TY - JOUR A1 - López-Comino, José Ángel A1 - Cesca, Simone A1 - Niemz, Peter A1 - Dahm, Torsten A1 - Zang, Arno T1 - Rupture directivity in 3D inferred from acoustic emissions events in a mine-scale hydraulic fracturing experiment T2 - Frontiers in Earth Science N2 - Rupture directivity, implying a predominant earthquake rupture propagation direction, is typically inferred upon the identification of 2D azimuthal patterns of seismic observations for weak to large earthquakes using surface-monitoring networks. However, the recent increase of 3D monitoring networks deployed in the shallow subsurface and underground laboratories toward the monitoring of microseismicity allows to extend the directivity analysis to 3D modeling, beyond the usual range of magnitudes. The high-quality full waveforms recorded for the largest, decimeter-scale acoustic emission (AE) events during a meter-scale hydraulic fracturing experiment in granites at similar to 410 m depth allow us to resolve the apparent durations observed at each AE sensor to analyze 3D-directivity effects. Unilateral and (asymmetric) bilateral ruptures are then characterized by the introduction of a parameter kappa, representing the angle between the directivity vector and the station vector. While the cloud of AE activity indicates the planes of the hydrofractures, the resolved directivity vectors show off-plane orientations, indicating that rupture planes of microfractures on a scale of centimeters have different geometries. Our results reveal a general alignment of the rupture directivity with the orientation of the minimum horizontal stress, implying that not only the slip direction but also the fracture growth produced by the fluid injections is controlled by the local stress conditions. KW - directivity KW - earthquake source KW - induced seismicity KW - hydraulic KW - fracturing KW - acoustic emissions Y1 - 2021 UR - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/64126 SN - 2296-6463 VL - 9 PB - Frontiers Media CY - Lausanne ER -