The Oroville Dam’s overflow channel failed in 2017.
Major dams in California are five times more likely to flood this century than the last one due to global warming, a new study finds, possibly leading to overtopping and catastrophic failures that threaten costly repairs and evacuations.
Deep underwater, and deeper underground, scientists see surprising hints that gas and oil deposits can be replenished, filling up again, sometimes rapidly.
Although it sounds too good to be true, increasing evidence from the Gulf of Mexico suggests that some old oil fields are being refilled by petroleum surging up from deep below, scientists report. That may mean that current estimates of oil and gas abundance are far too low.
Recent measurements in a major oil field show “that the fluids were changing over time; that very light oil and gas were being injected from below, even as the producing [oil pumping] was going on,” said chemical oceanographer Mahlon “Chuck” Kennicutt. “They are refilling as we speak. But whether this is a worldwide phenomenon, we don’t know.”
The ocean, coastal, and Great Lakes waters of the United States are foundational to the economy, security, global competitiveness, and well-being of the United States. Ocean industries employ millions of Americans and support a strong national economy. Domestic energy production from Federal waters strengthens the Nation’s security and reduces reliance on imported energy. Our Armed Forces protect our national interests in the ocean and along the Nation’s coasts. Goods and materials that support our economy and quality of life flow through maritime commerce. Our fisheries resources help feed the Nation and present tremendous export opportunities. Clean, healthy waters support fishing, boating, and other recreational opportunities for all Americans.
“The economic and environmental significance of the Great Lakes cannot be overstated,” Stabenow wrote. “Our Great Lakes are the largest surface freshwater system on Earth, supply drinking water to over 40 million people, and sustain a $6 trillion economy and over 50 million jobs. Given the existing ban on drilling and the importance of the Great Lakes, I call on you to reverse course and oppose any efforts to open our waters to oil and gas drilling as a result of your recent Executive Order.”
Earthquake Hazard Associated
With Deep Well InjectionA Report to the U.S. Environmental
By CRAIG NICHOLSON and ROBERT L. WESSON
Prepared in cooperation with the
Environmental Protection Agency
Under certain circumstances, the increased pore pressure
resulting from fluid injection, whether for waste disposal,
secondary recovery, geothermal energy, or solution mining,
can trigger earthquakes. This report discusses known cases
of injection-induced seismicity and how and why earthquakes
may be triggered, as well as conditions under which the
triggering is most likely to occur. Criteria are established
to assist in regulating well operations so as to minimize
the seismic hazard associated with deep well fluid injection
U.S. GEOLOGICAL SURVEY BULLETIN 1951
The seismic waves began roughly 15 miles off the shores of Mayotte, a French island sandwiched between Africa and the northern tip of Madagascar. The waves buzzed across Africa, ringing sensors in Zambia, Kenya, and Ethiopia. They traversed vast oceans, humming across Chile, New Zealand, Canada, and even Hawaii nearly 11,000 miles away.
These waves didn’t just zip by; they rang for more than 20 minutes. And yet, it seems, no human felt them.
Only one person noticed the odd signal on the U.S. Geological Survey’s real-time seismogram displays. An earthquake enthusiast who uses the handle @matarikipax saw the curious zigzags and posted images of them to Twitter. That small action kicked off another ripple of sorts, as researchers around the world attempted to suss out the source of the waves. Was it a meteor strike? A submarine volcano eruption? An ancient sea monster rising from the deep?
“I don’t think I’ve seen anything like it,” says Göran Ekström, a seismologist at Columbia University who specializes in unusual earthquakes.
Death of American missionary could put this indigenous tribe’s survival at risk
“It doesn’t mean that, in the end, the cause of them is that exotic,” he notes. Yet many features of the waves are remarkably weird—from their surprisingly monotone, low-frequency “ring” to their global spread. And researchers are still chasing down the geologic conundrum.
Why are the low-frequency waves so weird?
In a normal earthquake, the built-up tensions in Earth’s crust release with a jolt in mere seconds. This sends out a series of waves known as a “wave train” that radiates from the point of the rupture, explains Stephen Hicks, a seismologist at the University of Southampton.
The fastest-traveling signals are Primary waves, or P-waves, which are compression waves that move in bunches, like what happens to an extendedslinky that gets suddenly pushed at one end. Next come the secondary waves, or S-waves, which have more of a side-to-side motion. Both of these so-called body waves have relatively high frequencies, Hicks says, “a sort of ping rather than a rumbling.”
Finally, chugging along at the end come slow, long-period surface waves, which are similar to the strange signals that rolled out from Mayotte. For intense earthquakes, these surface waves can zip around the planet multiple times, ringing Earth like a bell, Hicks says.
However, there was no big earthquake kicking off the recent slow waves. Adding to the weirdness, Mayotte’s mystery waves are what scientists call monochromatic. Most earthquakes send out waves with a slew of different frequencies, but Mayotte’s signal was a clean zigzag dominated by one type of wave that took a steady 17 seconds to repeat.
“It’s like you have colored glasses and [are] just seeing red or something,” says Anthony Lomax, an independent seismology consultant.
