CHANGES IN CRATER MORPHOLOGY ASSOCIATED WITH VOLCANIC ACTIVITY AT TELICA VOLCANO, NICARAGUA: INSIGHT INTO SUMMIT CRATER FORMATION AND ERUPTION TRIGGERING
Open Access
- Author:
- Hanagan, Catherine Elise
- Area of Honors:
- Geosciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Peter Christopher La Femina, Thesis Supervisor
Dr. Maureen Feineman, Thesis Honors Advisor - Keywords:
- Telica Volcano
Nicaragua
Structure from Motion
Photogrammetry
Volcanology
Pit Crater
Morphology
Point Cloud
Eruption
Hazard - Abstract:
- Telica is a persistently active basaltic-andesite stratovolcano in the Central American Volcanic Arc of Nicaragua. Poorly predicted sub-decadal, low explosivity (VEI 1-2) phreatic eruptions and background persistent activity with high-rates of seismic unrest and frequent degassing contribute to morphologic change in Telica’s active crater on a small spatiotemporal scale. These changes sustain a morphology similar to those of commonly recognized calderas or pit craters (Roche et al., 2001; Rymer et al., 1998), and have been related to sealing of the hydrothermal system prior to eruption (INETER Buletin Anual, 2013). We use photograph observations and Structure from Motion point cloud construction and comparison (Multiscale Model to Model Cloud Comparison, Lague et al., 2013; Westoby et al., 2012) from 1994 to 2017 to correlate changes in Telica’s crater with sustained summit crater formation and eruptive pre-cursors. Two previously proposed mechanisms for sealing at Telica are: 1) widespread hydrothermal mineralization throughout the magmatic-hydrothermal system (Geirsson et al., 2014; Rodgers et al., 2015; Roman et al., 2016); and/or 2) surficial blocking of the vent by landslides and rock fall (INETER Buletin Anual, 2013). We observe collapse from the crater walls (up to 25 m) and accumulation over the active vent and surrounding crater floor (up to 40 m) as a result of persistent activity. The highest-rate mass wasting areas correlate with long-lived high-temperature crater wall fumaroles, which contribute to hydrothermal weakening of the wall rock (Finn et al., 2001; van Wyk de Vries et al., 2000) and subsequent collapse. Eruptions exclusively cause material subtraction from the crater floor (up to 20 m) through vent clearing or formation. These patterns of change sustain the over-steepened crater walls and flat crater floors characteristic of pit craters and calderas (Roche et al., 2001), but absence of a shallow depressurized chamber suggests possible formation as a summit explosion crater instead. Though landslide talus blocks the vent, observed persistent fumaroles provide pressure release that negates shallow vent-blocking landslide talus as the primary sealing mechanism prior to eruption. This study shows the promise and utility of photogrammetric techniques in correlating morphologic change with crater formation and volcanic activity; however, we recommend more complete and accurate photo coverage in addition to combined analysis with other geophysical and geochemical datasets to better evaluate eruptive precursors that may occur at Telica.