3-D Earth In The Making

A thorough understanding of the ‘solid Earth’ system is essential for deciphering the links between processes occurring deep inside Earth and those occurring nearer the surface that lead to seismic activity such as earthquakes and volcanic eruptions, the rise of mountains and the location of underground natural resources. Thanks to gravity and magnetic data from satellites along with seismology, scientists are on the way to modelling inner Earth in 3-D.

Solid Earth refers to the crust, mantle and core. Because these parts of our world are completely hidden from view, understanding what is going on deep below our feet can only be done by using indirect measurements.

New results, based on a paper published recently in Geophysical Journal International and presented at this week’s Living Planet Symposium, reveal how scientists are using a range of different measurements including satellite data along with seismological models to start producing a global 3-D Earth reference model.

The model will make a step change in being able to analyze Earth’s lithosphere, which is the rigid outer shell, and the underlying mantle to understand the link between Earth’s structure and the dynamic processes within.

Juan Carlos Afonso, from Australia’s Macquarie University and Norway’s Centre for Earth Evolution and Dynamics, said, “We are realising the new global model of Earth’s lithosphere and upper mantle by combining gravity anomalies, geoid height, and gravity gradients complemented with seismic, thermal, and rock information.”

Wolfgang Szwillus from Kiel University, added, “Data from ESA’s GOCE satellite mission served as input for the inversion. It is the first time that gravity gradients have been inverted on a global scale in such an integrated framework.”

While this is just a first step, 3-D Earth offers tantalizing insights into the deep structure of our world. For example, the new models of the thickness of the crust and the lithosphere are important for unexplored continents like Antarctica.

Jörg Ebbing from Kiel University, noted, “This is just a first step so we have more work to do, but we plan to release the 3-D Earth models in 2020.”

The 3-D Earth research, which involves scientists from nine institutes in six European countries, is funded through ESA’s Science for Society programme. ESA’s GOCE gravity mission and Swarm magnetic field mission are key to this research.

Bermuda Volcano Formed In a Way That Has Never Been Seen Anywhere Else On Earth

A volcano beneath Bermuda formed in a way that has never been seen before, scientists have discovered. The volcano appears to have been created by material rising up from a region deep beneath Earth’s surface—the transition zone.

The transition zone is the region between the upper and lower mantle. It extends between 250 and 400 miles beneath the surface of the planet and is rich in water, crystals and melted rock.

Volcanoes normally form when the tectonic plates are pushed together or pulled apart, producing a crack in Earth’s surface where magma can escape. They can also form at “hotspots,” where mantle plumes rise up and melt a hole in the plate—Hawaii is an example of this.

Now, researchers have found volcanoes can also form when material moves up from the transition zone. The team believes there was a disturbance in the transition zone that forced the material in this layer to melt and move up towards the surface. Their findings are published in the journal Nature.

The researchers were analyzing a now dormant volcano beneath the Atlantic Ocean that was responsible for the formation of Bermuda. They were looking at the chemical composition of a 2,600-foot core sample—by understanding its makeup they could build a picture of Bermuda’s volcanic history.

“Before our work, Bermuda has been interpreted as the result of a deep thermal anomaly in the Earth’s mantle, but there was no direct data to support this. This is due to the fact that the volcanic edifice is completely covered by limestone,” Cornell’s Esteban Gazel, one of the study authors, told Newsweek.

In a statement, he said they were expecting to show that the volcano was a mantle plume formation like Hawaii. This was not what they found, however. The measurements taken from the core sample were unlike anything seen before, suggesting the lava came from a previously unidentified source.

The samples contained signatures from the transition zone. Compared to samples taken from subduction zones, there was more water trapped in the crystals. The transition zone is known to contain vast quantities of water—one study calculated there is three times as much water in this region of Earth than is present in all the world’s oceans.

“I first suspected that Bermuda’s volcanic past was special as I sampled the core and noticed the diverse textures and mineralogy preserved in the different lava flows,” lead author Sarah Mazza, from the University of Münster, Germany, said in the statement. “We quickly confirmed extreme enrichments in trace element compositions. It was exciting going over our first results … the mysteries of Bermuda started to unfold.”

Numerical models developed by the team indicate a disturbance in the transition zone forced the material up. This is thought to have taken place about 30 million years ago and provided the foundation that Bermuda sits on today.

“We found a new way to make volcanoes,” Gazel said in the statement. “This is the first time we found a clear indication from the transition zone deep in the Earth’s mantle that volcanoes can form this way.”

The researchers believe there will be other examples of volcanoes being formed in this way. “With this work we can demonstrate that the Earth’s transition zone is an extreme chemical reservoir,” Gazel said. “We are just now beginning to recognize its importance in terms of global geodynamics and even volcanism.”

Speaking to Newsweek, he added: “I think many hotspot locations … are not deeply rooted to the core-mantle boundary probably have past similar to Bermuda’s.”

A Massive ‘Blob’ of Rock Stretching Under Asia Might Be Triggering Hundreds of Earthquakes

The Hindu Kush mountain range — which stretches about 500 miles (800 kilometers) along the border of Afghanistan and Pakistan — shudders with more than 100 earthquakes at a magnitude of 4.0 or greater every year. The area is one of the most seismically active spots in the world, especially for intermediate-depth quakes (tremors forming between 45 and 190 miles, or 70 and 300 km, below the planet’s surface). And yet, scientists aren’t sure why.

The mountains don’t sit on a major fault line, where high earthquake activity is expected, and the region is many miles away from the slow-motion crash zone where the Eurasian and Indian tectonic plates are steadily colliding. So, what’s the deal with this mountain earthquake epidemic?

A new study published April 17 in the journal Tectonics may have an answer to the mystery quakes of the Hindu Kush — and, like all great geologic mysteries, it involves blobs.

According to the study, the Hindu Kush mountains may owe their incredible seismic reputation to a long “blob” of rock slowly dripping away from the range’s subterranean underbelly and into the hot, viscous mantle below. Like a lone water droplet pulling away from the edge of a faucet, the 100-mile-deep (150 km) blob of mountain may be pulling away from the continental crust at a rate as fast as 4 inches (10 centimeters) per year — and this subterranean stress could be triggering earthquakes, the authors of the new study wrote.

The researchers discovered the troublesome blob after collecting several years’ worth of earthquake observations near the Hindu Kush mountains. They saw that the quakes formed in a pattern, creating what looked like a “round patch” of seismic activity on the planet’s surface, study co-author Rebecca Bendick, a geophysicist at the University of Montana in Missoula, told the website Eos.org. Those quakes also formed along a clear vertical axis, beginning between 100 and 140 miles (160 and 230 km) below the continent, and were most common deeper down, where the solid continental crust meets the hot, viscous upper mantle. Here, the researchers wrote, is where the slowly-stretching blob is strained the most.

All of these observations were consistent with a blob of solid rock slowly dripping into the gooey underworld below — a hypothesis that has previously been used to explain similar seismic activity underneath the Carpathian Mountains in central Europe. According to the researchers, the Hindu Kush blob likely began dripping no earlier than 10 million years ago, and continues to stretch downward nearly 10 times faster than the surface of the mountains move, as the Indian and Eurasian plates collide.

If accurate, these results may be more evidence that geophysical forces beyond just the subduction of tectonic plates can send earthquakes rattling through the planet.

Tsunami Alert Issued, 7.5 Quake Hits New Guinea

A powerful earthquake struck Papua New Guinea late Tuesday evening, triggering a tsunami alert for coastal areas up to 1,000 kilometers (620 miles) away.

The U.S. Geological Survey said the quake measured magnitude 7.5 and was located 45 kilometers (28 miles) northeast of Kokopo, a remote town with a population of about 26,000. It was centered at a relatively shallow depth of 10 kilometers (6 miles), it said.

Shallow earthquakes tend to cause more damage on the Earth’s surface, but the USGS estimated that damage and injuries would be low because of the area’s sparse population.

The U.S. Pacific Tsunami Warning Center said tsunami waves of up to 1 meter (3.3 feet) were possible along coastal areas up to 1,000 kilometers (620 miles) from the epicenter, including Papua New Guinea and the nearly Solomon Islands. It later said the tsunami threat had largely passed and no waves had been observed, but that there were no sea level gauges in the area for measurement.

It said there was no tsunami threat to Hawaii or Guam.

Papua New Guinea is located on the eastern half of the island of New Guinea, to the east of Indonesia.

It sits on the Pacific’s “Ring of Fire,” the arc of seismic faults around the Pacific Ocean where much of the world’s earthquakes and volcanic activity occurs.

A magnitude 7.5 earthquake in February 2018 in the nation’s central region killed at least 125 people and forced another 35,000 from their homes. That quake hit areas that are remote and undeveloped, and assessments about the scale of the damage and injuries were slow to filter out.

With Hurricane Season Approaching, Researchers Work To Better Predict Storm Intensity

Many residents in the southeast U.S. and along the Gulf Coast are already thinking about the 2019 Atlantic hurricane season, which begins on June 1. Last year brought two of the most destructive storms to ever hit the U.S.: Hurricane Florence and Hurricane Michael.

There have been dramatic improvements in hurricane forecasting over the past 20 years. The greatest progress has been made in forecasting a hurricane’s track, including where and when it will make landfall. But the harder challenge is predicting a storm’s intensity, especially for hurricanes like Michael that continue to strengthen as they approach the coast.

As the next hurricane season approaches, researchers are working on new tools to help forecast the intensity of forthcoming storms, enabling residents and emergency managers to be more prepared.

For Hurricane Michael, the National Hurricane Center began issuing advisories five days before it struck Florida’s panhandle, when it was just a disturbance moving toward the Gulf of Mexico. Two days later it was a hurricane, one that continued to strengthen.

No forecasts anticipated how powerful the storm would be at landfall, slamming into Mexico Beach, Fla., as a Category 5 hurricane. It’s one of only four storms that powerful ever to hit the U.S. mainland. “The intensity forecasts were too low,” says Eric Blake, a meteorologist with the National Hurricane Center in Miami. “They’re better than they would have been 20 years ago but still too low.”

Three days before Michael made landfall, it was just a tropical storm. Forecasters warned residents along Florida’s Gulf Coast to prepare for a possible Category 2 hurricane with 100 mile-per-hour winds. A day later, as Michael strengthened, the forecasts upgraded it to Category 3. But as Michael neared Florida’s panhandle, it kept getting stronger, taking even seasoned meteorologists by surprise when it came ashore as a Category 5, with 160 mile-per-hour winds and a 14-foot storm surge.

Blake says a more accurate forecast of Michael’s intensity would have helped emergency managers and residents make decisions about evacuating. “It would have gotten the message out earlier,” he says. “If we were saying right off the bat, ‘Here it is. We’re expecting … Category 4, Category 5,’ that’ll catch people’s attention.”

Researchers with the National Oceanic and Atmospheric Administration are working on the problem with improved hurricane models. One is the Hurricane Weather Research and Forecasting model. It uses data gathered from satellites and aircraft to better understand what’s going on inside a hurricane. It has been in operation for only about a decade but has improved every year.

Meteorologist Jason Sippel says that like other models, HWRF underestimated Hurricane Michael. But it got some key things right.

“From the very first forecast HWRF issued, it showed a rapidly intensifying major hurricane making landfall on the U.S. Gulf Coast,” he says. “So, you have to kind of keep things in perspective. Yes, the errors were large. But all those forecasts did show a major hurricane making landfall and were getting the warning out.”

Frank Marks, the director of NOAA’s Hurricane Research Division, has overseen HWRF’s development. Other countries have global weather forecast models that sometimes outperform the main U.S. model, known as GFS. But no other countries have a regional hurricane model like HWRF, which still needs to be improved.

But, Marks says, HWRF is already helping save lives. “The day before the storm hit, there were 250 people still on Mexico Beach. But by the next morning, the morning before when the storm made landfall, there were only 25. So the messaging got through.”

