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Eyjafjallajökull 2010:Ash and aerosol during and after the eruption

Evgenia Ilyinskaya, Guðrún Nína Petersen, Sibylle von Löwis,

Halldór Björnsson, Matthew J. Roberts, Steinunn S.

Jakobsdóttir, Sigurlaug Hjaltadóttir, Þórður Arason, et al.

Overview of the talk• Volcano monitoring systems in Iceland

• Course of Eyjafjallajökull eruption

• The volcanic plume and the atmosphere

• Aerosol and ash measurements during and

after the eruption

At the edge of the ash plume on April 17 (E. Ilyinskaya)

Geophysical monitoring network

• 62 seismic

stations

• ~70 GPS

stations

• 6 strainmeter

stations

Start of the summit eruption

5

Eruptions of Eyjafjallajökull after the settlement

• ~ 920

• 1612

• 1821-1823

• 2010

Photo: B. Sveinsson

Eyjafjallajökull

The 2010 eruption: unusual in many ways

• Explosive

activity went

on for a long

time

• Unusually

high

proportion of

fine ash April 17, photo: B. Palmason

Eyjafjallajökull eruption in 2010: Two distinct eruption phases

1. Flank eruption on

Fimmvörðuháls March 20 –

April 12:

- Lava fountaning and lava flows

- Tourist attraction

- Negligible ash

2. Summit crater eruption

April 14 – May 23:

- With highly explosive phases

- Tephra and ash production

- Disruptions to air traffic

- Significant local ash fall

Phase I

Phase II

Photos: E. Ilyinskaya

Fimmvörðuháls

Highly ash-rich activity I (April 14 – 17)

• Plume height 9.5 km on the

first day, then 5-7 km

• Intraglacial eruption:

contact of magma and

glacial meltwater -

explosivity intensified (?)

• Ash output 1 105 kg s-1

• Significant local ash fall

• Fine grain size

Summit crater on April 15, 17:18 UTC (radar image)

April 16, 18:00 April 17, 18:00

Photos: E. Ilyinskaya

Mildly explosive activity (April 18 – 30)• “Dry eruption”. Commencement of lava flow.

• Plume height 3-5 km

• Decrease in ash output 1 103 kg s-1

• Coarser ash grain size

• Change in wind direction - airports in Iceland close for the

first time April 24

‚Mixed‛ eruptive phase: ash generation + lava flows

Highly ash-rich activity II (May 1– 18)

• Plume height 6-7 km.

• Lava flow halts

• Further European airspace closures

Explosive phase II: SO2 increase preceeds ashMay 4 14:09 UTC : Low SO2 output May 5 13:13 UTC: High SO2 output

May 5 20:27 UTC : Low ash output May 6 11:50 UTC: High ash output

Ash characteristics

Photo: Joe Palca, NPR

Ash grain size distributions

XRD analysis (Ilyinskaya et al. 2011, Atmospheric Environment, in press)

Red: Highly explosive

activity (April 15-17)

• Poorly sorted

• 30 % of fallout < 18 µm

• Up to 7% < 1µm

Green: Mildly explosive

activity (April 18-30)

• Better sorted

• 2.5 % of fallout < 18 µm

• < 0.1 % < 1µm

Ash morphologyHighly explosive activity: fine, poorly sorted grains commonly as aggregated clusters

Mildly explosive activity: coarser, better sorted grains, more ‘fluid’ and vesiculated

(SEM images: E. Ilyinskaya, PhD thesis)

Near-source aerosol optical thickness and size distributions

Retrievals of Sun photometry measurements on April 1, 17 and 23 (Ilyinskaya et al. 2011, Atmos. Env., in press)

Flank eruption (black)

• Dominated by 0.2-0.4 µm

particles.

Highly explosive activity (red)

• Significant short-interval

fluctuations in the N ratio of

coarse/fine particles

Mildly explosive activity

(green)

• Strongly bimodal size

distribution (<0.4 and >1µm)

Composition of soluble aerosol and gas: difference between explosive phases

April 14 – 17: Intraglacial, highly explosive

• Gaseous emissions of SO2, HCl and HF not

detected (direct sampling and remote sensing)

• Suspended aerosol: water droplets, other

species b.d.l.

• Ash-adsorbed aerosol: F:Cl ratio 0.3

April 18 – 30: Dry, mildly explosive eruption

• Detection of gaseous SO2, HCl and HF

• Suspended aerosol: dominated by Cl- (> 1 µm)

and SO42- (< 0.4 µm)

• Drastic change in ash-adsorbed aerosol: F:Cl

ratio ~10. Up to 1000 mg/kg ash of F-.

Ash-adsorbed aerosol April 15-17

Ash-adsorbed aerosol April 18-25

Eruption cessation (May 23– ?)

• May 18 onwards: decreased activity

• May 23: No juvenile material, but still some seismic unrest

August 2010. Photo: K. Weber

March 2011. Photo: J. Sigurdsson

The aftermath: Resuspended ash

Reykjavík, June 4 2010Photo: S. Karlsdóttir

www.ust.is

Visibility: Very goodAir quality: Good

www.ust.is

Visibility: >16 kmAir quality: Acceptable

www.ust.is

Visibility: 4 kmAir quality: Bad

www.ust.is

Visibility: 1.6 kmAir quality: Very bad

www.ust.is

Visibility: 1 kmAir quality: Very bad

www.ust.is

Visibility: < 400 mAir quality: Very bad

Resuspended ash in the atmosphere• Resuspended ash and dust spreads over a large area• Several hundred kilometres away from source, the

dust cloud is still visible• TPCs correspond to wind speed dependent on

wind direction

MODIS image 30.10.2010

29.10.2010 12:00 30.10.2010 00:00 30.10.2010 12:00 31.10.2010 00:00

0

100

200

300

400

500

600

0

60

120

180

240

300

360

< 2.5 µm

2.5-32 µm

max ~ 900 cm-3

TP

C [

cm

-3]

Date / Time (UTC)

0

4

8

12

16

20

24

Win

d v

elo

city [

ms

-1]

Tindfjöll - Drangshlíðardalur

Win

d d

ire

ctio

n [

°]

What now?New techniques deployed:

• Mobile radar (CPA, Italy)

• Lidar (NCAS)

• OPC instrument (UAS Dusseldorf) in the field (0.25 –

32 µm)

• UV gas spectrometers (DOAS) in the field (Chalmers)

• Several instrument grant applications submitted

Extensive report on Eyjafjallajökull eruption (ICAO) –

useful for future eruptions

Unanswered questions• Quantification of produced ash

• Would the same amount of fine ash have been produced

without magma-ice interaction?

• Unprecendented problem with resuspended ash:

timescale?

• "Missing" gas emissions April 14 – 17

• Discrepancies between ground and satellite

measurements in the later eruptive stages

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Takk fyrir

Photo: Ó. Sigurjónsson