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Why
do geophysicists use geophysical surveying in the ocean?
How
many geophysical surveys does UTIG conduct each year?
What
are the scientific objectives of UTIG geophysical survey's of the Hess Deep?
Do
you have permission to carry out a research cruise at Hess Deep?
Why do geophysicists use seismic surveying
in the ocean?
Geophysical
seismic surveying enables geophysicists to "see" the structure
of the Earth beneath the seafloor. Instead of using light waves reflected
off objects to perceive things visually, they use sound waves to "see"
deep into the earth's crust. The reason is that sound waves can travel through
seawater to penetrate layers of rock and sediment beneath the seafloor,
while light waves can't. These waves are reflected or refracted (bent) as
they pass through the Earth and can be detected by devices placed on the
seafloor or towed by a ship, providing scientists with an image of the structure
and geology beneath the seafloor. The overarching goal of this work is to
document the history of the earth and the processes by which it evolves.
This knowledge is vital for understanding climate and sea-level change,
earthquakes and other natural hazards, and the formation and distribution
of natural resources.
How many geophysical surveys does UTIG conduct
each year?
UTIG scientists are involved
in about two to three marine geophysical surveys each year. In comparison,
the oil and gas industry conducts over 100 geophysical surveys annually in
the Gulf of Mexico alone, particularly off Louisiana and Texas.
What are the scientific objectives of
UTIG study of the Hess Deep?
The Hess
Deep is a steeply plunging rift adjacent to the East Pacific Rise, one
of the planet’s fastest-spreading mid-ocean ridges. Because the
Hess Deep slices through recently created crust, it provides a window
into the Earth’s crust-making processes. The purpose of the
geophysical
survey is to generate a “picture” of the structure of Earth’s
crust at Hess Deep from the geophysical data, which scientists can compare
with the outcrop geology observed by NSF-sponsored submersible dives carried
out in 1999 and 2001.
Do you have permission to carry out a
research cruise at Hess Deep?
Hess Deep is located in international
waters of the Eastern Tropical Pacific. However, since the survey ship
that we used is U.S. owned and operated, we had to comply with the provisions
of the Marine
Mammal Protection Act (MMPA) enacted by Congress in 1972 (16
U.S.C. 1361-1407), which is intended to protect marine mammals in U.S.
waters and by any person under U.S. jurisdiction on the high seas. Columbia
University, the operator of the Ewing, applied for and received
a permit through the National Marine Fisheries Service (NMFS) for the Hess
Deep cruise. |
