RHUM-RUM, a Large-Scale Effort to Seismologically Image a Mantle Plume Under the Reunion Hotspot: Experiment Presentation and Initial Results

Abstract:

RHUM-RUM is a German-French geophysical experiment based on the seafloor and on islands surrounding the hotspot of La Réunion, western Indian Ocean. Its primary objective is to clarify the presence or absence of a mantle plume beneath the Reunion hotspot, which is thought to have first pierced the surface 65 million years ago with the eruption of the Deccan Traps on India.

 RHUM-RUM’s central component is a one-year deployment (Oct 2012 – Nov 2013) of 57 broadband ocean-bottom seismometers (OBS) and hydrophones on an area of 2000x2000 km² surrounding the hotspot. All OBS have been successfully recovered. We also have been operating 37 land seismometers on the islands of La Réunion, Mauritius, Rodrigues, southern Seychelles, îles Eparses, and on Madagascar between 2011 and 2014.

 As the data collection stage is drawing to a close, we discuss data yield and quality with respect to RHUM-RUM’s primary purpose (passive seismological imaging through all depth levels of the mantle) and secondary applications (“environmental seismology” in a sparsely instrumented area, e.g., tracking of tropical cyclones). We give an overview of the research questions investigated by the RHUM-RUM group, and present preliminary results.