The Earth Story

On the 12th of June, 2009, Sarychev Peak on Matua Island in the Kuril chain erupted and was captured by the International Space Station as it flew overhead.. This awesome image reveals some cool details about the eruption. As you can clearly see, the volcanic plume extends high into the sky. If you look closer, you will note the atmospheric shockwave of the eruption; pushing the clouds back causing a ring shape to develop. Also visible is a smooth, fluffy white cloud on top of the rapidly rising ash column, likely the result of rapidly rising water vapour condensing on top of the plume.

-Jean Image courtesy of NASA’s Earth Observatory.

Giant lava bubble exploding. Etna provided us with this amazing photo of a runny basaltic lava bubble exploding. The explosion is hundreds of metres high, being powerful enough to generate a spherical shockwave outlined in lava, and showering the area with glowing bomblets of lava.  Eruptions are driven by gases exsolving from the magma as it rises and the pressure of the surrounding rocks drops. As it reaches the surface, and effect rather like opening a shaken bottle of champagne occurs. Below we link to a film of the event. Loz Image credit: Martin Rietze http://www.youtube.com/watch?v=vEaL5VLBPEA&feature=share

Zoomed in version of the eruption of Mount Tavurvur, Rabaul Caldera, Indonesia 2 years ago. In this version, zoomed in from ones I saw previously, you can not only make out the shockwave from the blast and hear the shockwave pass, you can also see debris tossed upwards in the explosion.

Shatter Cones

When an extraterrestrial object, such as a meteorite or comet, impacts the surface of the Earth it releases a tremendous amount of energy. This nearly instantaneous energy release creates a high pressure, high velocity shock wave which radiates away from the impact zone. As this shock wave travels through rocks it interacts with inhomogeneities or discontinuities, creating shock features called shatter cones. High pressure shock waves, between 2 – 20 GPa, are needed to produce shatter cones. The only other known method to release sufficient energy to fracture rocks in this way are underground nuclear explosions. Shatter cones are the only diagnostic shock features of an impact zone that can be seen with the naked eye.

Shatter cones are conic features in rocks that exhibit grooved striations and conical fracture surfaces which penetrate through the rock. There is a large variation in the size of the cones produced, from less than a centimeter to several meters in width. The apex of the cone generally points towards the impact point and has been used as a proxy to determine the location and angle of an impact. Shatter cones can occur in any rock type but are best preserved in finer-grained rocks. In cases of extreme shock, the rocks can undergo so much damage that they fall apart, known as shatter cleavage. Shatter cones are generally found towards the central uplift zone of impact craters. It has been hypothesized that the formation of shatter cones can reduce the strength of the rock contributing to post-impact crater collapse. While it is well accepted that shatter cones form due to hypervelocity impacts, scientists still do not fully understand the mechanisms that create these features.

One of the most well known impact crater sites is found in Canada, near Sudbury Ontario. The Sudbury impact crater formed when a large comet, up to 15 km in diameter, collided with the Earth 1.85 billion years ago. This collision released so much energy that it created a 200 – 250 km wide impact crater and formed a 2.5 km thick sheet of melted rock. As it cooled the magma in this melt sheet differentiated, forming the Sudbury igneous complex, and concentrating pre-existing metals such as nickel, copper, and platinum group elements into economic ore deposits. The recognition of shatter cones in Sudbury in the 1960’s cemented the theory that the Sudbury igneous complex formed from an impact, a theory that was hotly debated up to that point.

-CD

Sources http://bit.ly/2qEpWXh http://bit.ly/2pmaMlR http://bit.ly/2pSlvHL http://bit.ly/2pSlvHL

Image Credit Gavin Kenny http://bit.ly/2p8quVG

Boom

This video clip was captured by webcam at Mexico’s Colima Volcano on Friday, February 3. The volcano sent a column of ash about 4 kilometers into the air after a strong explosion; early in this clip you can see that the shock wave from the blast kicked up loose ash from much of the cone as it traveled down it.

Explosive eruptions like this one can happen frequently as magma rises through a volcano like Colima. As molten rock is rising beneath the volcano, volatile compounds like H2O dissolved in the magma begin to separate into bubbles. However, the magma is viscous enough that those bubbles can grow, but they can’t rise up through the magma. Eventually, the pressure in these bubbles becomes so much that the magma can’t hold it in place and the magma fractures. The gas pressure in the bubbles is suddenly released, triggering an explosion in the magma and fracturing it into ash. The ash spat out by this volcano was recently molten rock in the volcano’s neck; it is tossed up into the air when these bubbles explode and rip the magma apart.

-JBB Video: https://www.youtube.com/watch?v=PlEGjoG7g-U

Shocked

This researcher is using a petrographic microscope to examine a mineral grain recovered from the just-completed effort to core and sample the rim of the crater generated during the Chicxulub Impact on the shores of what is today the Yucatan Peninsula (https://tmblr.co/Zyv2Js237-vel). The monitor shows the grain being seen under the microscope and also adds a scalebar.

The projected image is a grain of very fine sand only a hundred or so micrometers across. You’re actually looking at a bit of a sand grain that was shocked during the impact that killed the dinosaurs and was recovered from that drill core.

When an asteroid impacts a planet, part of the energy of that impact is converted into a shock wave. That wave propagates outwards through everything, distorting the atomic structures of every mineral grain it travels through. As the wave passes, first atoms are squeezed together, then they move back apart after the wave releases.

Shock waves can do lots of damage as they pass through a mineral. Some minerals can take the stress, but others fracture and some even completely melt. The mineral quartz responds to shock by producing “planar deformation features” – basically specific planes in the mineral have been kinked or broken, creating features that can be seen under a microscope.

The pattern of lines defined by the dark dots running from the upper left to the lower right of this grain establishes that it is a bit of shocked quartz (https://t.co/1N6HchliLV), a relic of the Chicxulub impact. The initial coring of this site is now complete and 1300 meters of core through the ring of the crater have been collected. They will now be taken back to facilities in the US and Germany where they will be opened and characterized.

-JBB

Image credit: Max Alexander/B612/Asteroid Day/BBC http://www.bbc.com/news/science-environment-36377679

Reference: http://bit.ly/1Z0rliw

In honor of International Mountain Day, lets watch one blow up!

This beauty of a picture comes courtesy of the International Space Station, which just happened to be passing over Sarychev Volcano in the Kuril Islands, northeast of Japan, on June 12, 2009.

This volcano is one of the most active in the Kuril Islands. As a result of the eruption, multiple flights had to be diverted due to the danger of an engine ingesting ash. The ash from this eruption was detected as far as 2400 km away.

You may have noticed the ‘hole in the clouds’ by now, and there is not just one answer as to what caused it. In fact, according to various meteorologists and volcanologists there are three possibilities: 1) the hole has nothing to do with the eruption (boring), 2) the hole is caused by descending air around the eruption plume (better), and 3) this is my personal favorite, the hole is caused by the shockwave from the eruption blast (YAY!!).

Have a happy International Mountain Day!!

---Adam

Photo Credit: NASA Earth Obervatory

References: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=38985

This is going to be the single coolest video you see of a volcanic eruption this week and that's saying something. This was taken by a person filming from a boat offshore of the explosion of Tavurvur volcano in Papua New Guinea last week. You can actually see the shock wave propagate outward from the volcano at the second it explodes, and then 15 seconds later the shock hits their boat. Holy Smokin' Toledos.

Video from.