Kilauea is an active shield volcano, produced by the Hawaiian hot spot and is located on the main Island of Hawaii. It consists of a summit caldera and a rift zone comprised of two sections, the East and the Southwest  (see Fig. 2),  moving away from one another.

Figure 1: Google Map of the Kilauea Rift Zone and surrounding features, located on the main island of Hawaii, USA. 

Figure 2: Geologic map of the area, including both sections of the Kilauea Rift Zone. Image found in the Bulletin of Volcanology (Moore, R.).

The East portion of the Kilauea Rift Zone extends eastward, from the summit caldera, for 125km (Moore, R.). This length includes 75km of underwater trace, where it reaches the seafloor (5). The Kilauea volcano's summit is located on the side of Hawaii's Mauna Loa volcano, at an elevation of 522km (Moore, R.) and as it makes its way downslope, it is observed on the surface as a wide ridge (5). The theolitic basalts making up the surface layer are approximately 400 years old, with some exposed lava remnants that date back to 2500 years ago (5). 

Recently, this active site has experienced around 100 eruptions (Moore, R.) and the first one to ever occur here is estimated at half a million years ago, before it had ever reached the island rock (4). Along the caldera, past eruptions have left volcanic debris, such as cones and tuffs (Moore, R.), along the slope, as it descends to the sea. The reason for why the outpouring of lava flows, both aa and pahoehoe (4), moves South-East is due to the presence of the large mass of Mauna Loa. It comes into contact with this Kilauea volcano along the North side, and stops the movement of rock or intrusions in that direction, as seen in Figure 3. This leads to a build up of stress, resulting in parallel faults and largely displaced fissures, with offset on the scale of metres (Moore, R.) 

Also seen in Figure 3, are the many dikes which rise up eastwardly (Swanson) from the underlying magma chamber situated below the rift zone (5). They reach metres wide, creating new ones towards the South, the youngest labelled #5 in Figure 3. According to the University of Hawaii Manoa, the Kilauea volcano has one of the greatest heat outputs worldwide, which is due to the high activity of the East Rift Zone (4). With the last eruption in 1961, it "may be overdue for its next [one]" (Moore, R.). 

Figure 3: Diagram of how the intrusions influence the growing volcano slopes of Kilauea at the East Rift Zone, found in Swanson and others (1976). http://hvo.wr.usgs.gov/gallery/kilauea/erz/spreading.html

The Southwest section of the Kilauea Rift Zone does not lead to any lava eruptions onto the volcano. However, there is still rifting occurring here, with a seaward extension as the southwest side of Kilauea is displaced by sliding and counterclockwise rotation of the crustal rock (Myer, D. et al). Both along the rift zone and at the caldera high seismic activity is found, with many shallow, low intensity earthquakes causing displacement (Myer, D. et al). Due to all the stress concentrated here, many slope failures occur and led to the formation of many faults and consequently the Hilina Slump (6). This slumping action is growing every year, with an outwards stretch of 10cm/year on average, as it heads towards the South coast (6). 

Additionally, both InSAR and GPS technologies have been used to measure and track the crustal inflation surrounding the main caldera and surrounding rift zones. The data recorded that over the past decade, inflation has occurred over an area which extends for 12km with a width of 8km (Myer, D. et al). Refer to the figure below to view vectors representing the magnitude and directions of displacement (in terms of velocity). 

Figure 4: Close up view of the main caldera on Kilauea, with faults outlined in white and velocity vectors for various recent events of uplifting are shown. Image as seen in Journal of Volcanology and Geothermal Research (Myer, D. et al). 

Figure 5: Kilauea's magma supply pathway: The magma rises from the hot spot supply and reaches below the surface of Kilauea, where it moves along the rift, rises up to the caldera or pushes through fractures before pouring out onto the surface.  Image found at: http://volcanoes.usgs.gov/activity/methods/deformation/tilt/kilauea.php.

Video taken by Keith Trego, uploaded by John Langton on March 31, 2010. 

A triple junction is a point where three tectonic plates intersect. A few kilometers offshore of Cape Mendocino, in northern California, is the Mendocino Triple Junction, at which the North American Plate, the Pacific Plate and the Gorda Plate (the southern-most part of the Juan de Fuca Plate, a fragment of the now broken-up Farallon Plate) meet. It is studied extensively by geoscientists because of its close link to the San Andreas Fault system, its important seismic activity (frequent earthquakes) and  high crustal deformation rates and extent. Approximately 80 magnitude 3 or higher earthquakes of per year have been detected in the area since 1983 (Oppenheimer).

