Sinabung

Volcano number:261080
Region:Indonesia
Country:Sumatra
Geodetic measurements?Yes
Deformation observation?Yes
Measurement method(s):InSAR, GPS - continuous
Duration of observation:06/2006-06/2009; 02/2007-01/2011; 03/2011-10/2013
Inferred cause of deformation:Magmatic
Characteristics of deformation:

The ongoing eruptions of Mount Sinabung, the first of which occurred in August 2010 and the most recent of which began in September 2013, precipitated several analyses of observational data preceding and immediately following the initial event. Many of these studies utilise ALOS InSAR data, such as the 2012 paper by Chaussard & Amelung, which involved an InSAR survey conducted over the West Sunda Arc, covering 400,000km2 between mid-2006 and mid-2009. This study noted an unsteady inflation of 3-8cm/yr during this period, with the peak uplift (8cm) occurring between 2007-2008. The source was determined to be a shallow magma reservoir, at a depth of approximately 0.9km below sea level. The same study noted similar patterns of inflation at two other Sumatran volcanoes, Kerinci and Slamet, both of which also erupted within 0.3-2 years of the end of the study period, prompting the authors to conclude that inflation may be a common precursor to eruptive activity in this region.

A second InSAR-based study, conducted by Lee et al and using ALOS data from February 2007 – January 2011, also recognised a period of inflation preceding the 2010 eruption, though this study estimated a much lower rate of inflation at ~1.7cm/yr, which increased greatly in the sixth months prior to the eruption to an estimated 6.6cm/yr. Lee et al noted that the inflation was largely confined to the summit of the volcano, but agreed with Chaussard & Amelung in that the rate of inflation fluctuated significantly over the course of the study.

Between the conclusion of the eruption, which ended in September 2010, and January 2011, Lee et al observed a steady period of deflation at the volcano summit, totalling around 3cm. The average volumetric change during the entire period was approximated to have ranged from -2.7×10-5 to 1.9×10-6 km3/yr. The study concurs with Chaussard & Amelung that the magmatic source of the deformation was likely to have been shallow, at a depth of between 0.3-1.3km.

Continuous GPS data has also been employed at the volcano; a study by Kriswati et al used data collected between March 2011 and October 2013 to identify a period of horizontal displacement at Sinabung between June and October 2013, on the order of 8-11.3mm. This study identified continued inflation at the volcano following the first explosions of the September 2013 eruption, and observes that displacement increases significantly after June of that year. The authors link this to a Mw6.1 earthquake which occurred in the region on 2nd July 2013, suggesting that this event may have affected the magma reservoir, triggering the increased deformation and possibly the eruption itself.

Reference:Chaussard, E. and Amelung, F. 2012. Precursory inflation of shallow magma reservoirs at west Sunda volcanoes detected by InSAR. Geophysical Research Letters, 39 (12) DOI: 10.1029/2012GL053817
Reference:Lee, C-W. et al. 2015. Volcanic activity analysis of Mt. Sinabung in Indonesia using InSAR and GIS techniques. IEEE International Geoscience and Remote Sensing Symposium, 4793-4796
Reference:Kriswati, E., Kuncoro, H. and Meilano, I. 2015. Low Rate of Sinabung Deformation Inferred by GPS Measurement. AIP Conference Proceedings, 1658 DOI: 10.1063/1.4915046
Location:98.392, 3.17

Photo by Tom Casadevall, 1987 (U.S. Geological Survey). From: Global Volcanism Program: Sinabung