Research reveals processes that sculpt submarine canyons

Deep below Monterey Bay lies one of the largest submarine canyons on the west coast of North America. Monterey Canyon has a topography that rivals the Grand Canyon, but its scale and grandeur remain out of sight beneath the ...
A team of researchers from MBARI, USGS, Durham University, the University of Hull, and Pontificia Universidad Católica de Chile has conducted surveys of a site on the floor of Monterey Canyon with an innovative sensor suite designed by MBARI engineers. Their surveys have provided new insight into the processes that sculpt canyons. The team has published their findings in a recent issue of Journal of Geophysical Research: Earth Surface.

"Thanks to advanced MBARI technology, we've now mapped parts of Monterey Canyon in remarkable detail. Repeated mapping surveys have given us a valuable new perspective to study the processes that sculpt the canyon. This is vital context for understanding not only life on the ocean floor but also how the underwater infrastructure that we depend on may be vulnerable to underwater landslides," explained Monica Wolfson-Schwehr, previously a postdoctoral fellow at MBARI and lead author of this study.
From 2015 to 2017, MBARI's Coordinated Canyon Experiment aimed to monitor the passage of sediment gravity flows— known as currents—at multiple locations in the canyon simultaneously. Understanding the complex that shape Monterey Canyon can help us better understand how submarine canyons might be tied to coastal geohazards, like local tsunamis or risks to underwater telecommunications infrastructure.

Lidar technology on MBARI’s Low-Altitude Survey System (LASS) uses pulses of lasers to record the bathymetry, or underwater topography, on the seafloor at centimeter-scale resolution. Surveys with this sensor suite at a scour field 1,840 meters (6,037 feet) deep on the floor of Monterey Canyon revealed how turbidity currents (green) and tides (blue) affected the structure of the seafloor. Credit: Monica Wolfson-Schwehr, MBARI
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Monterey Canyon (A) is located just offshore of MBARI’s research facilities in Moss Landing, California. MBARI researchers conducted high-resolution, low-altitude surveys in a part of the canyon floor 50 kilometers (31 miles) from the canyon head (B) and deployed the Seafloor Instrument Node (SIN) to monitor environmental conditions, like currents, at the site. Together, these shed new light on processes that sculpt submarine canyons. Credit: Monica Wolfson-Schwehr, MBARI
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Four repeat surveys with MBARI’s LASS sensor suite between November 2015 and April 2017 provided an incredibly detailed view of the changes to the floor of Monterey Canyon. The LASS combines various sensors, including sonar bathymetry at a resolution of five centimeters (two inches) (A) and lidar bathymetry (B and C) at a scale of one centimeter. Lidar data provide richer detail about the seafloor, revealing objects that are too small to be seen by sonar. Credit: Monica Wolfson-Schwehr, MBARI
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