While researchers are making progress, efforts to improve NOAA’s hurricane models have had setbacks. Some involve science, but some are political. As they prepared for the upcoming hurricane season, researchers had to suspend work earlier this year for six weeks because of the partial government shutdown. Some are worried now about another possible government shutdown in October at the height of hurricane season.

Geomagnetic Storm Headed For Earth Could Mean Auroras Will Be Visible Over Parts Of U.S.

A geomagnetic storm warning has been issued following three coronal mass ejections (CME) from a giant sunspot. The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center said that a minor geomagnetic storm watch is in effect for May 15 and May 16.

As a result of the storm, northern parts of the U.S. may be able to see auroras over the next few nights. A forecast map showing where the auroras may be visible can be seen below.

CMEs come from our sun’s outer atmosphere. This is a region that has extremely strong magnetic fields. When these fields close, they can suddenly eject matter in a huge explosion—a CME. This matter—sometimes a billion tons of it—is ejected into space, impacting any object it comes across.

When a CME explodes in the direction of Earth, the solar material interacts with atoms and molecules in our atmosphere. The collisions produce auroras.

The three CMEs responsible for the latest geomagnetic storm came from the sunspot group Region 2741. The series started on May 10 and material from the first two is expected to arrive on May 15. The third will likely reach Earth on May 16.

“The source location for the CMEs has been associated with disappearing solar filaments (DSF) along areas of the magnetic neutral line in the vicinity of the unipolar sunspot group, Region 2741,” an NOAA statement said.

A solar filament is a long line of colder material that hovers above the sun’s corona. NASA notes that these filaments can float along like this for days before they disappear. “Sometimes they also erupt out into space, releasing solar material in a shower that either rains back down or escapes out into space, becoming a moving cloud known as a coronal mass ejection, or CME,” the space agency noted.

Sunspots are temporary regions on the surface of the sun that are darker and colder than the surrounding area—around 4,500 degrees Celsius cooler.

According to SpaceWeather, the sunspot that the latest three CMEs came from appears to be disintegrating and is no longer able to produce huge CMEs that pose a greater risk to Earth. When the sun does produce large explosions, a strong geomagnetic storm has the potential to cause disruption to GPS systems, satellites and power grids.

At the moment, the sun is in a period of quiet known as the solar minimum. The sun’s activity increases and decreases on an 11-year cycle. The solar maximum, when activity peaks, sees an increase in the number of sunspots. The next solar maximum is expected to peak around 2024.

6.1 Magnitude Earthquake In Panama Injures Two

A 6.1 magnitude earthquake rattled homes in southwest Panama on Sunday near the border with Costa Rica, damaging buildings and injuring at least two people, but there were no immediate reports of fatalities, authorities said. The quake struck some 4 miles southeast of Plaza de Caisán, Panama, at a depth of about 12 miles, the U.S. Geological Survey (USGS) reported.

Graphic shows large earthquake logo over broken earth and Richter scale reading

Panamanian authorities said there was no tsunami alert from the quake. Panama’s President Juan Carlos Varela said on Twitter that some shops and houses were damaged and that a woman was injured in the Panamanian port of Puerto Armuelles when the quake caused the ceiling of her home to cave in.

Puerto Armuelles is near the epicenter of the quake. A local police spokeswoman said some buildings were damaged, but there were no initial reports of fatalities.

Images posted on social media showed simple wooden homes that partially collapsed in rural areas, deep fissures in tightly packed beach sand and entire grocery store shelves that spilled containers of processed food and bottled beverages on the floor.

“I was in the supermarket and everything swayed,” Carla Chavez said by phone from David, the capital of Panama’s Chiriqui province near the quake’s epicenter. “Merchandise fell on the floor. Everything happened so fast.”

Panama’s National Civil Protection Service said via Twitter that walls cracked at a hospital and two supermarkets in Changuinola in Bocas del Toro province.

The USGS later pinpointed the epicenter of the quake as a few miles north of Paso Canoas in Costa Rica, right on the border with Panama. Local emergency services in Paso Canoas said they had no initial reports of damage or fatalities there.

Panama’s firefighting association said on Twitter it had received reports of the ground shaking from residents in different regions of the country, and urged calm.