One Scientist’s Search for the Causes of the Deadly Seti River Flash Flood

January 24th, 2014 by Jeffrey Kargel

Editor’s Note: Jeffrey Kargel is a hydrologist at the University of Arizona and for the Global Land Ice Measurements from Space project. This is his account of the research he did during the aftermath of a deadly flash flood in Nepal’s Seti River Valley to determine its cause. You can read more about the event here.

Seti66''-KharapaniMontage_sm

Silt and gravel deposits trace the path of the 2012 hyperconcentrated slurry flood, which ravaged Kharapani village, shown here. Annotations show where people died and where they survived. Our research group has undertaken a detailed demographic and sociological investigation of the losses and survivors all along the devastated parts of the Seti River. The panel at lower right was a 1-year anniversary meet-and-greet commemoration, where we met survivors, media, and politicians still very much concerned about the disaster. (Photos courtesy of Jeffrey Kargel, University of Arizona.)

On May 5, 2012, I was attending a conference at ICIMOD (the Kathmandu-based International Centre for Integrated Mountain Development). I heard about the terrifying disaster that day. A flash flood—what geologists call a hyperconcentrated slurry because it was thick with suspended silt—had torn through some villages along the Seti River, in north-central Nepal, just north of the country’s second largest city, Pokhara. It was immediately recognized as a very deadly event, but the death toll—and a tally of those who remain missing but were clearly also killed—was not known exactly for several months. Seventy-two souls lost. Though not large on the scale of global disasters, this event was terrifying for the fact that it seemed to come from nowhere—literally from beneath a blue sky. Furthermore, there was no immediately evident cause. Nobody and no camera captured the whole event, but there were bits and pieces that had to be spliced together, and missing parts of the story had to be built from the ground up—literally from the rocks and sediment involved in the disaster.

Seti2_720'

The source area for the avalanche of May 5, 2012. Annapurna IV is just off image to the upper left. The rocks here are layered metamorphosed sedimentary rocks deposited originally in the Tethys Sea before the Himalaya rose; the rock layers are now tilted up. Ice hangs precariously at the ridgeline, and apparently an icefall started the whole messy disaster. A dust cloud lingers from a small debris fall just moments after we first landed in Sabche Cirque 6 months after the disaster. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

Seeing that the disaster occurred at the foot of the Annapurna Range, within the Greater Himalaya, probably every expert’s first thought was “glacial lake outburst flood” (GLOF), because these were common in Nepal’s Himalaya, and the news accounts of the disaster event resembled accounts of GLOFs from other parts of the country.  It took me 10 minutes to examine recent satellite imagery enough to see that there were no lakes, at least not in the images I examined, that could have burst out like this.  So either there was a hidden glacial lake somewhere—maybe under the glacier ice—or a glacial lake developed very rapidly and then drained that tragic day, or—far more probable—this was not a GLOF at all.  It was, however, clearly a disaster that had its source in a high Himalayan amphitheatre-like bowl, a glacially-carved structure called the Sabche Cirque. This structure was rimmed by some of Nepal’s most famous, picturesque mountain peaks, including the storied, holy Machapuchare (the “fishtail” peak) and Annapurna IV, a 24,688-foot (7525 m) soaring metamorphic buttress of metamorphic rock.

Seti6'_720

View of the avalanche deposit of rock and ice shed from Annapurna IV, which is just beyond the upper right corner. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

One of the most important pieces of information on the cause of the disaster was obtained from wingtip cameras mounted on a tiny 2-seater tourist plane.  The pilot, Captain Maximov, had observed what was obviously a giant avalanche—bigger and browner than any snow avalanche he had ever seen before; he then he saw a massive flood wave pouring down the Seti River valley.  It was evident immediately that this brown cloud of roiling airborne debris was connected to the trigger for the disastrous flood.

