Tag Archives: geology

Update on Hawaiian lava eruption

Link here. This news article is particularly informative, as it includes a map that outlines the extent of the lava flows and what they have engulfed, including the most recent flows that are threatening a geothermal power plant that has been providing the Big Island about 25% of its power.

“Lava flow from Fissures 7 and 21 crossed into PGV [Puna Geothermal Venture] property overnight and has now covered one well that was successfully plugged,” declared the Hawaii Civil Defense Agency in a statement released on Sunday, May 27 at 6:00 pm local time. “That well, along with a second well 100 feet [30 meters] away, are stable and secured, and are being monitored. Also due to preventative measures, neither well is expected to release any hydrogen sulfide.”

Those preventive measures included a complete shutdown of the geothermal plant, the capping of all 11 wells, and the removal of some 60,000 gallons of flammable liquid. Those precautions aside, this is the first time in history—as far as we know—that lava has ever engulfed a geothermal power plant, so it’s all uncharted territory. There’s fear that a rupture of the wells could set off an explosion, releasing hydrogen sulfide and other dangerous gasses into the environment. As of this posting, the lava flows on the PGV grounds have stopped moving.

Environmentalists often promote geothermal power as an alternative to fossil fuels. Environmentalists also sued to prevent this plant from being built because of its proximity to the volcano.

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Chaos on Mars

chaos terrain

Cool image time! The image on the right, cropped and reduced in resolution to post here, shows an area on Mars that geologists have dubbed “Chaos Terrain.” If you click on the image you can see the full image, which also includes several canyons oriented in what seem to be random directions.

I first heard this geological term for regions on Mars shortly after the first orbital missions circling Mars began taking images back in the 1970s. It applied to places where the terrain was hummocky, a crazy collection of hills forming no pattern at all. Earth does not really have such terrain.

The close-up to the right also shows that at least one of these hills is fractured, made up of several large pieces that have separated over time.

This image was part of the May 2nd image release from the high resolution camera on Mars Reconnaissance Orbiter. What makes it interesting is its location on Mars. The image below shows that location, indicated by a white cross.
» Read more

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Big earthquake in South Korea linked to geothermal power plant

South Korea’s second largest earthquake has now been linked by two different studies to the injection of water deep below the surface at a new geothermal power plant.

Perched on South Korea’s southeast coast and far from grinding tectonic plates, Pohang is an unlikely spot for a big earthquake. Before the geothermal plant’s two wells were drilled, there had never been an earthquake there of any significance, says Kwanghee Kim, a seismologist at Pusan National University in Busan, South Korea, and lead author of one study. But while Kim was monitoring the aftermath of an unrelated earthquake in 2016, he began to detect rumbles from Pohang. That prompted his lab to deploy eight temporary seismic sensors at the site, which were finally in place on 10 November 2017. He expected any quakes to be small—after all, the largest previous quake tied to enhanced geothermal power, in Basel, Switzerland, was just 3.4 in magnitude.

It took only 5 days to be proved wrong. “The Pohang earthquake was larger than any predicted by existing theories,” Kim says. Although some initial measures placed the source of the quake several kilometers away from the plant, Kim’s network revealed that the earthquake, and several of its foreshocks, all began right below the 4-kilometer-deep well used to inject water into the subsurface to create the plant’s heating reservoir. Indeed, it appears likely that the well’s high-pressure water lubricated an unknown fault in the rock, causing it to slip and triggering the quake, Kim says.

A second paper, by European scientists who used regional seismic data, reinforces the South Korean team’s results, in particular its shallow depth. That study also points out that an earlier 3.1-magnitude earthquake also took place near the well bottom, increasing the odds of a common source. Satellite measures of shifts in the surface after the November 2017 quake support that idea, says Stefan Wiemer, the second study’s lead author and director of the Swiss Seismological Service in Zurich. It’s clear the locked fault was storing energy that was waiting to be released, Wiemer says. “If that fault would have gone next Tuesday or 50 years from now, we’ll never know.”

The article notes that scientists had previously concluded that injecting water underground for geothermal purposes was okay (since it reduced use of fossil fuels) while doing the same for fracking (to obtain and use fossil fuels) was bad.. The data here actually suggests just the reverse, since fracking has never produced an earthquake as large as the 5.5 magnitude Pohang quake.

