New insights on the interaction between seismic waves and mantle plumes

Abstract:

Mantle plumes are notoriously challenging to image using seismic observations, leading to a controversy over their existence and structure. In this study we present new findings from waveform modelling studies of synthetic plumes and array seismic observations.

Synthetic plumes are generated via geodynamic and mineral physics modelling, giving structures that are dynamically plausible with realistic seismic properties. Wave propagation around and through the plumes is simulated via the latest spectral element methods, at low and high frequencies, and recorded in seismometers at the Earth’s surface. We compare our synthetic seismograms for different plumes and source-receiver configurations, also with observations in real data. A robust observation in the plume models is of the wavefronts diffracting and bending around the plume conduit, leading to energy arriving in the opposite direction than one would expect for scattering. This behaviour can be detected as far away as 90 degrees from the source and potentially allows us to locate plume tails close to the core-mantle boundary. But can this behaviour be detected in real data?