This distant view provided in the tourist plane’s video, in addition to later observations I was able to make from the Sabche Cirque itself, led to a confident sourcing of the brown cloud and the disaster’s trigger on a ridgeline near Annapurna IV.  Apparently part this ridge—probably initially the glacier ice— collapsed, dropping ice and rock over 3000 m almost vertically (about 10,000 feet) onto unconsolidated rock debris (glacial moraines and ancient glacial lake silts and gravels) resting unstably in the deep bowl of the Sabche Cirque.  Some of that loose debris was also swept up by the avalanche, and the mass flowed an additional 1,500 meters (about 5,000 feet) into the Seti River gorge.

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Ancient glacial lake sediments such as these in the Sabche Cirque were swept up by the avalanche and ingested both into the ground surge and airborne cloud, then ingested into the reservoir, which then burst forth onto unsuspecting people below.(Photo courtesy of Jeffrey Kargel, University of Arizona.)

The triggering avalanche—though enormous and bigger than almost any normal avalanche—was the easy part of the explanation of the disaster.  The hard part was identifying the source of the water, because there was no glacial lake or no known lake at all in the area.  Somewhere a large amount of water had been stored and then suddenly released. Speculation centered on water contained within unseen and unknown caves, or within the deep gorge of the Seti River, and last of all, possible subglacial lakes or lots of little ponds that acted like one big lake. This flood appeared to behave like a glacier lake outburst flood, and the news media can be pardoned for having assumed that it was. From that first day, I and other experts tried to counter the media view that it was a GLOF, but anyway, it was a lot of floodwater.

Since I was in Nepal, I immediately contracted for a helicopter to fly me and some colleagues over the Sabche Cirque. We observed directly evidence of the avalanche—boulders and dust and snow-like pulverized ice in a huge sheet, and streamers of debris emanating from the base of Annapurna IV to the head of the enormous Seti River gorge. We helicoptered over the glaciers and found some small ponds, but nothing that could explain the volume of water; and besides, the ponds were in the wrong place to have been strongly affected by Annapurna IV’s ice/rock avalanche. The pathway of the avalanche became ever clearer after post-disaster Landsat and ASTER images showed clear details of the avalanche deposits.

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The avalanche route through the upper gorge. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

Speculation was now focused toward the gorge. Could something have blocked it?  Well corroborated resident eyewitnesses interviewed by our team indicated that one to three weeks prior to the disaster, the Seti River had slowed to a mere trickle of clean water, unlike the usual turbid, sediment-laden “glacial milk.” (Seti means white, so it is the White River.)  These various observations and ideas had already started to coalesce when my assistant, Greg Leonard, observed a speck of change that had occurred in “before” and “after” ASTER satellite images.  We had a specific spot to look for a rockfall into the gorge.  Then looking at our helicopter-borne photography, we found it. It was indeed a fresh rockfall straight into the gorge, right at a place from which it appeared a backed-up reservoir had issued a flood. Furthermore, Greg showed that the gorge had experienced many smaller rockfalls or other erosional events over the previous decade, but this bigger one seemed to be fresh. The gorge now seemed the likeliest culprit, but at first it seemed difficult to comprehend how much water could be stored in the gorge behind a rockslide dam.

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Flattened forest blown down by the avalanche winds. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

In the days after the disaster, I examined amateur video of the event taken from Pokhara, a couple dozen kilometers downstream from the gorge. I watched as the flood reached Pokhara and as floating trees trunks poured over a dam. It provided the first best opportunity to measure the speed of the floodwaters and its depth and width, and thus measure the volume rate of flow and estimate the total flood volume. The flood came in waves, and the first wave alone was around a quarter of a million cubic meters in just a few minutes. There were about 27 waves in all over the next hours, according to eyewitnesses, so several million cubic meters overall.

