Tag: volcanism

Another study finds evidence of active volcanism on Venus

9:52 am

Changes in volcanic vent on Venus over eight months
Click for original image.

Using archival data from the Magellan spacecraft that orbited Venus in the early 1990s scientists think they have identified an active vent that appeared to change shape based on radar images taken eight months apart.

From the abstract of their paper:

We examine volcanic areas on Venus that were imaged two or three times by Magellan and identify a ~2.2 km2 volcanic vent that changed shape in the eight months between two radar images. Additional volcanic flows downhill from the vent are visible in the second epoch images, though we cannot rule out that they were present but invisible in the first epoch due to differences in imaging geometry. We interpret these results as ongoing volcanic activity on Venus.

This result is different that other research released last month that used Magellan data to identify geological features on Venus most likely to be active. In today’s results the scientists think they have spotted an actual volcanic eruption, as shown in the two images to the right. The image is taken from Figure 2 of the paper, with the changes in the center bottom vent clearly visible.

There is much uncertainty in these results that must be mentioned. The images are not optical but radar, so the scientists had to do a lot of computer processing to get the final result. They also compared this work with computer simulations to help confirm their conclusions.

The results also leave open the question of the total amount of volcanism presently active on Venus. As the scientists note in their conclusion, “With only one changed feature, we cannot determine how common currently active volcanism is on Venus.”

Nonetheless, the research using both new and archival data in the past thirty years is increasingly telling us that there is some active volcanism on Venus, hidden beneath its thick hellish cloudy atmosphere.

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The lava tubes on the western slopes of Alba Mons as potential Martian colonies

12:20 pm

Lava tubes on western flank of Alba Mons
Click for full figure.

In a new paper detailing work they first began in 2019, scientists have now carefully mapped the extensive lava tubes that appear to radially descend westward from the caldera of Alba Mons, the volcano on Mars that has the largest surface area but with a relatively low peak.

The mapped population of 331 lava tube systems has a mean length of 36.2 km, with a total length in the western flank geologic map quadrangle of ∼12,000 km. Individual lava tube systems extend up to ∼400 km, and it is likely that some of our mapped lava tubes are connected such that the total number is actually smaller and lengths (average and maximum) longer.

The map above, figure 10 of their paper, shows volcanic ridges as yellow, collapsed lava tube segments as red, and collapsed lava tube on the volcanic ridge as maroon. The wider map below, shows where this region is located, and gives the larger context.
» Read more

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Mahma Comparisons – Biggest volcano eruptions known

6:01 pm

An evening pause: I run this at 2x speed, but if you aren’t impatient enjoy it as it is. The size difference between the smallest and largest is quite daunting. Note too that this video only lists the known giant eruptions, explosive events that happened suddenly. It does not include some of the Earth’s largest long term volcanic events, such as the Deccan Traps, that happened repeatedly lasting millions of years that is thought to have possibly contributed to the extinction of the dinosaurs.

Hat tip Alton Blevins.

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Active volcanoes on Pluto?

9:16 am

Elevation map of Wright Mons on Pluto
Elevation map of Wright Mons on Pluto

The uncertainty of science: According to new research published yesterday, scientists now posit that there might be recent volcanic activity on Pluto, based on data and images sent back by New Horizons during its fly-by of the planet in 2015.

You can read the paper here. From its abstract:

The New Horizons spacecraft returned images and compositional data showing that terrains on Pluto span a variety of ages, ranging from relatively ancient, heavily cratered areas to very young surfaces with few-to-no impact craters. One of the regions with very few impact craters is dominated by enormous rises with hummocky flanks. Similar features do not exist anywhere else in the imaged solar system. Here we analyze the geomorphology and composition of the features and conclude this region was resurfaced by cryovolcanic processes, of a type and scale so far unique to Pluto. Creation of this terrain requires multiple eruption sites and a large volume of material (>104 km3) to form what we propose are multiple, several-km-high domes, some of which merge to form more complex planforms. The existence of these massive features suggests Pluto’s interior structure and evolution allows for either enhanced retention of heat or more heat overall than was anticipated before New Horizons, which permitted mobilization of water-ice-rich materials late in Pluto’s history. [emphasis mine]

The image to above is Figure 10 in the paper’s supplementary material [pdf]. It shows the volcano-like appearance of Wright Mons on Pluto, a mound approximately 3,000 feet high with a central depression equally deep, with a volume “similar in magnitude to that of the Hawaiian volcano Mauna Loa.”

