|Measurement method(s):||InSAR, GPS - continuous|
|Duration of observation:||2014-2015 (InSAR, GPS)|
|Inferred cause of deformation:||Hydrothermal, Magmatic, Faulting/tectonics|
|Characteristics of deformation:|
No deformation was detected at Chiles-Cerro Negro between 2006 and 2009 during an ALOS surveys of Colombian volcanoes (Parks et al., 2011).
Starting in 2013, there were several seismic swarms under Chiles-Cerro Negro, which culminated in a magnitude 5.6 earthquake on Oct. 20 2014 and up to 7000 smaller events per day. InSAR observations of the event showed it to be almost purely tectonic and dip slip in nature, with a maximum surface uplift of 23 cm (Ebmeier, 2015). GPS observations show a slight uplift signal starting ~10 days before the M5.6 event, which has been attributed to either magmatic or hydrothermal fluid accumulation in a deep source ~ 15 km south of the volcanoes (Ebmeier, 2015).
|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|
|Reference:||Ebmeier, S. K., (2015), Stress controlled magma-earthquake interaction during unrest at Chiles-Cerro Negro Volcanoes (Ecuador-Colombian border); Oral Presentation, AGU Fall Meeting 2015.|
View from the south of Cerro Negro de Mayasquer (left) and Chiles (snow capped, centre). Photo: Minard Hall, 1985 (IG-EPN, Quito).
Interferogram showing the M5.6 earthquake on Oct. 20 2014. One fringe represents ~1.5 cm ground motion. Triangles show the locations of Cerro Negro and Chiles. Image: Susanna Ebmeier, 2014.