At first it seemed a stretch for any one of the suggested water sources to explain the water volume, and this still is a part of the challenge to provide the full explanation of this event. Even my grandson, also intrigued as well as horrified by the disaster, brought his 7-year-old intellect to bear and suggested that it was friction that melted snow and ice that had tumbled off the peaks. Indeed, the conversion of gravitational potential energy to heat could have melted roughly a tenth of the falling snow and ice by the time it reached the Seti River. Nothing seemed quite sufficient; every potential source at first appeared an order of magnitude insufficient to explain the water volume. It seemed that all of the possible sources together might explain the floodwater volume.  Yet one source seemed to be definitely involved, and that was a rockslide-dammed reservoir in the gorge.

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A view of the gorges and also the distant peaks of the Sabche Cirque and the ancient glacial deposits in between. The avalanche entered the gorge from the upper right corner of the scene.

I returned with colleagues to the Sabche Cirque three more times, and we were able to land and set up camp and undertake detailed geological observations. The Sabche Cirque is a violent but beautiful place, with rockfalls, snow and ice avalanches, and flood dangers abounding, and evidence of big and recent geologic activity everywhere we walked or flew. We sampled and later chemically and mineralogically analyzed the dust fallout from Captain Maximov’s brown cloud, and linked it to the sediment deposited by the flood on the ravaged villages downstream. We analyzed the bedrock, the boulders of the avalanche, and searched for other evidence of floods and debris flows. That evidence is everywhere. However, the more we searched, the more it became evident that this was definitely not a GLOF, but was caused by a rockslide into the Seti River gorge, formation of an impoundment reservoir over a several week period due to damming of spring snow and ice melt, and then the final triggering event of the mighty rock and ice avalanche off Annapurna IV. On our most recent trip we used a laser device to determine the depth and width of the gorge and discovered that it is so immense that it alone might account for the required water volume.

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Our first view of the rockslide that initially dammed the Seti River some weeks prior to May 5, 2012, and set the stage for the deadly terror. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

Although this was a terrifying and deadly event, by geologic standards it was not particularly huge. The death toll was due foremost to people living in harm’s way on the lowest terrace and even on the lowest floodplain. Our findings do not bode well for the future of the small settlements scattered along the riverside, and there would seem to be a strong case for resettlement.

Seti60''-Village&LittleWoman'sHouse-DSC_5547_sm

Another devastated area, where there were losses and survivors. A year after the disaster, we were surprised to see a woman living in a house that had barely escaped destruction. Her husband was a river worker. Cattle were grazing nearby. Survivors told harrowing and heart-breaking stories of their tragic losses. (Photos courtesy of Jeffrey Kargel, University of Arizona.)

ACKNOWLEDGMENTS.  This sequence of events was pieced together from many data sources, and many people were involved, among them my colleagues and myself, but also Captain Maximov, local villagers, landslide blogger David Petley and his associates; research staff and my field assistants from ICIMOD, especially Sharad Joshi; my other Nepalese colleagues, including Dr. Dhananjay Regmi and Dr. Lalu Poudel; our chief climber, JB Rai and his Sherpa assistants; and two doctoral students, Khagendra Poudel and Bhabana Thapa, who are investigating the geomorphology and sociology of the disaster. I also need to give special thanks to my tireless assistant, Greg Leonard, who was the prime satellite image analyst as well as my chief field assistant.  Finally, I express gratitude to the NASA/USAID SERVIR Applied Sciences Team,  NASA’s Cryosphere Program, and the USAID Climber Science Program, who funded different aspects and phases of this work, and the U.S.-Japan ASTER project, which provided the ASTER imagery. This work will be presented in more complete detail within an upcoming peer-reviewed scientific publication.

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A mosaic of images showing the rockslide area in the foreground in the glacial sediments and avalanche route in the background. (Photo courtesy of Jeffrey Kargel, University of Arizona.)

