Usoi, Tajikistan Landslide

On the night of 5/6 February 1911 a 7.4 magnitude earthquake struck the Rushon district of the Gorno-Badakshan province of Tajikistan. The village of Usoi was buried by a landslide, causing 54 deaths.  The landslide of ~2 million cubic metres also filled the valley of the Murghab River, producing a natural dam, 3km long and 550m high, reputedly the largest natural dam in the world.  This dam has resulted in the formation of Lake Sarez, about 65km long and containing 18 cubic kilometres of water. There is the risk that a future earthquake will cause a similar landslide to enter the lake and cause a failure of the dam.

The three-dimensional view is from Google Earth (38.28N, 72.60E) and the overview of Lake Sarez is from flashearth (the natural dam is at the NW end of the lake). Third image is taken from the NASA Earth Observatory image. 

Young River Landslide

On 27 August 2007 at 4:40 am a landslide of about 13 million cubic metres of schist dammed the north branch of the Young River in the Southern Alps of New Zealand creating a lake upstream of the debris fan.  The first two images here are from Google Earth (44.143S 169.124E), the third is from flashearth.

More details of the landslide from Dave Petley's Landslide Blog, and a GNS Science poster (warning pdf). 

Slumgullion Earthflow, Colorado

This is my favorite landslide in the world, mainly for personal reasons. My family had a place high in the San Juan Mountains of SW Colorado for many years when I was in college and grad school. We could see part of the 'Slumgullion slide' from our kitchen and crossed it in (yes) snowmobiles many times in the winters between 1984 and 1998 or so.

The flagrant head scarp / source area

Tango and I at the outermost tension crack above the head scarp (back in 1995 or so)

The sheer severity of the head scarp.

It is a late Holocene feature between about 300 and 600 years old. The landslide created a dam on the Lake Fork of the Gunnison River just upstream of Lake City, Colorado to create Lake San Cristobal. I believe that the lake is the second largest natural lake in Colorado.

 It is a spectacularly well-expressed earth flow with an obvious source area and terminus. Wonder how long it can hold back the lake? Note that an older late Holocene earthflow once dammed the river downstream near Lake City but is now gone. Keep in mind that the failure of a landslide dam is one of the best ways to create a truly catastrophic flood.

Nice shot of Lake San Cristobal in the fall (sometime in the early 90s)

Ideal perspective afforded by Google Earth.

Take me there.

More on the Slumgullion Earthflow:

http://pubs.usgs.gov/bul/b2130/

http://www.ess.washington.edu/~gomberg/Papers/GombergetalGeology95.pdf

Blackhawk: Truly Pathological

I'm posting a few additional views of the Blackhawk Landslide in California, to emphasize the truly pathological geomorphology of the area. In the views showing slide toe and slide source, I've moved the source area farther into the mountain from the original given by San Diego State (kmz). I've done this based on prior knowledge and published maps. Basically, the entire steep northern face of Blackhawk Mountain is the slide source area.

Additionally, there are other older landslides in the area, most notably the one sometimes called the Silver Reef landslide, which is just east of the Blackhawk. Also, many additional breccias and possible landslide deposits have been mapped in the area. The geologic maps (Big Bear City quad and Cougar Buttes quad) are really awesome, especially if you know how complex the geology really is. There are numerous thrusts from the south, placing brecciated rocks of multiple ages on usually older rocks. In at least one place, bedrock has been pushed over one of the older breccias. Or is it really bedrock?

Back in the 1980's, I mapped a large area of Blackhawk Mountain and surrounding areas at 1inch = 500 feet. I found, and so have others working in the nearby northern slopes of the San Bernardino Mountains, that if you start at the top, clearly in bedrock, sometimes brecciated, and map down, then you will be tempted to map bedrock until you are clearly in landslide debris. If you start from the top and map up, the opposite is likely to happen.

The reason for northward thrusting is the bend in the San Andreas fault, causing the westward, southward side to be pushed northward, breaking over the steepened San Bernardino Mountains in low-angle faults. The thrusts cause brecciation, and the steepening, brecciation, and low-angle faulting predisposes the area to massive sliding. Stratigraphy is somewhat retained in the slides, and gold has been mined from nicely pre-broken landslid rock of the Blackhawk Slide. Silver occurs in somewhat disturbed veins in the Silver Reef Slide.

