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Pluto’s peaks are ice volcanoes + Earthquakes can change tectonic plate behavior

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Pluto’s peaks are ice volcanoes, scientists conclude
https://www.theguardian.com/science/2022...s-conclude

EXCERPTS: Strung out in the icy reaches of our solar system, two peaks that tower over the surface of the dwarf planet Pluto have perplexed planetary scientists for years. Some speculated it could be an ice volcano, spewing out not lava but vast quantities of icy slush – yet no cauldron-like caldera could be seen.

Now a full analysis of images and topographical data suggests it is not one ice volcano but a merger of many – some up to 7,000 metres tall and about 10-150km across. Their discovery has reignited another debate: what could be keeping Pluto warm enough to support volcanic activity?

[...] As for the nature of this material, the compositional data suggests it is mainly water ice, but with some additional “antifreeze” components mixed in, such as ammonia, or methanol.

[...] Even this is quite surprising ... given the extremely low temperature, this material shouldn’t be mobile at all. Possibly, it suggests Pluto’s rocky core is warmer than anticipated, and that heat energy released from the radioactive decay some of its elements is being somehow becoming trapped, for example by an insulating layer of material, and periodically released, triggering volcanic eruptions.

All of this is speculation. [...] Whatever the explanation, the old idea of Pluto as just an inert ball of ice is looking increasingly improbable... (MORE - missing details)



Groundbreaking earthquake discovery: Risk models overlook an important element
https://science.ku.dk/english/press/news...t-element/

RELEASE: Like a gigantic puzzle, Earth’s tectonic plates divide the surface of our planet into larger and smaller pieces. These pieces are in constant motion due to the fluid-like part of Earth’s mantle, upon which they slowly sail. These movements regularly trigger earthquakes, some of which can devastate cities and cost thousands of lives. In 1999, the strongest European earthquake in recent years struck the town of İzmit, Turkey – taking the lives of 17,000 of its residents.

Among researchers and earthquake experts, it is well accepted that earthquakes are caused by a one-way mechanism: as plates move against one another, energy is slowly accrued along plate margins, and then suddenly released via earthquakes. This happens time and again over decades- or century-long intervals, in a constant stick-slip motion.

But in a new study, researchers from the Geology Section at the University of Copenhagen’s Department of Geosciences and Natural Resource Management demonstrate that the behaviour of tectonic plates can change following an earthquake.

Using extensive GPS data and analysis of the 1999 İzmit earthquake, the researchers have been able to conclude that the Anatolian continental plate that Turkey sits upon has changed direction since the earthquake. Data also show that this influenced the frequency of quakes around Turkey after 1999.

"It appears that the link between plate motion - earthquake occurrence is not a one-way street. Earthquakes themselves feed back, as they can cause plates to move differently afterwards," explains the study’s lead author, postdoc Juan Martin De Blas, who adds:

"As the plate movements change, it somewhat affects the pattern of the later earthquakes. If a tectonic plate shifts direction or moves at a different rate than before, this potentially impacts onto the seismicity of its margins with neighboring plates."

Quake models can be improved. According to the researchers, the new findings provide a clear basis for reevaluating the risk models that interpret data gathered from the monitoring of tectonic plate movements. This data is used to assess the risk of future earthquakes in terms of probability, somehow like the nice/bad weather forecast. 

"An important aspect of these models is that they operate under the assumption that plate movements remain constant. With this study, we can see that this isn’t the case. Therefore, the models can now be further evolved so they take the feedback mechanism that occurs following an earthquake into account, where plates shift direction and speed," says Associate Professor Giampiero Iaffaldano, the study’s co-author.

The assumption that plate movements are constant has largely been a "necessary" assumption according to the researchers, because monitoring plate motions over period of few years was once impossible. But with the advent of geodesy in Geosciences, and the extensive and ever-growing use of GPS devices over the last 20 years, we can track plate motion changes over year-long periods.

Could make us better at assessing risk. How tectonic plates are monitored varies greatly from place to place. Often GPS transmitters are positioned preferentially near the edges of a tectonic plate. This allows public agencies and researchers to track the movement of plate boundaries. But according to the researchers, we can also benefit from even more GPS devices continuously monitoring plate interiors, away from their margins.

"Plate boundaries undergo constant deformation and poorly represent the movement of plates as a whole. Therefore, GPS data from monitors positioned farther away from the plate boundaries should be used to a much greater degree. This can better inform us weather plates are changing motion and how, and provide information useful for assessing the risk of future events somewhere other than the known hot-spots," says Giampiero Iaffaldano.

The researchers point out that their study is limited to the Anatolian continental plate, as the İzmit earthquake is one of the few event for which a combination of sufficient seismic and GPS data is available. However, they expect that the picture is the same for other tectonic plates around the planet.
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