Gas, Grabens, and Clouds

TLDR: SO2 gas indicates that magma is flowing very near the surface and may erupt in or near Grindavik, Iceland. A disturbance in the Western Caribbean may develop into something next weekend as it crosses Jamaica/Cuba/Hispaniola/The Bahamas on its way to pelagic realms. Here’s more details and some Science!

The situation on the Reykjanes Peninsula remains tense. Gas monitors put in place around the area are now detecting Sulfur-Dioxide, which is a strong indication the magma is very close to the surface. The gas activity caused today’s visits by residents of Grindavick to be cut short as a precaution, and the town is again deserted. This morning’s briefing didn’t change the outlook a lot, and there remains a high risk of an eruption from the newly active graben, shown as the blue area in the recent vertical displacement map …

Click to embiggen. Blue/Purple areas have subsided over a meter (3 ft).

So what’s a graben you ask? A graben is a piece of Earth’s crust that is shifted downward in comparison to adjacent crust known as “horsts,” which are shifted upward (link to USGS definition and some neat info). They are usually associated with faults or volcanic activity. This has caused some serious damage in and around Grindavick, as you can imagine the ground collapsing 3 feet isn’t good for roads and buildings. Although it may seem confusing, what tends to happen is the ground will sink nearby as other areas are pushed upward as the magma starts upwelling and reaches the surface (and changes names to become lava – more USGS goodness at this link).

In summary, the short version is we are still waiting to see what Óðinn has in store (Hephaestus, Vulcan, or Pele if you are from warmer climes).

Click to see a neat cloud pattern over South America.

In the Caribbean, a persistent area of disturbed weather may become a tropical system by this weekend. NHC has it as a 70% chance of formation with the Magic Words invoked:

Interests in Jamaica, Cuba, Haiti, the Dominican Republic, the
southeastern Bahamas, and the Turks and Caicos Islands should
monitor the progress of this system.

The 12Z run didn’t really show it spinning up into a major storm, just becoming the tail end of a cold front that should push through the region next weekend. Either way, if you are in Jamaica, Cuba, Haiti, the DR, Bahamas or Turks and Caicos, “monitor” for developments, although more than likely just a non-dramatic rain/gusty wind event. No threat at all to the mainland US.

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