FDSCI 201 W5 volcanoes

Which of these is not a volcanic eruption hazard?

Liquefaction

What is a lahar?

A volcanic mud or debris flow

Which of these features were found in Pompeii and Herculaneum?

Public water fountains, paved sidewalks, art work

What do we call all the material that travels through the air in an eruption?

Tephra

What do we call the darkest-colored volcanic rocks?

Basalt

What do we call the columnar fractures in volcanic rocks?

Cooling joints

What do we call the tall, cone-shaped volcanoes that are so famous? These include Fuji, Rainier, Hood, and Shasta.

Composite volcanos

What volcanic feature has been growing in the crater of Mount Saint Helens since it erupted in 1980?

Lava domes

What do we call an eruption that sends ash and gas tens of thousands of feet, to the upper troposphere and lower stratosphere?

Plinian

What are the signs of a pending eruption?

Ground swelling, quake swarms & volcanic tremors, increased gas emissions

When did Mt. Rainier last have a significant eruption?

~1000 years ago

What primary volcanic hazard does Mount Rainier pose to Orting Washington?

Lahars

According to the map, what is the shortest recurrence of lahar events?

<100 years

What is the approximate distance between the summit of Mt. Rainier and the town of Orting, in miles?

30

How much time would there be to evacuate once a Lahar started, in hours?

0.53

How many rivers border Orting? (Make sure you have the boundary of Orting visible.)

2

How many bridges are there across the rivers around Orting? (Don't go up or downstream beyond the borders of Orting.)

1

Thinking of the movie Dante's Peak, list the thing in the movie that was most realistic and supported by volcano facts (questions 10 through 14 all deal with the movie Dante's Peak). If you have chosen to watch the alternative movie, please paste your report in the box below, and skip to the second to the last question.

I think that the most realistic thing in this movie was the contamination of the towns' water supply. Volcanic ash or other debris from the volcano could enter a towns' water supply through rivers, or the towns' water supply could be contaminated if the town's water supply comes from the same place as the volcano's groundwater.

Thinking of the movie Dante's Peak, list the thing in the movie that was most unrealistic and least supported by volcano facts.

I think that the most unrealistic part of Dante's peak is the earthquake. Combining our knowledge from last week and this week, we know that volcanic eruptions do not typically cause an earthquake large enough to destroy buildings. To make the damage shown in the movie plausible the earthquake needed to be at least a 6.1 on the rector scale, whereas volcanoes typically only let out a magnitude 5.0 earthquake.

Thinking of the movie Dante's Peak, are there ash and pyroclastics present during the eruption? Would they be consistent with a stratovolcano?

Yes, the movie did depict ash and pyroclastics. Yes, they are very characteristic of a stratovolcano

Thinking of the movie Dante's Peak, was the lava that was depicted (for example in the scene where the stolen Forest Service truck gets stuck in the lava) basaltic or rhyolitic and how can you tell?

Basaltic because the lava had the consistency of honey and was dark colored when cooled.

Volcanoes come from:

The little island of vulcano in the Mediterranean Sea of north Sicily. People believed that vulcano was the chimney of the forge of vulcan the blacksmith of the Roman gods.

Goddess of volcanoes-

Pele

volcanic ash

Affects more people, infrastructure and daily activities than any other eruptive phenomenon

Bombs

Largest rock fragments fall back to the ground within 2 miles of the vent. Wind shaped rocks

Vent

Opening of the volcano

Eruption column

Grows rapidly and reaches more than 12 miles above a volcano in less than 30 min.

Eruption cloud

What an eruption column creates

ash fall

Comes from ash clouds

silica

a material found in magma that forms from the elements oxygen and silicon

low silica

Basalt lava that forms fast moving (10-30mph)

high silica

Andesite and dacite lava is thick and sluggish

Lava domes

Formed by lava that piles over and around the vent

Lava dome collapse

High speed avalanche

pyroclastic flow

The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption. Can be as hot as 1,500 F and move at speeds of 100-150mph

Lahars

volcanic mudflows. Composed mostly of volcanic materials. Can travel 20-40mph

Historically have been one of the deadliest volcanic hazards

Mt. Etna, Sicily

Europe's highest active volcano. 10,991 ft. It has over run by flows 18 times

Vesuvius volcano

-suddenly exploded and destroyed the Roman cities of Pompeii and Herculaneum. It was considered extinct. 8/24. A.D. 79

Modern archeology was developed when the ruins were uncovered 1,700 years later

St Helen's

SW Washington. 5/18/80. Mudflows and flooding. 57 people dead or missing. Property damage 1.2b

How are volcanoes formed?

Accumulation of their own Eruptive products

Intrusive/plutonic rocks

Form when magma cools underground. Characterized by a coarsely crystalline texture (granite rock)

volcanic rock

fine-grained or aphanitic to glass in texture. Glassy, pyroclastic, vesicular texture.

Tuff

rock composed of fine-grained pyroclastic particles. Layers of Yellowstone canyon. Black rock Fragments

Pumice

Separation of gas from lava may produce rock froth

Basalt

A dark, dense, igneous rock with a fine texture, found in oceanic crust. Divergent. Low silica, rarely explosive

Andesite

Medium gray colored rock. Primarily found at convergent plate boundary. Explosively erupt

Rhyolite

Light colored rocks. Occurs on continental crust. High silica, often tuff, often pumice

oceanic hot spots

Made up of basalt

Continental hot spots

Basalt and rhyolite

Poly term- Aa:

Rough, blocky, looks like furnace slag

Poly term- pahoehoe:

Fluid variety with a smooth, satiny and ropey appearance

Obsidian

Glassy volcanic rock. Erupts at temps so high and then cools so quickly that no minerals form

Granite

intrusive igneous rock. Coarsely crystalline texture

Cooling Joints

When lava hardens, fractures open, breaking but lava into 6 sided columns

Cinder cones

Simplest type of volcano. Lava breaks down into small fragments and solidifies around the vent to form a circular or oval cone. Common in western. North America, Mauna, Kea, Hawaii. Paricutin, Mexico

composite volcano

Includes all 3 rock types. They are steep, symmetrical cones of large dimensions built of alternating layers. Some of the largest mountains. They erroed when they become dormant and the cone is stripped away

Calderas

Large, steep walled, basin shaped depressions formed by collapse of large area over and around. Volcanic vent

Shield volcanoes

Almost entirely built of fluid lava flows. Some of the largest volcanoes in the world. Basalt. They pour quietly from fissures and form broad plateaus. Many in Hawaii. Famous for "fire fountains"

Plugs (necks)

Volcanic plumbing system. Once the softer, outer layer of the volcano has eroded, an irregular columnar structure is left standing. They are resistant to erosion.

Maars (tuff cones)

Shallow, flat-floored craters that form from violent expansion of magmatic gas or steam. When lava touches water, violent phreatic explosion occurs when water flashes into steam. They form natural lakes

Impact craters

Formed by collision with the earth of large meteorites, asteroids or comets

Strombolian eruptions

Huge clots of lava burst, stream down the slope in fiery rivulets only affect the volcanoes slopes

Vulcanian eruption

Dense cloud of ash laden gas explodes from the crater and rises thousands of feet above the peak. Its ash affects the local region

Plinian eruptions

A lot of ash laden gas is violently erupted and forms a mushroom shaped cloud. Dust and ash reach around the world

First type of pyroclastic flow

Contains toxic gas. Explosive eruption sends a massive quantity of gas, dust, ash and lava high into the air and then it falls back onto slopes

Second type of pyroclastic flow

When lava dome at the summit of a volcano collapses, sending hot avalanches down the slopes

Hawaiian eruptions

- Lava fountains and flows

lava flows like streams. May collect in old craters and form lava lakes.

Hawaiian eruptions

Fissure eruption-

Moves upward through crust through fracture

Plate tectonics and volcanoes

Volcanoes occur primarily at plate boundaries and hot spots. Plate tectonics explains the types of volcanic rock and why they occur where they do

Stratovolcanoes

Lava is thick, sticky lava which remains near and builds up around the cone of the volcano.

Famous for ash clouds and puroclastic debris.

True or false? Carbon dioxide gas can be released from active underground magma chambers?

True

Pinatubo, Philippines 1991 volcano

June 15, 1991

7.8

Stratovolcano

Destructive plate boundary

28 miles high

Andesite and dacite

Killed 722 or 847?

22+ miles

Decrease of sunlight globally

    This convergent boundary stratovolcano’s last major eruption had a VEI=6 and allowed volcanologist to apply, and expand on, what was learned from the eruption of Mount Saint Helens.

·         This volcano’s most recent eruption was the 2nd largest eruption of the 20th century and caused a global temperature drop of 1 degree Fahrenheit.  The U.S. Air Force’s Clark Air Force Base and the U.S. Navy’s Subic Bay Naval Base were both closed by this eruption.

·         This volcano’s last major eruption killed about 847 people, mostly through roofs collapsing under the weight of ash.  Evacuations removed most people from the range of pyroclastic flows.

Kilauea, Hawaii eruption

January 3, 1983-2018

Cinder cone

Shield volcano

Eruptive activity for 3 weeks

Basalt

East rift zone

Hot spot

Tephra 30,000ft

0 deaths

Bomb lava tubes to stop lava flow

1790 last eruption that was bigger

Summit- 4,207 meters

Mauna Loa- 13,678

  This Hot Spot Shield volcano’s latest eruption has a VEI=1 but  has been erupting essentially continuously since 1983.

