Earthquake interactions during the 2013 Ebeichsdorf aftershock sequence

Autor(en)

Jean-Baptiste Tary, Maria-Theresia Apoloner, Götz Bokelmann

Abstrakt

The Vienna Basin Fault System (VBFS) is one of the most seismically active regions of Austria, delineating the southern part of the Vienna Basin. This sinistral, strike slip fault system, accommodates part of the deformation due to the northward push of the Adriatic microplate. In 2000 and 2013, two pairs of main shocks followed by a few tens of aftershocks occurred in the region of Ebreichsdorf, one of the clusters of seismicity along the VBFS. The main shocks seem to be located closely in both cases, even though high-resolution double-difference locations are available only for the sequence in 2013. Focusing on this sequence, we investigate the interactions between the two main shocks and their 18 aftershocks. The two main shocks are located almost at the same place, at a depth of 10.5 km, while the aftershocks constitute a shallower ellipsoid with its long axis parallel to the main trace of the VBFS. We use two Coulomb failure stress models to study possible static stress transfer between the main shocks and the aftershocks of this sequence, the apparent friction model and the isotropic poroelastic model. Both models yield Coulomb failure stress changes below 0.01 MPa at the aftershocks locations. Static stress transfer seems then unlikely to explain their occurrence, even though interactions between aftershocks could play a role in their triggering. Two other mechanisms are considered, namely pore pressure diffusion along an idealized fault plane, and aseismic creep. A high hydraulic diffusivity of about 1-10 m

²/s would be however required to account for the spatial extent of the possible interactions (~0.5-1 km) and the inter-event times (hours to days). The shallower location of the aftershocks compared to both main shocks could also point to the migration of fluids toward the surface. The occurrence of collocated events of comparable sizes and focal mechanisms, also named seismic repeaters, is often attributed to the presence of aseismic creep. But without further observations it would be difficult to support or rule out this hypothesis. Either the presence of high pore pressure or aseismic slip has important implications for the present-day earthquake potential of the VBFS to produce large earthquakes.

Organisation(en)

Institut für Meteorologie und Geophysik

Externe Organisation(en)

University of Alberta

Journal

Austrian Journal of Earth Sciences

Band

108

Seiten

209-218

Anzahl der Seiten

10

ISSN

0251-7493

DOI

https://doi.org/10.17738/AJES.2015.0022

Publikationsdatum

2015

Peer-reviewed

Ja

ÖFOS 2012

105106 Geodynamik, 105122 Seismik, 105102 Allgemeine Geophysik

Schlagwörter

ASJC Scopus Sachgebiete

Geology, Palaeontology, Stratigraphy

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/earthquake-interactions-during-the-2013-ebeichsdorf-aftershock-sequence(b96cf01a-cb6d-479e-9f78-56990e0f1539).html