The 2013-2014 Effusive Eruption of Sinabung Volcano, Sumatra, Indonesia: Satellite Thermal Observations and Ground-Based Photogrammetry of a Growing Lava Lobe

Abstract:

Sinabung is a 2460 m high andesitic volcano located in northern Sumatra, Indonesia. Sinabung had no confirmed historical activity until a small (VEI 2) explosive eruption in August-September 2010. In September 2013, explosions began again and were accompanied by lava dome growth and subsequent dome-collapse generated pyroclastic flows (Bulletin of the Global Volcanism Network 35:07; 39:01). The Center for Volcanology and Geological Hazard Mitigation (Indonesia) estimated dome growth at 3.5 m³/s in late December 2013. From January to March 2014 lava extrusion continued and formed a lobe down Sinabung’s south flank. As of this writing, effusion and growth of the lava lobe continues, but at a much slower rate. Pyroclastic flows generated by collapse of the steep sides of the lobe remain a hazard. We use thermal infrared (TIR) images from the Moderate Resolution Imaging Spectroradiomter (MODIS) to observe volcanic activity at Sinabung during the 2013-2014 eruption and estimate effusion rates following the methods of Harris & Ripepe (2007, Geophys. Res. Let. 34). We also use new analysis of those thermal images to characterize style of activity, distinguishing pyroclastic flow activity from pure lava lobe growth. Preliminary results from satellite images show an average effusion rate of 1.1 m³/s during January-March 2014, with peak effusion rates from individual TIR images of 4-7 m³/s in mid-January. These numbers are in good agreement with the ground-based estimates, and they provide improved temporal resolution of the activity as it evolved. Since March, effusion rates have decreased to below 0.01 m³/s on average. Using the MODIS images, we estimate the maximum possible total erupted volume to be 7 million m³, and have constrained the accuracy of this estimate using Structure-from-Motion (SfM) photogrammetry from ground-based visual images of the lava lobe. Following explosions in 2010 and 2013 and high effusion rates from January to March 2014, the ongoing slow effusion suggests a steady-state, open vent system has been established.