Comment on "Crustal deformations in the epicentral area of the West Bohemia 2008 earthquake swarm in central Europe" by Schenk et al. (JGR 117 (2012), B07408)
Abstrakt
The principal motivation to write this comment is a surface vertical displacement of 167 mm with a rebound of 55 mm at GPS site KOPA (latitude = 50.19700oN, longitude = 12.48473oE) in the West Bohemia earthquake swarm area (central Europe) in connection with the ML 3.8 earthquake swarm in 2008, which was reported by Schenk et al. [2012]. Such extraordinary amplitude greatly exceeds any other geodetic displacements ever observed in the region, and even within central Europe.
In order to justify these GPS results, Schenk et al. [2012] present a complex crustal deformation model of the earthquake swarm area in West Bohemia consisting of several rotating crustal blocks, which are derived from hypocenter distributions. Besides, they present numerous, mostly vague arguments related to geomorphology, geochemistry, brittle tectonics, and fluid emanations to support their idea of rotating crustal blocks and invoke an impression of well-based multidisciplinary study.
In this comment we present results of our GPS observations and leveling measurements, which show a quite different pattern of surface deformation in the West Bohemia earthquake swarm area. Besides, we show that seismological data used by Schenk et al. [2012] to support their crustal fabric model were erroneous, and their way of data processing was missing adequate quality control.