A new look 100 miles beneath a massive tectonic plate as it dives under North America has helped clarify the subduction process that generates earthquakes, volcanoes and the rise of the Cascade Range in the Pacific Northwest.

The largest array of seismometers ever deployed on the seafloor, coupled with hundreds of others operating in the continental U.S., has enabled University of California, Berkeley, researchers to essentially create CT scans of the Juan de Fuca plate and part of the earth’s mantle directly below it.

The plate, about the size of the state of Michigan, is grinding under the continent along an 800-mile swath that runs from Northern California to Vancouver Island, known as the Cascadia subduction zone.

The 3-D imaging process, known as seismic tomography, has revealed with unprecedented clarity a huge, buoyant, sausage-shaped region of the upper mantle, or asthenosphere, pressing up on the oceanic plate.

The imaging casts new light on the competing hypotheses about the drivers of plate tectonics, a dynamic earth process that has been studied for more than 50 years but is still poorly understood.

Different evidence has led to three different plate movement scenarios: either the plates are pushed from mid-ocean ridges; or they are pulled from their subducting slabs; or their movement is driven by the drag of the viscous mantle material that lies directly below.

The new research suggests that the third scenario does not apply to the Cascadia subduction zone. Rather, it reveals that a distinct, thin – and difficult to observe – layer separates the plate from the mantle beneath, at least in the Cascadia subduction zone.

The layer acts as a kind of berm that the plate rolls over before descending beneath the continent, says UC Berkeley seismologist Richard Allen, leader of the research and co-author of a paper appearing in the Sept. 23 edition of the journal Science.

“What we observe is an accumulation of low-viscosity material between the plate and the mantle. Its composition acts as a lubricant, and decouples the plate's movement from the mantle below it,” Allen explains. The plates may move independently of the mantle below, he adds.

The finding, he says, will help refine models of plate tectonic dynamics, aiding the long-range effort to understand the connection between tectonics and earthquakes.

“It is the motion of the plates that causes earthquakes,” Allen says. “Models like this help us understand that linkage so we can be better informed of the coastal hazards.

“First though, we need to learn if what we find here is typical of subduction zones across the planet, or if it is unique for some reason.”

Japan has recently deployed a massive seafloor seismic network to study subduction and earthquakes. Allen hopes to next apply the tomography strategy there. Alaska also beckons.

Lead author on the Science paper is William Hawley, a graduate student in Allen’s lab.

“Plate tectonics is the most fundamental concept explaining the formation of features we see on the earth’s surface,” Hawley said, “but despite the fact that the concept is simple, we still do not know exactly why or how it operates.

“If the asthenosphere acts as a lubricant for tectonic plate movement throughout the planet, it will really change our long-term models of the process” – dynamic changes that occur over a 100 million years, Hawley said.

“Modelers will have to take this lubricating layer into account because it changes the way the mantle and the plates talk to each other,” according to Hawley.

Seismic tomography generates 3-D images of the earth’s interior by measuring how differences in shape, density, rock type and temperature affect the path, speed and amplitude of seismic waves traveling through the planet from an earthquake.

Much as in CT scans, computers process differences in energy measured at the receiving end to infer interior 3-D detail. CT scans use X-rays as the energy source, while seismic tomography measures energy from seismic waves.

A dense array of seismometers directly over the region of interest yields the best images and provides the highest resolution of the structures, which can then inform models of the process.

This study used the data from the largest scale ocean-floor deployment to complement the onshore data already available. Together, they generated the best images of the region to date.

The four-year seafloor research effort was made possible by the National Science Foundation’s ambitious $20 million Cascadia Initiative.

The NSF aimed to spur greater understanding of plate structure, subduction processes, earthquakes and volcanism by deploying seismometers at 120 sites on the ocean floor, arrayed throughout the 95,000-square-mile Juan de Fuca plate.

Over the four years, the offshore and onshore seismometer array measured thousands of earthquakes throughout the planet, ranging from magnitudes of 5 to about 9 on the Richter scale. The study examined a subset of 321 quakes with magnitudes between about 6 and 7.5.

