Emmy-Noether-Projekt "Brückenschlag zwischen Geodäsie und Seismologie"

An active ring fault detected at Tendürek volcano by using InSAR

Bathke, H., Sudhaus, H., Holohan, E.P., Walter T.R. and Shirzaei, M., (2013).

Journal of Geophysical Research, 118(8), 4488-4502.  DOI: 10.1002/jgrb.50305

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Abstract

Although ring faults are present at many ancient, deeply eroded volcanoes, they have been detected at only very few modern volcanic centers. At the so far little studied Tendürek volcano in eastern Turkey, we generated an ascending and a descending InSAR time series of its surface displacement field for the period from 2003 to 2010.

We detected a large (~105 km2) region that underwent subsidence at the rate of ~1 cm/yr during this period. Source modeling results show that the observed signal fits best to simulations of a near-horizontal contracting sill located at around 4.5 km below the volcano summit.

Intriguingly, the residual displacement velocity field contains a steep gradient that systematically follows a system of arcuate fractures visible on the volcano's midflanks.

RapidEye satellite optical images show that this fracture system has deflected Holocene lava flows, thus indicating its presence for at least several millennia. We interpret the arcuate fracture system as the surface expression of an inherited ring fault that has been slowly reactivated during the detected recent subsidence.

These results show that volcano ring faults may not only slip rapidly during eruptive or intrusive phases, but also slowly during dormant phases.

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