Full version, low resolution, 7.5MB - InterRidge

International Research
Abstract
The equatorial Mid-Atlantic Ridge is distinctive for its long-offset
transforms and an inferred mantle thermal minimum south of
Romanche fracture zone, resulting in overall low melt production. In
addition, the North America-South America-Africa triple junction
has migrated through the region. Consequently, the equatorial
Atlantic provides an ideal laboratory for testing ideas about modes
of spreading, short-term earthquake predictability and triple
junction dynamics at slow-spreading ridges. The centerpiece of this
project is an autonomous hydrophone array, which will obtain a twoyear,
continuous record of seismicity at the equatorial Mid-Atlantic
Ridge. The temporal and spatial patterns in seismicity will be
exploited to answer questions regarding the role of detachment
faults in plate accretion, earthquake nucleation in oceanic lithosphere
and deformation associated with triple junctions. Here we present
the regional multibeam bathymetric dataset, collected on the transit
legs of Cruise AT21-03 in June/July 2012, during which two
hydrophones were deployed and maintenance carried out on a third
instrument. We also suggest that in the future, the community could
benefit from the opportunistic acquisition of valuable multibeam
data through sharing information on the planned routes of
upcoming cruises.
The hydrophone instrument and mooring
Autonomous hydrophones continuously record data, sampling at
250 Hz with a 110 Hz cut-off and a 16-bit analog/digital resolution.
The hydrophone element is a single ceramic hydrophone attached to
a titanium pressure case, with a pre-whitening filter to reduce the
effects of ambient noise. Timing is constrained with a Q-Tech
crystal oscillator clock (accurate to