 

 The Mendocino Triple Junction (MTJ) joins three active boundaries: extending North, the Cascadia subduction zone, where the Gorda plate (oceanic plate) is subducting under the North American Plate (continental plate); extending South, the San Andreas Transform Fault and to the West, the Mendocino Transform Fault. It is therefore classified as FFT (Fault-Fault-Trench).

 





The Cascadia subduction zone, where subduction happens at a rate of 36–40 mm/year in a N55ºE direction (Riddihough, 1984), is accompanied by the Gorda Ridge at the western edge of the plate, a mid-ocean ridge where mantle upwelling occurs, creating new oceanic crust. The Pacific and Gorda plates converge at a rate of 5 cm/year at N115ºE (Oppenheimer). The Gorda plate is not very big, only about 45 000 km2, and the age of its rocks ranges from 0 to 7 Ma (Chaytor, 2004) while the Pacific Plate in that region is aged 25-27 Ma (Gulick, 2001). The rocks close to the MTJ are mainly sandstones, shales, cherts, metagreywackes, melange, mafic volcanics and blueschist and eclogite facies metamorphic rocks, all from an exhumed accretionary wedge, the Fransiscan Complex (Furlong, 2004).



 

The MTJ is migrating north, in conjunction with the south-migrating Rivera triple junction, at the other end of the San Andreas fault system. This movement can be explained with the history of the MTJ, dating back to approximately 30 Ma.

This animation made by Tanya Atwater shows the same process of the Farallon plate subduction creating two triple junctions moving apart from each other along the San Andreas Fault System. The lighter shades of blue indicate younger rocks created at divergent plate boundaries.

 

Deformation
  
A concentration of active plate boundaries at a single point will inevitably produce abundant crustal deformation. The crust North of the MTJ is being thickened and the crust south of the MTJ is being thinned by a mechanism referred to as the “Mendocino Crustal Conveyor” (Furlong, 2003), in which material upwelling in the slab window slowly cools and accretes to both the Gorda Plate and the North American Plate, inducing deformation (folding, faulting) on the North American coast when the mantle material is entrained with the North-migrating Gorda plate (Furlong, 1999). This is called viscous coupling and, while still being debated, is thought to be a significant way of creating continental crust (by accretion). The related process of thickening-thinning happens over timescales of less than 5 my (Furlong, 1999).

Cliquez ici pour modifier.

This figure from (Gulick, 2001) depicts the magnetic anomalies on the Gorda and Pacific plates as grey strands. The scale to the right indicates the ages of these anomalies, starting at 35 Ma, coinciding with the MTJ formation. This indicates that the collision of the Farallon plate with North America marked an abrupt rise in deformation in this region. The bottom image shows a concentration of major seismic events near the MTJ, particularly along the Mendocino transform fault, as well as the location of the reactivated faults.





Sources

-Chaytor, JD, Goldfinger, C, Dziak, RP, Fox, CG. “Active deformation of the Gorda plate: Constraining deformation models with new geophysical data” (2004). Geology 32 (4): pp. 353-356. DOI: 10.1130/G20178.1

 -Dickinson, W.R., Snyder, W.S. “Geometry of triple junctions related to San Andreas Transform”.(1979) Journal of Geophysical Research, vol. 84 no.B2.

-Eakin C, Obrebski M, Allen R, Boyarko D,Brudzinski M, Porritt R. (2010). “Seismic anisotropy beneath Cascadia and the Mendocino triple junction: interaction of the subducting slab with mantle flow”
Earth Planet. Sci. Lett., 297 (2010), pp. 627–632

 -Furlong, K. P., Lock, J ,Guzofski, C ,Whitlock J., Benz H. (2003) “The Mendocino Crustal Conveyor: Making and Breaking the California Crust”, International Geology Review, 45:9, 767-779, DOI: 10.2747/0020-6814.45.9.767

