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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
{
Takk fyrir
Photo: Ó. Sigurjónsson