Southeast Indian Ridge Rifting Drops Seafloor 4 Meters, Unleashing 160 Million m3 of Lava
Updated
Updated · Nature.com · Jul 8
Southeast Indian Ridge Rifting Drops Seafloor 4 Meters, Unleashing 160 Million m3 of Lava
3 articles · Updated · Nature.com · Jul 8
Summary
A seafloor observatory captured the first in situ mid-ocean-ridge rifting event, which began on April 26, 2024, at the Southeast Indian Ridge and rapidly split the ridge axis.
Measurements showed about 4.2 meters of valley-floor subsidence and more than 1 meter of horizontal extension as a sill-like magma reservoir deflated and fed dykes propagating along the ridge.
Bathymetry and hydroacoustic data indicate roughly 148 million to 160 million cubic meters of lava erupted over about 16 days, with the largest new flows exceeding 90 meters thick in places.
The rifting also triggered nearby transform-fault earthquakes, including a Mw 5.9 event on the Amsterdam transform fault, shortly after the dyke propagation stopped.
Modeling suggests about 76% of the normal-fault slip was aseismic, helping explain why mid-ocean ridges release less earthquake energy than their long-term spreading rates imply.