Eruption of a deep-sea mud volcano triggers rapid sediment movement.

Tomas Feseker,Dirk De Beer,Antje Boetius,Dana R Yoerger,Richard Camilli,Jerome Blandin,Christopher R German,Frank Wenzhöfer,Karine Olu

doi:10.1038/ncomms6385

Abstract

Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Håkon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4 m per day, and significant emissions of methane and CO2 from the seafloor.

Highlights

Submarine mud volcanoes are important sources of methane to the water column
The objective of the long-term observations on mud-volcano eruptions (LOOME) observatory was to derive a timeline of temperature gradients and mud transport, combined with seafloor observations that would allow us to test the hypotheses that temperature dynamics, morphological and bathymetrical changes could be related to eruptions of gas and mud[20]
The LOOME observatory frame with data loggers was deployed in July 2009 within the peripheral hummocky area

Summary

Introduction

Submarine mud volcanoes are important sources of methane to the water column. the temporal variability of their mud and methane emissions is unknown. Correspondence and requests for materials should be addressed to D.d.B. Submarine mud volcanoes are geologic structures deeply rooted into the subsurface seafloor, formed by mud expulsions and associated transport of warm, deep-sourced fluids and gas, predominantly methane[1,2]. Anaerobic and aerobic microbial oxidation consume the majority of the methane advected to near-surface sediments, where sulphate and oxygen are available as electron acceptors[6,7] This microbial filter is less efficient when the ascent rates of subsurface fluids are high, as the flux of electron acceptors (for example, sulphate) into the sediments decreases[1,8]. To investigate the temporal variability of deep-sea mud-volcanic activity, we deployed a seafloor observatory for a period of 431 days in 2009–2010 at the active Håkon Mosby mud volcano (HMMV), located at 1,250 m water depth on the Barents Sea slope[17]. The objective of the LOOME observatory was to derive a timeline of temperature gradients and mud transport, combined with seafloor observations that would allow us to test the hypotheses that temperature dynamics, morphological and bathymetrical changes could be related to eruptions of gas and mud[20]

Methods

Results

Conclusion