Five geophysical survey companies are seeking permits to
test for potential oil and gas reserves off the Atlantic Coast.
If approved, the testing will involve the use of seismic airgun
arrays that will blast acoustic pulses at the ocean floor that
can be heard for hundreds of miles every 10 to 16 seconds,
up to 24 hours a day, for months at a time. Significantly,
the permit process for seismic testing is separate from
that required for offshore drilling. This means that testing
could begin before the Administration’s proposed 2019-
2024 National Outer Continental Shelf Oil and Gas Leasing
Program is finalized and/or before Atlantic offshore drilling
leases are approved.
Scientists are very concerned that seismic testing will
disrupt sea life and harm the lives of sea creatures. At all
levels of ocean life, from zooplankton 1 at the base of the
food chain to whales, research is showing that
noise creates an unsettling environment that
changes feeding, communication, and
mating patterns and can even cause
death. Of course, this means that
our beloved sea turtles, bottlenose
dolphins, and even commercial
fishing and shrimping would
be affected. Seismic blasting
itself, not to mention the
offshore drilling it supports,
would undoubtedly upset the
lifestyle and economy of coastal
communities.
Water is an excellent, efficient
conductor of sound. Marine life,
including mammals, use their sense
of hearing to find food, avoid dangers,
and communicate with each other. Being
underwater has never been quiet; the sounds of natural
events like thunderstorms and earthquakes and human-made
noise from commercial vessels already reverberate through
the ocean.
In the field of acoustics, physicists and engineers use
decibels (dB) as the standard unit of sound measurement. A
dB is an abbreviation of the term “decibel,” named in honor of
Alexander Graham Bell. Breathing is calculated as about 10
dB, and a whisper at 20 dB, normal speech at 60 dB. A loud
rock concert could be 120 dB. A jet engine take-off is 140
dB. A decibel is an exponential or logarithmic measure, so
a change from 10 dB to 20 dB is a 10-fold increase in sound
density, which corresponds to a doubling in loudness. A 20dB
increase represents a 100-fold increase. Each 10 dB increase
means multiplying the impact by a factor of ten (e.g., “adding
a zero”).
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The threshold at which humans feel pain is 130 dB; human
eardrums rupture at 150 dB. 2 The average decibel level for a
blast from a seismic airgun array is 185 dB, which translates
to 246 dB in water. 3
Since the 1880s, noise has been recognized as a public
health hazard for humans. In 1966, what once was considered
merely a nuisance was coined “noise pollution.” 4 The Noise
Control Act of 1972 “establishes a national policy to promote
an environment for all Americans free from noise that
jeopardizes their health and welfare.” 5
For humans, the National Institutes of Health advises
that regular exposure to noise above 85 dB can damage
the sensory cells causing gradual and irreversible damage
resulting in permanent hearing loss.
Distance from the source of the sound and the length
of noise exposure are also important factors in
determining the amount of possible damage.
Because of water’s superior conductivity
of sound, sounds travel great distances
before dissipating. As the dB water
conversion above suggests, sounds
are also louder underwater.
For many years, the military,
particularly the US Navy,
has used SONAR (SOund
NAvigation Ranging) to
determine water depth and
locate underwater objects like
submarines. By emitting sound
waves and listening for an echo,
they can determine the size of and
distance from an object. SONAR is
often used to explore and map the ocean
floor. It works much like the natural ultra-high
frequency echolocation methods used by porpoises and
other marine animals to navigate their environments.
SONAR is a much quieter, less intensive technology than
seismic blasting. Even so, scientists have been studying
SONAR and have identified its adverse effects on sea life. 6
The University of St. Andrews, Scotland, is a leading facility
in marine mammal research, and one of their foci is “[m]
itigating environmental impacts of naval sonar” on whales
and other sea life.
State and local governments along the Atlantic and Pacific
coasts are working hard to prevent seismic blasting in US
waters. They believe that the risks to marine life, tourism, and
commercial fishing posed by seismic testing and subsequent
oil and gas drilling are simply not worth it. In 2015 and
again in 2017, the Town of Kiawah Island passed resolutions
opposing both seismic testing and offshore drilling.
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