GLY 150: Earthquakes and Volcanoes Spring 2005: 032905

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GLY 150 Earthquakes and VolcanoesSpring 2005
03/29/05
Steamboat Geyser Yellowstone National park
Lecture 19
http//www.nps.gov/yell/nature/geothermal/index.ht
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AnnouncementsGLY 150 Earthquakes and Volcanoes

• The next journal assignment is due this Thurs.
  If you still have questions regarding the grading
  the grading criteria please see me or the T.A.
  (recent small magnitude earthquake in NMSZ)
• Instructor office hours are Mon. 200-300 and
  Wed. 200-300
  
• Remember, use your texts to supplement the
  lecture notes, especially as we start case
  studies next week. It will be impossible to
  cover all the material in the text but it will
  appear on exams and its actually interesting.

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Test InfoGLY 150 Earthquakes and Volcanoes

• The second exam is next Tues. (April 12th). It
  will cover lectures 8-21 (excluding lecture 17).
  For lecture 8, only include the portion dealing
  with earthquake hazards. You will also have to
  know volcano types as they relate to volcanic
  hazards.
• Note new date for the exam
• Homework numbers 4-5 will be covered. The
  solutions are posted on the class website.
  
• Some of the questions will come directly from the
  quizzes. Answers are given on the class website.
  
  
• Questions will come from the reading material
  assigned for each lecture. This is especially
  true for the specific case studies discussed in
  class.
• Questions will come from the movie guides that
  were posted on the web. Material not addressed
  in the movie guide (but included in the film)
  will not be included on the test.

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Test InfoGLY 150 Earthquakes and Volcanoes

• There will be some time to review at the end of
  class on Thursday, April 7. If you have no
  questions, I will review subjects that a large
  proportion of class had trouble with as
  determined from the quiz comments. Use the time
  to your advantage.
• There will likely be no written review material.
  If I said it or it was covered in the above
  material it may appear on the exam. I will post
  a list of subjects/terms that will not be
  covered. I will try to update the original list
  as you ask me about certain concepts (via email
  or office hours, etc.).
• Instructor office hours are Mon. 200-300 and
  Wed. 200-300. Use them to your advantage.
  Rachel will also be available.

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Events this QuarterSpring 2005
Note Some of the eruptions may be ongoing so be
sure to check their current status
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Hot SpotsWorldwide Locations

• Total number of hot spots still debated

http//pubs.usgs.gov/publications/text/hotspots.ht
ml
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Hot SpotsWhat Are They?

• Mantle plumes rise from deep within the mantle,
  possibly the core-mantle boundary
  
• Rise via convection
• Hot material is more buoyant than colder
  material
  
• When reaches base of lithosphere, plume head
  spreads out, potentially feeding multiple
  volcanoes simultaneously

Both from http//www.geo.cornell.edu/geology/Galap
agosWWW/GalapagosGeology.html
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Hot SpotsFormation
Plume Head
Plume Tail
http//www.geolsoc.org.uk/template.cfm?namefbasal
ts
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Hot SpotsPlume Dynamics
Plume Head

• When plume head initially penetrate crust
  (Oceanic or Continental), hot spots produce large
  flood basalt provinces
  
• Older hot spots do not produce flood basalts
• After magma in plume head is exhausted, tail of
  plume continues to produce large, explosive
  caldera forming eruptions

Plume Tail
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Imaging A Hot SpotSeismic Methods And Modeling
http//volcano.und.nodak.edu/vwdocs/volc_images/no
rth_america/yellowstone.html
Iceland
Yellowstone
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Hot SpotsFormation of Hot Spot Tracks
Or Continental Crust

• Plumes are stationary for millions of years
• Provide a continuous source of magma
• As the tectonic plate moves over stationary
  mantle plumes, a line of volcanoes is formed
  
• Only the volcanoes immediately above the plume
  are active
  
• As volcanoes move away from the plume they become
  extinct and the ocean starts to erode them

Or Continental Crust
http//www.geographyjim.org/volcanoe.htm
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Hot Spots Tracks Oceanic
Even older volcanoes have been subducted
Oldest Volcanoes
Change in Plate Motion Directions
Youngest volcanoes location of active hot spot
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Continental Hot SpotsThey Occur Here Too

• When plum head initially penetrates crust
  (oceanic or continental), new hot spots may
  produce large flood basalt provinces (a.k.a.
  large igneous provinces)
• Older hot spots do not produce flood basalts
• Igneous Rock of volcanic origin
• Older hot spots beneath continental crust can
  produce
  
• Large, explosive caldera forming eruptions

http//www.ees.nmt.edu/condie/student_ops.html
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Hot SpotsLarge Igneous Provinces

• Many thought to be formed as the initial hot spot
  plume penetrated the crust
  
• Siberia (Siberian Traps)
• Columbia River Flood Basalts
• India (Deccan Traps)
• Iceland
• Oceanic

http//www.geolsoc.org.uk/template.cfm?namefbasal
ts
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Types of VolcanoesFlood Basalt Plateaus
www.greatbasinnaturalhistory.org/ Geology/Imag
Great Basin

• Flood Basalts typically produce large volcanic
  plateaus with small shield volcanoes

Yellowstone
http//imnh.isu.edu/digitalatlas/geo/topo/map5.htm
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Types of VolcanoesContinental Flood Basalts

• Major flood basalt provinces
• Siberia (Siberian Traps)
• Cover even larger area than the Deccan Traps
• United States (Columbia River Flood Basalts)
• Relatively small flood basalt province
• India (Deccan Traps)
• 1-2 km thick (3000-6000 ft)
• Cover half-million square kilometers
• Iceland
• Oceanic

http//filebox.vt.edu/artsci/geology/mclean/Dinosa
ur_Volcano_Extinction/pages/deccantr.html
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Hot SpotsWorldwide Locations

• The Deccan Traps erupted over much longer
  timescales - over 500,000 years or more
  
• Probably emitted huge amounts of gas, affected
  world climate
  
• Impact of large asteroid or comment thought to
  explain demise of dinosaurs, gasses from Deccon
  traps eruption may have contributed

http//www.people.fas.harvard.edu/mukhop/BBC20Ne
ws2020SCI-TECH/BBC20News2020SCI-TECH2020Qui
ck20demise20for20the20dinosaurs.htm
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Hot SpotsDeccan Traps
http//volcano.und.nodak.edu/vwdocs/volc_images/eu
rope_west_asia/india/deccan.html
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Hot Spot VolcanoesFlood Basalts

• Covers smaller area then typical flood basalt
  provinces
  
• Was this formed by a hot spot initially
  penetrating the continental crust??
  
• Some sort of side show due to subducting Pacific
  plate???
  
• Engulfed about 63,000 square miles of the Pacific
  Northwest. Over a period of perhaps 10 to 15
  million years accumulating to a thickness of more
  than 6,000 feet.

http//vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlatea
u/
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Hot SpotsColumbia River Flood Basalts
http//library.thinkquest.org/17457/volcanoes/feat
ures.plateaus.php
http//www.geolsoc.org.uk/template.cfm?namefbasal
ts
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Hot SpotsIceland
www.union.edu/.../ labs/iceland/iceland.htm
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Hot SpotsWorldwide Examples
Columbia River Basalts16.5 Ma Washington, USA
Deccan Traps 66 Ma India
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Hot SpotsRole in Continental Break-Up
http//jan.ucc.nau.edu/wittke/GLG100/PlateTectoni
cs.html
Hot Spot
Sinai Peninsula

• Hot spots may play an critical role in initiating
  continental break-up

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Hot Spot VolcanoesAfar, Africa

• Combination of a hot spot and divergent plate
  boundary
  
• Progression from hot spot to oceanic spreading
  center
  
• Hot spots may play an critical role in initiating
  continental break-up
  
• Hot spots expand into continental rifts
• Continental rifts are grow into oceanic spreading
  centers

Some rifts fail to develop into active
spreading centers, i.e. the Reelfoot rift in the
New Madrid Seismic zone
http//pubs.usgs.gov/publications/text/East_Africa
.html
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Hot SpotsTracing the Hot Spot Track to Its Origin

• When hot spot head initially penetrates crust it
  produces a flood basalt province
  
• Thereafter hot spot tail produces a series of
  huge, caldera forming eruptions which get older
  as the crust moves away from the position of the
  hot spot
• Can help in determining past plate motions
• Some flood basalt provinces have been cut in two
  as they pass over spreading centers

Your Text, pg 187
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Hot SpotsPlate Tectonic Motions vs. Hot Spots

• Mid-ocean ridges, subduction zones, and transform
  faults move relative to the location of the hot
  spot

Your Text, pg 188
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Volcanic EventsRelative Eruption Sizes
http//volcanoes.usgs.gov/yvo/

• No great eruptions in modern time

Yellowstone
Yellowstone
Long Valley
Yellowstone
Mt. St. Helens
Mt. Pinatubo
Novartuba
Tambora
Krakatau
Prehistoric
19th Century
20th Century
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Yellowstone Hotspot TrackSnake River Plain
http//www.artlex.com/ArtLex/Tf.html
Basin and Range Province
Snake River Plane
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Yellowstone Hotspot TrackSnake River Plain

• Thought to be a continental hot spot track
• Flat area lacking topography
• Resurfaced by erupted lava

Both from http//volcano.und.nodak.edu/vwdocs/volc
_images/north_america/yellowstone.html
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Hot Spot VolcanoesSnake River Plain

• Series of ancient calderas that gets younger from
  west to east
  
• Oldest part of plain in vicinity of Columbia
  River flood basalts
  
• Youngest part of plain at Yellowstone National
  Park

Youngest Caldera
Oldest Caldera
http//www.ldeo.columbia.edu/manders/SRP_erupt.ht
ml
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Yellowstone National ParkLocation
http//volcanoes.usgs.gov/yvo/
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Hot Spot VolcanoesYellowstone Hot Spot

• The Yellowstone hot spot has produced multiple
  large, explosive eruptions
  
• Much larger than anything recorded by modern
  humans (note relative size vs. Mt. St. Helens)
  
• 3 within boundaries of Yellowstone National Park

Both from http//volcano.und.nodak.edu/vwdocs/volc
_images/north_america/yellowstone.html
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Volcanic EventsRelative Eruption Sizes
http//www.nps.gov/yell/nature/geothermal/index.ht
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Yellowstone Hot SpotCaldera Forming Eruptions
http//volcanoes.usgs.gov/yvo/
A repeat of these events would affect large
portions of the continent This isnt likely any
time soon
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YellowstoneAsh Deposits From Caldera Forming
Eruptions
http//volcanoes.usgs.gov/yvo/

• In Yellowstone National Park

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YellowstoneGeologic Structure
http//www.nps.gov/yell/nature/geothermal/index.ht
m
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Yellowstone Hot SpotWider Structure
http//volcanoes.usgs.gov/yvo/

• Seismicity and mountains form a bow-wave as North
  America travels over the hot spot
  
• No seismicity in the Snake River Plain

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Yellowstone Seismicity

• Lots of small earthquakes throughout park

http//volcanoes.usgs.gov/yvo/
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YellowstoneStructure

• Earthquake swarms when hot fluids force their way
  though brittle rock

http//volcanoes.usgs.gov/yvo/
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YellowstoneEarthquake Swarms

• Earthquake swarms are frequent
• Shows swarms in 1985, 1995, 2004

http//volcanoes.usgs.gov/yvo/
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YellowstoneHebgan Lake Earthquake

• Most powerful earthquake in Yellowstones
  history
  
• Triggered huge landslide
• 28 fatalities
• 11,000 million in damage
• Caused widespread changes in Yellowstones
  geothermal
  
