Volcano News & Questions from Students VOLCANIC ERUPTIONS Physical Phenomena Causes – movement at plate boundaries Geography – spatial distribution Forms and eruption styles Magnitude Prediction – looking back & monitoring Hazards – quakes, blasts; release of ash, gas & lava Impacts Fatalities Economic Mitigation & Preparedness Begins with understanding vulnerability

Recently, eruption of Icelandic volcano halted air travel Breaking Volcano News

http://www.volcanolive.com/news.html

…and news of breaking volcanoes

History shows that when Eyjafjallajökull erupts, it’s larger neighbour Katla is generally not far behind. Katla is overdue.

Katla’s eruption may be 10 or more x the size of the Eyjafjallajökull eruption –significant floods of fresh glacial-melt water into the sea (flow equal to Amazon + Mississippi + Nile + Yangtze occurred following 1755 eruption), a column of ash rising Chaiten, Chile 20km, or more, into the jet stream and spread over N Hemisphere.

The Laki eruption in Iceland in 1783 resulted in famine across W Met Office, summer 2010 Europe, and as far S as Egypt, one of the longest and coldest ..as ash entrained in the atmosphere moved from winters on record in N America, and the death of 10,000s of Iceland across the Atlantic. people from gas poisoning and famine.

1 Merapi is at a subduction zone, where the Indo-Australian Plate is sliding NEWS beneath the Eurasian Plate and part of the Pacific Ring of Fire Stratigraphic analysis reveals that eruptions in the Merapi area began about Merapi Eruption 400,000 years ago, and from then until about 10,000 years ago, eruptions were effusive, and outflowing lava emitted was basaltic.

More recent than 10,000 y ago, eruptions have become more explosive, with viscous andesitic lava generating lava domes. Dome and column collapse Have generated large explosions and pyroclastic flows.

Typically, small eruptions now occur every 2-3 y, larger ones every 10-15 y.

Notable eruptions, often causing many deaths, have occurred in 1006, 1786, 1822, 1872, and 1930—when 13 villages were destroyed and 1400 people killed by pyroclastic flows. A very large eruption in 1006 is claimed to have covered all of central Java with ash.

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Old News • >1300 volcanoes known to have erupted in Holocene epoch (last 10 000 years)

• ~500 classified as ‘active’ (i.e. http://video.google.com/videoplay?docid=39774163 known to have erupted in 82972126736#docid=-3680513146102540221 recorded history)

• Remainder classified as ‘dormant’ (may become active again) or ‘extinct’ (not expected to erupt again), but Vesuvius was thought Plus new vents: e.g. to be extinct before AD 79! Paricutin (Michoacan, Mexico) shown erupting in 1943 (graphic by Diego Rivera)

Tectonic plate boundaries subducting – spreading - sliding Physical Phenomena Causes – movement at plate boundaries Geography – spatial distribution Forms and eruption styles

2 Spreading centers Oc-Cont: Subduction- W coast of Americas

Cont-Cont: Convergence- Himalayan Mt. Rifting (or Spreading)- E African Rift Valley

Oc-Oc: Subduction- Aleutian Islands Spreading- Mid-ocean ridges

Distribution of active volcanoes Volcanoes

Eruptive style and hazard depends on:

•Tectonic setting

•Depth of magma formation

•Rate of magma movement to the surface

•Percent and type of volatiles (gases) 60% around Pacific; 20% in Mediterranean region

Volcanoes - tectonic settings Oceanic ridge, Subduction Hotspots zones examples? Basic/Mafic volcanics Acidic/Felsic volcanics

•Low SiO2 •High SiO2

•Fluid lava (10 m/s) •Viscous lava (3 m/s)

•Low gas pressure > •High gas pressure > little explosive activity explosive activity

3 As magma cools, crystals form & viscosity, & gas & steam content increase Classification of volcanic eruptions 1) Ultramafic- Kaolinic, Very high Temp, Very low Si content (after Scheidegger) (<45%) , Fluid, River of molten rock, Gas bubbles escape gently, Rare because earth’s core has cooled over time Low Risk High Risk Gas Pressure 2) Mafic- Basaltic, High Temp, Low Si content, Int viscosity Low profile shield domes Low 3) Intermediate- Andesitic, Moderate temp, Moderate Si content, Relatively high viscosity, Steep composite volcanoes High Lava Type Lava 3) Felsic- Rhyolitic, Medium Temp, High Si content (>65%), Viscous, Gases trapped leading to violent explosions of ash & pyroclastic flows, Lava domes Oceanic ridge, Subduction Hotspots zone

SHIELD -Non explosive -Ocean setting Basaltic lava flows

STRATO/STEEP COMP -Explosive -Convergent plate boundaries

FISSURE -Low power -Fissures & faults “Aa” (blocky lava) flow, Hawai “Pahoehoe” (ropy lava) flow, Reunion

CINDER CONE/ LAVA DOMES Hazards - property burnt and buried by lava -Accumulation around vent -Highly explosive

Explosive eruptions occur when gases are trapped and magma becomes bouyant..

Recent major lava flows, Hawai’i

4 Pyroclastic flows, a ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas that is more dense than atm and therefore rushes down volcano flanks

VEI Volume of tephra Eruption (m3)type “Super-volcanoes”

0 nonexplosive Icelandic/ Eruption Hawaiian magnitude 1<105 6 = 2~10 Strombolian 3~107 Vulcanian Volcanic 4~108 Vesuvian Explosivity 5~109 Plinian 10 Index 6~10 Peléan 7~1011 8~1012 “supereruption”

Identification of high-risk volcanoes

PREDICTING OCCURRENCE & IMPACTS OF VOLCANIC ERUPTIONS • Frequency and nature of past eruptions

• Distribution and nature of eruptive products

• Population density and property value in vicinity of volcano

RISK = HAZARD X VULNERABILITY

5 Vesuvius and region

Campi Flegrei

La Solfatara

MISENUM

Identifying tephra layers in ancient lake sediments help determine occurrence of eruptions and establish hypothetical recurrence intervals

Why wasn’t Vesuvius recognized as high-risk by the Romans?

Mount Vesuvius: Eruptive style- 2 main Bed Date (BP) Volume (km3) recent major eruptions types Pompeii ~1900 Plinian 2.8 • A.D. 79: destruction of Pompeii and AP6 ~2200 Strombolian ? Strombolian to AP5 ? 0.08 Herculaneum; Vulcanian AP4 ? Phreato-Plinian 0.12 Strombolian to AP3 ~2700 0.15 • 80 eruptions since then - Vulcanian Sub-Plinian to phreato- most violently in 1631 and 1906; AP2 ~3000 0.14 Plinian quiet since 1944 Sub-Plinian to phreato- AP1 ~3300 0.15 Plinian Avellino ~3450 Plinian 1.5

From data in: Andronico, D. and Cioni, R. 2002. Bull. Volcanology 64, 372-391.

• Can we predict when a volcano will erupt? Identification of high-risk volcanoes (1984) • clues from past eruptions & remnant pyroclastic flows • monitoring for warning signs such gas emission & small SE Asia and Pacific = 42 Total = 89 EQ Americas and Caribbean = 40 of ~500 active Africa and Europe - 7 volcanoes) • The problem of prediction Despite prediction of likelihood, it is difficult to pinpoint exactly when an eruption may occur. . Omissions can be significant, e.g. Nevado del • Often, moving magma doesn't result in an eruption, but Ruiz ~25000 killed in1985 instead cools below the surface. . Caveat: “low ratings may simply reflect • Monitoring is expensive. incomplete or incorrect information, not • Many volcanoes erupt only every few hundred or thousand necessarily low risk. In fact, volcanoes not years. listed should be the focus of... investigation” • Nevertheless, volcanic eruptions don't occur without [Yokohama et al. (1984)] warning and monitoring devices can allow time for evacuation as in the case of Merapi

6 Monitoring techniques Tools to detect warning signs: seismographs detect Gas sampling at vents small earthquakes, tiltmeters and geodimeters measure subtle swelling, correlation spectrometers (craters, fumaroles) measure amounts of sulfur dioxide.

Tectonic deformation, Campi Flegrei, Italy (1982-1985 pulse)

City of Naples

Monitoring and prediction

at Mt St Helens, 1982

La Solfatara, one of several small active craters in the Campi Flegrei

7 Predicting Impacts of Katla Eruption

Air travel – the recent 6-day chaos would potentially be dwarfed by one that could last months. This would not only impact passengers, but freight, too. Tourism would certainly be impacted negatively, but so would food imports and general freight movement.

Agriculture – the impact of a prolonged cold spell would drastically affect crop production in Europe and, potentially, elsewhere in the Northern Hemisphere. For Europe, this would Recent uplift in Iceland in vicinity of just add to the difficulties faced by the lack of air transport to bring underice volcanoes suggest a large in fresh produce from elsewhere. eruption may be imminent with Power – of course, a lengthy period of exceptionally cold weather potentially catastrophic would push up power consumption dramatically. prolonged cold consequences as a result of takes its toll. Where would this wealth go, and who would benefit? Caldera collapse.

Mt. Vesuvius Types of

modern volcanic Herculaneum hazards excavated area of Roman http://www.yo Herculaneum utube.com/wa (20 m below tch?v=uphPM modern city) FFC5GI&feat ure=related

http://volcanoes.usgs.gov/Hazards/What/hazards.html

VOLCANIC HAZARDS •Earthquake Volcanic hazards: • deaths (AD 1900-2000) •Directed Blast

•Tephra deposition

•Gas Release

•Lava Flow

•Debris Avalanche, Landslide, and Tsunami

•Pyroclastic Surge • •Pyroclastic Flow • •Lahars

8 Ash cloud from the eruption of Mt. Volcanic Spurr (Alaska) in 1992 ash

Yakima, WA (May, 1980) Fine-grained volcanic ash can cause health problems in susceptible people, clog ventilation systems, cause electrical short circuits, damage crops, and wreck jet engines (e.g. the BA 747 that lost all 4 engines and dropped 4 km after encountering an ash cloud over Indonesia in 1982).