 

49 Responses to “One Scientist’s Search for the Causes of the Deadly Seti River Flash Flood”

  1. Chuck Kargel says:

    Just wanted to thank you for posting this. I enjoy and learn from you all the time. I think this is outstanding …..Green with envy again. Thanks Jeff

  2. Himanshu Thakkar says:

    Many thanks, this is an amazing account of the events that unfolded in that distant gorge in May 2012. We hope we can publish parts of it (with due credit) on our blog (http://sandrp.wordpress.com/) for public education.

  3. Kanak Mani Dixit says:

    Thank you for this detailed report of the event and tragedy on the flanks of Annapurna. Find the details riveting, including of the blast that flattened trees and apparently undid the rockfall dam. For future ref, it would be good to try and understand whether there are links between this ‘micro-event’ and the mega-event of the formation of Pokhara Valley itself, with rock and debris from on high. Thank you again.

    • Jeff Kargel says:

      Kanak, good point, and yes, this is an active area of investigation in our project, including a PhD project. For this public communication, I didn’t want to mix the two stories. Though in some respects they are related, and the older bigger events have much to inform about the potential for future events bigger than May 5, 2012, I don’t want misunderstandings to spread about the degree of hazard and risk present. So I would like to keep the two stories separate, even though scientifically there’re some relationships swell as huge differences in cause and magnitude and expected frequency. But it is a good point.

  4. Ambarish says:

    Good job in Nepal. Thanks Kargel

  5. Ranjan K Dahal says:

    Good job, I enjoyed your writing. I had also similar experience when flying there!

  6. Alec says:

    A great morning read. Now I want to be part of an investigation like that.

  7. Gerrit Holl says:

    Thank you for this detailed and interesting report with the beautiful photos. Is this project finished or is it still going on?

    • Jeff Kargel says:

      Gerritt, it is still going on in the sense that we are preparing a scientific report. I would normally wait until after that was completed to do a blog like this, but NASA was going ahead with their post related to the astronaut photography, and they made a request for assistance, and this was an opportunity for outreach. But there will be more. I would not expect the qualitative story to change,but there will be many more details,more photos, lab analysis, gorge dimensional measurements, a lot of observations, a lot of testing of other hypotheses, and so on that I could not post here. So you can stay tuned. But the bottom line will be the same as here, and so I think there will be nothing newsworthy or of general public interest, but we need to present our full results and need to take methodical and peer reviewed approach with that. This said, there are still many outstanding/unresolved questions, most of a technical geological nature. And our paper will show why continued monitoring is needed. So in that sense even the field work is ongoing, and you can always expect new details to provide important new insights or even alter some conclusions. We are confident about the basic conclusions to date, however.

  8. Laba Guragain says:

    dear kargel,

    thank you very much for all those information

  9. Umesh Singh says:

    Thank you for a wonderful piece of work. I am optimistic that it will add great value to the further research, particularly on hazard mapping and frequency of such events within the area.

    After reading your story, I am quite curious to know the impacts of the event in near future. Such as how the river will react to find the new equilibrium now. Huge amount of loose sediment deposits seems to remains at the disposal of the river as the source of sediment to change its morphodynamics. There are still people living close to the river.

    Cheers

    • Jeff Kargel says:

      Umesh,
      Yes, the river will continue to adapt to the sediment that was supplied by this slurry flow, but that is a continuous process even without a large influx of sediment. Meanders always change, sediment bars shift, and so on. I would not expect anything disastrous to occur regarding this re-adaptation. But your point about there still being people living near river’s edge is an important one. Without wishing to cause undue alarm (the residents are already alarmed enough by their own observations and experiences as survivors of the 2012 event), it is clear that some people are living in harm’s way. There is no doubt. Questions arise, which I cannot answer, about what to do. On their own resources, many of these people cannot move elsewhere. There is a conundrum. The resolution of that conundrum is beyond my pay grade to resolve. But the residents may rest assured that I and my team have their lives and livelihoods very close to our team’s hearts and minds. This is exactly why we are doing this work so intently. In the whole Earth there are many geological stories much bigger for me to work on; but when I walk through these villages, I cannot turn my back on the residents. With some science investigations, the science turns into a real responsibility and a burden which I and my colleagues must carry.