-Furlong, K.P., Govers, R. “ Ephemeral crustal thickening at a triple junction: The Mendocino crustal conveyor” (1999). Geology 27, pp.127-130, DOI: 10.1130/0091-7613(1999)027<0127:ECTAAT>2.3.CO;2

-Furlong, K.P., Schwartz, S. Y., “INFLUENCE OF THE MENDOCINO TRIPLE JUNCTION ON THE TECTONICS OF COASTAL CALIFORNIA” (2004).Annu. Rev. Earth Planet. Sci. 32:403–33 doi: 10.1146/annurev.earth.32.101802.120252

-Gulick, S.P.S.; Meltzer, A.S.; Henstock, T.J.; Levander, A. (2001). "Internal deformation of the southern Gorda plate: Fragmentation of a weak plate near the Mendocino triple junction". Geology 29 (8): 691–694. doi:10.1130/0091-7613(2001)029<0691:idotsg>2.0.co;2.

-Dengler, L., Carver G., McPherson, R,.”Sources of North Coast Seismicity” .California Geology, March/April 1992

Oppenheimer, D."Mendocino Triple Junction Offshore Northern California". USGS.http://woodshole.er.usgs.gov/operations/obs/rmobs_pub/html/mendocino.html. Webpage visited on 29/03/2015

 - M. Liu

Where Moses’ famed parting of the Red Sea most obviously differs with the geological parting of the Red Sea lies in orientation. In the biblical account Moses parted it widthwise from coast to coast, whereas contemporary continental drift parts it lengthwise straight down the middle. 

One can convincingly argue that ever since biblical times, the Red Sea has played an important role in human civilization. Today, the Suez Canal linking the Mediterranean to the Gulf of Suez makes the Red Sea a crucially important junction for trade between Europe and Asia. As such, over the millennia it has seen plenty of contest, war, and exchanges of power along its banks. However, one thing has remained constant - for the past few million years, the Red Sea has slowly and quietly gotten wider. In this post, we shall seek to explain concisely the reasons behind this width gain.

A divergent continental boundary between the previously attached Arabian and African plates is responsible for the creation of the Red Sea. We summarize the concepts illustrated above. A hot mantle plumes lifts up the continental crust, causing the crust to stretch, fracture, and eventually form a rift valley (note the formation of normal faults). As the crust slides atop of the mantle away from the elevated magma plume, a rift valley is formed (5). Eventually the crust stretches thin enough to be below sea level and an infantile sea, such as the Red Sea, is born. As the plates are pulled apart, new oceanic crust is formed when magma rises up through the rift. As expected, we see volcanic activity in the Red Sea Rift - the most recent submarine eruption having occurred in 2007 (1, 2). Hot brine and metalliferous mud on the sea floor are further evidence supporting the presence of magma beneath the rift. As slab pull continues to pull the coasts apart, in a few million years, we might expect a renaming of the Red Sea to the Red Ocean.  

We know that the Red Sea is young from observing its outwardly visible geological features, but there is another, less obvious method to quantitatively determine its age. 

As a stretch of new oceanic crust is formed from magma along a mid ocean ridge, iron in the hot magma orients itself with the earth’s magnetic field and this magnetization becomes permanent once the magma cools (5). Well known to geologists, the Earth’s magnetic poles are not fixed and over the past 5 million years, have swapped positions around 20 times. The ages of these paleo-poles are well documented. Thus, by measuring how magnetization reverses along bands of oceanic crust can we not only date these bands, but by measuring each band’s width and the corresponding time period of the paleo-pole, we can also calculate the rate of sea floor spreading (3). For the Red Sea, this rate has been determined to be around 1cm/yr on average over the last 4 million years. For reference, the Mid Atlantic Ridge spreads at a much faster 2.5 cm/yr. 

Sources (all primary)

1 - Butler, Rob. "The Dead Sea Transform in Lebanon." The Dead Sea Transform in Lebanon. Leeds University, n.d. Web. 30 Mar. 2015. <http://www.see.leeds.ac.uk/structure/leb/index.htm>.

2 - Eva, Hartai. "Geology." N.p., n.d. Web. 25 Mar. 2015. <http%3A%2F%2Fmeip.x5.hu%2Ffiles%2F1529>.

