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Dynamic full-field imaging of rupture radiation: Material contrast governs source mechanism
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  • Johannes Aichele,
  • soumaya latour,
  • Stefan Catheline,
  • Philippe Roux
Johannes Aichele
Swiss Federal Institute of Technology in Zurich

Corresponding Author:[email protected]

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soumaya latour
Université Toulouse 3 - Paul Sabatier
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Stefan Catheline
Lyon 1 University - INSERM
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Philippe Roux
Université Grenoble Alpes & CNRS
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In seismology, the rupture mechanism of an earthquake, a glacier stick-slip and a landslide is not directly observed, but inferred from surface measurements. In contrast, laboratory experiments can illuminate near field effects, which reflect the rupture mechanism but are highly attenuated in the case of real-world surface data. We directly image the elastic wave-field of a nucleating rupture non-invasively in its near-field with ultrasound speckle correlation. Our imaging yields the particle velocity of the full shear wave field at the source location and inside the 3D frictional body. We experimentally show that a strong bimaterial contrast, as encountered in environmental seismology, yields a unidirectional or linear force mechanism for pre-rupture microslips and decelerating supershear ruptures. A weak contrast, characteristic for earthquakes, generates a double-couple source mechanism for sub-Rayleigh ruptures, sometimes preceded by slow deformation at the interface. This deformation is reproduced by the near field of a unidirectional force.