These conclusions are quite tantalizing, but the amount of data is sparse, and thus it is wise not to take them too seriously. For example, the scientists have no idea how Pluto could presently have any form of liquid or active volcanism. Another mission to Pluto — studying it over a long time from orbit — will be required to determine how active the planet really is, or if it is active at all.

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The steep sudden foothill of Olympus Mons

2:27 pm

Olympus Mons on Mars

Today’s cool image starts from afar and zooms inward. The elevation map to the right shows Olympus Mons, the largest volcano on Mars and in fact the entire solar system. About 600 miles across, from the edge to its peak this volcano rises about 54,000 feet, with an actual height relative to Mars’ “sea level” of just under 70,000 feet, more than twice as high as Mount Everest on Earth.

The cross-section of this volcano is so large it would cover almost all of France if placed on Earth. As a shield volcano, it was formed by many many volcano flows that laid down many layers of lava, with some in its northwest quadrant thought to be as recent as 2 to 115 million years ago.

Our cool image today is located at the white rectangle at the southeast edge of this volcano, and illustrates how those many lava flows could create such a large shield volcano with such a large cross section.
» Read more

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The crack that splits the giant volcanoes on Mars

2:34 pm

Source of Arsia Mons rille
Click for full image.

Cool image time! In the April download of new images from the high resolution camera on Mars Reconnaissance Orbiter (MRO) was the photo to the right, taken on February 23, 2021 and cropped and reduced to post here, of what was labeled as “Source Region of Possible Rille on South Flank of Arsia Mons.”

Arsia Mons is the southernmost of the string of three giant volcanoes that sit between Mars’ biggest volcano to the west, Olympus Mons, and Mars’ biggest canyon to the east, Valles Marineris. This depression is on the mountain’s lower southern flank, and likely shows an ancient resurgence point where lava once flowed out from beneath the ground to form a rill meandering to the southwest. Today there is no visible resurgence. The floor of the depression appears to be filled with sand and dust, with the surrounding slopes spotted with scattered boulders.

What makes this particular image more interesting is how, when we take a very wide view, it reveals one of the most dramatic geological features on Mars, the 3,500 mile-long crack that caused these three volcanoes, and is actually not obvious unless you know what to look for.

So we need to zoom out. Let us first begin with a mosaic of three wider MRO context camera images, showing the entire rille and the immediately surrounding terrain.
» Read more

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Cassini evidence suggests volcanoes on Titan

4:04 pm

Scientists are now proposing that. based on a close look at data and imagery of Titan from the Cassini mission archive, that this moon of Saturn might have volcanoes, and that they might even be active today.

Volcano-like features seen in polar regions of Saturn’s moon Titan by NASA’s Cassini spacecraft could be evidence of explosive eruptions that may continue today, according to a new paper by Planetary Science Institute Senior Scientist Charles A. Wood and coauthor Jani Radebaugh of Brigham Young University.

Morphological features such as nested collapses, elevated ramparts, halos, and islands indicate that some of the abundant small depressions in the north polar region of Titan are volcanic collapse craters, according to “Morphologic Evidence for Volcanic Craters near Titan’s North Polar Region” that appears in the Journal of Geophysical Research: Planets. A few similar depressions occur near the south pole of Titan. “The close association of the proposed volcanic craters with polar lakes is consistent with a volcanic origin through explosive eruptions followed by collapse, as either maars or calderas,” Wood said. “The apparent freshness of some craters may mean that volcanism has been relatively recently active on Titan or even continues today.”

The data being somewhat think, there is a great deal of uncertainty with this theory. Nonetheless, it makes perfect sense, and in fact it would be a surprise if some sort of volcanic activity was not occurring on Titan.

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The eroding edge of Mars’ largest volcanic ash field

1:45 pm

Eroding yardangs at the edge of Mars' largest volcanic ash field
Click for full image.

Cool image time! In the regions between the biggest volcanoes on Mars is the Medusae Fossae Formation, a immense deposit of volcanic ash that extends across as much surface area as the nation of India. As planetary scientist Kevin Lewis of Johns Hopkins University explained to me previously,

In general, much of the [formation] seems to be in net erosion now, retaining very few craters on the surface. …One hypothesis is that this long term erosion, since it’s so enormous, is the primary source of the dust we see covering the much of the planet’s surface.

