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Anthony Martella

on 4 November 2016

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Transcript of VOLCANOES

2,577 MILES
Mount St. Helens; Washington state, USA
Location: Washington, Skamania County
Latitude: 46.2° N
Longitude: 122.18° W
Elevation: 2,549 (m) 8,363 (f)
Volcano type: Stratovolcano
Composition: Basalt to Rhyodacite
Most recent eruption: 1980, 2004-2008
Nearby towns: Castle Rock, WA; Olympia, WA; Vancouver, WA; Yakima, WA; Portland, OR
Alert Level: Normal
May 18, 1980
V.E.I. 5 eruption; 1 cubic kilometer of ejecta
Lateral blast devastated an area of 230 square miles around the volcano
57 people killed
The ash cloud spread across the U.S. in three days and circled the Earth in 15 days.
Total of 520 million tons of ash
Pyroclastic flows roared down the mountain at 300 mi/hr and spread as far as 5 mi to the north creating the Pumice Plain.
Northern bulge and summit slid away as a huge landslide—the largest debris avalanche on Earth in recorded history.
The total avalanche volume is about equivalent to 1 million Olympic swimming pools.
Mount. St. Helens Fact Sheet
west of where you are...
Mount St. Helens is part of the Cascade mountain range; Mount Rainier is the tallest peak of the range, at 14,410 ft, and potentially the most dangerous of the Cascade volcanoes because it is close to Seattle and Tacoma; Mount Hood is Oregon's tallest peak, at 11,240 ft
May 17, 1980
April, 1986
8,400 miles
west of where you are...
Mount Pinatubo, Philippines
Location: Luzon, Philippines
Latitude and Longitude: 15.13° N, 120.35° E
Elevation: 1,485 m 4,900 ft
Volcano Type: Stratovolcano
Composition: High silica magma
Most Recent Eruption: 1992
Eruptions in 20th Century: 2
Largest Eruption: 1991, VEI = 6
Notable Feature(s): Ash cloud, lahars.
Notable Statistic: Second largest eruption of the 20th Century in terms of amount of material blown out of the vent. Affect on global weather. 722 deaths.
June 15, 1991
The second-largest volcanic eruption of this century, and by far the largest eruption to affect a densely populated area, occurred at Mount Pinatubo in the Philippines on June 15, 1991. The eruption produced high-speed avalanches of hot ash and gas, giant mudflows, and a cloud of volcanic ash hundreds of miles across. The impacts of the eruption continue to this day.
Pinatubo photo gallery
Surviving Mount Pinatubo
Pacific Plate boundary; Western rim of "Ring of Fire"
Mount Vesuvius- Naples, Italy
After eruptions volcanoes can remain dangerous for many years.
Residual ash can combine with water to form mudflows in areas that receive heavy rains, like the Philippines.

Long-term effects

Series of huge waves that are started by earthquakes and volcanic landslides or caldera collapses.
Can travel at speeds of 450mph (in the open ocean) and reach heights of hundreds (potentially thousands) of feet.
Essentially become fast-moving debris glaciers on land.


Pyroclastic flows

Knocks down and burns everything in its path.
Fast moving flows can sweep up and over hills then race back downhill.
Saint Pierre, West Indies (1902): 30,000 people killed in minutes.

Loose rocks and soil mixed with ice and snow from the top of the volcano.
Rivers of ash.
Fast moving mudflows have buried entire towns long distances away.

Lava flows

Pyroclastic Flows

"Mount Vesuvius is currently the most threatening volcano in the world, because of the dense population living in the area.”
- Prof. Franco Barberi, Rome University

Lava cut off routes into Goma, dividing the city in two.
40% of the town was destroyed.
Tens of thousands of people left homeless.
Tremors kept shaking the area, collapsing remaining structures.

The Damage:

Uncommon, but can be devastating.
Happens when lava hits water.
May be responsible for the entire island of Krakatau exploding in 1883, causing tsunamis that killed over 36,000.