  10. Rashmi Kiran Shrestha says:

    Very interesting. we were just awfully surprised and sad by that event in Nepal. Now we have a reason. It is a very good reference for our research on Asian Development Bank on Upper Seti hydropower dam project. Thank you so much for this kind of study.

    • Jeff Kargel says:

      Rashmi, I think we should have a private discussion offline. Perhaps that can be done via Dhananjay Regmi, who I understand you may know. Can you call him? Or he can call you.

  11. Shreekamal Dwivedi says:

    I am eager to see your paper supporting your theory of rock dam failure during the Seti Flood of 5th May 2012. I would be happy to read your answer to the following :-
    1) Your blog itself agrees that the huge amount of sediments brought by the avalanche routed through the upper gorge (showing high level marks in the photograph), now why it could not progress in the downstream part as you suggesting that it plunged down the gorge into your assumed huge lake inside the gorge formed by rockslide dam?
    2) What was the form the avalanche material – solid dust or slurry ! Your theory of dam break should answer how that sediment in the upper gorge mixed with the assumed lake water more than 3.5 km downstream of the origin of the avalanche. And if the material could flow in the upper gorge the why it cannot travel to the lower gorge area?
    3) You did not mention the energy generated by the impact of the ridge collapse. You have enough resources , so please calculate the heat which was generated by the impact able to generate surface wave of 3.8 richter scale (this was measured by the National Seismological Center, Nepal) . Please calculate also the volume of the mountain that broke off from the ridge.
    4) You said that your laser investigation showed deep gorge having the space to hold water, it would be really interesting to see the proof of impounded water before the event using high resolution images in visible band or NIR band . I have tried many hours to find the damming by the landslide in the satellite image of 20 April 2012 (provided in the NASA website ), but I could not find the lake.
    5) The seismic record shows the rock fall hit the ground at 9:09.56 AM. local time and the photograph taken by Shiva Acharya shows the arrival of the debris flow at Kharapani ( 20 km. downstream at 9:38 AM. That is about 28 minutes that is at the velocity of almost 12 meters/second. For your dam break theory there should be some delay at the assumed lake for the sediments to plunge into the lake till the dam break progressed. for But the seismic record has shown continuous signal of surface waves for 70 minutes at seismic station in Dansing , Kaski.
    6) Even if there was a small volume of water in the gorge lake , it cannot be held as the main cause of the event as it seems to me that for the continuous debris flow which was generated and travelled in the upstream of the gorge area has progressed continuously downstream without time delay.
    7) I would like to thank you for the nice photographs of the area which are going to be very useful for the researchers to understand the mechanism of the event.

    • Jeff Kargel says:

      Shreekamal,
      Your questions are important, and mainly they will be addressed in a technical paper, which will be more relevant than this blog, to your technical questions.

      • Shreekamal Dwivedi says:

        In the run to propose “some new mechanism”, I know that you and ICIMOD disagree on my and other other researcher’s results. You can find the research I did to find the above answers presented in the paper “Cause and mechanism of the Seti Flood of 5th May 2012, Western Nepal , Journal of Nepal Geological Society, 2013, Vol. 46, pp. 11-18″. Interestingly, one of your research partner Dr. Lalu Poudel was the chief editor of the volume which contains this paper along with the paper Hanisch, J., Koirala, A., and Bhandary, N., 2013, The Pokhara disaster: a last warning sign sent by nature?, Journal of Nepal Geological Society, Vol. 46, pp 1-10. I really wonder how you could not have access to these papers??

  12. JoAnn Kargel Walker says:

    I am delighted to have the opportunity to read this. Thank you for sharing. I hope to send it on to my son Scott who has had some study and great interest in prehistoric land and rock formations.

  13. Sagarmatha says:

    This is no-sense report. The writer does not what is he talking about? The great American noise for nothing~, this is how the whole world is being formed.

  14. Jagat K. Bhusal says:

    Great job ! Thanks to Dr. Kargel for bringing the cause of seti flood.

    My suggestion : It would be more clear if damming height, impounded area, volume and location as well as erosional and depositional length (river reaches) are identified further. These information will be much beneficial in establishing flood warning system in Seti river in Nepal .

  15. Dave Rennolds says:

    Thank you for your report. Do you know if the collapse of the Annapurna IV ice ridge was due to natural causes i.e collapse of the rock due to weathering, excessive build- up of snow, or due to seismic activity? I hope your work in the area prevents further loss of life – good luck

    • Jeff Kargel says:

      Dave,
      I don’t know exactly what triggered the movement of ice and rock off Annapurna IV. However, it probably was a very normal/usual kind of event that happens frequently on different magnitudes. One thing can be ruled out. It was not thawing, as the high elevations close to the peak and ridge line were very cold. Lower down, where the avalanche impacted, it was probably thawing (certainly it was a couple weeks later),and it would seem that the seismic activity that was observed was a result of the avalanche, not a cause of it. Excessive ice build up, as you call, was probably involved– that is always a usual thing in such glaciered terrain of high peaks and ridges;and then such build-ups of cornice ice has to be released by avalanches. However, if you are seeking ideas about what could trigger a future event, thawing, excessive ice build-up, thawing or freeze-thaw cycles, seismic activity, and so on are all likely and probably usual causes of small and big avalanches. The question then is how will the bigger events affect the “bedrock” and unconsolidated deposits immediately below. Will further material be ingested? Then how is that material channeled? How much water is available from supra glacial ponds and lakes, from wet snow, from other water bodies? And then what happens? So most avalanches, even big ones, will probably not do anything harmful in this case. But sometime, there will be harmful events,and they can happen in 100 different ways, due twosome many things happening in the Sabche Cirque and gorge.

  16. Barry says:

    Having been in that part of Nepal I was horrified and fascinated.

    I am a little disturbed at your remarks about being surprised a the location of some houses. As I am sure you appreciate the Nepalese people who live in such locations are poor and cannot afford to either build or buy housing in the ‘best’ places.

    • Jeff Kargel says:

      Barry,
      The disturbance to me is the fact that people are living that way. Of course the material resources of many of these people are very limited. So a good solution must be found. Ignoring the presence of the villages is probably not taking their interests to heart, and allowing urbanization of the lower terrace and floodplain to continue is really not what I would recommend (UNDERSTATEMENT). What the solution is is a more difficult matter than identifying the fact that there is a problem. But the problem should be fairly evident.

  17. AASHUTOSH says:

    WOW…Really a good news to hear….thumbs up for your research….inspired…

  18. Joerg Hanisch says:

    This report announcing a forthcoming paper is right mainly in the very first word: it is the opinion of ONE searcher!

    A scientist would have not written such a poorly founded article; a scientist would have carefully checked the existing literature and correctly referred to and discussed the various papers on the disaster. The extremely complex event of May 5, 2012 causing the death of more than 70 people would have merited a much deeper and much more founded study.

    Some points:
    - How to explain the up to 27 surges of the mud flow/hyper-concentrated flow by a singular landslide dam? Roll waves are an integrate part of debris flows and have nothing to do with temporary landslide damming.
    - The small rockslide with in the upper Seti River gorge was present already in the Google Earth image of December 30, 2011. Even if it had grown big enough to store some water in the extremely narrow gorge (where are attempts to estimate the possible volume of such an assumed lake) and where is the evidence within the gorge? In the report of ICIMOD of July 2012, with Jeff Kargel as the key author, climbing down into the gorge was announced also to proof his curious idea of hidden and water-filled karst caverns which released their water during the event!??
    - The extremely heavy impact of about 12 Mio cubic meters of rock onto the glacier ice at the foot of the slope (see Petley) and the formation of a Huascarán-like flow in the Sabche Cirque (see recent high-resolution images in Google Earth) are simply neglected.
    - Neglected is also the wider significance of the disaster: about 750 b.p. we had a well-documented similar – but giant – event filling the whole Pokhara Valley with up 5 cubic kilometers of debris (today there are about half a million of inhabitants).

