Category: Breaking News

Mantle Rock Behind Yellowstone’s Supereruptions Extends To Northern California

Victor Camp has spent a lifetime studying volcanic eruptions all over the world, starting in Saudi Arabia, then Iran, and eventually the Pacific Northwest. The geology lecturer finds mantle plumes that feed the largest of these eruptions fascinating, because of their massive size and the impact they can have on our environment.

Over the past two years, this abiding interest helped him connect the dots and discover that the mantle source rock that rises upward from beneath Yellowstone National Park to feed its periodic supereruptions also spreads out west all the way to Northern California and Oregon.

On its westward journey, it acts as the catalyst for fairly young—meaning less than 2 million years old—volcanic eruptions at places such as Craters of the Moon National Monument and Preserve in Idaho, before reaching Medicine Lake Volcano in the northeastern tip of California, close to the Oregon border.

The mantle rock spreads laterally through narrow flow-line channels well below the earth’s crust for over 500 miles, bifurcating twice: once as it leaves Yellowstone and again as it reaches the California-Oregon border. These lines end at Medicine Lake, an active volcano near Mount Shasta, and at Newberry Volcano, an active volcano about 20 miles south of Bend, Ore.

This discovery is significant because it reveals how mantle plumes similar to the one beneath Yellowstone behave as they feed the majority of the world’s largest volcanic eruptions of basaltic lava, including the ones in Hawaii.

“Since the plume is not controlled by plate tectonics, it can rise and emerge anywhere on earth, depending on where it manages to break through the earth’s surface,” Camp said. “So, knowing this will help us understand supereruptions that have occurred before, and those that will occur in the future.”

The results of his self-funded study were published in the journal Geology in May.

Mantle plumes are composed of very hot, low-density mantle rock. Mantle is one of three major layers of planet earth—we live on the earth’s crust, the thinnest layer, and mantle is the second denser layer that extends from about 100 kilometers (62 miles) below the earth’s surface all the way down to about 2,700 kilometers (about 1,680 miles), and further down is the core of the earth comprised mostly of iron mixed with a few other elements.

Mantle plumes are technically mantle rock, but because they are hotter and more buoyant than surrounding mantle they rise in a plume-like form. When the Yellowstone plume first reached the base level of the North American tectonic plate, it was blocked by the rigidity of the cold plate base which acted as a barrier. At this depth of about 100 kilometers, the plume began to decompress and melt, while simultaneously spreading laterally to the west.

The mantle rock that Camp traced to California took many millions of years to move out west. What’s interesting is that the source of the mantle rock under Yellowstone today originated at the core-mantle boundary geographically centered near present-day San Diego, but very deep beneath the earth’s surface we reside on—and took a circuitous route through different regions of the mantle before it rose up underneath the Yellowstone volcano.

Camp sourced seismic tomography images, similar to X-rays and CT-scans (computerized tomography scans), that show how the mantle plume ascended, and he analyzed field data as well as published chemistry and age data on volcanic rocks at the surface, to demonstrate its westward flow.

Earth’s Last Magnetic Field Reversal Took Far Longer Than Once Thought

Earth’s magnetic field seems steady and true—reliable enough to navigate by.

Yet, largely hidden from daily life, the field drifts, waxes and wanes. The magnetic North Pole is currently careening toward Siberia, which recently forced the Global Positioning System that underlies modern navigation to update its software sooner than expected to account for the shift.

And every several hundred thousand years or so, the magnetic field dramatically shifts and reverses its polarity: Magnetic north shifts to the geographic South Pole and, eventually, back again. This reversal has happened countless times over the Earth’s history, but scientists have only a limited understanding of why the field reverses and how it happens.

New work from University of Wisconsin-Madison geologist Brad Singer and his colleagues finds that the most recent field reversal, some 770,000 years ago, took at least 22,000 years to complete. That’s several times longer than previously thought, and the results further call into question controversial findings that some reversals could occur within a human lifetime.

The new analysis—based on advances in measurement capabilities and a global survey of lava flows, ocean sediments and Antarctic ice cores—provides a detailed look at a turbulent time for Earth’s magnetic field. Over millennia, the field weakened, partially shifted, stabilized again and then finally reversed for good to the orientation we know today.

The results provide a clearer and more nuanced picture of reversals at a time when some scientists believe we may be experiencing the early stages of a reversal as the field weakens and moves. Other researchers dispute the notion of a present-day reversal, which would likely affect our heavily electronic world in unusual ways.

Singer published his work Aug. 7 in the journal Science Advances. He collaborated with researchers at Kumamoto University in Japan and the University of California, Santa Cruz.