3 - Freund, Raphael, Israel Zak, and Zwi Garfunkel. "Age and Rate of the Sinistral Movement along the Dead Sea Rift." Nature.com. Nature Publishing Group, n.d. Web. 30 Mar. 2015. 
<http://www.nature.com/nature/journal/v220/n5164/abs/220253a0.html>.

4 - JOKELA, ARTHUR W. "SUBMARINE GEOLOGY OF THE RED SEA." (1965): n. pag. MIT. Web. 25 Mar. 2015. <http://dspace.mit.edu/bitstream/handle/1721.1/59607/26057777.pdf>.

5 - Larh, John C. "Sea-Floor Spreading and Subduction Model." Sea-Floor Spreading and Subduction Model. USGS, n.d. Web. 30 Mar. 2015. <http://pubs.usgs.gov/of/1999/ofr-99-0132/>.

6 - Lindquist, Sandra J. "The Red Sea Basin Province: Sudr-Nubia(!) and Maqna(!) Petroleum Systems." (n.d.): n. pag. USGS. Web. 25 Mar. 2015. <http://pubs.usgs.gov/of/1999/ofr-99-0050/OF99-50A/OF99-50A.pdf>.

by Fiona Clerc

The East African rift system is a continental active rift system spanning the boundary between the diverging Nubian and Somali plates. It is made up of a series of graben basins, which are connected by transform fault zones. It is composed of a Western and Eastern branch, which split off from the Afar Triple Junction in the north. The Eastern branch is made up of the Main Ethiopian Rift and the Kenyan Rift Valley further south, while the Western branch is made up of the Albertine Rift and a series of lake valleys, such as the Lake Malawi Valley. [2]

Overall tectonic setting
The tectonics of the EARS are affected by the diverging plates. The lithosphere undergoes extensional strain locally, as a result faulting and subsidence occurs in the crust, creating elongated rifts. The resulting ductile thinning in the lithosphere causes asthenospheric intrusion. [3]

Refer to the "Stress contributing to the formation of the EARS" section for more information and a map showing the location of the tectonic plates and their boundaries.

3. Deformation contributing to the formation of the EARS (also refer to relevant information in sections 1 and 2)

It is widely accepted that the evolution of the EARS is due to extension, however the initial trigger is more debated. As in the West European rift system, the rifting could be due to collision. However, in the south of Africa, the Karroo compression ended in the Jurassic, before the formation of the EARS, and compression events in the Mediterranean were too old and localized. Compression from oceanic ridges is also unlikely, since both the Central Indian oceanic ridge and the Atlantic ridge formed too early. [1]

The rupture of the lithosphere occurs either by active rupture (due to forced intrusion of the asthenosphere, a result of its plume movements) or passive rupture (in which the asthenosphere rises to fill a gap in the lithosphere caused by the extension caused by plate boundaries). The tectonic rupture could be due to a combination of simple shear (caused by planar faults) in the upper brittle layer, delamination in the lower crust, and pure shear (and plastic deformation) in the lithospheric mantle. [1]

The lithosphere first failed in the north, which corresponds to the onset of the plume, under Lake Tana. The plume was 1000 km wide around 30 Ma, weakening a large area by heating and thinning it. The Pan-African suture zone was also present and also contributed to the lithospheric failure. These weakening effects and the tension caused by the tectonic plates led to the first tension fractures and faults in the Afar (after the formation of the Red Sea-Gulf of Aden opening), resulting in the Afar triple junction. Later, the plume moved to the south, arriving at the Kenyan dome before 20 Ma, where crustal up-warping and flood volcanism followed at 15 Ma. The failure that started in the Afar (as a result of the weakening discussed above) spread to the south causing the MER (main Ethiopian rift) as it followed the suture zone. Another suture zone located more to the south allowed the failure to spread to the Kenyan dome. Since the MER and the Kenyan rifts followed different suture zone, they could not link and formed splayed graben basins between them. As it spread to the south, the failure was stopped by the thicker lithosphere, where it formed the north Tanzanian divergence. After the plume had traveled down the western branch, the failure spread to the Kivu-northern Tanganyika area. The rifts eventually linked with the eastern branch through the Aswa transform zone. In general, important parts of the rift system were formed far from the plume, since the lithospheric thinning, which helped initiate failures and asthenospheric intrusions was initiated by the plume but continued along ancient weak lines. [1]

