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| Titel |
Estimation of lava flow field volumes and volumetric effusion rates from airborne radar profiling and other data: Monitoring of the Nornahraun (Holuhraun) 2014/15 eruption in Iceland |
| VerfasserIn |
Tobias Dürig, Magnús Guðmundsson, Thórdis Högnadóttir, Ingibjörg Jónsdóttir, Snaebjörn Gudbjörnsson, Örnólfur Lárusson, Ármann Höskuldsson, Thorvaldur Thordarson  , Morten Riishuus, Eyjólfur Magnússon |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108751
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| Publikation (Nr.) |
 EGU/EGU2015-8519.pdf |
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| Zusammenfassung |
| Monitoring of lava-producing eruptions involves systematic measurement of flow field
volumes, which in turn can be used to obtain average magma discharge over the
period of observation. However, given inaccessibility to the interior parts of active
lava fields, remote sensing techniques must be applied. Several satellite platforms
provide data that can be geo-referenced, allowing area estimation. However, unless
sterographic or tandem satellite data are available, the determination of thicknesses is
non-trivial.
The ongoing eruption (“Nornaeldar”)at Dyngjusandurin the Icelandic highlands offers an
opportunity to monitor the temporal and spatial evolution of a typical Icelandic lava flow
field. The mode of emplacementis complex and includesboth horizontal and vertical stacking,
inflation of lobes and topographic inversions. Due to the large extent of the flow field (>83
km2 on 5 Jan 2015, and still growing) and its considerable local variation in thickness (30 m) and surface roughness, obtaining robust quantification of lava thicknesses is very
challenging,despite the lava is being emplaced onto a low-relief sandur plain. Creative
methods have been implemented to obtain as reliable observation as possible into
the third dimension: Next to areal extent measurements from satellites and maps
generated with airborne synthetic-aperture radar (SAR), lava thickness profiles are
regularly obtained by low-level flights with a fixed-wing aircraft that is equipped
with a ground clearance radar coupled witha submeter DGPS,a system originally
designed for monitoring surface changes of glaciers above geothermally active
areas.The resulting radar profile data are supplemented by analyses of aerial photos and
complemented by results from an array of ground based thickness measurement
methods.
The initial results indicate that average effusion ratewas ~200 m3/s in the first
weeks of the eruption (end August, early September) but declined to 50-100 m3/s in
November to December period. We discuss the used methods and their range of
application in detail, present the resulting volume estimates of the new lava field and
pinpoint the implications with emphasis on the temporal evolution of its effusion rate. |
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