I know there have been two recent topics started about Yellowstone. This isn't a "what if" type topic. What I am going to show you is real data
collected over the past several years.
Over the past several months I have been very concerned with the lack of earthquake activity in Yellowstone. We are talking about a very active
region. In 2002 the park saw 2350 quakes (
www.yellowstoneparknet.com...) . There were over 500 in November of
2002 alone. You expect a hundred quakes a month. This was not the case in November of 2005. This was the official USGS report on Yellowstone for
November 2005.
"November 2005 Yellowstone Seismicity Summary
During the month of November 2005, 34 earthquakes were located in the Yellowstone region. The largest of these shocks was a magnitude 2.1 on November
17, 2005 at 3:00 PM MST, located about 8.0 miles north of West Yellowstone, Montana. No earthquakes in this period were reportedly felt.
Earthquake activity in the Yellowstone region is at relatively low background levels"
There were 34 quakes in one of the most active regions in the country. There were two things that came to mind. Perhaps things were shutting down.
But I also remember what a scientist said when he went out to Mount St. Helens back in 1980 after there had been a great deal of earthquake activity
and ground deformation. He went out to Washington to observe the mountain but became discouraged after the mountain went quiet. Basically when it
seemed as if nothing significant was going to happen a major quake hit the mountain which resulted in the largest landslide ever observed and the
explosion of the mountain.
Does the activity at Yellowstone fit either of these scenarios? It is hard to say because Yellowstone is so unlike any other volcano on earth. But
lets look at some of the information that has come from the USGS.
In Feb 2006 the USGS issued its report on Yellowstone for Jan 2006. Here is what their report stated.
"January 2006 Monthly Update
During the month of January 2006, 67 earthquakes were located in the Yellowstone region. The largest of these shocks was a magnitude 2.6 on January
17, 2006 at 10:20 AM MST, located about 18.5 miles west northwest of West Yellowstone, Montana. No earthquakes in this period were reportedly felt.
Earthquake activity in the Yellowstone region is at relatively low background levels.
During the past year, continuous GPS stations have recorded between 4 and 8 cm of uplift over much of the Yellowstone caldera (except the northern
part near the Norris geyser basin). An example can be found at: www.mines.utah.edu
The magnitude of uplift is within the bounds of typical Yellowstone deformation, but at a somewhat higher rate. Over the same time period, earthquake
activity has been relatively low. YVO scientists continue to monitor the ground deformation and seismic data in the Yellowstone region. Many similar
caldera systems around the world regularly exhibit changes greater than those observed at Yellowstone and do not progress to eruptive activity. The
changes we are measuring at Yellowstone Caldera are scientifically interesting and will be watched closely.
Later this month, we will publish an article on the YVO website to describe deformation data in more detail. We'll discuss acquisition,
interpretation, and recent observations at Yellowstone and elsewhere."
Yes it is a long quote but all the information contained is of great significance. It is important to preserve this data because it is contained on a
page that changes every month and within a few days to a week this information will be gone. You can find the monthly updates here.
volcanoes.usgs.gov...
If you look back to the November 2005 review you will see what a normal USGS report looks like. They don't elaborate on things. It is pretty much cut
& dry. The Jan 2006 (posted in Feb) report contained a significant amount of information. And has been the case over the past months the quake total
is relatively low. But lets look at some of the key points.
Earthquake activity in the Yellowstone region is at relatively low background levels.
During the past year, continuous GPS stations have recorded between 4 and 8 cm of uplift over much of the Yellowstone caldera (except the northern
part near the Norris geyser basin)
Many similar caldera systems around the world regularly exhibit changes greater than those observed at Yellowstone and do not progress to eruptive
activity.
The changes we are measuring at Yellowstone Caldera are scientifically interesting and will be watched closely.
The first bolded topic mentions low activity which is obvious but important to remember. The 2nd issue mentions uplift of 4cm to 8cm for the past
year. It is significant but you will see shortly just how significant it really is. And just what did happen at Norris? I have yet to find the
answer to that. Why do they bring up the eruption scenario in the 3rd point? I think the 4th point speaks volumes. There is something going on that
they are very interested in.
Lets look at the uplift. 2005 saw 4cm to 8cm with the exception of Norris which remains a missing puzzle piece. Just recently a report was issued on
Yellowstone that discusses the uplift from 1996 to 2003 which states the park has seen uplift of 12 cm (actually 125mm). The image posted in the
report says the uplift was 125mm from 1996 to 2000. One of the dates is wrong. Lets assume the 2000 date is wrong and the uplift is actually
through 2003 which would make the uplift a little more conservative. It just means that 2004 would be unaccounted for. The reports I had seen said
the uplift ended in 2003 which would make sense with the 1996-2003 timeframe and no uplift info for 2004. The USGS report can be found here.
volcanoes.usgs.gov...
Here are the important uplift images.
The first 2 images show uplift through 2000 or 2003 depending on which year you think is accurate. The final image shows a change in uplift unlike
anything seen in the past decade with 80mm of uplift in 18 months.
There are unanswered questions for me.
What is happening at Norris?
Did the 125mm of uplift occur between 1996 and 2000 or 1996 and 2003?
Was there much deflation during the early parts of 2004 prior to the significant uplift?
What is the net uplift since 1996?
Quakes in a volcanic system are usually a sign of rock fractures. When it gets quiet like this and the uplift continues it makes me wonder if the
magma has done the work it needs to clear a path and now things can flow freely. It may be nothing but the significant uplift with so little quake
activity is something to keep an eye on.
I know this has been a long post and hopefully I didn't ramble too much. If anyone has anything they'd like to contribute to this please feel free
to add on.