• some geysers stopped erupting
• others were newly formed or came back to life
  after years of dormancy
  
• Old Faithful is no longer as faithful

http//volcanoes.usgs.gov/yvo/
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YellowstoneHebgan Lake Earthquake

• Scarps formed during the M-7.5 Hebgan Lake
  Earthquake

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YellowstoneGeography

• Most resent caldera rim
• Resurgent domes

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YellowstoneGeothermal Features

• Features fueled by heat from a large reservoir of
  partially molten rock (magma), just a few miles
  beneath Yellowstone
  
• Drives one of the worlds largest volcanic
  systems.

http//www.nps.gov/yell/nature/geothermal/index.ht
m
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YellowstoneGeysers
Castle Geyser

• Geysers are hot springs that episodically erupt
  fountains of scalding water and steam
  
• Eruptions occur when groundwater is heated to its
  boiling temperature in a confined space (for
  example, a fracture or conduit)
  
• A slight decrease in pressure or increase in
  temperature causes some of the water to boil
  
• Resulting steam forces overlying water up through
  the conduit and onto the ground
  
• Loss of water further reduces pressure within the
  conduit system
  
• Most of the remaining water suddenly converts to
  steam and erupts at the surface.

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YellowstoneGeysers

• What makes them rare and distinguishes them from
  hot springs is that somewhere, usually near the
  surface in the plumbing system of a geyser, there
  are one or more constrictions
• Expanding steam bubbles generated from the rising
  hot water build up behind these constrictions,
  ultimately squeezing through the narrow
  passageways and forcing the water above to
  overflow from the geyser
• Release of water at the surface prompts a sudden
  decline in pressure of the hotter waters at great
  depth, triggering a violent chain reaction of
  tremendous steam explosions in which the volume
  of rising, now boiling, water expands 1,500 times
  or more
• This expanding body of boiling superheated water
  bursts into the sky in pulses

http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneHot Springs

• Snow or rain and slowly percolates through layers
  of porous rock, finding its way through cracks
  and fissures in the earths crust created by the
  ring fracturing and collapse of the caldera
• Sinking to a depth of nearly 10,000 feet, this
  cold water comes into contact with the hot rocks
  associated with the shallow magma chamber beneath
  the surface
• As the water is heated, its temperatures rises
  well above the boiling point to become
  superheated
  
• This superheated water, however, remains in a
  liquid state due to the great pressure and weight
  pushing down on it from overlying rock and water
  
• The result is something akin to a giant pressure
  cooker, with water temperatures in excess of
  400F.

http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneHot Springs

• The highly energized water is less dense than the
  colder, heavier water sinking around it. This
  creates convection currents that allow the
  lighter, more buoyant, superheated water to begin
  its slow, arduous journey back toward the surface
  through rhyolitic lava flows, following the
  cracks, fissures, and weak areas of the earths
  crust
• Rhyolite is essential to geysers because it
  contains an abundance of silica, the mineral from
  which glass is made.
  
• As the hot water travels through this "natural
  plumbing system," the high temperatures dissolve
  some of the silica in the rhyolite, yielding a
  solution of silica within the water.

Emerald Spring
A hot spring's color often indicates the presence
of minerals
http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneHot Springs

• At the surface, these silica-laden waters form a
  rock called geyserite, or sinter, creating the
  massive geyser cones the scalloped edges of hot
  springs and the expansive, light- colored,
  barren landscape characteristic of geyser basins
• While in solution underground, some of this
  silica deposits as geyserite on the walls of the
  plumbing system forming a pressure-tight seal,
  locking in the hot water and creating a system
  that can withstand the great pressure needed to
  produce a geyser
• With the rise of superheated water through this
  complex plumbing system, the immense pressure
  exerted over the water drops as it nears the
  surface
• The heat energy, if released in a slow steady
  manner, gives rise to a hot spring, the most
  abundant and colorful thermal feature in the park

Crested pool is 42 feet deep and is constantly
superheated
http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneHot Springs

• Grand Prismatic Spring
• Known for its rainbow colors produced by
  thermophilic (heat loving) organisms.
  