4. Stress contributing to the formation of the EARS
The deformation contributing to the formation of the rift system (a lithospheric opening in the African continent) is the extension caused by the divergence of large blocks. The direction of  movement of the extension is debated, no consensus has been reached through analysis of local paleostress fields. There are two types of movements affecting the faults. First, there is the NW-SE movement of the large continental blocks. Second, smaller local movements are triggered along the major border faults, where the high relief creates gravity gliding effects. Local extension occurs in the E-W direction, especially in the eastern branch. The combination of these movements explains the changing pattern of stress and deformation, even though the kinematic schemes do not vary. [1]

References:
[1] Chorowitz, J., 2005. The East African rift system. J. Afr. Earth Sci. 43, 379–441.
[2] Corti, G., 2009. Continental rift evolution: From rift initiation to incipient break-up in the Main Ethiopian Rift, East Africa. Earth-Science Reviews. 96, 1-53.
[3] Isola et al., 2014. Spatial variability of volcanic features in early-stage rift settings: the case of the Tanzania divergence, East African rift system. Terra Nova. 26. 461-468.
[4] MacGregor, D., 2015. History of the development of the East African Rift System: A series of interpreted maps through time. J. Afr. Earth Sci. 101, 232-252.

By Kassandra Sofonio
The Corinth rift is a product of extensional processes that lead to the creation of the Gulf of Corinth.

Figure 1: Embedded Google Map showing the Gulf of Corinth

Analyzing the Geological Maps:

Looking at figure 2, we can see that there are numerous major normal faults dipping towards the north on the land of the southern border of the Gulf.   Some faults that are shown on Figure 2 include the southern faults Helike, Xylocastro, Doumena etc. Faults between Aigion and Akrata have a strike varying between 070°N and 120°N and a dip between 70° and 45°, averaging around 60°-55° (2). The faults along the southern coast are en echelon, meaning they are closely spaced, approximately parallel and overlapping. (3) Evidence from seismological studies support the view that these faults are planar surfaces that continue to depth. The other model proposed consists of regional listric faults and a low angle detachment system (2). On the southern edge we also see many synrift sediments (which is basically sediments deposited at the same time as the rifting) of Pllo-Quaternary deposits. According to the Corinth Rift Laboratory, there is increase of thickness in the synrift deposits from south of Akrata to Xylocastro. (2) When observing the northern border, it is interesting to note that the faults are not actually on the shore. These faults  are dipping towards the south and are located in the actual Gulf. In addition, there is no synrift deposits. These two factors have led to the acceptance of an asymmetric model, as mentioned previously in the overview. 
On the southern border we also have an uplift of coastlines, while on the eastern side, near the Gulf of Alkionides, we have a bit of submerging coastlines. The southern coast is uplifting at a rate of 1 to 1.2mm/year (2). The mechanisms used to explain this uplifting include lateral flow of the lower crust or the elastic rebound of the footwalls (2). Reasonably, there are also alluvial deposits around the water edge (most apparent near the Gulf of Lechanios above the marine terraces). 
When comparing this map which Figure 3, we can see that the alluvial deposits correspond with the white Holocene deposits (deposits from the Holocene epoch). In this geological map, however, we can also see the exhumation of Tyros Beds and the Phyllites-Quartzites. The Zaroukla detachment and the Cretan detachment, mentioned previously, are also clearly illustrated. 

Deformation History:
The Corinth Rift is thought to undergo extension by a combination of: westward propagation of the North Anatolian fault (NAF), back-arc extension due to the subduction of the African plate at the Hellenic Trench (see figure 5, the Hellenic Arc), and gravitational collapse of the lithosphere (3). According to the theory of the involving the NAF , the purpose of the Corinth Rift is to accommodate the “strike-slip motion by extension and rotation of the fault system”. (2)

As mentioned previously in the geological map analysis, there is a slight divergence in ideas concerning the structures involved in the Corinth rift. Some people believe that it is composed of a dominant steep fault while others think it has a detachment zone. In the southern margin, there are steep active normal faults. Normal faults generally don’t go further than 10-15 km deep, and further than that, we have a shallow-dipping shear zone in the middle and lower crust.  Other models show that the steeply dipping normal fault in the upper crust continues at depth by a ductile flow in the lower crust. There is no detachment required in this model.  The other model involves a deep, low angle North dipping detachment zone (3). According to Jolivet’s research paper, low angle normal faults are detachments and can cut across a nappe stack. In addition, the juxtaposition of a superficial unit on top of a deep metamorphic unit results from motion along a detachment. However, as it is mentioned in Bell's paper,  this model is not compatible with factors such as the  offshore basin stratigraphy,  These two ideas are clearly summarized and illustrated in Figure 7. 