    If this is the whole outcome of several field visits and helicopter flights into the Sabche Cirque and the funds of several tens of thousands of Dollars spent – one must raise the question who gave the money for such a poor study.

    • Jeff Kargel says:

      Joerge, maybe give some time….not much. I would have preferred to wait, but NASA was going ahead with their Earth Observatory piece framed around the astronaut photography. I am sorry I left you out of the credits,but there will be a time and place (in the peer reviewed literature)to give full due credit. We did not even give acknowledgment tour own ideas and methodology. Furthermore, the photos documenting this were reduced by 60% relative to what was posted. Earth Observatory and Notes from the Field is nota scientific publication…Earth Observatory is a showcase of satellite and astronauts images of Earth,and Notes from the Field are notes from the field. But all that said, thanks for your contributions in the literature, and also for your comments here.

      • Joerg Hanisch says:

        Hi Jeff,
        Thanks for clarifying a bit. Nevertheless I insist that gorge blocking only was a minor detail of the story.
        Let us wait for the main paper – hopefully thoroughly peer-reviewed.

  19. Bharat Kumar Shrestha says:

    I am interested to read this paper as I had visited the place at the time of disaster.

  20. Donald Alford says:

    I recommend that Kargel and his colleagues at NASA and Arizona familiarize themselves with the work of Dr. Hanisch before announcing a “final solution”. Hanisch, J., Koirala, A., and Bhandary, N., 2013, The Pokhara disaster: a last warning sign sent by nature?, Journal of Nepal Geological Society, Vol. 46, pp 1-10.

    • Himanshu Thakkar says:

      Donald, can you send a link to this paper or the paper itself to my email address: ht.sandrp@gmail.com? Thanks in anticipation,

      Himanshu

    • Jeff Kargel says:

      Donald and Joerg, This paper will be very well represented and well considered in our work. Thanks for bringing it to the attention of blog readers.

      • I Swart says:

        Very interesting findings, good work. Did a meteorite perhaps add some heat to the mix – hence the unexpected volume of meltwater?

        • Jeff Kargel says:

          I Swart, whereas I and my group, and other scientists have considered this event in the framework of multiple working hypotheses, and we (OK, I’ll speak for my group here) have ruled out certain mechanisms and placed quantitative limits on others, meteorite impact was not one of the mechanisms we considered. As I come from a planetary science as well as geological background, the idea of impact is not unusual to me. However, this particular area has many different types of mass movements, some small, some large, and in general they are clearly not impact related. If this was an area where no other likely cause of a mass movement (and heating/melting) was possible or likely, then the consideration of multiple working hypotheses could include impact. However, when there are so many actual and potential nonimpact sources of floods and mass movements, and also where there is no direct or circumstantial evidence for an impact, that would seem extremely improbable. Anyway, thanks for your interest.

      • Joerg Hanisch says:

        Hi Jeff, reading your reply in Dave Petley’s blog a word of Goethe comes to my mind:
        I hear the message well but lack faith’s constant trust, meaning that all what we can observe from you is publicity, eg the public presentation of very early findings in Pokhara in October last year.
        Reducing the Seti disaster to a simple rockslide-dam outburst in my mind is irresponsible. Such temporay dams are very frequent in any high-mountain areas; the impact of perhaps 35 m tons of rock on a glacier leading to sturzstroms like in Chile (Parraguirre), Russian Caucasus (Karmadon), or now in Nepal (Sabche Cirque) is a completely different story.

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