Dominant wind directions, Spurr Mt. Baker

Cleveland Okmok Kasatochi

http://videos.howstuffworks. com/discovery/30022- assignment-discovery- yellowstones-super- eruption-video.htm

9 Volcanic hazards - Hawai’i Pyroclastic flow (nuée ardente)

Five active volcanoes; hazards are mainly lava flows, although tephra and gas emissions also occur.

Hazard profile similar for all three. Ruins of St. Pierre, Martinique. Pyroclastic flow (>700°C; ~200 km/h) Collapse of eruption from Mt. Pelée in 1902 killed 30 000 column (Mt. Mayon people; 2 survived. Phillipines, 1968)

Lake Nyos (Cameroon, 1986). More than 1700 people killed as a result of a massive release of CO2; Lahars: volcanic mudflows formed a ‘river’ about 50m deep that flowed for 25 km. L. Nyos currently contains about 350 M m3

of CO2. Similar event at L. Monoun (Cameroon) in 1984 resulted in 37 •Eruptive deaths. “volcanic rain” (e.g. Herculaneum) melting of summit snow/ice Volcanic gases (e.g. Nevado del Ruiz) In 1783 a massive fissure eruption near Laki, Iceland released huge amounts of basaltic lava (5 000 m3/s), and a ‘dry fog’ rich in SO2 and flourine. Some 75% of stock animals in Iceland died, the •Post-eruptive subsequent famine killed 10 000 people. intense rainstorms (e.g. Hurricane Mitch)

Nevado del Ruiz, Colombia

Lahar resulting from volcanic rain

10 Lahars, Mt Rainier

Osceola lahar: age: 5600 yrs BP length: 120 km volume: 40x Ruiz depth: 20m velocity: >70 km/h pop: 100 000

Jokulhlaups (e.g. Vatnajokull, Iceland) BENEFITS?

Ruins of Roman 1976 market, Pozzuoli; inundated by sea, uplifted by 2m in <10 years as a result of volcano-tectonic forces beneath Campi Flegrei caldera

In 1996 a subglacial eruption released 4 km3 of meltwater 1984

DIASTER AT THE GLOBAL SCALE “Super-volcanoes”

11 10 km The last super-eruption from Long Valley caldera

Bishop Tuff

3 Since 1980 some 2M m of CO2 released and substantial earthquake activity (some quakes M ~ 6) associated with intrusion of magma tongue

A supervolcano produces > 1,000 cubic km or thousands x larger than most The after-effects of a super-eruption volcanic eruptions. (from Rampino, 2002, Icarus, v.156, p. 562) Supervolcanoes occur when magma rises into crust but is unable to break through.  Stratospheric loading of ~1000 Mt of SO2 and Pressure builds until the crust gives way under pressure. sulphate aerosols  Aerosol veil persists for 5 - 10 years Can form at convergent plate boundaries and continental hotspot locations,  Global cooling of 3-5°C (locally 15°C) e.g. Yellowstone, and Valles Caldera in the US; Lake Toba, N Sumatra,  Collapse of agricultural production for several Indonesia; Taupo Volcano, N Island, NZ; and Aira Caldera in Japan. years --> famine --> conflict There have been only a handful of supervolcanoes during the Quaternary,  Last great supereruption (Toba, ~73,000 BP) may but eruptions typically cover huge areas with lava and volcanic ash and have reduced human population to ~10,000 people cause a long-lasting change to weather (such as the triggering of a small ice (Ambrose, 1998, J. Human Evolution., v. 34, 623) age sufficient to threaten the extinction of species.

Quaternary Period 2.588 ± 0.005 million y ago to the present

Understanding Global Impacts of Eruptions

Not only long-lasting, ash and aerosols spread quickly through the atmosphere. Formation of atmospheric sulfur aerosols has a more substantial effect on global temperatures (by reflecting For example, on August 26-27, 1883, Krakatau erupted ejecting 20 km3 of material in an eruption column almost 40 km high and absorbing solar irradiance) than simply the volume of ash produced during an eruption. Darkness immediately enveloped the neighboring Indonesian islands of Java and Sumatra. Sulfate aerosols appear to take several years to settle out of the atmosphere, which is one reason their effects Fine particles, however, rode atmospheric currents westward and can be widespread and long lasting. August 28, haze from the eruption had reached South Africa and by September 9 had circled the globe, only to do so several more times before settling out of the atmosphere.

12 Major volcanic eruptions since AD1600 >8000 deaths PHYSICAL ATTRIBUTES IMPACT ON HUMANS ~ HUMAN RESPONSE ~ EFFECTS OF HUMANS ON HAZARDS

HAZ Avg Avg Magnitude of Impact‐ Consider last 110 ySpatial Spatial Net Humans Benefit> Duration Spatial Freq scale scale Benefits to Exacerbation Cost s,m,h,d,y scale of Max Death Max Death & Mitigated Monitored Humans of hazard Yes/No of event /Event Cost Cost to L, R, G L, R, G List H, M, L ‐ Impact F, INT, 10? /Event change with Explain L, R, G IF 10? Dev ? Inc/Dec EQ

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