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Zooming in on a Martian surprise

Global map of Mars

Let’s take a journey. Above is a global map of Mars, showing its largest and well known geological features. While far smaller than Earth, its lack of oceans means that Mars’ actual dry surface has about the same square footage as the continents of Earth. It is a vast place. Getting a close look at every spot is going to take many decades of work, and probably won’t be finished until humans are actually walking its surface.

Let’s pick a spot, zoom in and find out what’s there.
» Read more

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Is it a volcano or an impact crater? Mars Express wants to know!

Europe’s Mars Express orbiter has taken a high resolution image of Ismenia Patera, a very large crater located in the Arabia Terra region of Mars, the largest part of the transition zone between the low flat northern plains and the high rough southern terrain.

The crater is intriguing to scientists because they are not sure if it was created by an impact, or a volcano.

Certain properties of the surface features seen in Arabia Terra suggest a volcanic origin: for example, their irregular shapes, low topographic relief, their relatively uplifted rims and apparent lack of ejected material that would usually be present around an impact crater.

However, some of these features and irregular shapes could also be present in impact craters that have simply evolved and interacted with their environment in particular ways over time.

There is also additional evidence that this region was once home to volcanic activity. If so, that activity would have changed the terrain, and thus made its geological history more complex and difficult to decipher, a fact that is important since this is also a region that might have been at the edge of theorized northern Martian Ocean.

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A Martian snake of collapsed hills

A Martian snake of collapsed hills

Close-up of collapsed hills

Time to once again delve into this month’s release of high resolution images from Mars Reconnaissance Orbiter. The image above, cropped, rotated, and reduced in resolution to post here, shows a string of strange mounds or hills, each with similar collapse features on their tops. If you click on the picture, you can see the full resolution image, rotated properly with north up. You can also go to the MRO post, which provides some additional information.

The white box indicates the location of the cropped close-up, at full resolution, to the right. This area is typical across the entire snake-like ridge. You have these mounds or hills, each with chaotic depressions at their tops. The depressions suggest that this ridge follows an underground void, like a lava tube. The ridge-like nature of the line of hills also suggest that this tube has been exposed by erosion over time, with the surrounding terrain more easily blown or washed away while the more resistant ridge remains.

At the same time, the line of hills is baffling. Why would a lava tube expand periodically to form something that looks like a string of pearls?

The location of this snaking ridge provides some additional context.
» Read more

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A spray of volcanic ejecta on Mars?

pit features on floor of crater

Time for some more weird Mars geology! Today the science team for the high resolution camera on Mars Reconnaissance Orbiter released its monthly batch of new images. There is a lot of interesting stuff buried therein, some of which I will feature periodically in the next month.

The image on the right, reduced in resolution to post here, is a good example. (If you click on the image you can see the full resolution version.) It shows a scattering of pits in three specific areas on the crater floor, all in a line going from the northeast to the southwest. Yet, the rest of the crater floor lacks similar pits, and is either very smooth or has a mottled appearance. Both the smooth and the mottled areas appear to have a very faint trend going from the northwest to the southeast, which to my eye appears caused by the general wind direction that flows across the crater floor.

Even more intriguing, the pits in these three areas appear to be mostly oblong and also trend from the northeast to the southwest, cutting across the general trend of the rest of the crater floor. You can see this in the cropped closeups from the full resolution image below, showing the two boxed areas indicated on the image on the right.
» Read more

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Near the Martian shoreline

One of the prime areas of research for Mars planetary geologists is the region on Mars where the geography appears to transition from the southern cratered, rough terrain to the northern low, generally smooth, and flat plains. It is theorized by some scientists that the northern plains were once an ocean, probably shallow and probably intermittent, but wet nonetheless for considerable periods. The global map of Mars below, created by the laser altimeter on Mars Global Surveyor, clearly shows the obvious elevation differences between the low northern plans (blue) and the high, more cratered southern regions (changing from yellow to orange as you move higher).

Labeled global Map of Mars

Scientists have spent a considerable effort studying this transition zone (green on the map), illustrated by just one example I recently highlighted, showing that, though there does not appear to be a clear shoreline in many places, there is strong evidence that a shallow ocean repeatedly rose and fell in this transition zone, leaving behind geological ripple marks vaguely reminiscent of those seen on a beach caused by the rise and fall of the tides.

