Scientific Reports
Scientific Reports
Date: Wed, 6 Dec 2000 10:43:13 -0800 (PST)
From: John Chatwood <chatwood@sdsioa.ucsd.edu>
Reply-To: John Chatwood <chatwood@sdsioa.ucsd.edu>
Subject: Revelle science report
To: shipsked@sio.ucsd.edu
Cc: scg@sdsioa.ucsd.edu
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Wed, 6 Dec 2000 18:33:33 GMT
Date: Wed, 6 Dec 2000 18:33:33 GMT
From: jacobson@rv-revelle.ucsd.edu (Dan Jacobson)
To: scg@sdsioa
Subject: Revelle science report
Cc: jacobson, jah, shipsked@ucsd.edu
Mime-Version: 1.0
NECR05RR - Weekly Report December 5, 2000
The goal of this project is to monitor the submerged portions of the
Hilina fault and landslide system on the submerged southeast flank of
Kilauea Volcano, Hawaii. During the past week we have completed the
construction and measurement of six precision acoustic transponder
arrays designed to monitor horizontal deformation. At each array we
have collected about 24 hours of acoustic ranging data while monitoring
a geodetic array of shipboard GPS receivers which provide the ship's
position and attitude to the centimeter. In addition, we have
deployed five seafloor bench marks which are designed to monitor
vertical deformation. On each bench mark, we have collected pressure
measurements which provide a vertical reference with 10 centimeter
accuracy.
Tomorrow, we will deploy one final bench mark and a seafloor
hydrophone for monitoring of seismic activity. We will then place the
seafloor precision acoustic transponders into a low-power "sleep"
mode to await our return to this site for re-measurement in early
2002. A five hour transit will take us to Hilo where we will bid a
fond farewell to R/V Revelle with many thanks for her excellent
service during the cruise.
John Hildebrand & Dave Chadwell
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id PAA00048 to ; Wed, 29 Nov 2000 15:42:48 GMT
Date: Wed, 29 Nov 2000 15:42:48 GMT
From: revelle!jacobson@sdsioa.ucsd.edu (Dan Jacobson)
To: shipsked@sio.UCSD.EDU
Subject: NECR05 Chief Sci Report
Cc: jacobson@sio.UCSD.EDU, jah@sio.UCSD.EDU, master@sio.UCSD.EDU,
scg@sdsioa.ucsd.edu
From jah Wed Nov 29 07:34 GMT 2000
Date: Wed, 29 Nov 2000 07:34:35 GMT
From: jah (John Hildebrand NECR05)
To: jacobson
Weekly Report - NECR05RR
During the past two weeks we have been constructing a seafloor
geodetic array on the submerged southeast flank of Kilauea Volcano,
on the Big Island of Hawaii. Volcanic activity within the East Rift
Zone of Kilauea create debris slides and steep island flanks, leading
to large scale undersea landslides. On the southeast flank of
Kilauea Volcano is the most active of these features - the Hilina
fault and landslide system. Where exposed on the subaerial portions
of the island, this fault system has an average deformation rate of
10 cm per year, monitored by an array of GPS satellite tracking
stations. The goal of our project is to monitor the submerged
portions of the Hilina fault and landslide system.
At first arrival on station we collected complete SeaBEAM 2112
bathymetic multibeam sonar data, and then partial coverage sidescan
sonar data and seafloor photographs using the DeepTow fish. These
data helped us to define the geologic setting of the fault and
landslide system. The upper portions of the slide, although steep
(15 deg average slope) have a smooth surface texture, even at the
photographic scale. A bench is located at mid-depths along the
slide; this feature defines the boundary between smooth materials of
the upper slope and extremely rough materials - boulder sized rock
fragments - of the lower slope and toe of the landslide. Using these
data, sites were selected for seafloor precision transponder
deployments to monitor the submerged motions of the landslide.
Seven precision transponders are now deployed on the southeast flank
of Kilauea, configured as a connected chain of triangular arrays.
These transponders allow 5 triangle centers - groups of three
transponders each - to be points whose location can be determined by
acoustic ranging to the ship. The Revelle position is determined to
the centimeter level using three GPS antennas, two located on
fan-tail towers and one located on the main mast. A fixed GPS
station recording at a one-second rate was installed at the USGS Hawaii
Volcano Observatory to tie the shipboard measurements to land GPS.
Combining these GPS and acoustic data provide a seafloor virtual benchmark
whose location is determined to the centimeter level. The successful
deployment of the seafloor transponders in this unforgiving, rocky
terrain required some instrument recoveries and redeployment using
the MPL Control Vehicle. The precise dynamic positioning system of
the Revelle, the availability of the fiber optic wire allowing high
quality camera images, and the reliable operation of the Control
Vehicle seafloor thrusters have been key elements in the success of
these operations.
We will disembark some of the engineering staff tomorrow morning in
Hilo, and then return to the array for on-going GPS/acoustic
measurements. Although the wind has been steady and higher than our
preference (20-30 knots), the ship has performed extremely well and
provides a surprisingly stable ride.
John Hildebrand Dave Chadwell
This cruise is being funded by a grant from the National Science Foundation.
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