Does Magmatism influence low angle faulting

Good article concerning faulting and magmatism

Geological reconstructions, thermochronology, paleomagnetic studies, and seismic reflection profiles, mainly published in the last 5 years, reinforce the view that active low-angle normal faulting in the brittle crust is widespread, underscoring the paradox of the seismicity data.  Take a look at this figure

Intruding magma relative to the high pressures and crustal stresses can take an active role in driving low-angle faults.  Please read the rest of this by click on the link below

http://walrus.wr.usgs.gov/reports/reprints/Parsons_G_21.pdf

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#4 Lab field final: Whaleback (finally)

This past Tuesday (27. April) the Structural Geology class drove the three-hours up to the Whaleback (or Bear Valley Strip Mine) for our field final.   The students had a variety of questions to address and data to collect.   Luckily, though it rained on Monday, Tuesday was simply partially cloudy with occasional large wind bursts.   It was chilly, but it was a great chance to visit some structure that had a dip of more than 20 degrees!

east wall; I think that's Dalton & Cam for scale...

looking south at the Whaleback itself; Dalton & Blake for scale

a more straight on south view of the Whaleback with Cam, Dalton & Blake for scale

south wall with Art & Matt for scale

Mark & Kristy taking measurements on the north fold

the whole class: Greg, Mark, Dalton, Blake, Will, Art, Matt, Kristy & Cam

We ended the day with dinner at Friendly’s in Danville (bacon was consumed–big surprise) before heading back to Johnstown, where the students headed back to studying.   Will claimed that he got more sleep in the van than he had in the previous several days…

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#3 Geology banquet

Last Sunday, 25. April, the department gathered at the Homestead to celebrate our accomplishments for the year and bid our seniors a fond farewell.

The banquet is held each year and provides a place for current students, parents, professors (both current and past), and alumni to gather & discuss the past year.

Honors given out Sunday night:

• College Scholar (best senior GPA) – Matt Petrowsky
• Hal Fry Scholarship (support to attend field camp ) – Frank Karmonocky
• Jonathan Lee Groft Memorial Scholarship (rising senior with a love of the outdoors & geology) – Blake Towarnicki
• American Mineralogist Undergraduate Award (best mineralogy student from Spring 2009) – Bryant Shue
• Association of Environmental & Engineering Geologists undergraduate poster prize – Bryant Shue

(The William Bryce Award was not given this year.)

We have a number of seniors graduating this year:

Matt Petrowsky, Bryant Shue, Kristy Goughnour, Frank Karmonocky, and Ry Jones

(missing from the event were Greg Nelson and Shawn Dravis)

Each student received a copy of the “Geology of Pennsylvania” (the thick tome each is holding) plus a gift bag containing a variety of geology-related items (e.g. timescale, polished slabs).

rising seniors Blake & Cam celebrate the fact the semester is almost over

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#2 Connemaugh Gorge on 403

In case you have never been to Johnstown, structure around here is not of the “in your face” variety.   On 6. April the structure class went out to 403 between Cramer & Johnstown to examine an anticline over the course of four stops.   403 is not exactly the safest road out there, so we hauled out the stylish UPJ Geology orange vests.   (Maximum dip, btw, on either limb was <20 degrees)

Will, Kristy, Art, and Matt in sporting their new runway look

There were a few places were someone just “had” to see what the overlying rock was on a given outcrop.

Cam & Blake take bets on whether or not Matt was going to come sliding back down

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A few older trips to catch up on… #1: Mt St. Helens

(I was about to post some pictures from our field final for Structure on Tuesday, but suddenly realized I had a number of other trips I should quickly cover first.   So, without further ado…)

In the fall, GSA was in Portland, OR and four of our students attended (Kristy, Greg, Matt, & Frank) in addition to all three faculty members from our department.   With the exception of Frank, all of the students were in Petrology that semester and I had promised a trip to Mt. St. Helens for anyone who chose to attend GSA.   On 17. October we headed out early, driving through on & off again showers to reach Johnston Observatory.   Completely swathed in clouds.   We spent time looking at the various exhibits and stopping at a variety of places on the drive back down the valley to examine the destruction & regrowth, but Helens kept in the clouds for our entire trip.   The gang with the “best” view of the day:

Kristy, Greg, Frank & Matt with the cloud covering Mt. St. Helens

(Carrie, by the way, managed a clear day when she drove up later in the week!)

