Mud volcanism, fluid flow and seismicity: new discoveries and results from recent expeditions in the Gulf of Cadiz

Mud volcanoes (MVs) are expulsion features ubiquitously present in areas of tectonic convergence both on land and on the seafloor. Due to their km-deep feeding channels, MVs are highly episodic structures, acting as valves to dissipate excess pore pressure building up at depth. Eruptions are deemed crucial to understand the regional geology and fluid-sediment interactions. However, the main drivers behind these sporadic bursts in activity still remain fairly obscure. It is hypothesized that different events can trigger MVs eruptions (e.g. gas accumulation, diagenetic processes, pore pressure build up), therefore originating a plethora of different effects with corresponding ejecta, channelled through the main conduits. Of all the MVs triggers, earthquakes (EQs) are the only ones for which a direct cause-effect relationship has been already established. The Gulf of Cadiz (GoC) is arguably one of the best playgrounds for the study of MVs and paleoseismology, due to the presence of an accretionary wedge with active fluid and solid expulsion structures (>90 MVs, at least three major transform faults, several pockmarks fields) and because of the numerous large magnitude EQs happened in the past, which are well preserved in the sedimentological record. Recently, three major seagoing expeditions led by MARUM (University of Bremen) and the ICM-CSIC set out to investigate the episodicity and nature of mud volcanism in the GoC, as well as its relationship with the tectonic and seismic history of the region. This talk will explore the main results from the aforementioned expeditions, which contributed to shed new light on the fluid and solid cycles of the SW Iberian Margin with an unprecedented level of detail, highlighting how a plethora of different processes is, in fact, fuelled by and contributing to the GoC mud volcanismPeer reviewe