Ground Deformation at Lokanthali, Kathmandu, Due to the M w 7.8 2015 Gorkha Earthquake

Author(s):  
Binod Tiwari ◽  
Daniel Pradel
2021 ◽  
Author(s):  
Masataka Shiga ◽  
Kazuo Konagai ◽  
Rama Mohan Pokhrel ◽  
Takaaki Ikeda

Abstract The April 25, 2015 Gorkha earthquake jolted the central region of Nepal causing extensive damage to buildings and earthen structures in both mountainous and urban areas of Nepal. Kathmandu-Bhaktapur road, one section of the Araniko Highway, crosses a small valley in the center of the Kathmandu Basin with an embankment. This embankment and adjacent area were deformed in the earthquake. To examine the cause of this ground deformation, several in-situ tests such as micro-tremor measurements, standard penetration tests (SPT), multi-channel analyses of surface waves (MASW), and C 14 dating were conducted. These tests show that a silty sand layer with low plasticity has most likely been liquefied 5 to 8 meters underground. It is also shown that groundwater lowering using existing wells can decrease the liquefaction-prone area by 81%.


Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 678
Author(s):  
Mark van der Meijde ◽  
Md Ashrafuzzaman ◽  
Norman Kerle ◽  
Saad Khan ◽  
Harald van der Werff

It remains elusive why there was only weak and limited ground shaking in Kathmandu valley during the 25 April 2015 Mw 7.8 Gorkha, Nepal, earthquake. Our spectral element numerical simulations show that, during this earthquake, surface topography restricted the propagation of seismic energy into the valley. The mountains diverted the incoming seismic wave mostly to the eastern and western margins of the valley. As a result, we find de-amplification of peak ground displacement in most of the valley interior. Modeling of alternative earthquake scenarios of the same magnitude occurring at different locations shows that these will affect the Kathmandu valley much more strongly, up to 2–3 times more, than the 2015 Gorkha earthquake did. This indicates that surface topography contributed to the reduced seismic shaking for this specific earthquake and lessened the earthquake impact within the valley.


2017 ◽  
Vol 714-715 ◽  
pp. 146-157 ◽  
Author(s):  
S. Rajaure ◽  
D. Asimaki ◽  
E.M. Thompson ◽  
S. Hough ◽  
S. Martin ◽  
...  

Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 437 ◽  
Author(s):  
Meena ◽  
Tavakkoli Piralilou

Despite landslide inventories being compiled throughout the world every year at different scales, limited efforts have been made to critically compare them using various techniques or by different investigators. Event-based landslide inventories indicate the location, distribution, and detected boundaries of landslides caused by a single event, such as an earthquake or a rainstorm. Event-based landslide inventories are essential for landslide susceptibility mapping, hazard modeling, and further management of risk mitigation. In Nepal, there were several attempts to map landslides in detail after the Gorkha earthquake. Particularly after the main event on 25 April 2015, researchers around the world mapped the landslides induced by this earthquake. In this research, we compared four of these published inventories qualitatively and quantitatively using different techniques. Two principal methodologies, namely the cartographical degree of matching and frequency area distribution (FAD), were optimized and applied to evaluate inventory maps. We also showed the impact of using satellite imagery with different spatial resolutions on the landslide inventory generation by analyzing matches and mismatches between the inventories. The results of our work give an overview of the impact of methodology selection and outline the limitations and advantages of different remote sensing and mapping techniques for landslide inventorying.


Author(s):  
Alessandra Mayumi NAKATA ◽  
Hikaru TOMITA ◽  
Kazuo KONAGAI ◽  
Masataka SHIGA ◽  
Takaaki IKEDA ◽  
...  

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