On July 10, 2018, the Yellowstone National Park authorities closed the area near Jenny Lake in Grand Teton National Park due to concerns about cracks in the surrounding rock massif.
We made a small analytical material about this incident, suggesting that the mantle plume, moving southeast, began to heat the magma chamber in the area of Lake Jenny, which caused surface deformations and, as a result, cracks in the rock, which stood unchanged for thousands of years …
To everyone's great regret, neither the USGS, the Yellowstone Park administration somehow bothered to further inform the public about the situation, although photographs of these cracks would become very important information. Fortunately, help came from a completely unexpected direction.
Grand Teton National Park, where this very Lake Jenny is located and where the rocks began to crack, is like a separate administrative organization within the Yellowstone National Park administration. They have their own tourist tours, their own rangers looking after the park and so on. In particular, his site Jackson Hole News, which tells about the events of the minipark.
And on July 25 of this year, local ranger Simeon Caskey decided to post on the website a report on the work he had done to rescue tourists.
In the report, the ranger talked a lot and tediously about how beautiful the Hidden Waterfalls are at this time of the year, how many tourists arrive there, and urged everyone to drop everything and urgently go to see these waterfalls. However, most importantly, Simeon Kasku attached to his advertising booklet a photo of these very cracks, and because of which part of the park was closed:
Promotional video:
It is clear that the photo report on the situation, to put it mildly, is incomplete, nevertheless, even this scanty data is enough to assess what is happening.
As can be seen from photo # 2, a tree once grew in the area of the crack, so if there had been even the slightest hint of a crack there, the tree would have crawled into it with roots. But the roots are not there. This suggests that the fault is fresh and it appeared, as they say, out of the blue - it took a stone and cracked.
The crack, as far as can be judged from photo No. 3, runs almost parallel to the rock wall over a very large extent and the most likely mechanism of its formation is the so-called fault - vertical tectonic shear of rock layers:
In other words, the rock under the center of the rock has lifted, causing the edge of the rock to lose support and break under the influence of gravity.
Discharge, shear, horst - these are all known geological processes that either last for millennia, or occur abruptly as a result of a strong earthquake. Since there were no strong earthquakes in this place, according to the USGS, it seems that the geology there has accelerated dramatically and magma is actively propping up the surface from underground.
Therefore, we believe that in the near future something else will be hastily closed in the Grand Teton National Park, as the cracks will grow. And although Mr. Simeon Kasku described the steepness of these places very colorfully, we would refrain from trips to this area, because now anything can happen there.