Volcanic Eruptions: How Wet? How Hot? How Fast?

Volcanic Eruptions: How Wet? How Hot? How Fast?

Terry Plank, Lamont-Doherty Earth Observatory of Columbia University

Pavlof Volcano, Alaska March 27, 2016

15 Volcanoes Erupting or in a State of Eruption/Unrest Now

Where are the erupting volcanoes?

Mayon Volcano, Philippines Over 90,000 people evacuated

VEI = Volcanic Explosivity Index order of magnitude scale: 0 - 8

• eruptive mass • plume height • duration

How to Quantify Volcanic Explosivity?

VEI = 0-1non-explosive

Kilauea, Hawaii, 1952 - 1982

VEI = 1-2 �Strombolian� gentleAnak Krakatau (4. - 7. June 2009)

http://www.swisseduc.ch/stromboli/perm/krakatau/night-on-anak-krakatau-en.html

MSH - what about Pelee, Vesuvius, Krakatau??

VEI = 2-3 explosive, severeAnatahan, Marianas Islands: May 2003

Photograph by Heilprin, 1902 ttp://www.swisseduc.ch/stromboli/perm/guadeloupe-martinique/pelee-geology-en.html

VEI = 4 cataclysmicMt. Pelee, Martinique, 1902: 29,000 fatalities

VEI = 5 paroxysmalMt. Vesuvius, AD 79

Joseph Wright: �Vesuvius from Portici�

�Plinian� 1 km3

VEI = 6 colossalPinatubo, Philippines, 1991 10 km3

Also Krakatau, 1883

Global Climate Effects

VEI = 8 �super-volcano!�Yellowstone, 600,000 yrs ago

VEI 7 (100 km3) Tambora, 1815, Indonesia

1000 km3

Last%“super+volcano”%erup2on:%26,000%yrs%ago,%NZ%

VEI = 1 VEI = 4

Anak Krakatau, Indonesia Strombolian

Fuego, Guatemala Sub-Plinian

Volatiles?

Volatile Fuel Drives Eruption

How Much Water do Magmas Contain Before they Erupt?

And does it Relate to Eruptive Vigor?

Henry%Towbin%2nd%yr%Grad%Student%

LDEO%

Melt Inclusions May Preserve Undegassed H2O

0 1 2 3 4

0 1 2 3 4 0 200 400 600 800

H2O

CO2

H2O (wt%) in melt CO2 (ppm) in melt Pr

essur

e (kb

)

0 4 8 12 16

Depth (km)

degassed magma

Closed-system degassing from VolatileCalc (Newman and Lowenstern, 2001)

melt inclusion ~ 50 microns

olivine

Erik Hauri & Ion Microprobe, Carnegie Institution of Washington

Spots analyzed with: • ion microprobe, • electron microprobe • laser ablation ICPMS

Scoria'('Yes!'Bombs,

Boo!

< 2 cm lapilli

(and ash) YES!

Lloyd et al. (2012) CMP– water loss from clasts of different size

Google Earth

NSF/GeoPrisms+AVO/USGS+Deep%Carbon%Obs.%Joint%Expedi2ons%

2016%Team%on%the%Mari2me%Maid%with%the%Mari2me%Helicopter%

“Slab'to'the'Surface”'

First Volcanic Gas Data in the Western Aleutians (2015) DCO/DECADE/GeoPrisms (Tobias Fischer, Taryn Lopez, Cynthia Werner, Christoph Kern)

Kiska%

Dan%Rasmussen%4th%%yr%Grad%Student%

LDEO%

Diana%Roman,%Carnegie%

Aleu2ans%2015+2016%

Seguam Volcano (Alaska), 1977 Eruption

0 100 200 300 400 500 600

0 1 2 3 4 H2O (wt%)

CO2 (p

pm)

8 km 4 km

2 km Ascent

olivine-hosted melt inclusions

From Zimmer et al. (2010) J. Pet.

max

0 2 4 6 8

10 12 14

1 N = 56 volcanoes, 7 arcs, maximum H2O

Maximum H2O (wt%)

n

Why do Most Mafic Arc Magmas Have 4 +/-1 wt% H2O?

3.9 +/- 0.4 arc average 3.9 +/- 1.2 volcano average

2 3 4 5 6 7

0

1

2

3

4

5

6

1 2 3 4 5 6

VEI

(Vo

lcanic

Exp

losivi

ty In

dex)

H2O wt% in pre-eruptive magma

No Obvious Relationship between Eruptive Intensity and Pre-Eruptive H2O

Akutan 340 CE

Seguam 1977

C.Negro 1992

Fuego 1974 Arenal ET3

Okmok 1997

Shishaldin 1999

Irazu 1723

So.......

Total Volatile Fuel Does Not Scale to Eruption Intensity

What about decompression rate?

Why does the rate of magma rise matter?

1. Bubble-liquid segregation and bubble coalescence

high ascent rate

2. Bubble number density

3. Shear heating along conduit walls

low ascent rate

Also:%Bri[le%failure,%microlites,%diseq%degassing%

bubble%are%white%here%

bubble%are%black%here%

bubble%are%white%here%

bubble%are%black%here%

bubble%are%white%here% bubble%are%white%here%

Edmonds, 2008

How fast do our clocks have to be?.......

Minutes to Hours?

The Mantle

How Fast do Our Clocks Have to Be?

20-50 km

3-6 km

The Crust

Thermal Diffusion and Turkeys

With credit to England, Molnar and Richter, 2007

the turkey the ice-box

180°F

32°F

20 minutes

2 cm

80 minutes

4 cm

Chemical%Diffusion%

Initial ConcentrationH2O

Diffusion Clock

center edgeedge

1 mm

H2OH2O

magma

Diffusion Clock

center edgeedge

1 mm

H2O%loss%with%2me%

H2O concentrationin crystal

Community Volcano Experiments'

National Academies ERUPT Report (2017)