Today we highlight another example, taken in January 2018 at the location indicated by the cross on the above map.
» Read more

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New theory suggests Mars’ oceans formed earlier and intermittently

Scientists have proposed a new model for the existence of oceans on Mars’ northern plains that proposes they formed earlier, were shallower, were variable in size, and formed in conjunction with the eruptions that formed the planet’s giant volcanoes.

The proposal by UC Berkeley geophysicists 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.

…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.”

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Dawn finds recent changes on Ceres

New data from Dawn has found at least one spot on Ceres where recent changes appear to have occurred on the surface.

Observations obtained by the visible and infrared mapping spectrometer (VIR) on the Dawn spacecraft previously found water ice in a dozen sites on Ceres. The new study revealed the abundance of ice on the northern wall of Juling Crater, a crater 12 miles (20 kilometers) in diameter. The new observations, conducted from April through October 2016, show an increase in the amount of ice on the crater wall. “This is the first direct detection of change on the surface of Ceres,” said Andrea Raponi of the Institute of Astrophysics and Planetary Science in Rome.

Raponi led the new study, which found changes in the amount of ice exposed on the dwarf planet. “The combination of Ceres moving closer to the sun in its orbit, along with seasonal change, triggers the release of water vapor from the subsurface, which then condenses on the cold crater wall. This causes an increase in the amount of exposed ice. The warming might also cause landslides on the crater walls that expose fresh ice patches.”

There is a certain irony here. For eons, the only alien body that humans were able to get a good look at, the Moon, was also an object where almost nothing changed. Even today, after humans have visited its surface and numerous orbiting spacecraft have photographed its surface in numbing detail, the Moon has generally been found to be stable and unchanging. Though impacts do occur, and the surface does evolve over time, the Moon is probably one of the most static bodies in the solar system.

The irony is that this lunar stability gave us an incorrect impression of the rest of the solar system. Based on the Moon, it was assumed that airless or almost airless bodies like Mercury, Mars, Pluto, the large moons of Jupiter and Saturn, and asteroids like Ceres would also be stable and unchanging. What we have instead found is that the Moon is the exception that proves the rule. Most of these other worlds are unlike the Moon. They show a lot of surface evolution, over relatively short time scales. They change.

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More weird Mars geology

Low resolution of full image of crater

Cool image time! Yesterday the Mars Reconnaissance Orbiter team released 460 images taken by the spacecraft’s high resolution camera, HiRISE, as part of their normal and routine image release program. Obsessed with space exploration as I am, I like to scan through these new images to see if there is anything interesting hidden there that will show up eventually in a press release. For example, the first image in this release is a look at Vera Rubin Ridge and Curiosity. I would not be surprised if there is a press release soon using this image, probably aimed at outlining the rover’s future route up Mount Sharp. (The present overview traverse map is getting out of date.)

Sometimes however I find images that might never get a press release but probably deserve it. The image on the right, reduced in resolution to show here, is one such example. It is a strip taken from rim to rim across an unnamed crater located in the mid-northern latitudes of Mars, west of Olympus Mons. A review of past images by other Mars orbiters/probes suggests that no good high resolution image of this crater had ever been taken before.

If you click on the image on the right, or go to the actual image site, you can see the original in full resolution. It is definitely worthwhile doing this, because the strip shows some strange and inexplicable geology on the floor of the crater as well in its confusing central peak region. Numerous features appear to have been exposed by later erosion. The many small craters for example are I think what planetary geologists call pedestal craters. The surrounding terrain is less erosion-resistant, so as that terrain erodes away it leaves the crater behind, with its floor actually sitting higher than the surrounding flats.

What makes these craters even weirder however is that their rims appear to have eroded away even more than the surrounding terrain, so that all of these small craters (assuming that is what they are) have ringlike depressions surrounding a circular platform.

In the crater’s central peak region the terrain is even more strange. Sticking up out of the ground are some arched short ridgelines, which appear to have been exposed by erosion. That peak area however also has many strange flow features that I find completely baffling. It almost appears to me that as the molten peak area started to solidify after impact, someone went in with a stirring spoon and did some mixing!

