Nav: Home

Catastrophic medieval earthquakes in the Nepal

December 16, 2015

16.12.2015: Pokhara, the second largest town of Nepal, has been built on massive debris deposits, which are associated with strong medieval earthquakes. Three quakes, in 1100, 1255 and 1344, with magnitudes of around Mw 8 triggered large-scale collapses, mass wasting and initiated the redistribution of material by catastrophic debris flows on the mountain range. An international team of scientists led by the University of Potsdam has discovered that these flows of gravel, rocks and sand have poured over a distance of more than 60 kilometers from the high mountain peaks of the Annapurna massif downstream.

Christoff Andermann from the GFZ German Research Centre for Geosciences in Potsdam participated in the study, published now in the Science magazine. "We have dated the lake sediments in the dammed tributary valleys using 14C radiocarbon. The measured ages of the sediment depositions coincide with the timing of documented large earthquakes in the region".

One big boulder, situated on top of the sediment depositions, has raised the interest of the scientists: "The boulder has a diameter of almost ten meters and weighs around 300 tons. At the top of the boulder we measured the concentration of a Beryllium isotope which is produced by cosmogenic radiation." This 10Be chemical extraction was carried out in the isotope laboratory at the GFZ in Potsdam and was measured with the accelerator mass spectrometer at the Helmholtz-Zentrum Dresden-Rossendorf, Germany. The results show that the deposition of the big boulder matches the timing of another large earthquake from 1681. Pokhara lies at the foot of the more than 8000 meters high Annapurna massif; whether the big boulder was transported during the last dated earthquake with the debris, or was just toppled by the strong shaking needs to be further investigated. Nevertheless, the movement of the big boulder can be connected to this strong earthquake.

This research has several important implications reaching beyond fundamental earth sciences. The study provides new insights into the mobilization and volumes of transported material associated with strong earthquakes. Dating of such sediment bodies provides information about the reoccurrence intervals of earthquakes in the Himalayas, and ultimately demonstrates the role of earthquakes in shaping high mountain landscapes. This knowledge is crucial to better evaluate the risks in tectonically active mountain belts.
-end-
Wolfgang Schwanghart, Anne Bernhardt, Amelie Stolle, Philipp Hoelzmann, Basanta R. Adhikari, Christoff Andermann, Stefanie Tofelde, Silke Merchel, Georg Rugel, Monique Fort, Oliver Korup: „Repeated catastrophic valley infill following medieval earthquakes in the Nepal Himalaya", Science, 16.12.2015, DOI: http://www.sciencemag.org/lookup/doi/10.1126/science.aac9865

Photos in a printable resolution: (all photos: Christoff Andermann, GFZ) https://media.gfz-potsdam.de/gfz/wv/pm/15/10225_Nepal-Sediment_Christoff-Andermann-GFZ.JPG Bhim Kali boulder on top of the sediment deposits near Pokhara in Nepal. The boulder is approx. 10m in diameter and weighs around 300kg. The timing of deposition of this boulder has been dated in this study and coincides with the timing of a large earthquake in 1681 in Nepal.

https://media.gfz-potsdam.de/gfz/wv/pm/15/10224_Nepal-Sediment_Christoff-Andermann-GFZ.JPG

View from the airplane onto the river terraces cut into the massive sediment deposits in Pokhara Nepal. The sediments have been mobilized through several strong earthquakes and transported along the Seti Khola river (backround).

https://media.gfz-potsdam.de/gfz/wv/pm/15/10229_Nepal-Sediment_Christoff-Andermann-GFZ.JPG

View from the sediment terraces in Pokhara Valley onto the source area of the sediments in the high Annapurna Massif. Over the last 1000 years, strong earthquakes have mobilized roughly four cubic kilometers of sediments and redistributed them into the lower valleys.

GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre

Related Earthquakes Articles:

Distant earthquakes can cause underwater landslides
New research finds large earthquakes can trigger underwater landslides thousands of miles away, weeks or months after the quake occurs.
New model could help predict major earthquakes
Nagoya University-led researchers characterized several earthquakes that struck South America's west coast over the last 100 years by using seismographic data, tsunami recordings, and models of the rapid plate movements associated with these natural disasters.
Forecasting large earthquakes along the Wasatch Front, Utah
There is a 43 percent probability that the Wasatch Front region in Utah will experience at least one magnitude 6.75 or greater earthquake, and a 57 percent probability of at least one magnitude 6.0 earthquake, in the next 50 years, say researchers speaking at the 2017 Seismological Society of America's (SSA) Annual Meeting.
Anticipating hazards from fracking-induced earthquakes in Canada and US
As hydraulic fracturing operations expand in Canada and in some parts of the United States, researchers at the 2017 Seismological Society of America's (SSA) Annual Meeting are taking a closer look at ways to minimize hazards from the earthquakes triggered by those operations.
Oklahoma is laboratory for research on human-induced earthquakes
Earthquakes such as the February 2016 magnitude 5.1 Fairview quake, November 2016's 5.0 Cushing quake, and the September 2016 5.8 Pawnee quake -- the state's largest in historic times -- have made Oklahoma a laboratory for studying human-induced seismicity, according to researchers gathering at the 2017 Seismological Society of America's (SSA) Annual meeting.
Prediction of large earthquakes probability improved
As part of the 'Research in Collaborative Mathematics' project run by the Obra Social 'la Caixa', researchers of the Mathematics Research Centre (CRM) and the UAB have developed a mathematical law to explain the size distribution of earthquakes, even in the cases of large-scale earthquakes such as those which occurred in Sumatra (2004) and in Japan (2011).
Manmade earthquakes in Oklahoma on the decline
Stanford scientists predict that over the next few years, the rate of induced earthquake in Oklahoma will decrease significantly, but the possibility for damaging earthquakes to occur will remain high.
Crowdsourced data can help researchers study earthquakes
A new study on how people feel the effects of earthquakes illustrates the value that members of the public can add to the scientific research process.
Humans have been causing earthquakes in Texas since the 1920s
Earthquakes triggered by human activity have been happening in Texas since at least 1925, and they have been widespread throughout the state ever since, according to a new historical review of the evidence published online May 18 in Seismological Research Letters.
Bubble volcano: Shaking, popping by earthquakes may cause eruptions
A new study on the connection between earthquakes and volcanoes took its inspiration from old engineering basics.

Related Earthquakes Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...