“Reversals are generated in the deepest parts of the Earth’s interior, but the effects manifest themselves all the way through the Earth and especially at the Earth’s surface and in the atmosphere,” explains Singer. “Unless you have a complete, accurate and high-resolution record of what a field reversal really is like at the surface of the Earth, it’s difficult to even discuss what the mechanics of generating a reversal are.”

Earth’s magnetic field is produced by the planet’s liquid iron outer core as it spins around the solid inner core. This dynamo action creates a field that is most stable going through roughly the geographic North and South poles, but the field shifts and weakens significantly during reversals.

As new rocks form—typically either as volcanic lava flows or sediments being deposited on the sea floor—they record the magnetic field at the time they were created. Geologists like Singer can survey this global record to piece together the history of magnetic fields going back millions of years. The record is clearest for the most recent reversal, named Matuyama-Brunhes after the researchers who first described reversals.

For the current analysis, Singer and his team focused on lava flows from Chile, Tahiti, Hawaii, the Caribbean and the Canary Islands. The team collected samples from these lava flows over several field seasons.

“Lava flows are ideal recorders of the magnetic field. They have a lot of iron-bearing minerals, and when they cool, they lock in the direction of the field,” says Singer. “But it’s a spotty record. No volcanoes are erupting continuously. So we’re relying on careful field work to identify the right records.”

The researchers combined magnetic readings and radioisotope dating of samples from seven lava flow sequences to recreate the magnetic field over a span of about 70,000 years centered on the Matuyama-Brunhes reversal. They relied on upgraded methods developed in Singer’s WiscAr geochronology lab to more accurately date the lava flows by measuring the argon produced from radioactive decay of potassium in the rocks.

They found that the final reversal was quick by geological standards, less than 4,000 years. But it was preceded by an extended period of instability that included two excursions—temporary, partial reversals—stretching back another 18,000 years. That span is more than twice as long as suggested by recent proposals that all reversals wrap up within 9,000 years.

The lava flow data was corroborated by magnetic readings from the seafloor, which provides a more continuous but less precise source of data than lava rocks. The researchers also used Antarctic ice cores to track the deposition of beryllium, which is produced by cosmic radiation colliding with the atmosphere. When the magnetic field is reversing, it weakens and allows more radiation to strike the atmosphere, producing more beryllium.

Since humanity began recording the strength of the magnetic field, it has decreased in strength about five percent each century. As records like Singer’s show, a weakening field seems to be a precursor to an eventual reversal, although it’s far from clear that a reversal is imminent.

A reversing field might significantly affect navigation and satellite and terrestrial communication. But the current study suggests that society would have generations to adapt to a lengthy period of magnetic instability.

“I’ve been working on this problem for 25 years,” says Singer, who stumbled into paleomagnetism when he realized the volcanoes he was studying served as a good record of Earth’s magnetic fields. “And now we have a richer record and better-dated record of this last reversal than ever before.”

Scientists Uncover Deep-Rooted Plumbing System Beneath Ocean Volcanoes

Cardiff University scientists have revealed the true extent of the internal ‘plumbing system’ that drives volcanic activity around the world.

An examination of pockets of magma contained within crystals has revealed that the large chambers of molten rock which feed volcanoes can extend to over 16 km beneath the Earth’s surface.

The new study, published today in Nature, has challenged our understanding of the structure of ocean volcanoes, with previous estimates suggesting that magma chambers were located up to 6 km below the surface.

Interconnected magma chambers and reservoirs are the key driver of the dynamics of volcanic systems around the world, so understanding their nature is an important step towards understanding how volcanoes are supplied with magma, and, ultimately, how they erupt.

Mid-ocean ridges in particular make up the most significant volcanic system on our planet, forming a roughly 80,000 km-long network of undersea mountains along which 75 percent of Earth’s volcanism occurs.

However, because these volcanoes are located under thousands of metres of water, and sometimes permanent sea ice, we are only just starting to understand what the subsurface architecture of these volcanoes look like.

It is known that magma plumbing systems exist below the Earth’s surface, which can be thought of as a series of interconnected magma conduits and reservoirs, much like the pipes and tanks that make up plumbing systems in a house, instead at mid-ocean ridges the tap is a volcano.

In their study, the team analysed common minerals such as olivine and plagioclase which grew deep within the volcanoes and were subsequently erupted from the Gakkel Ridge located beneath the Arctic Ocean between Greenland and Siberia.

These minerals act as tape recorders from which changes in the physical and chemical conditions of the environment within which they grew can be measured. Critically, the team were able to record what processes occurred and at what depths these minerals began to crystallise in magma reservoirs.

Lead author of the study, Ph.D. student Emma Bennett, from the School of Earth and Ocean Sciences, said: “To calculate the depths of magma reservoirs we used melt inclusions, which are small pockets of magma that become trapped within growing crystals at different depths in the magmatic system. These pockets of melt contain dissolved CO2 and H2O.

“Because the melt cannot dissolve as much CO2 at shallow pressure as it can at high pressure, we can determine what pressure the melt inclusion was trapped, and in turn work out the depth at which crystallisation occurred, by measuring the amount of CO2 in the melt inclusions.

“Put simply, crystal growth in a magmatic environment can be likened to the growth rings on a tree; for example, a change in the chemical environment will result in the growth of a new layer with a different crystal composition.

“By analysing multiple melt inclusions we can start to reconstruct the architecture of the magmatic system.”

The study was the first to use the mineral plagioclase as a proxy for the depth of magma reservoirs, with previous studies using the mineral olivine.

The results showed that magma plumbing systems at mid-ocean ridges extend to much greater depths than previously thought. Oceanic crust is normally only around 6 km thick, and conventionally magma chambers were thought of as being located here.

Yet the new data has shown that the plumbing system extends to at least 16 km depth, which means that the magma chambers that fed the Gakkel Ridge volcanoes are located much deeper down in the mantle.

NASA’s MMS Finds First Interplanetary Shock

The Magnetospheric Multiscale mission—MMS—has spent the past four years using high-resolution instruments to see what no other spacecraft can. Recently, MMS made the first high-resolution measurements of an interplanetary shock.

These shocks, made of particles and electromagnetic waves, are launched by the Sun. They provide ideal test beds for learning about larger universal phenomena, but measuring interplanetary shocks requires being at the right place at the right time. Here is how the MMS spacecraft were able to do just that.

What’s in a Shock?

Interplanetary shocks are a type of collisionless shock—ones where particles transfer energy through electromagnetic fields instead of directly bouncing into one another. These collisionless shocks are a phenomenon found throughout the universe, including in supernovae, black holes and distant stars. MMS studies collisionless shocks around Earth to gain a greater understanding of shocks across the universe.

Interplanetary shocks start at the Sun, which continually releases streams of charged particles called the solar wind.

The solar wind typically comes in two types—slow and fast. When a fast stream of solar wind overtakes a slower stream, it creates a shock wave, just like a boat moving through a river creates a wave. The wave then spreads out across the solar system. On Jan. 8, 2018, MMS was in just the right spot to see one interplanetary shock as it rolled by.

Catching the Shock

MMS was able to measure the shock thanks to its unprecedentedly fast and high-resolution instruments. One of the instruments aboard MMS is the Fast Plasma Investigation. This suite of instruments can measure ions and electrons around the spacecraft at up to 6 times per second. Since the speeding shock waves can pass the spacecraft in just half a second, this high-speed sampling is essential to catching the shock.

Looking at the data from Jan. 8, the scientists noticed a clump of ions from the solar wind. Shortly after, they saw a second clump of ions, created by ions already in the area that had bounced off the shock as it passed by. Analyzing this second population, the scientists found evidence to support a theory of energy transfer first posed in the 1980s.

MMS consists of four identical spacecraft, which fly in a tight formation that allows for the 3-D mapping of space. Since the four MMS spacecraft were separated by only 12 miles at the time of the shock (not hundreds of kilometers as previous spacecraft had been), the scientists could also see small-scale irregular patterns in the shock. The event and results were recently published in the Journal of Geophysical Research.

Going Back for More

Due to timing of the orbit and instruments, MMS is only in place to see interplanetary shocks about once a week, but the scientists are confident that they’ll find more. Particularly now, after seeing a strong interplanetary shock, MMS scientists are hoping to be able to spot weaker ones that are much rarer and less well understood. Finding a weaker event could help open up a new regime of shock physics.

6.0 Earthquake Strikes Taiwan’s Yilan, Whole Country Feels Shock Waves

A magnitude 6.0 earthquake struck northeastern Taiwan’s Yilan County at 5:28 a.m. this morning (Aug. 8), according to the Central Weather Bureau (CWB).

The epicenter of the temblor was 36.5 kilometers southeast of Yilan County Hall at a depth of 22.5 kilometers, based on CWB data.

The quake’s intensity, which gauges the actual effect of the tremor, registered a 6 in Yilan County and a 4 in Hualien County, New Taipei City, Taipei City, Hsinchu County, Taoyuan City, and Taichung City. An intensity level of 3 was felt in Nantou County, Keelung City, Miaoli County, Hsinchu City, Changhua County, and Yunlin County.

