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| Titel |
Eruptive SO2-plume measurements at Piton de la Fournaise (Ile de La Réunion) by stationary NOVAC scanning MAX-DOAS instruments |
| VerfasserIn |
K. Garofalo, T. Staudacher, V. Ferrazzini, P. Kowalski, P. Boissier, A. Dupont, A. Peltier, B. Villemant, G. Boudon |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024312
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| Zusammenfassung |
| Since September 2007 stationary scanning MAX-DOAS instruments are installed on the
Enclos Fouqué caldera around Piton de la Fournaise volcano (PdF), integrating the volcano
monitoring network of the OVPF (Observatoire Volcanologique du Piton de la Fournaise).
The instruments are about 4 km away from the summit and can measure volcanic SO2
degassing downwind from Dolomieu crater or from a source located inside the caldera, since
activity is mostly concentrated here. The instruments work during daylight between 7:00 a.m.
and 6:00 p.m. local time, acquiring data on average every 7 minutes during favorable weather
conditions.
During the first year, corresponding to a pause in eruptive activity, the DOAS network did not
record any SO2 as PdF shows no significant degassing except during eruptions. Since then the
volcano has erupted three times recently (September 2008, November 2008 and December
2008, the latter is still ongoing).
Volcanic unrest started in August 2008 with an increase in seismicity and deformation.
Numerous seismic crises were recorded beneath the summit of the volcano, but still no SO2
emission was detected by the instruments during these events. On September 12th the DOAS
network detected for the first time SO2 degassing from the volcano. It was associated to
volcanic tremor under the summit indicating the presence of magma at shallow level in the
volcano edifice. Volcanic tremor and SO2 degassing lasted only some few hours,
announcing the forthcoming resumption in eruptive activity, which started nine days
later.
On September 21st, after a short seismic crisis, eruptive tremor appeared at 11:38 (UT), SO2
degassing followed immediately at 11:47 (UT). Lava emission occurred from a vent in
the West wall of the Dolomieu crater, probably from a relatively shallow magma
reservoir.
The eruption continued for 12 days. In the months that followed several seismic crises were
recorded, the last one on November 27th that shortly preceded eruptive tremor at the volcano
(07:50 UT) and signed the resumption of eruptive activity from the same vent as September
21st. SO2 degassing was recorded by the DOAS stations but poor weather conditions
prevented the detection of a well defined gas plume. The eruption lasted 26 hours,
terminating with “gas piston” activity. Low seismic but higher deformation activity was
recorded in the following days.
On December 14th at 22:45 (UT), after 16 hours-long seismic crisis, eruptive tremor
appeared again and a glowing in the crater was detected by webcams placed at the rim of the
Enclos Fouqué caldera. In the morning SO2 degassing was recorded by the DOAS stations. In
this still ongoing eruption SO2 emissions show major variations and good correlation with
tremor intensity. Further plume traverses had been performed in the field using mobile
mini-DOAS instruments.
Since September 2008, high time-resolved eruptive SO2 plume data had been acquired at
Piton de la Fournaise volcano. We investigate the correlation of SO2 data with geophysical
(seismic and acoustic) data, geodetic (GPS) data and modeled dike injection events and
location of magma reservoirs as well as petrological parameters to gain an integrated
understanding on volcano (magmatic and degassing) dynamics during these eruptive events at
Piton de la Fournaise. |
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