Remote Area Survey with the Z-Boat 1800RP
Background
In October of 2015, a massive landslide was detected at Tyndall glacier in
southeast Alaska, sending an estimated 145 million tons of valley wall into Taan
Fiord. The landslide’s significant mass created a seismic signature that was
detected by seismologists thousands of miles away at Columbia University in
New York. Taan Fiord is an arm of Icy Bay in southeast Alaska. Over thousands of
years, Tyndall Glacier eroded the valley walls creating very steep sidewalls. Over
the past several decades, Tyndall Glacier has retreated, no longer supporting
those sidewalls. The steepening and then debuttressing of the walls caused the
sidewalls to collapse catastrophically in the form of a massive landslide.
The Challenge
With a grant from the National Science
Foundation, researcher Dan Shugar from the
University of Washington Tacoma traveled with
a team to investigate the damage caused by
the landslide in the summer of 2016. The terrain
and its inherent hazards and shallow areas
posed significant challenges for both the team
and the technology they would use to survey
the region.
The Mission
Shugar’s team, equipped with a new
ruggedized Teledyne Oceanscience Z-Boat1800-RP remotely operated unmannedsurface vehicle, set out on an expedition into
the affected area. The goals of that trip were
to map the fjord floor with multibeam sonar
and other seismic geophysical techniques that
would allow them to see below the surface
to determine the thickness of the landslide
debris. Along with Shugar were a large group
of scientists from Columbia University, the
National Park Service, University of British
Columbia and elsewhere.
The team’s plan was to map the submarine
deposits with the UW-Tacoma’s Z-Boat 1800
RP named ‘Jökull’ (Icelandic for glacier) with
help from Jeremy Venditti, a professor from
Simon Fraser University in Canada, and
Doug Bonno, an undergraduate student at
UW Tacoma. Also on site was another much
larger boat, the USGS Gyre, carrying larger
instrumentation aboard including a Teledyne
Reson T50 and a couple of seismic systems.
The Z-Boat was equipped with a Teledyne
Odom Hydrographic MB2 multibeam sonar and
an SBG Ekinox-D INS, which gave the team
Real Time Kinematic (RTK) position as well as
heave, pitch, and roll of the vessel. The RTK data were being broadcast from a Trimble R10 base station that Shugar’s team
brought on the excursion. Shugar’s team performed some velocity corrections
and CTD measurements with an AML Oceanographic MinosX instrument. Each
day, they set up a makeshift office, which was comprised of a small table with a
couple of chairs set on top of bouldery landside deposits on shore. A field laptop,
power supply with solar panels, and radio antennas was used to communicate
with the Z-Boat. The equipment was all powered by batteries, requiring the
researchers to work efficiently in the wilderness.
The Outcome
The Z-Boat proved to be a useful tool, dodging icebergs and getting into areas
too dangerous for the larger ship. “The Z-Boat was such a great tool for this
particular project. We were working on a gigantic landslide in very steep terrain
in front of a calving glacier, which is a pretty hazardous place to be around, so
you don’t necessarily want to have a vessel with people aboard in this kind of
environment. The slope that collapsed is potentially unstable even now and so
another landslide could occur. You don’t want to be too close to the calving face
of the glacier because if a big piece comes off, it could generate a wave that
might flip your boat,” explained Shugar.
“The Z-Boat allowed us to get into these otherwise inaccessible locations that
the larger USGS boat wasn’t comfortable doing, either because it was too
dangerous or potentially too shallow. We were able to fill in the gaps where the
big boat didn’t really want to go,” said Shugar.
Having the Z-Boat greatly increased the team’s chances of collecting important
data and gaining access to remote locations.
“As a geoscientist that studies geohazards in particular, the ability to go where
we have never been able to go or map what we have never been able to map,
with this kind of resolution, in these extreme environments and remote areas, is
a tremendous advantage. Not only can we answer more profoundly scientific
questions than we’ve been able to in the past but also we can ask entirely new
questions,” concluded Shugar.
