Volcano number:351080
Region:South America
Geodetic measurements?Yes
Deformation observation?Yes
Measurement method(s):InSAR, Levelling, Tiltmeter
Duration of observation:1989-2009 (tilt and levelling), 2006-2009 (InSAR)
Inferred cause of deformation:Magmatic
Characteristics of deformation:

Tilt and levelling stations detected uplift at Galeras, starting in 1989, with peak uplift rates between June and November 1991 (Ordoñez and Rey, 1997). The source was modelled as a magmatic body, which rose from a depth of 2-3 km in late 1990 to less than 500 m in Dec. 1991.

3 cm of subsidence were detected at Galeras during an ALOS survey of Colombian volcanoes (Parks et al., 2011). The deformation occurred between Dec. 2007 and Jan. 2008, coincident with an eruption on Jan. 17 2008, and was modelled as a deflating magma body with 6.5 x 105 mvolume loss at 2 km depth. The same source was modelled by tilt to have a volume loss of ~ 7 x 10m3 at 1.4 km depth between 17 and 19 Jan. 2008 (Parks et al., 2011).

Reference:Ordóñez, V. M. I. G. C. A. Rey (1997), Deformation associated with the extrusion of a dome at Galeras volcano, 1990–1991,
J. Volcanol. Geotherm. Res., 77 (1997), pp. 115–120, doi:10.1016/S0377-0273(96)00090-X
Reference:Parks, M. M., J. Biggs, T. A. Mather, D. M. Pyle, F. Amelung, M. L. Monsalve, and L. Narváez Medina (2011), Co-eruptive subsidence at Galeras identified during an InSAR survey of Colombian volcanoes (2006–2009), Journal of Volcanology and Geothermal Research 202, no. 3, 228-240, doi:10.1016/j.jvolgeores.2011.02.007
Location:-77.37, 1.22

View of Galeras from the south. Photo: Norm Banks, 1989 (U.S. Geological Survey).

Fig. 3 from Parks et al. (2011): A) Galeras stacked interferogram, derived by averaging 7 L-band interferograms from tracks 152 and 153 over the period 20 June 2007–5 September 2008. The reference point used to scale amplitudes is displayed as a cross and the traverse used for extracting phase and elevation data is shown as the NW-SE trending line. The triangle marks the location of the summit at Galeras volcano. B) Profiles extracted from interferograms and DEM across Galeras. Profiles across individual interferograms are displayed as thin coloured lines. The profile across the DEM is displayed as the green shaded area. The profile across the stacked interferogram is displayed as the black line and the difference between minimum and maximum values as the grey filled area. Interferogram master and slave dates are in the format yymmdd.