Mars’ Oceans Formed Early, Possibly Aided By Massive Volcanic Eruptions

A new scenario seeking to explain how Mars’ putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million years earlier and were not as deep as once thought.

The proposal by geophysicists at the University of California, Berkeley, links the existence of oceans early in Mars history to the rise of the solar system’s largest volcanic system, Tharsis, and highlights the key role played by global warming in allowing liquid water to exist on Mars.

“Volcanoes may be important in creating the conditions for Mars to be wet,” said Michael Manga, a UC Berkeley professor of earth and planetary science and senior author of a paper appearing in Nature this week and posted online March 19.

Those claiming that Mars never had oceans of liquid water often point to the fact that estimates of the size of the oceans don’t jibe with estimates of how much water could be hidden today as permafrost underground and how much could have escaped into space. These are the main options, given that the polar ice caps don’t contain enough water to fill an ocean.

The new model proposes that the oceans formed before or at the same time as Mars’ largest volcanic feature, Tharsis, instead of after Tharsis formed 3.7 billion years ago. Because Tharsis was smaller at that time, it did not distort the planet as much as it did later, in particular the plains that cover most of the northern hemisphere and are the presumed ancient seabed. The absence of crustal deformation from Tharsis means the seas would have been shallower, holding about half the water of earlier estimates.

“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later,” Manga said. “We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”

It’s likely, he added, that Tharsis spewed gases into the atmosphere that created a global warming or greenhouse effect that allowed liquid water to exist on the planet, and also that volcanic eruptions created channels that allowed underground water to reach the surface and fill the northern plains.

Following the shorelines

The model also counters another argument against oceans: that the proposed shorelines are very irregular, varying in height by as much as a kilometer, when they should be level, like shorelines on Earth.

This irregularity could be explained if the first ocean, called Arabia, started forming about 4 billion years ago and existed, if intermittently, during as much as the first 20 percent of Tharsis’s growth. The growing volcano would have depressed the land and deformed the shoreline over time, which could explain the irregular heights of the Arabia shoreline.

Similarly, the irregular shoreline of a subsequent ocean, called Deuteronilus, could be explained if it formed during the last 17 percent of Tharsis’s growth, about 3.6 billion years ago.

“These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards,” said first author Robert Citron, a UC Berkeley graduate student. Citron will present a paper about the new analysis on March 20 at the annual Lunar and Planetary Science conference in Texas.

Tharsis, now a 5,000-kilometer-wide eruptive complex, contains some of the biggest volcanoes in the solar system and dominates the topography of Mars. Earth, twice the diameter and 10 times more massive than Mars, has no equivalent dominating feature. Tharsis’s bulk creates a bulge on the opposite side of the planet and a depression halfway between. This explains why estimates of the volume of water the northern plains could hold based on today’s topography are twice what the new study estimates based on the topography 4 billion years ago.

New hypothesis supplants old

Manga, who models the internal heat flow of Mars, such as the rising plumes of molten rock that erupt into volcanoes at the surface, tried to explain the irregular shorelines of the plains of Mars 11 years ago with another theory. He and former graduate student Taylor Perron suggested that Tharsis, which was then thought to have originated at far northern latitudes, was so massive that it caused the spin axis of Mars to move several thousand miles south, throwing off the shorelines.

Since then, however, others have shown that Tharsis originated only about 20 degrees above the equator, nixing that theory. But Manga and Citron came up with another idea, that the shorelines could have been etched as Tharsis was growing, not afterward. The new theory also can account for the cutting of valley networks by flowing water at around the same time.

“This is a hypothesis,” Manga emphasized. “But scientists can do more precise dating of Tharsis and the shorelines to see if it holds up.”

NASA’s next Mars lander, the InSight mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), could help answer the question. Scheduled for launch in May, it will place a seismometer on the surface to probe the interior and perhaps find frozen remnants of that ancient ocean, or even liquid water.