By analyzing the sediments, Bell was able to construct a timeline for the evolution of the Corinth Rift which is summarized below:

Past till approximately 2 Ma
There was a wide western rift with activity along numerous faults (3) and it underwent little subsidence (we know this because there is no evidence of deposition).In the easternmost part of the system, extension was focused onshore at the NW-SE trending Megara basin (south of the present day Gulf of Alkionides, see figure 2 for a clearer visualization) (3)

Approximately 1-2 Ma to 0.4 Ma
The extension in the Megara basin ceased at about 0.8-2.2 Ma when activity transmitted to the Gulf of Alkionides to the north (3). Three individual depocenters (the location of the thickest deposition in a basin) are formed. The western depocenter is controlled by a South dipping fault system while the eastern depocenter is controlled by North dipping fault system. (3). Both North and South dipping faults are significant in this time period. 

Approximately 0.4 Ma to recent 
The depocenters are now linked. A single 80 km depocenter is formed and is controlled by the North dipping faults on the southern edge. 
Faults Derveni and Likoporia (see Figure 8) experienced an important increase in displacement. In addition, the slip rates of Derveni and Likoporia (located in the central part of the rift) were greater than those of Eliki and Xylokastro (faults located in the western and eastern part of the rift respectively) 
North dipping faults dominate basin subsidence (this generalization excludes the westernmost basin). 


Recent Activity is interpreted by seismicity and geodetic rates. Currently, "microseismicity is concentrated in the Aigon and Rion graben regions" (see western part of the Gulf in Figure 8)  (3)

Bell provides an excellent model summarizing the rift evolution which includes the following steps: 
1. rifting initiates in isolated depocenters
2. the major faults controlling the initially isolated basins dip both north and south (however the more the rift evolves, the north dipping faults become more dominant, as it is currently observed in present day) 
3. faulting migrates northward

Thus the Corinth Rift had a rather complex evolutionary history, including migration of fault activity, the linkage of depocenters and the tendency of dominating North dipping faults on the southern coast. It is these processes that lead to the creation of the beautiful (present day) Gulf of Corinth, located in Greece. 

References:

Primary Sources: 
(1)    Jolivet L., Labrousse L., Agard P. et al., Rifting and shallow-dipping detachments, clues from the Corinth Rift and the Aegean, Tectonophysics, 287-304, 2010

http://ardoise.ens.fr/IMG/pdf/Jolivet_et_al_Tectonophysics_2010.pdf

(2)  General Tectonic Context of the Corinth Rift (2009, May) Retrieved from http://crlab.eu/

(3)     Bell R., L. McNeill, J. Bull, T. Henstock, R. Collier and R. Leeder, Fault Architecture, basin structure and evolution of the Gulf of Corinth Rift, central Greece, Basin Research, 2009

http://ardoise.ens.fr/IMG/pdf/Bell_basin_research2009.pdf

Secondary Sources: 
(4)   The rift of Corinth. Retrieved from http://www.ipgp.jussieu.fr/~bernard/GAIA/resume-corinth.html

(5)  Robertson, A. (2006). Tectonic development of the Eastern Mediterranean region. London: Geological Society.  
https://books.google.ca/books?id=R3m1XNShu7IC&pg=PA134&lpg=PA134&dq=age+of+the+pq+nappe&source=bl&ots=uz3W8JIvzf&sig=gHPcaABI77oGTKRPoNycRFK-iSU&hl=en&sa=X&ei=DM8NVa_-E8qWgwTQ4YLYDg&ved=0CCsQ6AEwAg#v=onepage&q&f=false

(6) National Oceanography Centre, Southampton (UK). (2009, December 23). Formation of the Gulf of Corinth rift, Greece. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2009/12/091222105215.htm

(7) Imperial College Rock Library. Retrieved from https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?Term=cataclasite

Located in North-Western Wyoming, the Teton Fault runs for approximately 65 km along the eastern front of the Teton Range (3) with visible fault scarps extending for 55 km (1).  The Teton Fault is a normal fault (3), and is considered to be an active fault even though there has been no major earthquakes in recent history. The Teton Fault is responsible for the creation of the beautiful jagged mountains and along with the sprawling valley know as Jackson Hole. The highest peek in the fault zone is Grand Teton reaching an elevation of 13,770 feet and the lowest point is in the Jackson Hole Valley and it is 5,975 feet (4). 