The image above, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on January 25, 2020. It shows one very small area at the very edge of the Medusae ash deposit, in a region where that deposit is clearly being eroding away by the prevailing southeast-to-northwest winds. The mesas of this ash that remain are called yardangs, their ash more tightly pressed together so that it resists erosion a bit longer than the surrounding material.

In the context map below the location of these yardangs is indicated by the white cross, right on the edge of the Medusae ash field.
» Read more

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Sinkholes on Mars

2:01 pm

Collapse pit on Mars
Click for full image.

Cool image time! In this week’s exploration of Martian geology that is reminiscent of Earth-based lava geology, today’s image is of a collapse pit in Ceraunius Fossae, the vast region of north-south fissures found to the south of the volcano Alba Mons. The photo to the right, cropped to post here, zooms in on that pit.

The picture was part of the most recent image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). What makes it especially interesting is the sharpness of its rim, in comparison to the collapse channel to the east. This suggests the pit is younger and fresher than the channel, and happened more recently. This also implies that the voids below the ground in which the surface is sinking are either still there, or due to on-going processes might be still be forming (like caves are on Earth).

For example, if there is underground ice, temperature changes or even thermal heat from the nearby giant volcanoes could melt that underground ice periodically, allowing it to flow and erode the surrounding material, forming voids. That this pit is located at 30 degrees north latitude, just inside the northern hemisphere band where glaciers are found, adds weight to this possibility.

The image below, reduced and rotated so that north is to the left, shows the entire sequence of collapse channels, with the more distinct pit from above in the bottom center of the picture.
» Read more

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A new analysis of data from Messenger suggests that violent explosive volcanism occurred throughout much of Mercury’s history.

2:06 pm

A new analysis of data from Messenger suggests that violent explosive volcanism occurred throughout much of Mercury’s history.

What is interesting about this result is that previously it was believed that explosive volcanism didn’t happen at all on Mercury.

On Earth, volcanic explosions like the one that tore the lid off Mount St. Helens happen because our planet’s interior is rich in volatiles — water, carbon dioxide and other compounds with relatively low boiling points. As lava rises from the depths toward the surface, volatiles dissolved within it change phase from liquid to gas, expanding in the process. The pressure of that expansion can cause the crust above to burst like an overinflated balloon.

Mercury, however, was long thought to be bone dry when it comes to volatiles, and without volatiles there can’t be explosive volcanism. But that view started to change in 2008, after NASA’s MESSENGER spacecraft made its first flybys of Mercury. Those glimpses of the surface revealed deposits of pyroclastic ash — the telltale signs of volcanic explosions — peppering the planet’s surface. It was a clue that at some point in its history Mercury’s interior wasn’t as bereft of volatiles as had been assumed.

The new conclusions have not only found evidence of explosive volcanism, it found a wide range of ages for these deposits, indicating that the explosive volcanism took place across an extended period of time.

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New data suggesting the presence of granite on Mars also suggests that the planet is more geologically complex than previously believed.

9:17 am

The uncertainty of science: New data suggesting the presence of granite on Mars also suggests that the planet is more geologically complex than previously believed.

In my years of science writing, I can’t count the number of times I’ve written the phrase “more complex than previously believed.” For some reason, modern scientists seem to always assume that things will be simple, with one straight-forward answer. From gamma ray bursts to supernovae to planetary formation to whatever, the first example found and the first theory developed from that first example has repeatedly been expected to explain everything.

But that’s not how things work. Instead, the closer scientists have looked, the more complex and interesting things have always become. Many different things can cause gamma ray bursts. Supernovae come in many types. Solar systems don’t have to resemble ours. Everything is always more complex than you first believe.

Scientists would get things wrong less often if they simply kept this thought in mind, at all times.

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The location of the volcanoes on Titan are not where scientists had expected them to be.

9:30 am

The uncertainty of science: The location of the volcanoes on Titan are not where scientists had expected them to be.

As Io moves closer to Jupiter, the planet’s powerful gravity pulls hard on the moon, deforming it. This force decreases as Io retreats, and the moon bounces back. This cycle of flexing creates friction in Io’s interior, which in turn generates enormous amounts of volcano-driving tidal heat. Common sense suggests that Io’s volcanoes would be located above the spots with the most dramatic internal heating. But Hamilton and his colleagues found that the volcanoes are significantly farther to the east than expected.

Many of the news headlines, including the article above, have trumpeted how the volcanoes on Io are in the wrong place. (See also this article.) Not. The theories were wrong, not the volcanoes. Nature does what it wants to do. It is our job to figure out why.

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