 |
| Titel |
Lazufre volcanic complex, Chile: attempts to image a large scale magmatic inflation body using regional and teleseismic broadband recordings |
| VerfasserIn |
Sebastian Heimann, Stefan Trabs, Torsten Dahm |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250083935
|
|
|
|
|
|
| Zusammenfassung |
| The Lazufre volcanic area around Lastarria and Cordon del Azufre in the central Andes is the
second largest area of presently active volcano related uplift woldwide. A magma reservoir or
sill layer, filling in about 10 km depth, is thought to be causative for inflation of an area of
more than 1800Â km2 (more than four times larger than the total area of the city of Vienna).
Uplift rates of up to 3.2Â cm/yr were found from InSAR measurements during the past two
decades.
In 2008, we deployed a network of 17 broadband seismometers in and around the area of
active uplift for a period of 2 months. Hundreds of regional and several teleseismic
earthquakes were recorded during the experiment. Recorded seismograms show strong
anomalies in the region of maximum uplift. We tried to apply (1) tomography with regional
events and (2) the receiver function technique with teleseismic events in order to
interprete the recorded anomalies. Due to the relatively short dataset and the very
heterogeneous structure beneath Lazufre, both techniques could only be applied with limited
success.
(1) To gain a full tomographic image of the deep underground, ray coverage was not
dense enough. However, recorded delay times and amplitude decreases for rays passing
through the inflation center carry valuable information.
(2) Receiver functions were strongly influenced by 3D structure and could not be
intepreted using standard techniques. Nevertheless, careful data selection and comparison
with modelling results led to conclusions.
In combination, our results allow for some insights into the volcanic complex. We can
confirm the presence of molten or partially molten material at a depth of 8Â km in
the center and 12Â km in the outer parts and can derive constraints on the lateral
extent of the intrusion. We also find evidence for a huge low velocity zone at greater
depth. |
|
|
|
|
|
|