The map below the fold provides the location context for this crater, with the crater’s location indicated by the arrow.
» Read more

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Weird Martian geology: Kaiser Crater

Kaiser Crater bedrock

Cool image time! This week JPL’s image site highlighted a picture taken by Mars Odyssey of the floor and dunes inside Kaiser Crater, located to the west of Helles basin in an area dubbed the Noachis Region.

To my eye, the Mars Odyssey picture was interesting, but not worth a post here on Behind the Black. However, I decided to take a look at what HiRise, the high resolution camera of Mars Reconnaissance Orbiter (MRO), had taken of the same area, just out of curiosity. A search at the master HiRise image site at the same latitude and longitude (-45 latitude, 180 longitude) showed that HiRise had imaged a part of the same area, but at much higher resolution.

When I zoomed in on this hi resolution image I came across some interesting and weird geology, cropped to show here on the right. Now this, I thought, is worth posting. Notice how the dark tracks, caused by dust devils, leave no tracks as they cut across the brighter areas. Obviously, these bright areas have no dust or sand, and are likely solid bedrock of some kind. The depressions might be craters, but they also might not. The raised area around the depressions might have been caused by the impact, or it might have been caused by some internal geological process that caused the depression while also raising the surrounding bulge. Since then the wind has been steadily depositing sand in the depressions, causing it to get trapped there.

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A spectacular collapse feature at Arsia Mons

Collapse at Arsia Mons

Cool image time! This post could be called an update to my January 8th post, Exploring Arsia Mons. In that post I had compiled together the ten images of Arsia Mons, the southernmost volcano in the line of three giant volcanoes on Mars, that JPL had highlighted over several weeks in early January.

Today, I decided to do some of my own exploration of some of the many images taken of Arsia Mons by all of the Martian orbiters. My goal had been to explore the volcano’s western slopes (an area that had not been featured in the JPL releases) because that is the area where research has found evidence of past glacial activity as well as seasonal water clouds. I haven’t finished that survey, but in the process I came across a spectacular image of a collapse that had been visible in image nine of the January 8th post, but did not stand out there because of the lighting. The image on the right is that better image, cropped to focus in on the collapse itself.

The material at the base of the wall resembles piled up mud, which suggests this collapse is a Martian version of a mud slide. If so, it also suggests the presence of liquid. At the same time, the muddy look might not be from liquid but because of the lighter Martian gravity causing avalanches to be appear different there. The light gravity means material is not as dense, so when it collapses it might break apart more easily into a sandy type flow.

I am only an amateur geologist, so my theories here should not be taken very seriously. Nonetheless, I am sure there are planetary geologists who have looked at this closely because of the information about Martian geology that they can glean from it. I’d be curious to hear their thoughts.

Meanwhile, my exploration of the western slopes of Arsia Mons will continue. In Pioneer the science fiction book I wrote in the early 1980s (now available), I placed my Martian colony in Mangala Valles, a meandering canyon to the west of Olympus Mons that feeds out from the higher southern regions into the lower northern flat plains where even then some scientists thought an ocean might have once existed. My thinking then was that this might be a good location to find underground water. It now appears, with our greater knowledge, that the slopes of the volcanoes themselves might be more promising, and I am curious to find the most likely places in this region where a future colony might end up.

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Exploring Arsia Mons

Master index

In November over a period of two weeks the Mars Odyssey team posted ten images of Pavonis Mons, the smallest of the aligned three giant volcanoes just to the east of Olympus Mons, the largest known volcano in the solar system. I then made all of those images available in a single link, with some analysis.

They have now done the same thing for the southernmost (and possibly the most interesting) of those three aligned volcanoes, Arsia Mons. From the first image below:

Arsia Mons is the southernmost of the Tharsis volcanoes. It is 270 miles (450km) in diameter, almost 12 miles (20km) high, and the summit caldera is 72 miles (120km) wide. For comparison, the largest volcano on Earth is Mauna Loa. From its base on the sea floor, Mauna Loa measures only 6.3 miles high and 75 miles in diameter. A large volcanic crater known as a caldera is located at the summit of all of the Tharsis volcanoes. These calderas are produced by massive volcanic explosions and collapse. The Arsia Mons summit caldera is larger than many volcanoes on Earth.

