Abstract
Lava flows pose a significant hazard to infrastructure and property located close to volcanoes, and understanding how flows advance is necessary to manage volcanic hazard during eruptions. Compared to low-silica basaltic flows, flows of andesitic composition are infrequently erupted and so relatively few studies of their characteristics and behaviour exist. We use El Reventador, Ecuador as a target to investigate andesitic lava flow properties during a 4.5 year period of extrusive eruption between February 2012 and August 2016. We use satellite radar to map the dimensions of 43 lava flows and look at variations in their emplacement behaviour over time. We find that flows descended the north and south flanks of El Reventador, and were mostly emplaced over durations shorter than the satellite repeat interval of 24 days. Flows ranged in length from 0.3 to 1.7 km, and the length of flows generally decreased over the observation period. We measure a decrease in flow volume with time that is correlated with a long-term exponential decrease in effusion rate, and propose that this behaviour is caused by temporary magma storage in the conduit acting as magma capacitor between the magma reservoir and the surface. We use the dimensions of flow levées and widths to estimate the flow yield strengths. We observe that some flows were diverted by topographic obstacles, and compare measurements of decreased channel width and increased flow thickness at the obstacles with observations from laboratory experiments. Radar observations, such as those presented here, could be used to map and measure properties of evolving lava flow fields at other remote or difficult to monitor volcanoes.
Highlights
Lava flows pose a significant hazard to infrastructure and property located close to volcanoes, and understanding how flows advance is necessary to manage volcanic hazard during eruptions
We map 43 morphologically distinct lava flows that were active between 9 February 2012 and 24 August 2016
We have combined satellite radar amplitude maps of lava flow extent and radar phase measurements of topographic change to investigate flow parameters and how these parameters varied over Phase E of the post-2002 eruption of El Reventador, Ecuador between 9 February 2012 and 24 August 2016
Summary
Lava flows pose a significant hazard to infrastructure and property located close to volcanoes, and understanding how flows advance is necessary to manage volcanic hazard during eruptions. We observe that some flows were diverted by topographic obstacles, and compare measurements of decreased channel width and increased flow thickness at the obstacles with observations from laboratory experiments Radar observations, such as those presented here, could be used to map and measure properties of evolving lava flow fields at other remote or difficult to monitor volcanoes. Walker et al, 1973; Hulme, 1974; Eichelberger et al, 1986; Cashman et al, 2007; Harris and Rowland, 2009; Cashman et al, 2013). Understanding how there are fewer observations of active flows of andesitic lava flows advance and behave is crucial for hazard man- or dacitic composition (Borgia et al, 1983; Farquharson et al, 2015; agement at active volcanoes (e.g. Felpeto et al, 2001; Behncke et Harris et al, 2004; Navarro-Ochoa et al, 2002; Kilburn and Lopes, al., 2005; Favalli et al, 2009; Harris and Rowland, 2009; National 1991; Fink et al, 1987; Cigolini et al, 1984)
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