HISS - High-resolution Imaging of Swarm Systems through seismological re-processing of earthquake swarm episodes employing full waveform double-difference methods DFG – SPP ICDP
Duration: 1 November 2015 to 20 February 2018
PI Simone Cesca
People: Marius Kriegerowski, Simone Cesca, Torsten Dahm
Frank Krüger, Matthias Ohrnberger (Uni Potsdam),
Catherine Alexandrakis (TU Freiberg)
Crustal earthquake swarms are an expression of intensive cracking and rock damaging over periods of days to months in a small source volume in the crust. They are caused by stress changes in the source region, often associated with fluid or gas migration, possible in combination with pre-existing zones of weakness. Verifying and quantifying localized fluid movement at depth remains difficult since the area affected is small and geophysical prospecting methods often cannot reach the required resolution. NW Bohemia (Czech Republic) and the Vogtland (Germany) region is regularly affected by earthquake swarms at mid-crustal depths between 6-12km. Since 1997 the earthquake swarms concentrate around a small volume close to the village Novy Kostel, which has been suggested as the site of a deep drilling within ICDP.
It is still unclear whether the observed seismicity is caused by gas inflow under high pressure or direct magmatic intrusions. Anomalous seismic velocites ratios have been observed accompanying the swarm activity, which may indicate that the swarm is related to fluid or gas in a porous or fractured rock.
The HISS project aims at the development and implementation of full waveform based methods to improve the imaging of swarm seismogenic volumes and feeding regions. We aim to provide high-resolution images of seismic velocity and attenuation at the NW Bohemia swarm region, track significant velocities and attenuation variation during each swarm and among different swarms, and finally significantly contribute to model the swarm and its feeding system region.