Large Storm System To Bring Severe Weather To South; East Coast Expecting Snow Soon

A large storm system is moving through the Great Plains on Monday morning bringing unsettled weather from the Dakotas all the way to the southeastern United States.

Yesterday, more than three dozen damaging storm reports were made, most of them in east-central Texas where hail was larger than a baseball. There were also two reported tornadoes in the Texas panhandle and winds of 60 mph or greater in eastern Texas.

On the northern side of the storm, heavy snow fell around Denver, with anywhere from 5 to 10 inches overnight in the metro area.

The storm system is moving east Monday, and is now stretching from the Northern Plains to the Gulf Coast. To the north, snow is falling in the Dakotas while tornado warnings have been issued for part of the Florida panhandle.

The storm system will move further east Monday afternoon, and will pick up moisture from the Gulf of Mexico. Severe storms will break out from Jacksonville, Florida, to Atlanta; Birmingham, Alabama; and into Nashville, Tennessee.

The biggest threat will be huge damaging hail, tornadoes and wind. Flash flooding is also possible.

The biggest threat for tornadoes will be from Nashville to Birmingham and just west of Atlanta this afternoon and evening.

Developing in the East

As the storm moves east on Tuesday, a coastal low will try to develop in the southern Mid-Atlantic states producing a first wave of rain and snow from Washington, D.C. north into Pennsylvania and west into West Virginia. Several inches of snow is possible just west of Washington, D.C.

By Tuesday night into Wednesday, as the coastal low strengthens, it will produce a second wave of rain and snow, spreading along the I-95 corridor from Washington, D.C. into New York City and Boston.

Models are still not very confident where the low will form and how much snow or rain will fall in the heavily populated I-95 corridor. If major cities get precipitation, it would be mostly be on Wednesday.

The American model isn’t showing much snow for the major cities — maybe a dusting to 1 to 2 inches on Wednesday.

The European model has a different forecast with heavy snow accumulations for the major Northeast cities, but ABC News meteorologists predict the model is probably overdoing these amounts.

The short-term American model is showing the storm missing Washington, D.C., Philadelphia and New York City, with maybe some snow accumulations along the Mid-Atlantic coast and into Cape Cod.

It could go either way, but confidence is growing that some sort of storm system will form along the East Coast.

Volcano Watch: Kilauea Volcano’s Summit Eruption Is Now A Decade Old

A little more than 10 years ago, conditions around Kilauea Volcano’s summit were much different than today. The caldera floor was open to the public, and the air above it was normally clear. Halema‘uma‘u was an impressive sight, but peacefully in repose.

That quiet phase at Kilauea’s summit ended abruptly in 2008, ushering in a new era of lava lake activity that continues today.

Let’s review the past decade of this summit eruption.

After several months of increased seismic tremor and gas emissions, there was a small explosion in Halema‘uma‘u on March 19, 2008. The explosion marked the opening of a new crater, informally called the “Overlook crater.” During the remainder of 2008, several more explosions deposited spatter around Halema‘uma‘u, and the Overlook crater enlarged through collapses of its rim.

During 2009, small lava lakes were sometimes active deep within the Overlook crater. But since early 2010, the lava lake has been continuously present, steadily growing and rising higher.

The rise was interrupted March 5, 2011, when the lava lake briefly drained away because of the Kamoamoa eruption on Kilauea’s East Rift Zone.

The lava lake stabilized in 2012, rose to a higher level in 2013 and remained stable in 2014 and early 2015. In April 2015, the lava lake rose abruptly and briefly overflowed, spilling lava onto the floor of Halema‘uma‘u. High lake levels in 2016 allowed lava to be frequently observed from public viewing areas in Hawaii Volcanoes National Park, but a gradual drop in 2017 has made direct viewing of the lake less common during the past year.

The lava lake activity in 2018 is similar to that during the previous several years — relatively steady — and there are no signs that the summit eruption is slowing down.

Halema‘uma‘u now hosts one of the two largest lava lakes on Earth. It is likely the largest, but this cannot be said with complete certainty, as regular measurements are not available from the closest contender — Nyiragongo volcano in the Democratic Republic of the Congo.

Most persistent lava lakes are difficult to access, either because of geographic location (for example, Erebus in Antarctica) or political instability (for example, Nyiragongo). The size and accessibility of the Halema‘uma‘u lava lake, as well as the existing network of monitoring instruments, make it one of the premier locations to study lava lake behavior.

USGS Hawaiian Volcano Observatory scientists, along with collaborators from other institutions, are engaged in research to understand how the lava lake works and what it can tell us about the behavior and hazards of Kilauea.

For instance, we learned that the lake rises and falls in concert with changes in summit ground tilt. This tells us that the lake responds to the pressure of the magma chamber, so the lake level can be used like a pressure gauge.

The lake also fluctuates in concert with the lava pond at Pu‘u ‘O‘o on Kilauea’s East Rift Zone, illustrating the hydraulic connection between the two eruption sites. Lava chemistry at the two sites also is similar, adding further evidence of a close connection.

Another important finding deals with the nature of small explosions that occur at the lava lake from time to time.

HVO webcams revealed that the explosions are triggered by rockfalls from the Overlook crater rim impacting the lake surface. This observation is further evidence that the lava lake is very gassy, akin to lava foam. Rocks falling into this gas-rich, frothy lava triggers violent releases of gas that send spatter flying.

While the summit eruption has benefited science, it comes with many challenges, including persistent volcanic air pollution (vog) resulting from elevated sulfur dioxide gas emissions from the lava lake. Vog impacts the entire state at times, but the Ka‘u and Kona districts on the Island of Hawaii have been particularly hard hit.

Kilauea has a history of long-lasting summit eruptions, but it remains to be seen if the current eruption will go on for another decade. The past few years of stable activity suggest the summit lava lake is likely to continue into the near future.

However long it lasts, HVO will continue to study this awe-inspiring, unique feature to discover what more it can reveal about the volcano.

Volcano activity updates

This past week, Kilauea Volcano’s summit lava lake level fluctuated with summit inflation and deflation, ranging about 30.5-40.5 m (100-133 ft) below the vent rim. On the East Rift Zone, the 61g lava flow remained active downslope of Pu‘u ‘O‘o, with scattered breakouts on the upper part of the flow field and on Pulama pali, but no ocean entry. The 61g flows do not pose an immediate threat to nearby communities.

Mauna Loa is not erupting. Rates of deformation and seismicity have not changed significantly in the past week, persisting at above-long-term background levels. Sixteen microearthquakes (magnitudes less than 2) were located beneath the summit caldera, upper Southwest Rift Zone and western flank of the volcano at depths of 0-5 km (0-3 mi). GPS and InSAR measurements continue to show slow deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone. No significant changes in volcanic gas emissions were measured.

No earthquakes were reported felt in the Hawaiian Islands this past week.

Volcanic Activity Threatens Families Again On Ambae Island In Vanuatu

Volcanic activity on Vanuatu’s Ambae Island has picked up again over the last few days, with fresh ash fall reported across the island’s west and south.

Communities in the western and southern parts of Ambae are suffering badly from thick periodic ash fall which threaten their health, animals and vegetation.

The entire island was evacuated late last year when the volcano at the island’s centre erupted, blanketing the island in ash, suffocating crops and contaminating water sources.

The only population returned to their homes when the eruption settled down after a month, but on Sunday night the volcano’s alert level was raised from level 2 to 3, a “state of minor eruption.”

The Geohazards Department’s Melinda Aru said the volcano was showing increased activity and an exclusion zone had been extended to three km around the crater lake.

“We’ve got a few reports coming from Ambae concerning ash fall on the west, southwest and northwest as of last week until Sunday. We still have reports from Ambae concerning ash fall.”