In other words, you could fit almost all of Mauna Loa entirely within the caldera of Arsia Mons.

The image on the right above is the master index, annotated by me to show the area covered by each image. The images can accessed individually below.
» Read more

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Faults on Mars

Faults on Mars

Cool image time! The Mars Reconnaissance Orbiter (MRO) image on the right, reduced in resolution to post here, captures a distinctive fault line that cuts across some layered deposits. As noted by the MRO science team,

Some of the faults produced a clean break along the layers, displacing and offsetting individual beds (yellow arrow).

Interestingly, the layers continue across the fault and appear stretched out (green arrow). These observations suggest that some of the faulting occurred while the layered deposits were still soft and could undergo deformation, whereas other faults formed later when the layers must have been solidified and produced a clean break.

Meridiani Planum

These layers are located in Meridiani Planum, a relatively flat area on the Martian equator. Opportunity landed on this plain to the southwest of this region, as shown on the geology map to the left. The white cross in the southwest corner indicates Opportunity’s landing site, with Endeavour Crater just to the southeast. The white box in the northwest shows where the faulted layered deposits are located. Based on the scale of the map, this places Opportunity approximately 400 miles away.

What exactly caused these distinct faults remains unknown. The likely cause would be a earthquake, but since Mars does not have plate tectonics like the Earth, earthquakes would have to be caused by other geological processes not yet studied.

To my eye, they look like cracks in a mirror, though this provides no real explanation other than it illustrates how cool the image is.

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Squiggles on Mars

Squiggles on Mars

Cool image time! The image on the right, reduced and cropped to post here, shows a sand dune slope with numerous squiggly troughs that end either in a small pit or slowly fade away. At first glance one things the troughs were caused by a boulder rolling downhill, but there are no boulders at the base of the slope, and a rolling boulder wouldn’t create so many similar squiggles like this.

The explanation is that the boulders are made of carbon dioxide ice.

Just like on Earth, high-latitude regions on Mars are covered with frost in the winter. However, the winter frost on Mars is made of carbon dioxide ice (dry ice) instead of water ice. We believe linear gullies are the result of this dry ice breaking apart into blocks, which then slide or roll down warmer sandy slopes, sublimating and carving as they go.

The linear gullies exhibit exceptional sinuosity (the squiggle pattern) and we believe this to be the result of repeated movement of dry ice blocks in the same path, possibly in combination with different hardness or flow resistance of the sand within the dune slopes.

For a really entertaining explanation of this process, take a look at the embedded video below the fold.
» Read more

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The mysterious dark splotches of Mars

The dark splotches of Mars

Cool image time! The image on the right, cropped and reduced in resolution to post here, shows one particular dark splotch in a region with several similar dark areas.

Geologists aren’t quite sure what to make of the dark splotch in the middle of this image, one of several similar dark splotches that extend east and west for over 100 kilometers. From measurements made in infrared, this and other dark splotches have what we call “high thermal inertia,” meaning that it heats up and cools down slowly. Scientists use thermal inertia to assess how rocky, sandy, or dusty a place is. A higher thermal inertia than the surrounding area means it’s less dusty.

The image below the fold shows at full resolution the area indicated by the white box. It provides me no clue as to the cause for the darker color. I think we can speculate all we want, but the truth is that we simply don’t have enough information. We need a closer look, including boots on the ground, to figure this out.
» Read more

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Database of presumed human-caused earthquakes created

The uncertainty of science: Geologists have assembled a database of more than 700 earthquakes they think might have been caused by human activity.

The Human-Induced Earthquake Database, or HiQuake, contains 728 examples of earthquakes (or sequences of earthquakes) that may have been set off by humans over the past 149 years. Most of them were small, between magnitudes 3 and 4. But the list also includes several large, destructive earthquakes, such as the magnitude-7.8 quake in Nepal in April 2015, which one paper linked to groundwater pumping.

Miles Wilson, a hydrogeologist at Durham University, UK, and his colleagues describe the database in a paper set to be published on October 4 in Seismological Research Letters2. The scientists say that HiQuake is the biggest, most up-to-date public listing of human-caused quakes ever made. By bringing the data together in this way, they hope to highlight how diverse induced quakes can be — and help society to understand and manage the future risk.