An intensity level of 2 was recorded in Chiayi County, Chiayi City, and Tainan City. An intensity level of 1 was reported in Taitung County, Kaohsiung City, Pingtung County, and Penghu County.

Located along the so-called Pacific Ring of Fire, Taiwan uses an intensity scale of 1 to 7, which gauges the degree to which a quake is felt in a specific location.

Reports are filtering in of products falling off of store shelves and ceiling tiles falling in Yilan County. A woman in Taipei was reported to be in critical condition after her wardrobe fell on her during the initial 6.0 quake.

The MRT in Taipei is already running normally and Taiwan’s High Speed Rail is expected to resume normal operations shortly. Taiwan Railways Administration (TRA) train tracks are currently being inspected in Yilan City and Nan’ao, Taiwan, but the rest of the TRA’s trains are expected to operate normally.

CWB officials are warning the public to beware of aftershocks.

UPDATE :Typhoon Lekima Hammering Japan’s Ryukyu Islands and Soaking Taiwan Before Heading to Eastern China

Typhoon Lekima is hammering Japan’s southern Ryukyu Islands while also soaking Taiwan before heading for eastern China by this weekend.

Lekima is currently centered about 180 miles west of Kadena Air Base in Okinawa and is heading northwestward.

After rapidly intensifying Tuesday into Wednesday, Lekima became a super typhoon (winds 150 mph or greater) for a short time late Thursday into early Friday. Lekima has since weakened slightly to a Category 4 hurricane.

Damaging winds and heavy rain continue battering Japan’s southernmost Ryukyu Islands, including Ishigaki and Miyako, and the super typhoon’s outer eyewall tracks across the islands. Winds had gusted as high as 46.6 m/s or 104 mph at Miyako Shimojishima Airport as of early Friday morning local time (JST). Sustained typhoon force winds (33.5 m/s or 75 mph) has been reported in Miyako. Ishigaki has received 198 mm or around 7.8 inches of rainfall so far.

Typical of intense tropical cyclones, the eye of Lekima wobbled as it tracked through the Ryukyu Islands, passing near the islands of Tarama and Minna, about 200 miles east-southeast of Taipei, Taiwan.

Lekima will pull away from southern Japan during the early morning hours of Friday, and winds will begin to come down.

Japan’s Meteorological Agency has issued storm warnings, equivalent to typhoon warnings, for the southern Ryukyu Islands. Storm surge warnings have also been issued.

Lekima is forecast to move north of Taiwan on Friday afternoon into the evening, local time in Taiwan (CST). Heavy rain and strong wind gusts from Lekima will still impact parts of Taiwan even though the center of the typhoon won’t make landfall there.

The Central Weather Bureau in Taiwan has issued typhoon warnings for northern parts of Taiwan.

More than a foot of rain is currently forecast through Saturday in the higher elevations of Taiwan. The excessive rainfall could trigger flooding, as well as landslides.

Rainfall totals of more than 8 inches had already been reported on Thursday in parts of Taiwan as of early Friday morning, local time.

This weekend, Lekima will be on a weakening trend as it curls northward near the eastern coast of China, potentially including near Shanghai.

Heavy rain could trigger flooding in eastern China. Strong winds and storm surge flooding are also possible depending on the exact track and intensity of Lekima as it moves near, inland or offshore from the coastline.

Typhoon Krosa
Several hundred miles to the east of Lekima is Typhoon Krosa which now has winds equivalent in strength to a Category 2 hurricane.

Krosa may be getting weakened by its relatively slow motion, which cools water down in a process called upwelling.

Krosa is forecast to drift near Iwo Jima and the Ogasawara Islands later this week but will otherwise remain over the open waters of the Western Pacific the next five days. Extended periods of gusty winds and heavy rainfall are expected in the Ogasawara Islands.

When Krosa begins to gain more latitude, it’s possible Krosa could approach mainland Japan early next week as a typhoon, but the forecast this far out in time is highly uncertain.

Francisco made landfall in southern Japan as typhoon Tuesday morning local time, with maximum sustained winds of 85 mph, according to the U.S. Joint Typhoon Warning Center.

More than 15 inches of rain soaked the Tokushima Prefecture, according to the Japan Meteorological Agency. Parts of the Miyazaki Prefecture saw more than 10 inches of rain.

A Quiet Typhoon Season Before This Week
This year had been uncommonly calm for typhoon activity through Aug. 4 in the Northwest Pacific, which is normally the most active region on Earth for tropical cyclones. The only typhoon recorded in 2019 through Aug. 4 was Wutip, the first Category 5 super typhoon on record in February. Wutip passed south of Guam and Micronesia as a Category 4 storm, producing more than $3 million in damage.

Japan is accustomed to typhoons. In a typical year, three typhoons strike Japan, according to data from the Japan Meteorological Agency analyzed by nippon.com. Landfalls are most common in August, but the most destructive typhoons tend to be in September.

Since 1950, no other year had gone from Feb. 28 to Aug. 4 without any typhoons, as noted by Dr. Phil Klotzbach of Colorado State University. Francisco put an end to that streak when it became a typhoon on Aug. 5.

In a typical season (1981-2010), the Northwest Pacific sees about eight named storms and five typhoons by Aug. 2. This year had brought just five named storms and one typhoon by that date.

The amount of accumulated cyclone energy in the Northwest Pacific – which is calculated based on how strong tropical cyclones get and how long they last – was only a little over half of average for the year as of Aug. 2, according to data compiled by Colorado State University.

So, what’s the difference between this quiet period and now?

At least one factor that may be having its hand on the “on” switch for the west Pacific is the Madden-Julian Oscillation.

The MJO is essentially a wave of increased storminess, clouds and pressure that moves eastward around the globe once every 40 days or so.

In the tropics, the MJO is known to kick up or assist in tropical cyclone development.

A robust MJO wave is now moving through eastern Asia and the western Pacific, and likely helped the recent tropical cyclone outbreak fester.

Magnetic Plasma Pulses Excited By UK-Size Swirls In The Solar Atmosphere

An international team of scientists led by the University of Sheffield have discovered previously undetected observational evidence of frequent energetic wave pulses the size of the UK, transporting energy from the solar surface to the higher solar atmosphere.

Magnetic plasma waves and pulses have been widely suggested as one of the key mechanisms which could answer the long-standing question of why the temperature of the solar atmosphere rises dramatically, from thousands to millions of degrees, as you move away from the solar surface.

There have been many theories put forward, including some developed at the University of Sheffield — for example, heating the plasma by magnetic waves or magnetic plasma — but observational validation of the ubiquity of a suitable energy transport mechanism has proved challenging until now.

By developing innovative approaches, applied mathematicians at the Solar Physics and Space Plasma Research Centre (SP2RC) in the School of Mathematics and Statistics at the University of Sheffield, and the University of Science and Technology of China, have discovered unique observational evidence of plentiful energetic wave pulses, named after the Nobel laureate Hannes Alfvén, in the solar atmosphere.

These short-lived Alfvén pulses have been found to be generated by prevalent photospheric plasma swirls about the size of the British Isles, which are suggested to have a population of at least 150,000 in the solar photosphere at any moment of time.

Professor Robertus Erdélyi (a.k.a. von Fáy-Siebenbürgen), Head of SP2RC, said: “Swirling motions are everywhere in the universe, from sinking water in domestic taps with a size of centimeters, to tornadoes on Earth and on the Sun, solar jets and spiral galaxies with a size of up to 520,000 light years. This work has shown, for the first time, the observational evidence that ubiquitous swirls in the solar atmosphere could generate short-lived Alfvén pulses.

“The generated Alfvén pulses easily penetrate the solar atmosphere along cylinder-like magnetic flux tubes, a form of magnetism a bit like trees in a forest. The pulses could travel all the way upward and reach the top of the solar chromospheric layers, or, even beyond.”

Alfvén modes are currently very hard to observe directly, because they do not cause any local intensity concentrations or rarefactions as they make their journey through a magnetised plasma. They are hard to be observationally distinguished from some other types of magnetic plasma modes, like the well-known transversal magnetic plasma waves, often called kink modes.

“The energy flux carried by the Alfvén pulses we detected now are estimated to be more than 10 times higher than that needed for heating the local upper solar chromosphere,” said Dr Jiajia Liu, postdoctoral research associate.

“The chromosphere is a relatively thin layer between the solar surface and the extremely hot corona. The solar chromosphere appears as a red ring around the Sun during total solar eclipses.”

Professor Erdélyi added: “It has been a fascinating question for the scientific community for a long while — how the Sun and many other stars supply energy and mass to their upper atmospheres. Our results, as part of an exciting UK-China collaboration, involving our very best early-career scientists like Drs Jiajia Liu, Chris Nelson and Ben Snow, are an important step forward in addressing the supply of the needed non-thermal energy for solar and astrophysical plasma heating.

“We believe, these UK-sized photospheric magnetic plasma swirls are also very promising candidates not just for energy but also for mass transportation between the lower and upper layers of the solar atmosphere. Our future research with my colleagues at SP2RC will now focus on this new puzzle. “