Alban Hills

Observations of Deformation

Volcano number:211004
Geodetic measurements?Yes
Deformation observation?Yes
Measurement method(s):InSAR, GPS - continuous, GPS - campaign, Levelling
Duration of observation:1950 to present
Inferred cause(s) of deformation:Magmatic
Characteristics of deformation:

From Anzidei et al., 2010: An uplift of ~30 cm over the last 43 years was recently detected by levelling surveys performed in the time span 1950-1993 along a levelling line that crosses the highest elevation area of the western flank of the volcano. The comparison between the 1950-1999 surveys show significant uplift, whereas the subsequent surveys (1997-1999 and 2002) have not shown uplift at a confidence level of 95%. From 2002 to 2006, a small uplift is detected along the leveling line and the Albano lake levelling circuit.

Space-based GPS and InSAR observations confirm that this uplift is distributed in a wide area around the craters of Albano and Nemi, where the most recent volcanic activity occurred. GPS data from continuous monitoring stations indicate that both horizontal and vertical deformations do occur and that can be addressed to a shallow magmatic source.

The simplest model able to fit the low number of GPS observations (14 measurements from 6 GPS stations, 4 rejected due to local effects) is a point-pressure source at a depth of about 4.7 km, on the western flank of the Colli Albani complex.

A SAR dataset used to study the Colli Albani area is composed by ERS1 and ERS2 images, for a total of 66 SAR descending acquisitions available from June 1992 to December 2000, whilst 34 images from April 1993 until November 2000 concern the ascending dataset. An uplift zone, mainly located on the west part of the Colli Albani caldera complex is clearly evident. A maximum of about 2.5 mm/yr is measured by the PS close to the villages of Ariccia and Albano (Salvi et al. 2004).

All data sets are in agreement and indicate that this volcano shows active deformation with uplift rates within 6 mm/year. These are mainly located in a well defined area that includes the surroundings of the Albano and Nemi lakes and the main villages of Marino, Albano and Ariccia, the area of the most recent volcanic activity.

Reference(s):Anzidei, M., F. Rigussi, and S. Stramondo (2010) Current geodetic deformation of the Colli Albani volcano: A review, in The Colli Albani Volcano, Eds., R. Funiciello and G. Giordano, The Geological Society of London.
Salvi, S., Atzori, S., Tolomei, C., Allevi, J., Ferretti, A., Rocca, F., Prati, C., Stramondo,
S., Feuillet, N., 2004. Inflation rate of the Colli Albani volcanic complex retrieved by the
permanent scatterers SAR interferometry technique. Geophysical Research Letter 31 (12).
Smithsonian Institution Global Volcanism Program
Location:41.73, 12.7
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