Many of these quakes were likely caused by human activity. Many however might not have been. The jury is still out, as the article reluctantly admits near the end.

All possible instances of induced quakes were included “without regard to plausibility”, writes the team, because of the difficulty involved in deciding what constitutes absolute proof that an earthquake was caused by human activity. But that could mislead people about the real hazard from induced quakes, says Raphaël Grandin, a geophysicist at the Institute of Earth Physics in Paris. “When you put a dot in the database, and a scientific reference behind it, then you may lead the non-expert to think that the earthquake was caused by humans,” he says. Such a listing might hide scientific uncertainty, as with the Chinese quake: despite the paper linking it to reservoir filling, many seismologists do not believe it was triggered by human activity.

In other words, they included every quake that had the slightest suggestion it was connected to human activity, without noting the uncertainties. This makes this database to me somewhat suspect. Rather than identify the known reliable links between human activity and quakes in order to learn what causes them, this database seems more designed as a political propaganda tool aimed at limiting future human activity. It certainly doesn’t clarify our knowledge on this subject, but instead muddies the water significantly.

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Astronomers discover complex molecules in protostar accretion disk

Astronomers have discovered several complex molecules in the accretion disk surrounding a very young baby star about 1300 light years away in the constellation Orion.

The research team’s ALMA observations have clearly detected an atmosphere of complex organic molecules above and below the disk. These include methanol (CH3OH), deuterated methanol (CH2DOH), methanethiol (CH3SH), and formamide (NH2CHO). These molecules have been proposed to be the precursors for producing biomolecules such as amino acids and sugars. “They are likely formed on icy grains in the disk and then released into the gas phase because of heating from stellar radiation or some other means, such as shocks,” says co-author Zhi-Yun Li of the University of Virginia.

What is even most interesting about this discovery is that these complex molecules are not scattered throughout the disk, but are concentrated in regions above and below its central plane, what the astronomers are labeling “an atmosphere.” This suggests that differentiation — the same process that separates the heavier molecules from lighter ones both in centrifuges and in the cores of planets — occurs quickly in accretion disks as well.

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A river canyon on Mars

A river on Mars

Cool image time! The image on the right, reduced in resolution significantly to show here, was taken by the Themis camera on Mars Odyssey, and shows an unnamed canyon on Mars. Be sure to click on the image to see the full resolution version.

This canyon of course no longer has anything flowing in it. Moreover, it is not clear whether this was formed by water or lava. Unfortunately, the image is part of a series of “Art images” from Mars Odyssey, where they pick an image and suggest it looks like something else. In this case, they are claiming this looks like a “snake, slithering down the image.” Cute, but not very helpful. And unfortunately, they don’t add any further details at all about the image or its location. The context image suggests this canyon is next to a volcano.

After doing further research at the Themis image site, I was able to locate this image on Mars (using latitude 32.0515 and longitude 152.236 given at the link) and look at the images surrounding this one. Further research identified the volcano as Hecates Tholus in the Elyesium Plantia region to the west of Mars’s giant volcanoes.

Looking at all the nearby Mars Odyssey images, it appears that there are a lot of flows like this in this area, and all of them appear to be lava flows, with this one being the largest. A close look at the area just to the south of where the deep canyon opens out shows that the small surface flow draining into the canyon also appears to sit on much larger surface flows (at least two) that left the surface higher than the surrounding terrain.

Elyesium Plantia itself is a plateau, somewhat close to the border between Mars’s southern highlands and the northern plains where some scientists think an ocean might have once existed. Thus, it makes sense that the canyon drains north, as it is following the dip down to those northern low plains.

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Largest quake in Yellowstone since 2014

The USGS today recorded a magnitude 4.5 earthquake at Yellowstone today, the largest since a magnitude 4.8 occurred in March 2014, and part of a continuing swarming of small quakes that began on June 12.

This sequence has included approximately thirty earthquakes of magnitude 2 and larger and four earthquakes of magnitude 3 and larger, including today’s magnitude 4.5 event.

It is hard to say whether this swarm of small quakes portend a really big volcanic event, or will simply die off in the coming days. Recent data at Yellowstone has suggested the former is possible, though not imminent.