In the annotated view, the Younger LS deposits (yellow) are Holocene or late Pleistocene; the Older LS deposists (turquoise and pink) are middle or early Pleistocene; the Moderately Old LS deposits (purple and orange) are middle or early Pleistocene; the very old debris flow fan deposit (purple) is middle or early Pleistocene; and the QT Breccias (blue and red) are Pleistocene or Pliocene.

'Out of the blue' landslide in Taiwan

I came across some killer mass-wasting photos via a long email chain
recently. A colleague who was in Taipei at the time indicated that
this event occurred on a dry day and with no corresponding seismic
activity...thus, 'out of the blue'.

Event occurred in April 2010 in vicinity of Keelung City:

http://goo.gl/maps/bc1t

Enormous Debris Avalanche at Mount Shasta, Northern California

From the USGS CVO page on the deposit:

The deposits of an exceptionally large debris avalanche extend from the base of Mount Shasta volcano northward across the floor of Shasta Valley in northern California. The debris-avalanche deposits underlie an area of about 675 square kilometers, and their estimated volume is at least 45 cubic kilometers. Radiometric limiting dates suggest that the debris avalanche occurred between about 300,000 and 380,000 years ago. Hundreds of mounds, hills, and ridges formed by the avalanche deposits are separated by flat areas that slope generally northward at about 5 meters per kilometer. The hills and ridges are formed by the block facies of the deposits, which includes masses of andesite lava tens to hundreds of meters across as well as stratigraphic successions of unconsolidated deposits of pyroclastic flows, lahars, air-fall tephra, and alluvium, which were carried intact within the debris avalanche. The northern terminus of the block facies is near Montague, at a distance of about 49 kilometers from the present summit of the volcano. The flat areas between hills and ridges are underlain by the matrix facies, which is an unsorted and unstratified mudflowlike deposit of sand, silt, clay, and rock fragments derived chiefly from the volcano. Boulders of volcanic rock from Mount Shasta are scattered along the west side of Shasta Valley and in the part of Shasta Valley that lies north of Montague, at heights of as much as 100 meters above the adjacent surface of the debris-avalanche deposits. The boulders represent a lag that was formed after the main body of the avalanche came to rest, when much of the still-fluid matrix facies drained away and flowed out of Shasta Valley down the Shasta River valley and into the Klamath River.

 Easily viewable from the main north-south route through the area, I-5, the volume and area covered by this landslide are breath-taking, and should be required viewing for those who live in the shadow of Cascade volcanoes, especially those to the NW of Mt. Rainier.

Goldau Landslide

Over at the History of Geology blog, David Bressan is commemorating the Goldau Landslide in Switzerland that occurred on September 2, 1806. A landslide from the Rossberg mountain killed nearly 500 people.  It was the first time that a natural, as opposed to supernatural, cause was assigned to a geological disaster.  Please visit David's blog for the full story.

What is fascinating I think, is that the views of the two contemporary paintings of the landslide that David uses to illustrate his post, one by Xaver Triner, the other by David Alois can be recreated in Google Earth and show the remains of the landslide today.

Further references in David Bressan's post.

Flashearth view and the Google version.

Blackhawk landslide, California

One of the largest known mass wasting events in North America is the Blackhawk slide in California’s Mojave Desert. Located in the Lucerne Valley area, north of the San Bernardino Range, the slide is ~5 miles long, ~2 miles wide, and between 30 and 100 feet thick. These extraordinary dimensions are attributed to almost frictionless sliding of the rock debris as it rode along a layer of compressed air, like a hovercraft or air-hockey puck. As the high pressure air squeezed out, the free ride ended, and the slide debris settled to the floor of the desert, somewhere in the neighborhood of 17,000 years ago.

A nice deposit of information on the slide can be found here:

http://www.lucernevalley.net/history/blackhawk.htm

Flash Earth link to the spot:

http://www.flashearth.com/?lat=34.37986&lon=-116.794111&z=12.9&r=357&src=msa

Goleta submarine landslide

Mass wasting is the theme for September and I'm gonna go subaqueous on day one and show one of my favorites -- the beautiful Goleta submarine landslide complex offshore of Santa Barbara, California. Pretty awesome!

Mam Tor Landslide

So September is officially mass wasting month. Since it was my suggestion, I suppose I had better make a contribution. 