Caused when part of a volcano collapses (see Mount St. Helens).
Rapid downhill movement of rock and soil.
Large landslides into the sea will cause tsunamis (see Krakatoa).


Heavy, made of tiny pieces of volcanic rock.
Causes roofs to collapse, makes roads slippery, clogs up machinery, suffocates plants and animals.
Most flows move very slowly.
Will knock down, cover, or burn nearly everything in their path.

Lava flows
Pyroclastic flows
Steam Explosions

Immediate Effects

Volcanoes affect Earth’s land, air and water

Naples, Italy
Population: 1.7 million

How dangerous?

How would you rank the following?
Try it this way... Make a list counting down from least dangerous (7) to most dangerous (1).

Steam Explosions
Lava Flows Volcanic Ash
Pyroclastic flows Landslides

Congo, Africa


Steam explosions

The last day of Pompeii; 79 A.D.
Mount Vesuvius, on the west coast of Italy, is the only active volcano on mainland Europe. It is best known because of the eruption in A.D. 79 that destroyed the city of Pompeii. Mount Vesuvius is considered to be one of the most dangerous volcanoes in the world due to the large population of the city of Naples and the surrounding towns on the slopes nearby.

The volcano is classed as a complex stratovolcano because its eruptions typically involve explosive eruptions as well as pyroclastic flows. Vesuvius and other Italian volcanoes, such as Campi Flegrei and Stromboli, are part of the Campanian volcanic arc. The Campanian arc sits on a tectonic boundary where the African plate is being subducted beneath the Eurasian plate.

Under Vesuvius, scientists have detected a tear in the African plate. This “slab window” allows heat from the Earth’s mantle layer to melt the rock of the African plate building up pressure that causes violent explosive eruptions. In the past, Mount Vesuvius has had a roughly 20-year eruption cycle, but the last serious eruption was in 1944.

Location: West coast of Italy
Coordinates: 40°49′ N 14°26′ E
Elevation: 1281 meters (4000 feet)
Volcano Type: Stratovolcano
Composition: High silica magma
Last Eruption: 1944 (VEI 3)
Most Notable Eruption: 79 AD (Pompeii)
VEI/Total Ejecta: VEI 6; 3 cubic kilometers
Nearby Volcanoes: Etna Stromboli
Pompeii- ash statues
Mount Vesuvius Fact Sheet
Strombolian Eruption
Mount Yasur
Strombolian Eruption
Shield volcano
Fissure eruption
Fast Facts
Location: Indonesia (Sunda Straight)
Most notable eruption: 1883
VEI: 6
Total ejecta: 26 cubic kilometers
Deaths: 36,000
Major effects: Pyroclastic flow; tsunami
Created loudest sound in recorded history
Elevation (Anak Krakatau): 2667 ft
Type: Stratovolcano
Composition: Mixed magmas
Throughout the early morning of August 27th, 1883 and into the late afternoon, the inhabitants of Rodriguez Island—a small speck of land in the southwest Indian Ocean—heard the sound of heavy guns firing in the distance. Or so they thought. What they had actually heard was a series of volcanic explosions emanating from another small island in the Indian Ocean, Krakatau (also known as Krakatoa), which lay nearly 5,000 km (3,000 miles) to the northeast. The noise from these explosions ranks as the loudest and farthest traveled sound in recorded history.

During its final cataclysmic eruption Krakatau, which had been an island of about 30 square kilometers (12 square miles), nearly vanished. A total of 25 cubic kilometers (6 cubic miles) of material, including both new magma and bits of the old island, were blown into the stratosphere, the eruption column reaching more than 30 kilometers (20 miles) high. A huge tsunami rushed from the exploding island and crashed against the nearby shorelines killing tens of thousands. At no time in history had more people been killed by a volcano.
Krakatoa: The Last Days
Krakatoa Fact Sheet
Clips 1-4
Full transcript