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The rings of Saturn

The rings of Saturn up close

Cool image time! The image to the right, cropped to post here, is part of one of the closest and highest resolution images that Cassini has yet taken of Saturn’s rings. The image was taken in January during one of the spacecraft’s ring grazing orbits, and has a resolution of 2,300 feet per pixel. And yet, as noted by the Cassini science team, “Even at this level of detail, it is still not fine enough to resolve the individual particles that make up the ring.”

In prepping the image, all I did was crop it to show the closest rings. I purposely did not reduce its resolution, so that you can see that no individual particles are visible. The rings of Saturn are truly made up of billions of small objects, behaving in many ways like liquid floating in the gravity well of Saturn. If you don’t believe me, download the full image and zoom in on it as much as you like. All you will see are pixels.

The fundamental science question therefore is not how Saturn’s rings behave (though this is certainly important and quite fascinating) but why did those rings end up the way they are. No other planet has rings anything like Saturn’s in their density and make-up. Why? Are Saturn’s rings a normal process that only occurs for short times around planets, which is why only Saturn has these types of rings at present? Or is it a rare event, so rare that we happen to be very lucky to see such a thing at all?

Even more important, Saturn’s rings and their behavior are likely linked closely to the same phenomenon that describe the formation of planets around a star. The more we can learn about why these rings exist, the more we will learn about why planets exist, both here circling the Sun as well as around stars everywhere else.

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The layered mesas of Mars

The mesas of Uzboi Valles

Cool image time! The image above, reduced and cropped to post here, shows the layered deposits and complex erosion that has taken place in this area of Mars dubbed Uzboi Vallis. As noted at the Mars Reconnaissance Orbiter post,

Layered deposits in Uzboi Vallis sometimes occur in alcoves along the valley and/or below where tributaries enter it. These deposits may record deposition into a large lake that once filled Uzboi Vallis when it was temporarily dammed at its northern end by the rim of Holden Crater and before it was overtopped and breached allowing water to drain back out of the valley.

It is important when looking at these erosion patterns, including the strangely shaped rippled sand dunes scattered through the larger image, that wind possibly plays an even more important part in causing erosion on Mars than liquid water might have in the far past.

Either way, the terrain here has the same stark and fascinating beauty as that seen in the American southwest. If we can ever make it possible to live on Mars, this will definitely be a place to visit when on vacation.

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Scientists estimate age of bright spots in Occator Crater on Ceres

Using crater counts and a careful analysis of features in Occator Crater on Ceres, scientists have estimated that the last major eruption occurred about 4 million years ago.

Nathues and his team interpret the central pit with its rocky, jagged ridge as a remnant of a former central mountain. It formed as a result of the impact that created Occator Crater some 34 million years ago and collapsed later. The dome of bright material is much younger: only approximately four million years. The key to determining these ages was the accurate counting and measuring of smaller craters torn by later impacts. This method’s basic assumption is that surfaces showing many craters are older than those that are less strongly “perforated”. Since even very small craters are visible in highly resolved images, the new study contains the most accurate dating so far.

“The age and appearance of the material surrounding the bright dome indicate that Cerealia Facula was formed by a recurring, eruptive process, which also hurled material into more outward regions of the central pit”, says Nathues. “A single eruptive event is rather unlikely,” he adds. A look into the Jupiter system supports this theory. The moons Callisto and Ganymede show similar domes. Researchers interpret them as volcanic deposits and thus as signs of cryovolcanism.

The volcano itself has slumped away, leaving behind the bright depression. Whether any cryovolcanism is still occurring underground remains unknown.

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The vanishing volcanoes of Ceres

New research based on Dawn data suggests that volcanoes on Ceres flatten and disappear over time.

NASA’s Dawn spacecraft discovered Ceres’s 4-kilometer (2.5-mile) tall Ahuna Mons cryovolcano in 2015. Other icy worlds in our solar system, like Pluto, Europa, Triton, Charon and Titan, may also have cryovolcanoes, but Ahuna Mons is conspicuously alone on Ceres. The dwarf planet, with an orbit between Mars and Jupiter, also lies far closer to the sun than other planetary bodies where cryovolcanoes have been found.