Here is probably England's most famous landslide at Mam Tor in Derbyshire. Actually initiated about 4,000 years ago, the landslide way traversed by a salt trading route across the Peak District which later became the A625 trunk road. It was continuously plagued by movement, particularly after heavy rains. The road, finally abandoned in 1979, shows several generations of tarmac and gravel several metres thick.  The landslide, displaying the classic crescentic back scar and debris flow toe, is monitored by the University of Manchester and moves on average about 25cm per year, more after heavy rain.

Mam Tor - or the Shivering Mountain, is comprised of Namurian turbiditic sandstones and mudstones. The summit shows the earthworks from a late Bronze Age to early Iron Age hill fort, probably occupied from about 1200 BC.

More details from the British Geological Survey.

The flashearth link is here but the Google Earth imagery is better.

Wave scarps and fault scarps and composites thereof. More pathological Nevada geomorphology.

Shoreline scarps look like faults with one exception, they follow contours. That is an important field camp lesson in the Great Basin. Faults have little inclination to follow elevation contours, whereas a lakeshore has little choice not to, so to speak. One interesting exception is when the two types of scarps are one in the same.

Trinity Canyon Fan near Oreanna, Nevada.

These kinds of areas provide a straightfoward perspective on how much alluvial fan activity has occurred since pluvial lake desiccation. Just look how that young fan overrides all of the recessional shorelines of Lake Lahontan. This is a hint toward a great study of Holocene sediment yield in the region that someone's student should work on.

The beautifully varnished fan remnant in the image below also shows an abrupt truncation along an elevation contour. Looks kinda like fault, except for its symmetry and the fact that depositional beach ridges and not erosional scarps are the lake level evidence.

Leach Canyon, Nevada

A stellar example of a wave-modified fault scarp is in the image below. 

Here you can see a series of shoreline features as obvious concentric bands in the image. Note that the right (east) most linear feature is a fault. Note its weakly sinuous shape and that it departs slightly from the curvature of the adjacent beach ridge where cuts through a distinct fan surface. It then verges northward with the shoreline feature to become a prominent wave-modified scarp. There are many situations like this in Nevada where the fault and the pluvial scarp are composite features. This particular area has good contrast to show off the phenomenon.

Hmmm...yes...I can see that...maybe. I will go check for myself.

Quaternary faults and ne(at)otectonic features of Nevada, Exhibit C

Let's leave the single-strand faults behind and check out some nicely sliced and diced Nevada piedmonts. First, we have spectacular piedmont of Lone Mountain near Tonopah, Nevada. Long one of my favorite places to hang out in the desert. Never a soul around. The various fault traces along the piedmont have produced / enhanced an interesting array of alluvial fans. Also, note the very nice beach cusp produced by what was once a very remote desert lake in the late Pleistocene.

Lone Mountain.

Next we go back up to Dixie Valley and learn that what looks like a simple fault in a previous entry is a mere hint of how things have gone in the Pleistocene.

Dixie Valley

For the final entry, down to Fish Lake Valley at the foot of the White Mountains. Luckily, Nevada shares part of this range with California. In fact, Nevada's highest peak, Boundary Peak, straddles the state line near the northern tip of the Whites.

The flight from Reno to Vegas goes right over this fan (in addition to 100s of others). Take that flight sometime. Truly a thing to behold.

Fish Lake Fan Fault Frenzy

There are many more examples, but I need to move on to a different pathology before my time in Nevada runs out.

Quaternary faults and ne(at)otectonic features of Nevada, Exhibit B

There was an impressive quake or two (~ M 7.1) in Fairview Valley and Dixie Valley, Nevada back in 1954. The results are some spectacular and very fresh fault scarps. Don't be fooled... that white line along the mountain front is no road.

Go check this place out...see how far you can follow the rupture and how it influences the landscape...in particular, look for older faults and evaluate them as well.

I wish I were in Dixie...Valley, Nevada

More on the Quakes in question.  

Quaternary faults and ne(at)otectonic features of Nevada, Exhibit A

There are many active faults in Nevada. A huge chunk of the state helps to accommodate the strain imparted by the relative motion of the Pacific and North American plates...at least that is what I am told. In any case, the array of active faults results in some pathological Quaternary geomorphic vignettes and some extremely cool map relations. As opposed to piling them all up in one post, I am going for a mini-series here. First up will be some particularly young ruptures.