Grad students and faculty scientists participated in 24 research cruises to deploy the instruments and move them between two swaths of the Juan de Fuca plate. Several of the seismic tomography cruises invited undergraduate students on the two-week trips.

On one Berkeley-led cruise aboard the R/V Thomas Thompson, the undergrads dubbed the trip the “Tom Cruise,” and sent daily video blogs ( https://www.youtube.com/playlist?list=PLaLpP50ifUEiz1cLei4aNZNfS4wtGihey ) .

Wallace Ravven writes for the UC Berkeley News Center.

NORTH COAST, Calif. – The Sonoma County Sheriff's Office is continuing it investigation into the death of a man whose body was found in a shallow grave on Sonoma State University property this past week, releasing new details on Saturday.

The body of Kirk Ryan Kimberly, 18, of Cotati was found in a wooded area on the outskirts of the campus by an employee on Wednesday, as Lake County News has reported.

Kimberly had been reported missing about two weeks before his body was found, officials said.

On Saturday Lt. Tim Duke of the Sonoma County Sheriff's Office Investigations Division offered new details on the case.

Duke said the investigation has revealed that Kimberly was stabbed multiple times by his assailant – or assailants. However, Duke did not release specifics about where Kimberly was wounded, how many wounds he had or the weapon authorities believe was used in the homicide.

“Preliminarily, detectives believe this was not a random act of violence but an isolated incident,” Duke said in his report. “Thus far, detectives have found no affiliation with the homicide and Sonoma State University or its students, other than where the body was found, which was on the property, in an isolated and secluded area of the campus.”

Duke said detectives, as well as other sheriff’s office personnel, are continuing to work around the clock on this case collecting and processing physical, trace and forensic evidence.

Anyone with information about Kimberly disappearance or who has knowledge of this incident is encouraged to call Detective Joseph Horsman of the Sonoma County Sheriff’s Office Violent Crimes Unit at 707-565-2185.

LAKE COUNTY, Calif. – Lake County Animal Care and Control has another group of big dogs ready for homes this week.

This week's dogs include mixes Labrador Retriever, pit bull, Rottweiler and shepherd.

Dogs that are adopted from Lake County Animal Care and Control are either neutered or spayed, microchipped and, if old enough, given a rabies shot and county license before being released to their new owner. License fees do not apply to residents of the cities of Lakeport or Clearlake.

If you're looking for a new companion, visit the shelter. There are many great pets hoping you'll choose them.

The following dogs at the Lake County Animal Care and Control shelter have been cleared for adoption (additional dogs on the animal control Web site not listed are still “on hold”).

'Perchuan'

“Perchuan” is a male Rottweiler mix with a short black and tan coat.

He's in kennel No. 11, ID No. 3557.

Rottweiler-shepherd mix

This young male Rottweiler-shepherd mix has a medium-length black and brown coat with white markings.

He's in kennel No. 19, ID No. 6412.

Labrador Retriever mix

This female Labrador Retriever mix has a short black coat with white markings.

She already has been spayed.

She's in kennel No. 21, ID No. 6308.

Rottweiler-shepherd mix

This young male Rottweiler-shepherd mix has a medium-length black and tan coat.

He's in kennel No. 22, ID No. 6411.

Rottweiler mix

This female Rottweiler mix has a black coat with some brindle markings.

Shelter staff said she need some training and is manageable on a leash. They said she is a very nice dog and knows not to jump when excited. After proper introductions, she has gotten along with other dogs she has met, including off-leash play. She would do best in a home with no cats.

She's in kennel No. 25, ID No. 5947.

To fill out an adoption application online visit http://www.co.lake.ca.us/Government/Directory/Animal_Care_And_Control/Adopt/Dog___Cat_Adoption_Application.htm .

Lake County Animal Care and Control is located at 4949 Helbush in Lakeport, next to the Hill Road Correctional Facility.

Office hours are Monday through Friday, 11 a.m. to 5 p.m., and 11 a.m. to 3 p.m., Saturday. The shelter is open from 11 a.m. to 4 p.m. Monday through Friday and on Saturday from 11 a.m. to 3 p.m.

Visit the shelter online at http://www.co.lake.ca.us/Government/Directory/Animal_Care_And_Control.htm .

For more information call Lake County Animal Care and Control at 707-263-0278.

Email Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it. . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.

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"I do not understand how anyone can live without some small place of enchantment to turn to." – Marjorie Kinnan Rawlings

LAKE COUNTY, Calif. – If you like a good mystery, you need go no farther than your closest state park.

Take a hike along a shadowy trail and listen to the restrained murmurs amongst the billowing leaf-fall which is occurring.

After you shake off the reverie of your walk, look at the clusters of leaves, both on top, and beneath their elongated, variegated puzzle-pieces.

Also, observe the tree's trunk and limbs, and you see orbs, balls and bubbles of differing hues – off-white to black.

The oak gall comes in all shapes and sizes, and, at first sight, presents a mystery. What on earth is that tan sphere attached to the oak tree? What can the perfectly pink, tiny chocolate chip-shaped object possible be, affixed to an oak leaf like that?

It appears that the Great Prankster has devised a myriad of ways to entertain and inform us. Nature, always ornate and exceedingly creative spares no effort in building tiny worlds for creatures to thrive.

Also known as oak apples, these are homes of tiny wasps, and are definitely not edible.

Galls are sometimes elusive, but through careful observation of oaks, and many other trees and plants, you will find all manner of shapes, sizes and kaleidoscopic colors beyond the aforementioned.

Galls can be found on alders, pines, manzanitas and more, in tints of yellow, red, green and even purple.

Through the science of cecidology, or galls and their producers, it has been found that trees may be home to not only one type of gall, but could be home-sweet-home to dozens.

According to Glenn Keator's book, “The Life of an Oak,” “The cynipid wasps are responsible for the majority of oak galls."

The tiny cynipid wasp is only millimeters in size, and has found oaks to be a favored place to survive and thrive in nature.

First, the wasp begins egg-laying in the trees' buds, leaves or, nearly any tree-tissue handy.

After the eggs hatch and change to larva, a chemical in the larva's saliva reacts with the cells, called meristematic that are in the oak tree's tissues, and voilà! A gall begins to form in which the wasp inhabits and metamorphoses – oh, and also feeds upon.

When the time comes to leave its gall, it tunnels out, leaving a miniscule opening in the formerly occupied home. Now the cycle begins once more- but, as they say, timing is everything. If the eggs are deposited too early or too late in the season, this entomologic ballet will not occur.

The swell of a gall's growth on a tree does not seem to do harm. Since galls are replete with tannic acid, they have been used historically for tanning, as dyes and in ointments.

In S. A. Barrett's book, entitled “Pomo Myths,” the story of Oak-ball who tricks Coyote is retold.

In the account an oak ball was seen drifting down as stream. Coyote was curious about why he could not float in water like the oak-ball. The oak-ball informs him that in order to float, you simply jump into the water, and after reaching the bottom you naturally float up.

After some trepidation Coyote got up his nerve and jumped in. He did not, however, bob up to the surface as Oak-ball had informed him, but was, instead, jettisoned roughly downstream, where he was drowning.

Oak-ball-people rescued Coyote, dragging him to the shore to rest, where Blue Jay came along to squawk and annoy him.

For more gall photos visit http://joycegross.com/galls_ca_oak.php .

Kathleen Scavone, M.A., is a retired educator, potter, writer and author of “Anderson Marsh State Historic Park: A Walking History, Prehistory, Flora, and Fauna Tour of a California State Park” and “Native Americans of Lake County.” She also writes for NASA and JPL as one of their “Solar System Ambassadors.” She was selected “Lake County Teacher of the Year, 1998-99” by the Lake County Office of Education, and chosen as one of 10 state finalists the same year by the California Department of Education.

Earth’s moon is an unusual object in our solar system, and now there’s a new theory to explain how it got where it is, which puts some twists on the current “giant impact” theory.

The work is published Oct. 31 in the journal Nature.

The moon is relatively big compared to the planet it orbits, and it’s made of almost the same stuff, minus some more volatile compounds that evaporated long ago.

That makes it distinct from every other major object in the solar system, said Sarah Stewart, professor of earth and planetary sciences at the University of California, Davis, and senior author on the paper.

“Every other body in the solar system has different chemistry,” she said.

The textbook theory of lunar formation goes like this: Late in the formation of the solar system came the “giant impact” phase, when hot, planet-sized objects collided with each other.

A Mars-sized object grazed what would become Earth, throwing off a mass of material from which the moon condensed. This impact set the angular momentum for the Earth-moon system, and gave the early Earth a five-hour day.

Over millennia, the moon has receded from the Earth and the rotation has slowed to our current 24-hour day.

Scientists have figured this out by looking at the moon’s current orbit, working out how rapidly angular momentum of the Earth-moon system has been transferred by the tidal forces between the two bodies, and working backward.

But there are a couple of problems with the textbook theory. One is the moon’s surprisingly Earth-like composition. Another is that if the moon condensed from a disk of material rotating around Earth’s equator, it should be in orbit in the plane of the ecliptic – the same plane as the other planets.

But the moon’s current orbit is tilted 5 degrees off the ecliptic, meaning some more energy must have been put in to move it.

An alternative to explain it all

Stewart, her former postdoctoral fellow Matija Ćuk (now a scientist at the SETI Institute in Mountain View, California), with Douglas Hamilton at the University of Maryland and Simon Lock, Harvard University, have come up with an alternative model.

In 2012, Ćuk and Stewart proposed that some of the angular momentum of the Earth-moon system could have been transferred to the Earth-sun system. That allows for a more energetic collision at the beginning of the process.

In the new model, a high-energy collision left a mass of vaporized and molten material from which the Earth and moon formed. The Earth was set spinning with a two-hour day, its axis pointing toward the sun.

Because the collision could have been more energetic than in the current theory, the material from Earth and the impactor would have mixed together, and both Earth and moon condensed from the same material and therefore have a similar composition.

As angular momentum was dissipated through tidal forces, the moon receded from the Earth until it reached a point called the “LaPlace plane transition,” where the forces from the Earth on the moon became less important than gravitational forces from the sun.

This caused some of the angular momentum of the Earth-moon system to transfer to the Earth-sun system.

This made no major difference to the Earth’s orbit around the sun, but it did flip Earth upright. At this point, the models built by the team show the moon orbiting Earth at a high angle, or inclination, to the ecliptic.

Over a few tens of million years, the moon continued to slowly move away from Earth until it reached a second transition point, the Cassini transition, at which point the inclination of the moon – the angle between the moon’s orbit and the ecliptic – dropped to about 5 degrees, putting the moon more or less in its current orbit.

The new theory elegantly explains the moon’s orbit and composition based on a single, giant impact at the beginning, Stewart said. No extra intervening steps are required to nudge things along.

“One giant impact sets off the sequence of events,” she said.

The research was supported by NASA.

Andy Fell writes for UC Davis News and Media Relations.

CLEARLAKE OAKS, Calif. – A Friday morning vehicle crash led to a propane leak, brief evacuations of some nearby homes and a closure of Highway 20.

The California Highway Patrol said the crash happened just before 8:30 a.m. on Highway 20 at Paradise Valley Boulevard.

A small green four-door sedan went off the highway and down an embankment next to the Paradise Cove subdivision, according to reports from the scene.

Northshore Fire Chief Jay Beristianos said the crash resulted in no injuries, but the vehicle hit a residential propane tank and knocked it over.

The result was that the overturned tank was leaking liquid propane in the backyard of the residence, Beristianos said.

Northshore and Cal Fire firefighters used water streams to disburse a propane gas cloud away from the home. Beristianos said a winch had to be used to upright the tank so the value could be turned off.

He said residents in nearby homes were asked to evacuate while the work at the scene involving the propane tank was taking place.

At the same time, Highway 20 was closed for about an hour to reduce the chance of igniting the propane cloud, Beristianos said.

Beristianos said Northshore Fire sent two engines, a heavy rescue and a medic unit, and Cal Fire sent two engines, with a total of 13 personnel on scene.

Email Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it. . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.