·         This volcano’s most recent eruption has produced about 4 cubic kilometers of lava but has only destroyed a couple of hundred houses, a few at a time.  It actually serves as an economic benefit by promoting tourism.

·         This volcano’s most recent eruption hasn’t produced any casualties, but an earlier eruption in the 18th century killed a group of people and tipped the political balance of power.

Mt. St. Helen's 1980 eruption

May 18, 1980

VEI 5 explosion

57 died

Most economically destructive volcanic even in US history

Horse shoe shaped crater

Subduction zone

Stratovolcano

25km rock erupted (15 miles/80,000ft)

Lahars

$1.1b spent to recover

Ring of fire

Destructive plate boundary

Basalt and andesite

     This convergent boundary stratovolcano’s last major eruption had a VEI=5 that resulted in the mountain losing more than 1300 feet of its height.

·         This eruption produced Pyroclastic fallout, Lahars and associated floods.  The lateral blast a  flattened forest giving new insight into the horizontal reach of a volcano.

·         This volcano’s eruption was preceded by earthquake swarms and small eruptions.  The resulting evacuations kept the death toll to only 57 people.  This volcano has had a number of minor eruptions in the 21st century.

Mt. Tamboura, Indonesia eruption

April 5, 1815

VEI 7

Stratovolcano

Convergent boundary

Subduction zone

36 cubic miles of gas

90,000 dead

Basalt

         This convergent boundary stratovolcano’s last major eruption had VEI=7 and is thus the largest known eruption of the last 200 years.

·         The eruption of this volcano resulted in what has been termed “the year without a summer.”

·         This eruption is credited with the loss of more than 71,000 lives.  At least 10,000 of those are attributed directly to the eruption and resulting tsunami.  Many more were due to famine resulting from the destruction of agriculture.  This eruption has a connection to the history of the Church of Jesus Christ of Latter-day Saints.  This volcano has continued to have minor eruptions in the 19th and 20th century.

Heimaey, Iceland 1973 eruption

January 23, 1973

VEI 4

250 million cubic meters of lava

224 meters high

Lasted more than 5 months

1 dead

District heating system created

Cinder cone

Mid Atlantic ridge tectonic boundary

Divergent

This divergent boundary volcanic complex’s eruption had a VEI=3 while producing a composite cone volcano now known as Eldfell and improving the protection of the town’s harbor.

·         The eruption of this volcano is most famous for the town’s efforts to halt the lava using sprinklers.

·         During this volcano’s last major eruption only 1 person died (a looter).  The last major eruption was the most recent eruption for this volcano.  The lava flows from this eruption are in places hundreds of feet thick and average over a hundred feet thick.

Krakatau, Indonesia 1883 eruption

May 20- Aug 1883

VEI 6

11 cubic meter of debris thrown into atmosphere

Stratovolcano

Transform boundary

Krakatoa

36,417 dead- mostly from tsunami

         This convergent boundary stratovolcano’s last major eruption had a VEI=6 and produced one of the largest explosions on Earth in recorded time.

·         The eruption of this volcano destroyed much of the island with the same name and sent a tsunami and ash around the world.

·         The eruption of this volcano killed more than 36,000 making it one of the deadliest volcanic disasters in historic time.  Recent eruptions of this volcano have been at Anak Krakatau, an island that emerged in 1927 and has been the site of frequent eruptions since.

Vesuvius and Pompeii, Italy 79 eruption

Year 79

VEI 5

Plinian eruption

Ash clouds 20km into the stomp sphere

Subduction

16-18,000 dead

  This convergent boundary stratovolcano’s last major eruption had a VEI=5 that buried entire cities and thus created archeological treasures.

·         About 1 cubic mile (4 cubic kilometers) of ash was erupted in about 19 hours.  The author of a contemporary account of the eruption lent his name to this “plinian” type of eruption.

·         Although this volcano’s eruption was preceded by earthquakes and smaller eruptions, the understanding of volcanoes at the time was poor.  We know for certain that at least more than 2000 people were killed, perhaps many more.  This volcano’s most recent eruption ended in 1944.

Santorini, Greece 1625 BC eruption

1625 BC

Plinian eruption

VEI 6

Tephra was 36km high

Subduction

 This convergent boundary complex of shield volcano’s last major eruption had a VEI=6 and likely gave rise to the legend of Atlantis.

·         The catastrophic caldera collapse of this volcano, and the accompanying tsunami, destroyed a major civilization and likely changed the course of human history

·         We don’t have any indication of how many people were kill by this eruption, but the archeological record does show us that at least some of the affected population evacuated their homes before volcanic debris buried the buildings.  The last small eruption was in 1950 which produced a small lava dome and flow.