Watching the seafloor spread… and abyssal hills shrink

Mid-ocean ridges are quintessential sites of tectonic extension, where divergence between lithospheric plates shapes abyssal hills that cover ~2/3 of Earth’s surface. While plate separation appears continuous on geological time scales, it is in fact accommodated by individual dike intrusions and fault slip events that recur on decadal time scales. Such seafloor spreading events can even be accompanied by seafloor shortening events, as evidenced by a 2022 swarm of reverse faulting earthquakes near the axis of the Mid-Atlantic Ridge. In this talk, I will discuss how the texture of the ocean floor may be understood as the cumulative sum of discrete magmatic, faulting, and “unfaulting” events. This discussion will build on mechanical models, seismological observations, and an ambitious seafloor geodetic observatory that we recently deployed across the axis of the Southeast Indian Ridge. Join Zoom Meeting https://cnrs.zoom.us/j/99828038210?pwd=sJeltLV6VweCbgQlBj0x3fjaNkoQY9.1