Mysterious "Swarm" of
Quakes Strikes Oregon Water
by Richard A. Lovett
16 Apr 2008
This weekend scientists will try to
puzzle out the cause of a "swarm" of earthquakes that has shaken the
seafloor near Oregon in recent weeks.
About 600 earthquakes have been recorded in a small region about 190
nautical miles (350 kilometers) offshore from Yachats.
Although most of the temblors were small, about magnitude 2 or 3, a
few were magnitude 4 or 5.
Earthquake swarms normally indicate volcanic activity. But they
could represent stresses being released in an unusual manner in the
middle section of the Juan de Fuca plate.
The scientists say they may find lava
oozing out onto the seafloor or hot water percolating up from
magma-heated undersea hot springs. They could also come across
colder water squeezed out of the underlying crust by tectonic
All of this, the scientists say, is an example of how much we still
have to learn about ocean tectonics.
To begin with, said Robert Embley of NOAA's Pacific Marine
Environment Laboratory, the area isn't even well mapped.
"We don't really know what the
topography looks like out there," he said. "Our good maps are
just along the plate boundary, where 98 percent of the [normal]
seismic activity occurs."
And we wonder why our oceans are
"Elsewhere, the ocean floor is
basically unmonitored," Embley said.
The Sounds of Climate Change
heating the seas?
8 Jan 2008
Researchers from the Oregon State
University (OSU) Hatfield Marine Science Center have journeyed to
the Antarctic region over the past 3 years to deploy hydrophones
into the deep waters surrounding the western Antarctic Peninsula.
The hydrophones are highly sensitive
microphones encased in titanium and lowered on three-quarters of a
mile of cable to listen to the rumble of undersea earthquakes.
"When an earthquake occurs, it makes
a distinct sound, and we can locate that," says Robert Dziak,
44, OSU associate professor of marine geophysics and expedition
"Earthquakes and magma spewing on the seafloor go hand
in hand, and what we are seeing is, there are new heat sources
right off the coast of Deception Island that no one was aware of
"It's the only place on the planet where active seafloor and
subaerial (above sea level) volcanoes are near large icebergs
and ice sheets."
Dziak hopes to learn more about how the
sea floor volcanoes and earthquakes contribute to the breakup of ice
in the region. The most significant find from the research so far
has been the discovery of thermal vents on the seafloor.
"Since three-quarters of the Earth
is covered by ocean, the vast majority of volcanic activity on
Earth is occurring without our knowledge undersea."
So it's unknown how much heat and
chemicals the underwater volcanoes spew into the ocean and
atmosphere (italics added), affecting global ocean temperatures and
climate, said Dziak.
According to Haru Matsumoto, research associate at OSU, scientists
know that the air temperature around the Western Antarctic Peninsula
has warmed by 4 degrees Fahrenheit during the past 40 years and that
noise levels in the waters nearby have increased about 10 decibels
in the past 30 years.
Matsumoto says the louder noise levels of the past four decades may
be the result of global warming.
(How in the world did Matsumoto reach that conclusion? Wouldn’t a
more reasonable conclusion be that the increased underwater volcanic
activity is causing global warming?)
Deep-Sea Temperatures Ended Last Ice Age
Study Validates My Theories
by Terah U. DeJong
27 Sep 2007
USC College researcher shows that
deep-sea temperatures rose 1,300 years before the buildup of
atmospheric carbon dioxide, ruling out CO2 as driver of
the last ice age’s meltdown.
In contrast to what is often inferred from the geologic record,
carbon dioxide did not cause the end of the last ice age, a new USC
study published in Science suggests.
"There has been this continual
reference to the correspondence between CO2 and
climate change as reflected in ice core records as justification
for the role of CO2 in climate change," said
paleoclimatologist Lowell Stott, the study’s lead author
and a professor of earth sciences at USC College.
"You can no longer argue that CO2 alone caused the
end of the ice ages."
Deep-sea temperatures warmed about 1,300
years before the tropical surface ocean and well before the rise in
atmospheric CO2, the study found. The finding suggests
the rise in greenhouse gas was likely a result of warming – but not
its main cause.
(Rising CO2 levels are a result of warming, not a
cause - just as I say in "Not
by Fire but by Ice.")
"What this means is that a lot of
energy went into the ocean long before the rise in atmospheric
CO2," Stott said.
But where did this energy come from?
Evidence pointed southward.
The warming deep water appeared to come from the Antarctic Ocean,
then moved northward, the scientists wrote
In addition, the researchers noted that the increases in deep-sea
temperature coincided with the retreat of Antarctic sea ice, both
occurring 19,000 years ago, before the northern hemisphere’s ice
Finally, Stott and colleagues found a correlation between melting
Antarctic sea ice and increased springtime solar radiation over
Antarctica, suggesting this was the energy source.
As the sun pumped in heat, the warming accelerated because of
sea-ice albedo feedbacks, in which retreating ice exposes more of
the ocean that can absorb heat from the sun, much like a dark
T-shirt on a hot day, and this results in more melting.
In addition, the authors’ model showed how changed ocean conditions
may have been responsible for the release of CO2 from the
ocean into the atmosphere, which like the albedo feedbacks, also
accelerated the warming.
(I also say this in "Not by Fire but by Ice" – that rising CO2
levels come from the warming ocean.)
The link between the sun and ice age cycles is not new. The theory
of Milankovitch cycles states that periodic changes in Earth’s orbit
cause increased summertime solar radiation in the northern
hemisphere, which controls ice size.
If CO2 caused the warming, one would expect surface
temperatures to increase before deep-sea temperatures, since the
heat slowly would spread from top to bottom. Instead, carbon-dating
showed that the water used by the bottom-dwelling organisms began
warming about 1,300 years before the water used by surface-dwelling
ones, suggesting that the warming spread bottom-up instead.
(Just as I say in "Not
by Fire but by Ice." It’s not global warming, it’s ocean
warming. And this time it’s leading us into an ice age.)
Stott is an expert in paleoclimatology and was a reviewer for the
Intergovernmental Panel on Climate Change. He also recently
co-authored a paper in Geophysical Research Letters tracing a
900-year history of monsoon variability in India.
underwater volcanic activity
13 Jul 2007
Many earthquakes in the deep ocean are
much smaller in magnitude than expected. Geophysicists from the
Woods Hole Oceanographic Institution (WHOI) have found
new evidence that the fragmented structure of seafloor faults, along
with previously unrecognized volcanic activity (italics added), may
be dampening the effects of these quakes.
Examining data from 19 locations in the Atlantic, Pacific, and
Indian oceans, researchers led by graduate student Patricia Gregg
have found that "transform" faults are not developing or behaving as
theories of plate tectonics say they should. Rather than stretching
as long, continuous fault lines across the seafloor, the faults are
often segmented and show signs of recent or ongoing volcanism.
Both phenomena appear to prevent
earthquakes from spreading across the seafloor, thus reducing their
magnitude and impact.
Gregg, a doctoral candidate in the
MIT/WHOI Joint Program in Oceanography and Oceanographic Engineering,
conducted the study with seismologist Jian Lin and
geophysicists Mark Behn and Laurent Montesi, all from
the WHOI Department of Geology and Geophysics.
Their findings were published in the
July 12 issue of the journal Nature.
Oceanic transform faults cut across the mid-ocean ridge system, the
40,000-mile-long mountainous seam in Earth’s crust that marks the
edges of the planet’s tectonic plates. Along some plate boundaries,
such as the Mid-Atlantic Ridge, new crust is formed. In other
regions, such as the western Pacific, old crust is driven back down
into the Earth.
If you imagine the mid-ocean ridge as the seams on a baseball, then
transform faults are the red stitches, lying mostly perpendicular to
the ridge. These faults help accommodate the motion and geometry of
Earth’s tectonic plates, cracking at the edges as the different
pieces of rocky crust slip past each other.
The researchers [examined] gravity data
collected over three decades by ships and satellites, along with
bathymetry maps of the seafloor.
Conventional wisdom has held that
transform faults should contain rocks that are colder, denser, and
heavier than the new crust being formed at the mid-ocean ridge. Such
colder and more brittle rocks should have a "positive gravity
"was surprised to find that the
faults were not exerting extra gravitational pull. On the
contrary, many seemed to have lighter rock within and beneath
"What we found was the complete opposite of the predictions,"
"It is also possible that magma, or molten rock, from inside the
earth is rising up beneath the faults. (italics added)
Earthquakes stem from the buildup of friction between brittle
rock in Earth’s plates and faults. Hot rock is more ductile and
malleable, dampening the strains and jolts as the crust rubs
together and serving as a sort of geological lubricant.
The findings by Gregg, Lin, and
colleagues may also have implications for understanding the theory
of plate tectonics, which says that new crust (2,150-degree magma)
is only formed at mid-ocean ridges.
By traditional definitions, no
crust can be created or destroyed at a transform fault. The new
study raises the possibility that new crust (2,150-degree magma) may
be forming along these faults and fractures at fast-spreading ridges
such as the East Pacific Rise.
(It’s not global warming, it’s ocean
warming, caused by underwater volcanic activity, and it’s leading us
directly into the next ice age.)
This story was originally entitled "Fragmented Structure Of Seafloor
Faults May Dampen Effects Of Earthquakes." I think the discovery of
so much unexpected underwater volcanic activity is the real
by Catherine Brahic
Journal reference: Geophysical
Research Letters (DOI: 10.1029/2007GL029874)
9 Jul 2007
Researchers have counted 201,055
underwater cones, 10 times more than have been found before, and
estimate that in total there could be about 3 million submarine
volcanoes, 39,000 of which rise more than 1000 meters over the sea
"The distribution of underwater
volcanoes tells us something about what is happening in the
centre of the Earth," says John Hillier of the University of
Cambridge in the UK.
That is because they give information
about the flows of hot rock in the mantle beneath.
Since the late 1960s, research vessels have been criss-crossing the
oceans using sonar instruments to measure the depth of the ocean
floor. They have generated 40 million kilometers of linear profiles
showing the topography of the ocean bed between 60E° North –– the
latitude of southern Alaska –– and 60E° South –– corresponding to
the tip of Patagonia.
But until now, no one had been able to sift through them all. So,
Hillier and a colleague designed a computer program that was able to
analyze the huge amount of data and identify volcano-like shapes in
the sonar lines.
The program found 201,055 volcanoes over 100m tall. Previously,
satellite data had identified 14,164 volcanoes over 1500 m high.
Hillier then extrapolated the data to estimate how many volcanoes
exist beyond the areas the research vessels sounded out.
(If you've read "Not
by Fire but by Ice" then you understand how important
this is. When I started writing this book, scientists thought there
were 10,000 underwater volcanoes in the entire world. Now they think
there are three million! As I've been saying all along, it's not
global warming, it's ocean warming -heated by underwater volcanoes-
and it's leading us into the next ice age.)
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