The fault runs near the boundary of the Quaternary rocks (bright green) and the precambrian gneiss.
(http://www.marlimillerphoto.com/images/GRTEgeomap.jpg )

Age
The Teton Range is considered to be a very young mountain range if it is viewed on geological timescale and when its formation is compared to that other ranges around the world.  This relative age of the mountain range is said to be the reason for the lack of foothills present and the reason for the sharp jagged shape of the mountain range.  Below is a table showing the rock type and the approximate age of the rocks that make up the Teton Fault zone taken from the geological map show above.

General Description
The Teton Fault extends for 65km along the base of the Teton mountain range. It is located near a junction of four tectonic provinces (Basin and Range, Idaho-Wyoming Thrust Belt, Rocky Mountain Foreland and Snake River Plain-Yellowstone Volcanic Plateau). The Teton Fault has an average strike of 010 degrees and has a dip of 45-75 degrees in the east direction (1).  The Teton Fault is credited for creating one of the most visually stunning mountain ranges in the world. Evidence of the presence of the fault can be seen by observing four major features of the Teton Range.  The strait and deep east face of the range, absence of foothill,  asymmetry of the range and the visible fault scarps along the eastern face of the range (2).


Deformation History
The fault underwent major compression and crustal thickening during the Mesozoic era and early Tertiary period causing the formation of thrust faults and folds (6).  This was cause by the Farallon slamming into and diving under the North-American plate (6). The crustal thickening process stopped in the late Tertiary period and changed into extensional forces. The expansion occurring west of the newly formed Rocky Mountains caused the cracks in crust of the earth, one which was the Teton Fault.  Nearly all the seismic activity which is responsible for the formation of this beautiful landscape occurred between 10 and 2 million years ago (1) during this extensional period.  This is a highly debated topic as the age of initial displacement of the fault has not been agreed upon by experts (1).  The expansion occurring caused a number of major earthquakes ranging from 7-7.5 on the richter scale (5) along the Teton Fault during this time. The combination of the stress from these massive earthquakes with the magma hotspot driving up under Yellowstone and the presence of the Teton Fault caused major movement along the fault, averaging 3 to 6 feet of vertical displacement per earthquake (Windows Into the Earth; Smith and Siegel, 2000) .  The result of this movement was the west block rose upward creating the Teton Range and the east block dropped creating the valley which is know today as Jackson Hole. During the 8 million year time period during which the vast majority of the movement along the fault occurred, 25,000 to 30,000 feet of displacement occurred (2).  Averaging at a rate of 1 foot every 300-400 years (2).  The intense landscape of the Teton Range can be credited to the harsh glaciers that formed and preceded to melt over hundreds of thousands of years (2).  These glaciers eroded the west block into the jagged mountains present today. 

Below is a video illustrating the deformation that occur along the Teton Fault and the formation of the Teton Range in chronological order.

References:
1. The Teton fault, Wyoming: Topographic signature, neotectonics, and mechanisms of deformation. 

John O. D. Byrd

Robert B. Smith

John W. Geissman.  

http://www.uusatrg.utah.edu/PAPERS/TetonFault.JGR.pdf 

2.Creation of the Teton Landscape: The Geologic Story of Grand Teton National Park.  
http://www.nps.gov/parkhistory/online_books/grte/grte_geology/sec3.htm

3.WYOMING STATE GEOLOGICAL SURVEY: Teton Range
http://www.wsgs.wyo.gov/research/stratigraphy/TetonRange/Default.aspx

4.National Park Service, Grand Teton: Park Statistics
http://www.nps.gov/grte/learn/management/statistics.htm

5.http://www.tetonwyo.org/em/topics/earthquake/201705/

6.Discover Grand Teton: Geological Timeline
http://www.discovergrandteton.org/teton-geology/geologic-timeline/