On the way back to Portland, we detoured a bit to make Kristy completely happy.   Kristy, in case you didn’t know, has a thing for the ocean…

Frank, Matt, Greg, and Kristy at the storm-tossed Oregon coast

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Boudins forming in gypsum powder, on top of sugar syrup (Structural Geology, analogue experiments)

I was looking for something to post about structural geology and came upon a nice youtube clip demonstrating with gypsum and syrup.

http://www.youtube.com/user/StrucGeology

The video shows how boudins form in the gypsum power on top of the viscous syrup layer.  The initial fractures are distributed over the brittle-layer, which is typical for unidirectional extension.

Very good video.  Enjoy!

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Lake Tahoe Due For An Earthquake

Scientists have been studying the Lake Tahoe Region and they have found that earthquakes that have a magnitute of 7 or more occurs in this region ever 2,000-3,000 years and the largest fault in the region which is West Tahoe ruptured around 4,100-4,500 years ago.  The most recent ruptures along the West Tahoe and Incline Village faults produced about 4 meter high offsets and the most recent occured on the Incline Village over 500 years ago.  This shows that the area is capable of a magnitude 7 earthquake, however with the overlying water, this may produce a fairly large tsunami wave that can be anywhere from 3-10 meters tall.

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Recent Earthquake Are Normal

I found this article that discusses how all there have been many earthquakes lately, which is quite normal.  I am glad I found this article, because it helped to ease my mind about this recent burst in earthquakes.  Since the 1900’s, there has been an average of 16 earthquakes a year that have a magnitude of 7 or more.  During some years there weren’t that many earthquakes, and some years there were more, and the record currently is 32 during one year.  There have been 6 major earthquakes so far this year, and scientists say this is within the normal range.  They say aftershocks will continue in these areas, however none of them will be larger than the earthquakes that were experienced.

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Glimpses of Experimental Structural Geology in India

     This begins by how structural geologist have used polymers, plastic, silly putty, sand and clay to simulate macro deformational processes such as buckling instability, fault movement, boudinage in layered rocks, fracturing etc. This gives geologist an idea of how things work on a large or small-scale.

 Experimentation with numerical models is now an important trend in every field of science. Earth scientists are also employing numerical experiments to investigate intricate physical processes that are difficult to handle with
appropriate physical experiments. A large number of Indian structural geologists are actively involved in the studies on different tectonic processes in the Himalaya and other mobile belts in Indian craton. Experimental studies dealing with the mechanics of thrusting and large-scale ductile flows in convergent tectonic belt is discussed below. Sandbox experiments are conventional method for showing how some things work.

Fig. 1: Scaled model laboratory experiments on thrust tectonies

Fig. 2: Mode of development of arcuate fold left in a simulated

I thought the experiments using the tools mentioned above were very interesting.

click the following link for the remaining demonstrations and info about India.  

http://www.iypeinsa.org/updates-09/art-30.pdf

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Earthquake Hits Indonesia

An earthquake hit Indonesia on April 6, 2010 and wounded 22 people.  It caused some damage to buildings but not that much.  There have been arguments among scientists on the exact magnitude, it is currently ranging from 7.2-7.8.  The quake had a depth of 19.3 miles and the epicenter was located 125 miles northwest of Sibolga.  It struck 30 miles into the Earth’s crust below the Indian Ocean, and there is a tsunami warning for parts of Sumatra.  However a earthquake with a shallow depth of around 10 kilometers would create a tsunami, so the deeper the earthquake, the less likely a large tsunami will follow.

http://www.redorbit.com/news/science/1846386/indonesia_hit_by_earthquake/index.html?source=r_science

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