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Originally posted by Bl0rg
yellowstone? damn doesn't it sit on a 70km caldera?
General principles of volcano seismology
Seismic activity (earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt and are a very important link to eruptions. Some volcanoes normally have continuing low-level seismic activity, but an increase may signal a greater likelihood of an eruption. The types of earthquakes that occur and where they start and end are also key signs. Volcanic seismicity has three major forms: short-period earthquake, long-period earthquake, and harmonic tremor.
* Short-period earthquakes are like normal fault-generated earthquakes. They are caused by the fracturing of brittle rock as magma forces its way upward. These short-period earthquakes signify the growth of a magma body near the surface and are known as 'A' waves. These type of seismic events are often also referred to as Volcano-Tectonic (or VT) events or earthquakes.
* Long-period earthquakes are believed to indicate increased gas pressure in a volcano's plumbing system. They are similar to the clanging sometimes heard in a house's plumbing system, which is known as "water hammer". These oscillations are the equivalent of acoustic vibrations in a chamber, in the context of magma chambers within the volcanic dome and are known as 'B' waves. These are also known as resonance waves and long period resonance events.
* Harmonic tremors are often the result of magma pushing against the overlying rock below the surface. They can sometimes be strong enough to be felt as humming or buzzing by people and animals, hence the name.
Patterns of seismicity are complex and often difficult to interpret; however, increasing seismic activity is a good indicator of increasing eruption risk, especially if long-period events become dominant and episodes of harmonic tremor appear.
Using a similar method, researchers can detect volcanic eruptions by monitoring infra-sound—sub-audible sound below 20Hz. The IMS Global Infrasound Network, originally set up to verify compliance with nuclear test ban treaties, has 60 stations around the world that work to detect and locate erupting volcanoes.
Originally posted by MagicaRose
reply to post by lernmore
Do you know if Florida would be harmed if Yellowstone erupts?
Would people in Florida die if this happens?
* Sunday, December 28, 2008 at 19:32:15 UTC
* Sunday, December 28, 2008 at 12:32:15 PM at epicenter
Location 44.511°N, 110.352°W
Depth 0.3 km (~0.2 mile) (poorly constrained)
Region YELLOWSTONE NATIONAL PARK, WYOMING
* 62 km (39 miles) ESE (106°) from West Yellowstone, MT
* 65 km (40 miles) SSE (154°) from Gardiner, MT
* 65 km (40 miles) SSW (210°) from Cooke City-Silver Gate, MT
* 436 km (271 miles) NNE (16°) from Salt Lake City, UT
Location Uncertainty horizontal +/- 0.8 km (0.5 miles); depth +/- 15.9 km (9.9 miles)
Parameters NST= 32, Nph= 32, Dmin=7 km, Rmss=0.54 sec, Gp= 65°,
M-type=local magnitude (ML), Version=1
* University of Utah Seismograph Stations
Event ID uu00002481
Originally posted by trusername
This is going to sound ridiculous - but here in San Francisco last night it was eerily quiet. Absolutely no wind or fog. The water was so calm you could see all the lights on the Bay which is really unusual. And no animal sounds - I live up on Twin Peaks and we can hear all the sounds of the city usually - it was a Saturday night and when I got out of my car the silence hit me. So much that when I came up stairs I told my family to go outside and see how weird and quiet it was. Extremely little traffic in our view for a Saturday, holiday night too.
It's cold here though - not what we call earth quake weather - and many say that's not a true indicator either.
There are a lot of birds and animals around where we live, crows, flocks of wild abandoned parrots, mockingbirds, not a peep. My cat on the other hand won't shut up.
Anyone else seeing odd animal reactions anywhere?
Yes. I live in WV and it was super quiet here too and unusually warm. High winds today but most has past now. I did comment on the quietness last night. Lots of wildlife and it was eeriely quiet.