| ESA | Earth Home | Missions | Data Products | Resources | Applications |
| 24-May-2012 |
 EO Data Access
|
|||
 |
How to Apply | ||
 |
|
|
|
| |
How to Access | ||
|
|||
| |||
| 3rd ERS SYMPOSIUM Florence 97 - Abstracts and Papers | |||
| |||
| >POST-ERUPTIVE DEFORMATION ASSOCIATED WITH THE 1986-87 AND 1989 LAVA FLOWS O | |||
| |||
| Services |
| Site Map |
|
| Frequently asked questions |
|
| Glossary |
|
| Credits |
|
| Terms of use |
|
| Contact us |
|
| Advanced Search |  |
POST-ERUPTIVE DEFORMATION ASSOCIATED WITH THE
1986-87 AND 1989 LAVA FLOWS OF ETNA DETECTED BY RADAR INTEFEROMETRY.
| Briole Pierre | Institut de Physique du Globe
4 place Jussieu 75252 Paris Cedex 05, France briole@ipgp.jussieu.fr http://www.ipgp.jussieu.fr | |
| Massonnet Didier | CNES | |
| Delacourt Christophe | Institut de Physique du Globe
Département Etudes Spatiales 4 place Jussieu 75252 Paris Cedex 05, France delac@ipgp.jussieu.fr http://www.ipgp.jussieu.fr |
Abstract
We analysed 92 interferograms produced using ERS1
SAR images taken on Etna between May 1992 and October 1993. Nineteen
show a local subsidence in the eastern flank of the volcano, correlated
with the location of the 30 October 1986 - 1 March 1987 and 27
September - 9 October 1989 lava flows.
Using fringe unwrapping and data gridding techniques,
and assuming that over the sampled time-window, deformation was
a linear function of time, we derive a map of along range rate
of motion. The correlation between the deformation field covered
by recent lavas suggests that compaction of the lava flows continues
several years after the eruptions.
The area of maximum subsidence (47 mm/yr.) is
localised at the narrowing of the 1989 flow, between 1500 and
1700 m a.s.l.We observe that subsidence extends outside the lava
flows, accounting for at least 12 mm/yr.
Assuming a relaxation process of the substrate
in response to loading produced by recent lavas, a simple 1D Maxwell
visco-elastic model predicts a maximum subsidence rate of 25 mm/yr
and a relaxation time of about 3.5 years.
The relaxation time agrees with those derived
from post-eruptive displacements observed by levelling on Etna
and Piton de la Fournaise after several eruptions.
We conclude that at the time of our measurements,
25 to 50% of the deformation was related to relaxation of the
substrate and the other part due to compaction of the lava flows.
- .
- Keywords: SAR differential interferometry.Ground
deformation lava-flow.Etna
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,
atmospheric chemistry
Abstract
We analysed 92 interferograms produced using ERS1 SAR images taken on Etna between May 1992 and October 1993. Nineteen show a local subsidence in the eastern flank of the volcano, correlated with the location of the 30 October 1986 - 1 March 1987 and 27 September - 9 October 1989 lava flows.
Using fringe unwrapping and data gridding techniques, and assuming that over the sampled time-window, deformation was a linear function of time, we derive a map of along range rate of motion. The correlation between the deformation field covered by recent lavas suggests that compaction of the lava flows continues several years after the eruptions.
The area of maximum subsidence (47 mm/yr.) is localised at the narrowing of the 1989 flow, between 1500 and 1700 m a.s.l.We observe that subsidence extends outside the lava flows, accounting for at least 12 mm/yr.
Assuming a relaxation process of the substrate in response to loading produced by recent lavas, a simple 1D Maxwell visco-elastic model predicts a maximum subsidence rate of 25 mm/yr and a relaxation time of about 3.5 years.
The relaxation time agrees with those derived from post-eruptive displacements observed by levelling on Etna and Piton de la Fournaise after several eruptions.
We conclude that at the time of our measurements,
25 to 50% of the deformation was related to relaxation of the
substrate and the other part due to compaction of the lava flows.
- .
- Keywords: SAR differential interferometry.Ground deformation lava-flow.Etna
Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry