|Measurement method(s):||InSAR, Tiltmeter|
|Duration of observation:||1998-present (tilt), 2007-2011 (InSAR)|
|Inferred cause of deformation:||Magmatic|
|Characteristics of deformation:|
Cycles of inflation and deflation were detected by a tiltmeter installed 2.5 km from the lava dome of Guagua Pichincha between September and December 1999 (Garcia-Aristizabal et al., 2007). The tilt signals were temporally correlated with VT and LP earthquake swarms, and the largest tilt change of 26 μrad corresponded with the growth of a small lava dome (0.5 million m3) between 18 to 21 November 1999. The inflation was followed by deflation on the 26 November 1999 when the lava dome collapse, suggesting the inflation was due to pressure build-up by the dome blocking the conduit (Garcia-Aristizabal et al., 2007).
A regional ALOS survey of Northern Andes volcanoes found the west flank of Guagua Pichincha to be inflating at a rate of 2.6 ± 0.5 cm/yr between 2007 and 2009 (Morales Rivera et al., 2016). The deformation was modelled by a Mogi source at a depth of 3 km inflating by 0.12 × 106 m3, and is thought to be either hydrothermal or magmatic in origin.
|Reference:||Alexander Garcia-Aristizabal, Hiroyuki Kumagai, Pablo Samaniego, Patricia Mothes, Hugo Yepes, Michel Monzier, Seismic, petrologic, and geodetic analyses of the 1999 dome-forming eruption of Guagua Pichincha volcano, Ecuador, Journal of Volcanology and Geothermal Research, Volume 161, Issue 4, 1 April 2007, Pages 333-351, ISSN 0377-0273, http://dx.doi.org/10.1016/j.jvolgeores.2006.12.007.|
|Reference:||Morales Rivera, A. M., F. Amelung, and P. Mothes (2016), Volcano deformation survey over the Northern and Central Andes with ALOS InSAR time series, Geochem. Geophys. Geosyst., 17, 2869–2883, doi:10.1002/2016GC006393.|
Aerial view from the east looking over Quito towards the Pichincha Volcano Complex. Photo: Patricio Ramon, 2004 (Instituto Geofisca, Escuela Politecnica Nacional).