Melinda Aru said the chance of the eruption increasing to the level seen in October last year was highly unlikely.

Reports on the Vanuatu Daily Post website on Monday said that people may need to shelter livestock and water tanks as the Lombenben volcano continues to emit ash.

The Vanuatu Meteorology and Geo-hazards Department still grades the Ambae volcano at major unrest stage.

Destruction caused by the ash fall in affected areas is described as literally similar to a cyclone wiping out trees and crops.

Its weight caused plants and crops in the gardens like banana, cassava and cabbages to collapse.

Destruction done by volcanic ash on people, plants and crops depend largely on its thickness. Though it may causes health problems to livestock and human such as skin irritation and eye problem, volcanic ash can make the soil fertile.

Responsible authorities have warned that everyone, particularly children should be protected from the volcano’s ash and poisonous gases that poses a health risk.

The Vanuatu Red Cross Society (RCS) said it was working to establish a sub-branch in west Ambae to support communities during disasters.

Madagascar Hit By Another Tropical Cyclone

Tropical Cyclone Eliakim has battered Madagascar with strong winds and torrential rain.

The storm made landfall on the peninsula of Masoala in northeastern Madagascar and tracked southwards along the coast.

Strong winds battered the island and torrential rain fell on already-saturated land, triggering landslides and flooding.

The cyclone comes less than two weeks after Dumazile grazed the east coast of the island nation.

Both storms hit Toamasina, Madagascar’s second largest city. Images on social media showed widespread flooding with roads and homes inundated.

According to local media, at least one person has been killed by Eliakim and many more have been injured.

The storm is now weakening as it moves southeast, away from Madagascar.

Rare Metals On Mars And Earth Implicate Colossal Impacts

New research has revealed that a giant impact on Mars more than four billion years ago would explain the unusual amount of “iron loving” elements in the Red Planet.

Planets form as small dust grains stick together and agglomerate with other grains, leading to bigger bodies termed “planetesimals.” These planetesimals continue to collide with each other and are either ejected from the solar system, gobbled up by the sun, or form a planet. This is not the end of the story, as planets continue to accrete material well after they have formed. This process is known as late accretion, and it occurs as leftover fragments of planet formation rain down on the young planets.

Planetary scientist Ramon Brasser of the Tokyo Institute of Technology and geologist Stephen Mojzsis of the University of Colorado, Boulder took a closer look at a colossal impact during Mars’ late accretion that could explain the unusual amount of rare metallic elements in Mars’ mantle, which is the layer below the planet’s crust. Their recently published paper, “A colossal impact enriched Mars’ mantle with noble metals,” appeared in the journal Geophysical Research Letters.

When proto-planets accrete enough material, metals such as iron and nickel begin to separate and sink to form the core. This explains why Earth’s core is mainly composed of iron, and it is expected that elements that readily bond with iron should also mainly exist in the core. Examples of such ‘iron loving’ elements, known as siderophiles, are gold, platinum and iridium, to name a few. Just like Mars, however, there are more siderophiles in the Earth’s mantle than would be expected by the process of core formation.

“High pressure experiments indicate that these metals should not be in the mantle. These metals don’t like being dissolved in silicate and instead they prefer to sink through the mantle into the Earth’s core,” Brasser tells Astrobiology Magazine. “The fact that we do have them at all means that they must have arrived after the core and the mantle separated, when it became much more difficult for these metals to reach the core.”

A 2016 paper by Brasser and colleagues conclusively showed that a giant impact is the best explanation for Earth’s high siderophile element abundance.

The amount of siderophiles accumulated during late accretion should be proportional to the ‘gravitational cross section’ of the planet. This cross section is effectively the cross hairs that an impactor ‘sees’ as it approaches a target planet. The gravitational cross section extends beyond the planet itself, as the world’s gravity will direct an object towards it even when the object was not on a direct collision course. This process is called gravitational focusing.

The earlier paper showed that Earth has more siderophiles in the mantle than it should, even according to the gravitational cross section theory. The scientists explained this by showing that an impact of a lunar-sized body on the Earth (in addition to the event that formed the moon) would have enriched the mantle with enough siderophiles to explain the current value.

An early giant impact

Analysis of Martian meteorites show that Mars accreted another 0.8 percent by mass (weight percent, or wt percent) of material via late accretion. In the new paper, Brasser and Mojzsis show that for Mars to have amended its mass by about 0.8 wt percent in a single impact event required a body at least 1,200 kilometers in diameter.

They further argue that such an impact ought to have occurred some time between 4.5 and 4.4 billion years ago. Studies of zircon crystals in ancient Martian meteorites can be used to date the formation of the Martian crust to before 4.4 billion years ago. As such, a giant impact should have caused widespread crustal melting and such a catastrophic event must have occurred before the evidence for the oldest crust. If the impact occurred as early in the planet’s history as 4.5 billion years ago, then the siderophiles should have been stripped away during core formation. This history provides firm bookend constraints on when the impact happened.

Understanding late accretion is not just important for explaining the siderophile abundance, but also for placing an upper limit on the age of Earth’s biosphere.

“During each impact, a small bit of Earth’s crust is locally melted,” says Brasser. “When the accretion is very intense, almost all of Earth’s crust is molten. As the accretion intensity decreases, the amount of crustal melting also decreases. We argue that the earliest time you could form a biosphere is when the accretion is low enough so that less than 50 percent of the crust is molten at any given time.”

The surface of Mars also has an unusual dichotomy, which could be explained by a giant impact. The southern hemisphere exists as an ancient cratered terrain, and the northern hemisphere appears younger and smoother and was influenced by extensive volcanism. A giant impact might also have created the Martian moons, Deimos and Phobos, although an alternative theory is that the highly porous Phobos could be a captured asteroid.

Scientists Helping To Improve Understanding Of Plate Tectonics

Scientists at The Australian National University (ANU) are helping to improve understanding of how rocks in Earth’s hot, deep interior enable the motions of tectonic plates, which regulate the water cycle that is critical for a habitable planet.

Research team leader Professor Ian Jackson said tectonic plates were continuously created at mid-ocean ridges and destroyed when they sink back into the Earth’s mantle.

“Plate tectonics is responsible for diverse geological phenomena including continental drift, mountain building and the occurrence of volcanoes and earthquakes,” said Professor Jackson from the ANU Research School of Earth Sciences.

The stirring of the Earth’s interior, which is responsible for the plate motions at the surface, has resulted in the Earth’s gradual cooling over its 4.5 billion-year life.

He said defects allowed the normally strong and hard minerals of the Earth’s deep interior to change their shape and flow like viscous fluid on geological timescales.

“We have found that flaws in the regular atomic packing in the dominant upper-mantle mineral, called olivine, that become more prevalent under oxidising conditions, substantially reduce the speeds of seismic waves,” Professor Jackson said.

Seismic waves, caused by earthquakes, are used to image the Earth’s deep interior in a manner similar to medical CAT scanning.

“Our new findings challenge a long-held theory that defects involving water absorption in these normally dry rocks could control both their viscosity and seismic properties,” Professor Jackson said.

ANU Research School of Earth Sciences (RSES) PhD scholar Chris Cline is the lead author of the study undertaken in collaboration with RSES colleagues and Professor Ulrich Faul at the Massachusetts Institute of Technology in the United States.

The team used specialised equipment in a laboratory at ANU to make synthetic specimens similar to upper mantle rocks and measured their rigidity, which controls seismic wave speeds, under conditions simulating those of the Earth’s mantle.

Professor Jackson said the research was particularly relevant to environments where old, cold, and oxidised tectonic plates sink into the Earth’s hot interior.

“We have the potential to help map the extent of oxidised regions of the Earth’s mantle that play such an important role in the chemical evolution of Earth,” he said.