared for the eruption?
The Colombian government had been warned about it, but they chose not to evacuate people, hazard map created but not distributed
What were the long term responses to the Nevado del Ruiz eruption?
Warning and evacuation plan established, public campaign in schools, Red Cross circulated fliers about evacuation warning sirens
Where is Mount St Helens located?
Washington state, USA
What date did Mount St Helens erupt?
18th May 1980 after an earthquake caused the collapse of the swelling north face
How many people died in the eruption of Mount St Helens?
57, mainly sightseers; included USGS geologist and photojournalist for USGS and National Geographic
How was the built environment affected by the Mount St Helens eruption?
200 houses and 47 bridges destroyed, along with roads and railway lines
What was the effect of the Mount St Helens eruption on industry?
Timber destroyed, crops buried, 12 million salmon killed, tourism decreased in the short term
When was the last eruption of Mount St Helens (before case study)?
1857
What were the main characteristics of the Mount St Helens eruption?
24km eruption column, lahars from melting ice cap, 2 mile wide crater formed, 300mph lahars, lateral blast, pyroclastic flows
How was the Mount St Helens monitored before the eruption and how is it monitored now?
Tilt metres and seismographs, vent search on foot, laser reading; satellites would now be used as they are safer, gas levels continually monitored, robots in craters
What effect did the pyroclastic flows have on the environment in Washington?
3000 acres of forest set on fire
What effect did the lahars have on the environment in Washington?
Flooding as rivers burst banks
What pre activity was recorded at Mount St Helens?
4.2 mag earthquake on 20th March signalled activity, first eruption on March 27th, glaciers collapsed into crater, swelling north face (a mile), lowest number of earthquakes in May on 17th, 5.1 mag earthquake caused eruption
What pre activity did scientists pick up on in Colombia?
Earthquake storms
Why were lahars created in Colombia?
The volcano was snow capped; a tenth of the cap melted, amounting to billions of tonnes of ice
What happened to many children in Armero?
They were taken by relief agencies and never seen again
How many people were trapped in mud, but still alive, in Armero?
1,000, most of whom could not be saved due to rescue teams lacking vital tools; planes coming into the area brought journalists, politicians and the military instead of supplies
When did equipment finally arrive in Armero?
3 days after the eruption
How many people died in the Armero tragedy?
23,000, of which 20,000 were from Armero (population 29,000)
