Fig. 5
From: Earthquakes in Switzerland and surrounding regions during 2017 and 2018
Fault-plane solutions and relative relocations of the ML 4.6 Urnerboden earthquake sequence of March 6, 2017. a Fault-plane solution (lower hemisphere projections) of the ML 4.6 mainshock based on first-motion polarities (top) and corresponding full-waveform moment tensor (MT) solutions (bottom). b, c Fault-plane solutions based on first-motion polarities of two aftershocks in 2017 and 2018. Symbols and explanation of focal mechanism as in Figs. 4 and 6, parameters listed in Additional file 1: Table S4. d Double-difference relative relocations including foreshocks and mainshock of March 6, as well as immediate aftershocks until 12:00 (UTC) the following day. In addition, the relative relocations of the ML 2.8 earthquake of August 2018 and the ML 4.0 earthquake of May 2003 are marked by the grey dots. Error bars indicate the relative horizontal location errors. The dashed red and green lines indicate the presumed geometry of the fault ruptured during the ML 4.6 mainshock as imaged by relative relocations of immediate aftershocks and fault strikes of focal planes. Relative relocations suggest that the mainshock triggered secondary structures, hosting e.g. the ML 2.8 earthquake of August 2018