Observations of Deformation

Volcano number:221060
Geodetic measurements?Yes
Deformation observation?Yes
Measurement method(s):InSAR
Duration of observation:2008 - 2010
Inferred cause(s) of deformation:Magmatic
Characteristics of deformation:

In November 2008 an eruption occurred at the Alu-Dalafilla volcanoes, causing lava flows to extend to the NE. Pagli et al. (2012) showed that this eruption was sourced by a 1 km deep elongated magma chamber that exists in two segments, and was probably trigged by an influx of magma from the north. Both magma chamber segments appeared to source the eruption though a connecting dyke. The magma chambers have since, rapidly, refilled.
InSAR was the primary tool to determine deformation during the eruption. Co-eruptive interferograms show an elongated, ~ 10-km-long, subsidence of 1.9m at the Alu volcano, and at Alu-South, maximum subsidence of 1m. From 5 November 2008 the deformation pattern at Alu-South reversed and uplift started, whereas at Alu minor subsidence continued between 5th November and 19th November but afterwards reversed to uplift. Since then, uplift occurred both at Alu and Alu-South. The maximum dyke opening to model this observation was 4.6m and the total dyke volume was 5.1×106m3. The observation of post-eruptive uplift is interpreted as the refilling of the source magma chamber.

Reference(s):Pagli, C., Wright, T. J., Ebinger, C. J., Yun, S. H., Cann, J. R., Barnie, T., & Ayele, A. (2012). Shallow axial magma chamber at the slow-spreading Erta Ale Ridge. Nature Geoscience, 5(4), 284-288.
Location:13.793, 40.55
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