Q: What kinds of unusual activity might be noticed before an eruption?
A: Common symptoms of volcanic unrest include an increase in the frequency or intensity of earthquakes beneath a volcano; the occurrence of volcanic tremor; swelling, subsidence, or cracking of the ground; increased steam emission or small steam explosions; melting snow or ice; changes in existing fumaroles or hot springs, or the appearance of new ones; and increased discharge of magmatic gases. Volcanologists assess the significance of volcanic unrest partly by monitoring the pace and intensity of such activity. It is important to remember that volcanic unrest is common and most times unrest does not lead to eruptions. By studying past unrest and eruptions, scientists can better figure out what might happen next at that volcano.
In fact, it is the very FIRST thing they say. Now some might argue that the nature of the recent earthquake swarms at Yellowstone were deemed by the USGS to be caused by fault line fractures, and not caused by magmatic activity. Well ok fine. But then what about this, from the same link?
Q: Do volcanoes produce different kinds of earthquakes?
A: Yes. A variety of earthquake types can occur at a volcano that is getting ready to erupt. These include earthquakes caused by rocks breaking along faults or fractures, termed tectonic-type earthquakes. Another common type a long-period or volcanic earthquake. These can occur when bubble-filled magma is on the move beneath a volcano. The differences between tectonic- type and volcanic-type earthquakes are so subtle that they can be distinguished only by using seismometers.
So in effect they themselves are saying that fault line fracture quakes in themselves, and not just direct magma movement quakes can be a sign that a volcano is getting ready to erupt! So if that's the case, then why bring the fault line argument up at all? It just doesn't make sense to, considering that either type of quake can still be a precursor.
And if that's the case, then surely this chart has got to mean something. The sukka's going to blow again one day, but what we now face is the daunting question of when. They say the caldera uplift has subsided recently, as a normal part of a uplift/subsidence routine. So currently, uplift decline would indicate otherwise. Gas emissions and water table levels appear to be normal for the moment.
I recently declared my unwillingness to believe this Super Volcano was going to erupt any time soon, but after looking at this chart, I find myself questioning this position again. If you read the links provided at the main link of the chart, where individual descriptions are given for each of these swarms, it becomes apparent that the big earthquake in California some time back actually triggered a swarm at Yellowstone, some 800 miles away.
I observed myself an increase in activity there after the recent 8.8 Chile quake for a brief period, which obviously did not help the situation any. Such powerful waves from distant bigger quakes do appear to have an effect.
Knowing all this, I cannot stress enough the eggshells we could be walking on here if a large enough quake occurred close enough to the park, or in the park itself, to act as a triggering mechanism for a potentially catastrophic event. I won't go into that here at ATS, as I am sure that by now most are aware what a monster this volcano truly is.
But just in case you don't know, here is a model of the gigantic magma plume, and really only the top part of it, that sits under this huge caldera:
Only 2% melt you say? But how much more lies beneath this that we don't know about, and what could be its percentage of melt?
Now let me be clear: My intent with this thread is not to second guess the USGS. I respect their knowledge and wisdom tremendously. It is rather, to those that live in the immediate area, a post that provides another perspective, and offers one more chance, and one more day, to seriously think about where they are living. And yes, I know it may not matter much anyway if Yellowstone blows.
There may be some comfort in the fact that the last known eruptions have overall decreased in intensity, thereby showing a trend to decrease. This may mean the next eruption could be serious, yes, but not catastrophic. But it may also mean that the next one will be incredibly huge, as magma way down deep has accumulated for way too long. There is just no way to tell. But my question to those that live nearby is simply: