Publication Date:
2018-12-07
Description:
In situ observations of mid-ocean ridge spreading events are rare, and no observations exist
at ultraslow spreading ridges. In 2013, two earthquake swarms and prominent, tidally modulated harmonic
tremor were accidentally recorded by ocean bottom seismometers at the Southwest Indian Ridge. After
relative relocation, the first swarm shows downward migrating hypocenters, while the second swarm
immediately spreads over a steeply dipping plane originating at the same location as the first swarm. The
tremor signal is temporally connected to the swarms and persists for more than 20 days after the second
swarm. Polarization analysis points to two source locations above the seismically active area at 2- to 8-km
depth. We interpret swarms and tremor as evidence for a dike intrusion event that caused disruption to an
existent hydrothermal system. The tremor may be generated by enhanced hydrothermal circulation caused
by the added heat of the intrusion with increased flow during low tides.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
