Preliminary results of R/V METEOR cruise M149: Shipboard and Post-Cruise Analysis, Recurrence of tsunamigenic hazards from MeBo drilling records and hazard mitigation using MeBo observatories, Las Palmas (Canary Islands) – Cadiz (Spain), 24.07.2018 – 24.08.2018

Abstract

Historical earthquakes such as the 1755 Lisbon earthquake and tsunami demonstrated that the plate boundary between Eurasia and Africa constitutes a significant earthquake and tsunami threat to neighboring coastal communities. Cruise M149 of R/V Meteor aimed at collecting short and long sediment cores and installing borehole observatories with the seafloor drill rig MARUM-MeBo70 (Meeresboden-Bohrgerät) to obtain records of the past and current tectonic activity of the plate boundary in the Gulf of Cadiz and Alboran Sea (W Mediterranean Sea). The cruise focused on 1) two NNW-SSE trending strike-slip faults (Lineament Center and South) cutting through the Gulf of Cadiz accretionary prism, 2) two SW-NE trending strike-slip faults in the Alboran Sea, and 3) adjacent mud volcanoes that are supposed to be hydraulically connected to deeper levels of the fault zones and plates interface. From July 24 to August 24, 2018, the M149 cruise collected in total 383.2 m of core, conducted 38 in situ heat flow measurements, mapped approximately 12500 km2 of seafloor and installed 3 borehole observatories. Three new mud volcanoes were discovered during the cruise (and at least two more supposed buried), of which one is located on the SW edge of the accretionary prism - outside of the predominant mud volcano distribution. We also re-visited various small mud volcanoes (Meknes, Rabat, El Cid, Almanzor) and the known Yuma and Ginsburg in the Gulf of Cadiz where we installed one of the borehole observatories at Ginsburg. Two further observatories were installed into strike-slip-faults – one in the Gulf of Cadiz and the other in the Alboran Sea. Thus, the M149 cruise fulfilled its primary objective of collecting long and short term records (i.e. sediment cores) of the tectonic activity associated with the plate boundary between Eurasia and Africa offshore SW Europe, which will provide the basis for further post-cruise research.