Granite Springs Valley / Sahwave Mtns, NV

I also got some sweet photos of this area from a geocentric plane ride last year: 

Pluvial pathology of Nevada, Part 1.

The legacy of pluvial lakes in Nevada may be the state's most redeeming Quaternary quality. Not only did it host the lion's share of Lake Lahontan (and its earlier precursors) but it hosted a small part of Lake Bonneville in addition to 10s of other large-ish lakes in isolated closed basins. I used to teach field camp out in Spring Valley, Nevada and recall that every year the crop of students was generally blown away by the presence of shoreline deposits and landforms in the arid interior of Nevada. Come to think of it, it is downright pathological...the freaking driest state in the country was full of lakes only 12,000 years ago.These images show some elaborate depositional forms including spits, bars, and cusps. Note how the cool array of cross-cutting relationships lends itself to an appreciation of surficial processes.

Spits, etc. in Grass Valley, NV:

Shoreline features in Ruby Valley, Nevada

This image also includes a nice reminder that all streams that cut through relief are not antecedent.

The pathological bar complex at the north end of Spring Valley, NV

I have posted this before, but it is amazing enough to post twice. At field camp, we would have an impromptu frisbee game on the big playa...aptly named: Big Hard Pan. This bar complex shows all kinds of evidence for downstream-cascading stream integration on a small scale.

The Barbie Fan: A pathologically perfect Nevada alluvial fan

The state of Nevada has more fans than Las Vegas has foreclosed properties (that's a lot). This particular fan was termed the 'Barbie' fan by my co-author and UNLV colleague Brenda Buck. The name is appropriate because the shape is almost too ideal. We mapped most of the Barbie fan as part of the Ivanpah Valley Mapping Project (the Ivanpah-viathan). 

The fan does have an ideal fan shape. It is also comprised of an elaborate assemblage of Quaternary alluvial surfaces of a broad range of ages, thus further substantiating its Barbie-ness. (see, for example, the paper about the Cedar Creek alluvial fan in Montana...this paper was a field camp staple when I used to run a course on fans in eastern Nevada). Here are links showing different characterizations of the geology of the Barbie Fan:

http://geofroth.posterous.com/the-ivanpah-megamap-in-kml-form

http://geofroth.posterous.com/nevada-geo-flood-hazard-map-in-kml

The Barbie fan is fed by a drainage that cuts right through the Lucy Gray Mountains. It obliquely straddles the border with California, and its outermost point creates a divide between two dry lakes where the fan grazes the southern extremity of the Spring Mountains. The 'lake' to the north (Roach Lake) is entirely in Nevada and the 'lake' to the south (Ivanpah Lake) is about 99.9% in California. The divide now hosts a casino and outlet mall complex (and a roller coaster....Nevada, remember?). The border runs through the parking lot. 

Take a look at the recent drainage courses on the fan and appreciate how a relatively small change in the position of a major distributary channel could convey a flood entirely to either state, or both. A dilemma for water lawyers, possibly. Certainly a potential dilemma for the major airport that has been planned (now on hold for economic reasons) to span the entirety of Roach Lake (yes, that is right, a major airport...Nevada, remember?). Note that Las Vegas is not too far away...just up I-15 about 35 miles.

http://www.flashearth.com/?lat=35.59174&lon=-115.363046&z=10.7&r=0&src=msa

Exquisite folds in the Anti-Atlas, Morocco

Flash Earth link to this fine area.

Nevada's mighty Humboldt River and its pathological meanders.

My first mapping project in Nevada (back in 1998!) was the Battle Mountain Quadrangle, which is completely dominated by the broad floodplain of the Humboldt River. The floodplain is inherited from an ancient lake bed and is extremely flat. Thus, the river meanders like crazy (despite the young age of its course!). The floodplain exhibits textbook fluvial forms and alluvial stratigraphic assemblages (including Pleistocene mega-meanders!). It is also bounded by numerous active faults which enhance its behavior in various ways. While we were working on this and a couple of other quads, the Washington Post published an article in which they named the town of Battle Mountain the 'Armpit of America'. Thus, we had to accept the fact that we were mapping meanderbelts that were essentially the curly hairs in the armpit.

Notably, It was on the broad, flat, and often monotonous floodplain of the Humboldt River that I truly learned the value of GPS in geologic mapping.

Oh, Battle Mountain, how I will miss you.

Visit Battle Mountain!