Now, scientists show there may have been cryovolcanoes other than Ahuna Mons on Ceres millions or billions of years ago, but these cryovolcanoes may have flattened out over time and become indistinguishable from the planet’s surface. They report their findings in a new paper accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed,” said Michael Sori of the Lunar and Planetary Laboratory at the University of Arizona in Tucson, and lead author of the new paper.

The cause of the flattening?

Viscous relaxation is the idea that just about any solid will flow, given enough time. For example, a cold block of honey appears to be solid. But if given enough time, the block will flatten out until there is no sign left of the original block structure. On Earth, viscous relaxation is what makes glaciers flow, Sori explained. The process doesn’t affect volcanoes on Earth because they are made of rock, but Ceres’s volcanoes contain ice – making viscous relaxation possible.

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USGS responds to Congressional inquiry about data tampering with blank documents

Why we got Trump: In response to a demand for documents from a Congressional investigation into data manipulation that the US Geological Survey allowed two chemists to do for nearly two decades, the USGS turned over documents with almost all the pages blank.

“Are we supposed to play tic-tac-toe on this?” Gohmert asked Tuesday, while waving one of the documents during a hearing of the House Natural Resources Subcommittee on Oversight and Investigations on the data manipulation. The USGS lab where two chemists skewed data for nearly two decades was finally closed in March 2016.

Gohmert’s subcommittee had requested the documents in September. The blanks received Tuesday represented only a small portion of the total sought by the panel. “We’re still waiting for documents we requested three months ago,” Gohmert said. “Some of the documents we did receive were redacted, they were duplicates or were even blank pages.”

Meanwhile, the USGS refuses to name the two chemists or describe how they were punished. For all we know, they still work there. And it is important to note, that the data manipulation took place in connection with “various energy-related topics, including coal reserves and uranium deposits.” Want to bet the manipulation was done to discourage development?

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Curiosity finds a meteorite

The Curiosity science team have identified and now analyzed a nickel-iron meteorite that Curiosity spotted on October 27.

Scientists of the Mars Science Laboratory (MSL) project, which operates the rover, first noticed the odd-looking rock in images taken by Curiosity’s Mast Camera (Mastcam) at at a site the rover reached by an Oct. 27 drive. “The dark, smooth and lustrous aspect of this target, and its sort of spherical shape attracted the attention of some MSL scientists when we received the Mastcam images at the new location,” said ChemCam team member Pierre-Yves Meslin, at the Research Institute in Astrophysics and Planetology (IRAP), of France’s National Center for Scientific Research (CNRS) and the University of Toulouse, France.

ChemCam found iron, nickel and phosphorus, plus lesser ingredients, in concentrations still being determined through analysis of the spectrum of light produced from dozens of laser pulses at nine spots on the object. The enrichment in both nickel and phosphorus at some of the same points suggests the presence of an iron-nickel-phosphide mineral that is rare except in iron-nickel meteorites, Meslin said.

The find is not unprecedented but it is interesting nonetheless.

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Comet 67P/C-G slowly breaking apart

A comparison of Rosetta images before and after Comet 67P/C-G’s close approach to the sun last year found new fractures and an enlargement of older fractures.

The fractures appear to be developing as forces subtly bend the comet to and fro, Stubbe Hviid, a planetary scientist at the German Aerospace Center Institute of Planetary Research in Berlin, reported October 17 in a press conference at a meeting of the American Astronomical Society’s Division for Planetary Sciences. Hviid and colleagues combined maps from Rosetta with computer simulations of all the forces at work within the comet to determine how the cracks develop. They found that the two bulbous ends rock in opposite directions as the comet spins, flexing the neck and creating severe stress. Because the comet isn’t held together strongly — it’s a conglomeration of dust and ice not much stickier than snow, Hviid said — the neck is starting to break. After a few hundred more years, he said, the comet could fold itself in half as the two lobes snap apart and smoosh together.

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Active volcano on Venus?

The uncertainty of science: A new analysis of past data from a variety of Venus orbiters suggests that at least one volcano is active there.

The review of old data from the Magellan and Venus Express orbiters suggests that some lava flows on the volcano’s slopes are fresh, though how fresh remains unknown. However, computer models and the detection of excess heat by Venus Express on the mountain’s eastern slopes adds weight to the theory that the volcano is spewing out lava.

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