Rapid reinflation following the 2011–2012 rhyodacite eruption at Cordón Caulle volcano (Southern Andes) imaged by InSAR: Evidence for magma reservoir refill

Abstract

Cordón Caulle is a large fissural volcano that has erupted rhyodacitic magma of the same composition in its past three historical eruptions in 1921, 1960, and 2011–2012. There was significant ground deformation observed before and during the 2011–2012 eruption—here we use C and X band interferometric synthetic aperture radar (InSAR) time series results to document posteruptive uplift up to 0.8 m between March 2012 and May 2015, with line‐of‐sight rates up to 45 cm/yr that have been largely aseismic, along with subsidence in the 2011–2012 lava flow. The 2012 uplift rate is one of the largest for silicic systems and was likely produced by the intrusion of ~0.125 km3 of magma in the same tectonically controlled plumbing system that has been active during the historical eruptions. Nevertheless, the uplift ended before the reservoir refilled with the erupted volume, maybe due to a change in the pressure gradient produced by the 2011–2012 eruption.

Renewed Posteruptive Uplift Following the 2011–2012 Rhyolitic Eruption of Cordón Caulle (Southern Andes, Chile): Evidence for Transient Episodes of Magma Reservoir Recharge During 2012–2018

“…The differential interferograms calculated for every satellite orbit show ∼12 cm of uplift between June 2016 and February 2017 (Figures c to i), with a mean velocity of ∼23 cm/year (Figure ), in agreement with an independent ALOS‐2 ScanSAR time series (Euillades et al, ). This rate is intermediate between ∼45 cm/year during 2012–2013 (Delgado et al, ) and ∼16–17 cm/year during 2013–2015 (Figure ). The onset of uplift can be inferred assuming uplift at a constant rate for the 2016 winter and then interpolating the ground displacement until it matches the period of no deformation in mid‐2016.…”

“…An intriguing feature of the 2012–2015 and 2016–2017 inflation events is the overall lack of abnormal seismicity (Delgado et al, ). The only abnormal seismicity since the onset of inflation in March 2012 occurred in April 2012 (Figure 11, Delgado et al, ), in June 08 2016 with a maximum local magnitude M L of 3.0 (OVDAS,2016), which could be related to the onset of the second inflation event in June–July 2016, and in early June 2018 (OVDAS,2018; Figure ).…”

“…An intriguing feature of the 2012–2015 and 2016–2017 inflation events is the overall lack of abnormal seismicity (Delgado et al, ). The only abnormal seismicity since the onset of inflation in March 2012 occurred in April 2012 (Figure 11, Delgado et al, ), in June 08 2016 with a maximum local magnitude M L of 3.0 (OVDAS,2016), which could be related to the onset of the second inflation event in June–July 2016, and in early June 2018 (OVDAS,2018; Figure ). A similar situation has also been observed at Long Valley caldera where only some of the seismicity is correlated with inflation events in its resurgent dome (Montgomery‐Brown et al, ), but it is different from other systems like Yellowstone where cycles of inflation‐deflation are correlated with seismic swarms (Hurwitz & Lowenstern, ).…”

“…The RS2, CSK, and S1 ascending time series have been offset from the CSK descending data so the end of the inflation can be better assessed in the latter. RSAT‐2 WF2 and CSK ascending data are from Delgado et al () and only shown for comparison with the 2016–2017 inflation. Campaign GPS observations in February–April 2016 are described in Delgado et al () and continuous GPS (cGPS) are recorded since late November 2017 by OVDAS (Southern Andes Volcano Observatory).…”

“…RSAT‐2 WF2 and CSK ascending data are from Delgado et al () and only shown for comparison with the 2016–2017 inflation. Campaign GPS observations in February–April 2016 are described in Delgado et al () and continuous GPS (cGPS) are recorded since late November 2017 by OVDAS (Southern Andes Volcano Observatory). Velocities are only shown for the periods of ground deformation.…”