• Largest hot spring in Yellowstone third largest
  in the world

http//volcanoes.usgs.gov/yvo/
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YellowstoneBubbling Mudpots

• Where hot water is limited and hydrogen sulfide
  gas is present (emitting the "rotten egg" smell
  common to thermal areas), sulfuric acid is
  generated
• Acid dissolves surrounding rock into fine
  particles of silica and clay that mix with what
  little water there is to form the seething and
  bubbling mudpots

http//www.nps.gov/yell/nature/geothermal/index.ht
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Hot SpotsFumaroles

• Fumaroles, or steam vents, are hot springs with a
  lot of heat, but so little water that it all
  boils away before reaching the surface
  
• May result is a loud hissing vent of steam and
  gases.

Black Growler Steam Vent Hottest of Yellowstone's
geothermal steam vents (fumaroles) - 199 to 280
degrees F (93 to 138 degrees C). 
http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneMammoth Terraces

• Ground water seeps slowly downward and laterally,
  coming in contact with hot gases charged with
  carbon dioxide rising from the magma chamber
  
• Some carbon dioxide is readily dissolved in the
  hot water to form a weak carbonic acid solution
  
• This hot, acidic solution dissolves great
  quantities of limestone as it works up through
  the rock layers to the surface hot springs
  
• Once exposed to the open air, some of the carbon
  dioxide escapes from solution
  
• As this happens, limestone can no longer remain
  in solution. A solid mineral reforms and is
  deposited as the travertine that forms the
  terraces.

Opal Spring
http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneMammoth Terraces

• Rarer kind of spring formed when the hot water
  ascends through the ancient limestone deposits
  (easily dissolved) instead of the silica-rich
  lava flows elsewhere in the park.
• Results are strikingly different and unique.
• Invoke a landscape that resembles a cave turned
  inside out, with its delicate features exposed
  for all to see
  
• Flowing waters spill across the surface to sculpt
  magnificent travertine limestone terraces.
  

Mammoth Hot Springs
http//www.nps.gov/yell/nature/geothermal/index.ht
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YellowstoneDeformation

• Record of earthquakes and deformation
• Just like other resurgent caldera
• Looks like the caldera is breathing

http//volcanoes.usgs.gov/yvo/
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YellowstoneFuture Eruptions
http//volcanoes.usgs.gov/yvo/
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Hot SpotsInfluence on Climate and Mass
Extinctions ?

• Two catastrophic processes that have been invoked
  to explain mass extinctions are (1) impacts of
  asteroids or comets and (2) large volcanic
  eruptions (flood basalt eruptions)
• If there is a causal link between flood basalt
  events and mass extinctions, it may lie in the
  environmental impact of the gases released.
  
• Several environmental effects have been
  suggested, including climatic cooling from
  sulphuric acid aerosols, greenhouse warming
  from CO2 and SO2 gases, and acid rain.
• Basaltic magmas are often very rich in dissolved
  sulphur, and sulphuric acid aerosols formed from
  sulphur volatiles (largely SO2) are injected into
  the stratosphere by convective plumes rising
  above volcanic vents and fissures
• Indirect environmental effects include changes in
  ocean chemistry, circulation, and oxygenation,
  from basaltic volcanism associated with large
  submarine oceanic plateaus that may represent
  flood basalt eruptions in an oceanic
  environment.
• A major uncertainty is the severity of
  environmental effects of the eruptions and their
  potential impact on life.
  
• Although the correlation between some flood
  basalt episodes and extinctions may implicate
  volcanism in the extinctions, it is also possible
  that other factors lead to an apparent
  association.

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YellowstoneMadison Plateau

• Formed by thick, viscous lava flows

http//volcanoes.usgs.gov/yvo/