Simulation of rockfall generated seismic signals and the influence of
Rockfalls seismic waves contain valuable information on event
properties. However, as rockfalls predominately occur in mountainous
regions, generated seismic waves are prone to be affected by strong
surface topography. For this reason, the influence of topography on the
wavefield, in particular surface wave propagation, is investigated using
the Spectral Element Method on a 3D domain with realistic surface
topography of Dolomieu crater on Piton de la Fournaise volcano, La
Réunion. Topography induced ground motion modification is studied
relative to a flat reference model. Peak Ground Velocity (PGV) and total
kinetic energy can be (de-)amplified by factors up to 10 and 20,
respectively. The spatial distribution of the amplification is strongly
influenced by the underlying geology as shallow low velocities guide
energy along the surface. Simulations on different topographies suggest
that the wavefield is affected more by variations of crater curvature
than crater depth. To reveal the effect of topography on recorded
signals at Dolomieu crater, inter-station spectral ratios are computed.
It is demonstrated that these ratios can only be simulated when taking
into account surface topography while the comparisons suggest that the
direction of the acting source and the resulting radiation patterns can
be ignored. Finally, the seismic signature of single impacts is studied.
Comparison with simulations help to associate signal pulses to impact
sources. It is revealed that a single impact can provoke complex
waveforms of multiple peaks, especially when considering topography.
Impact forces derived from Hertz contact theory result in comparable
magnitudes of real and simulated signal amplitudes.