Overview
- A swarm of extensional earthquakes that began on 26 April 2024 initiated rapid dike intrusions along the Southeast Indian Ridge and set the episode in motion.
- A dense array of more than 20 seafloor instruments directly recorded about 150–160 million cubic metres of lava, roughly 4.2 metres of axial-valley subsidence, and 2–4 metres of horizontal plate separation.
- Detailed modelling links the eruption to a sill-like magma reservoir that drained into fast-moving dikes and then collapsed, producing the mapped lava and deformation.
- Most fault displacement during the event occurred aseismically, with earthquakes accounting for only a small fraction of the total slip, which resolves a long-standing mismatch between measured plate motion and earthquake counts.
- The result shows that oceanic crust is built in episodic, rapid ‘quantum’ events and demonstrates that dense, multi-instrument seafloor observatories can change how scientists measure plate spreading and assess ridge hazards.