Mayotte’s volcanic roots
Based on the scientific sleuthing done so far, the tremors seem to be related to a seismic swarm that’s gripped Mayotte since last May. Hundreds of quakes have rattled the small nation during that time, most radiating from around 31 miles offshore, just east of the odd ringing. The majority were minor trembles, but the largest clocked in at magnitude 5.8 on May 15, the mightiest in the island’s recorded history. Yet the frequency of these shakes has declined in recent months—and no traditional quakes rumbled there when the mystery waves began on November 11.
The early period of rumbling was also overprinted with what seemed to be the P- and S- waves of tiny tremors, explains Lomax, who spotted the faint pings by filtering out the low-frequency signals. Such pings are commonly associated with magma moving and fracturing rock as it squirts through the crust. But even those signals were a little strange, says Helen Robinson, a Ph.D. candidate in applied volcanology at the University of Glasgow.
“They’re too nice; they’re too perfect to be nature,” she jokes, although she quickly adds that an industrial source is impossible, since no wind farms or drilling are taking place in the deep waters off Mayotte’s shores.
Ekström thinks that the events on the morning of November 11 actually did begin with an earthquake of sorts equivalent to a magnitude 5 temblor. It passed by largely unnoticed, he suggests, because it was what’s known as a slow earthquake. These quakes are quieter than their speedy cousins since they come from a gradual release of stress that can stretch over minutes, hours, or even days.
“The same deformation happens, but it doesn’t happen as a jolt,” Ekström says.
So what is actually causing the super-slow vibrations at Mayotte? A submarine eruption could produce these low rumblings, but evidence for such an event has yet to materialize.
Most current guesses revolve around resonance in a magma chamber, triggered by some type of subsurface shift or chamber collapse. The resonance itself can be any type of rhythmic motion, like sloshing of the molten rock, or a pressure wave ricocheting through the magma body, Ekström explains. Studying the intricate features of the seismic waves could yield clues to the size and shape of the molten material lurking below.
It is very difficult, really, to say what the cause is and whether anyone’s theories are correct.
“It’s like a music instrument,” says Jean-Paul Ampuero, a seismologist at the Université Côte d’Azur in France. “The notes of a music instrument—whether it’s grave or very pitchy—depends on the size of the instrument.”
The signal’s odd uniformity could be due, in part, to the surrounding rocks and sediments, Lomax adds. Perhaps the local geology is filtering the sounds and only letting this single 17-second wave period escape.
Robinson agrees with this idea, noting that the geology here is extremely complex. Mayotte sits in a region crisscrossed by ancient faults—including fracture zones from the final breakup of the southern supercontinent Gondwana. What’s more, the underlying crust is somewhat transitional, shifting between the thick continental crusts and the thinner oceanic crusts. Perhaps this complexity drives the simplicity of the escaping waves, Robinson says.
Secrets of the sea
For now, though, the lack of data makes it tough to say more about the wiggly forms. Hicks’ preliminary models hinted that the waves emanated from subsurface inflation, rather than a magma chamber draining or collapsing. But with a little additional data, the model flipped and pointed to chamber deflation instead.
It also could be a bit of both, notes Robinson: “Some collapse mechanisms, you can get inflation and deflation occurring at the same time,” she says. Or sometimes they can alternate, pumping up and down like Earth’s fiery lungs.
“It is very difficult, really, to say what the cause is and whether anyone’s theories are correct—whether even what I’m saying has any relevance to the outcome of what’s going on,” Robinson says.
BRGM plans to do ocean bottom surveys to get more detailed information about the region and investigate the possibility of a submarine eruption. In the meantime, the seismic sleuthing continues with the data that’s available. Whether the cause is ordinary or extraordinary remains to be seen, Lomax says, but the science—and the fun—is in the chase.
“Depending on what field and what time in history, 99.9 percent of the time, it’s ordinary, or noise, or a mistake, and 0.1 percent, it’s something” he says. “But that’s just the way it goes. That’s the way it should go. That’s scientific advance.”
2014 Napa earthquake may be linked to groundwater changes, study says
By ASSOCIATED PRESS
JUN 14, 2018 |2:00 AM
Research suggests the magnitude 6.0 earthquake that rocked California wine country in 2014 may have been caused by an expansion of Earth’s crust because of seasonally receding groundwater under the Napa and Sonoma valleys.
The vineyard-filled valleys flank the West Napa Fault, which produced the quake that killed one person, injured several hundred and caused more than $500 million in losses.
The study recently published in the American Geophysical Union’s “Journal of Geophysical Research: Solid Earth” suggests land between the valleys is stretched each summer as groundwater levels fall beneath the valleys and the ground in the valleys sinks and contracts.
The amount of the horizontal stretching measured is tiny — about 0.12 inch — but enough to stress faults, according to the researchers.
“We think it’s more of a localized effect, something related to the groundwater system. We don’t know if it is groundwater pumping specifically, or something related to how the natural aquifer system works, or a combination,” said lead author Meredith Kraner, formerly of the Department of Geosciences at Stony Brook University in New York and now with the University of Nevada, Reno.
Co-authors were William E. Holt of Stony Brook University and Adrian A. Borsa of the Scripps Institution of Oceanography at UC San Diego.
The early morning Napa quake on Aug. 24 was the largest to hit the Bay Area since the magnitude 6.9 Loma Prieta earthquake on Oct. 17, 1989.
The Napa quake left 8 miles of surface rupture and damaged many historical masonry buildings and older residences, according to the U.S. Geological Survey.