In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ German Research Centre for Geosciences. Even after strong earthquake the activity of landslides returns back over the course of one to four years to the background level before the earthquake.
The interactions over time between earthquakes and processing shaping the landscape are still not well understood. The geoscientists have investigated areas affected by landslides related to four moderate to severe earthquakes (6.6 to 7.6 on Richter scale).
"The main difficulty was that one must distinguish between the meteorological and the seismic causes of landsliding. Heavy rain can also produce landslides and can enhance landsliding after an earthquake", says GFZ scientists Marc Odin, the lead author of the study.
Two processes are interacting here. A strong earthquake shakes soil layer loose from the underlying bedrock and also damages the rock below the top soil. Water seeps into the resulting the cracks and crevices and acts like a lubricating film on which a mountain slope slides into the valley.
With the present results of the team of geoscientists, this conceptual model has to be modified. "We analytically separated the effect of the rain from the seismic activity and so were able to determine that the decrease of landslides through time is based on an internal healing process of the landscape," said Marc Odin.
The destabilization of the landscape caused by the quake gradually recovers. In the course of months to years, depending on weather, rocks and the strength of the earthquake, the slide rates return to the pre-earthquake level: The cracks slowly get closed again or are filled with sand and earth. The landscape self-heals its underlayer and returns to its background hazard potential.
This research is highly relevant: currently the GFZ analyzes these processes in the context of the Nepal-quake of April this year: "We had the chance to start a series of measurements directly after the quake and continue for the next few years," explained Niels Hovius, Head of the Section "Geomorphology" at the GFZ, about the current deployment of his team in the Himalayas.
O. Marc, N. Hovius, P. Meunier, T. Uchida, and S. Hayashi, “Transient changes of landslide rates after earthquakes”, GEOLOGY, Advance Online Publication, 21.08.2015; doi:10.1130/G36961.1
Franz Ossing | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America
Hurricane Harvey: Dutch-Texan research shows most fatalities occurred outside flood zones
19.04.2018 | European Geosciences Union
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy