Crustal fingering facilitates free-gas methane migration through the hydrate stability zone

Significance Widespread seafloor methane venting has been reported in many regions of the world oceans, challenging our current estimate of global carbon budget. Yet, we still do not fully understand the fundamental mechanisms by which methane gas migrates through the deep marine sediments, feeding these vents. A key challenge is the formation of methane hydrate, an ice-like solid that forms from a methane–water mixture under pressure and temperature conditions typical of deep marine settings. Here, we study the mechanics of gas percolation under hydrate-forming conditions using experiments and computational modeling. We uncover a phenomenon, which we call crustal fingering, that helps explain how, counterintuitively, hydrate formation may facilitate instead of prevent methane gas migration through deep ocean sediments.