Dr. Walter Menapace

The Philosopher's Stone of my research is to unravel subduction zones dynamics, particularly fluid and solid cycling and earthquakes occurrence, not only to shed some light on these complex environments, but also to provide the society with a better characterization of the multiple hazards which could generate from the subduction process (i.e. seismic activity, landslides, fluid expulsion, tsunamis, etc).

Main topic of my PostDoc project was the deep-rooted serpentinite mud volcanism of the Mariana Forearc, which I was developing following my participation to IODP 366 (Mariana Convergent Margin and South Chamorro Seamount).

The PhD project I was involved in was part of a cross-cutting project (CCP4) between two of the three MARUM´s research areas, geosphere-biosphere interaction (GB) and seafloor dynamics (SD) and it was focussed on the study of mud volcanoes (MVs) and their products. The main objectives were to investigate the interactions between geological, physical and geochemical processes in and around MVs by using complementary methods such as measuring ongoing changes with in-situ instruments (p-T monitoring), determining the physical properties in the laboratory and modelling these processes using different software. The final purpose was to define what causes the episodicity in MV evolution, what is the role of these features in subduction zones fluid/mass balance and their relationship with earthquakes.  

To study the products of mud volcanism (gas, water and sediments) and compare the characteristics of different features, three case studies were being considered (Anaximander Mountains, Azerbaijan and Kumano Basin). At the same time two experimental setups have been built, with which it was possible to observe and document temporal changes in heat flow, fluid flow and chemical diffusion in the tested mud breccias.
With the support of the  Marine Geotechnics group I took part to several expeditions in different key areas of the Mediterranean Sea and the Pacific Ocean (MSM35T, M112/2, POS498, SO251-2), which aimed to look into MVs and (fluid/heat) flow dynamics in those regions using state of the art techniques. I also coordinated the deployment and retrieval of long-term seafloor observatories.

• Mud Volcanoes and their products (sediment, gas and water)
• Pore water geochemistry and sediments physical properties
• Laboratory experiments (uniaxial consolidation, hydraulic seepage, permeability, rheology) on marine sediment samples
• MVs triggers (earthquakes vs pressure buildup)
• In situ long-term observatories (pore pressure, temperature)
• MVs in the subduction zone fluid and solid cycles
• Serpentinite mud volcanism
• Fluid seepage at the seafloor