Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence

2017 ◽  
Vol 714-715 ◽  
pp. 146-157 ◽  
Author(s):  
S. Rajaure ◽  
D. Asimaki ◽  
E.M. Thompson ◽  
S. Hough ◽  
S. Martin ◽  
...  
Keyword(s):  
Strong Motion ◽  
Earthquake Sequence ◽  
Kathmandu Valley ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake

scholarly journals The Influence of Surface Topography on the Weak Ground Shaking in Kathmandu Valley during the 2015 Gorkha Earthquake, Nepal

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 678
Author(s):  
Mark van der Meijde ◽  
Md Ashrafuzzaman ◽  
Norman Kerle ◽  
Saad Khan ◽  
Harald van der Werff
Keyword(s):  
Numerical Simulations ◽  
Surface Topography ◽  
Seismic Energy ◽  
Spectral Element ◽  
Kathmandu Valley ◽  
Ground Displacement ◽  
Gorkha Earthquake ◽  
Ground Shaking ◽  
Earthquake Scenarios ◽  
2015 Gorkha Earthquake

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.

scholarly journals Liquefaction hazard assessment and ground failure probability analysis in the Kathmandu Valley of Nepal

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Mandip Subedi ◽  
Indra Prasad Acharya
Keyword(s):  
Soil Liquefaction ◽  
Kathmandu Valley ◽  
Borehole Data ◽  
Gorkha Earthquake ◽  
Engineering Structures ◽  
Liquefaction Potential ◽  
Ground Failure ◽  
2015 Gorkha Earthquake ◽  
Scenario Earthquakes ◽  
Liquefaction Hazard

AbstractDuring the 2015 Gorkha Earthquake (Mw7.8), extensive soil liquefaction was observed across the Kathmandu Valley. As a densely populated urban settlement, the assessment of liquefaction potential of the valley is crucial especially for ensuring the safety of engineering structures. In this study, we use borehole data including SPT-N values of 410 locations in the valley to assess the susceptibility, hazard, and risk of liquefaction of the valley soil considering three likely-to-recur scenario earthquakes. Some of the existing and frequently used analysis and computation methods are employed for the assessments, and the obtained results are presented in the form of liquefaction hazard maps indicating factor of safety, liquefaction potential index, and probability of ground failure (PG). The assessment results reveal that most of the areas have medium to very high liquefaction susceptibility, and that the central and southern parts of the valley are more susceptible to liquefaction and are at greater risk of liquefaction damage than the northern parts. The assessment outcomes are validated with the field manifestations during the 2015 Gorkha Earthquake. The target SPT-N values (Nimproved) at potentially liquefiable areas are determined using back analysis to ascertain no liquefaction during the aforesaid three scenario earthquakes.

A Rapid Response Network to Record Aftershocks of the 2015 M 7.8 Gorkha Earthquake in Nepal

2020 ◽  
Vol 91 (4) ◽  
pp. 2399-2408
Author(s):  
Marianne S. Karplus ◽  
Mohan Pant ◽  
Soma Nath Sapkota ◽  
John Nábělek ◽  
Aaron A. Velasco ◽  
...  
Keyword(s):  
Plate Boundary ◽  
Strong Motion ◽  
Lessons Learned ◽  
Rapid Response ◽  
Earthquake Risk ◽  
Future Research ◽  
Motion Sensors ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake ◽  
Short Period

Abstract The Himalaya has experienced large damaging earthquakes over the past few centuries, most recently the damaging 25 April 2015 M 7.8 Gorkha earthquake in Nepal. Because of the continued earthquake risk presented by the continental collisional plate boundary at the Main Himalayan thrust and the high population densities in the region, collecting and processing data related to recent large earthquakes in this region is critically important for improving our understanding of the regional tectonics and earthquake hazard. Following the 2015 Gorkha earthquake, we deployed a National Science Foundation-funded rapid-response aftershock network known as the Nepal Array Measuring Aftershock Seismicity Trailing Earthquake network across the rupture area for 11 months beginning 7 weeks after the mainshock. The network consisted of 41 broadband and short-period seismometers, and 14 strong-motion sensors at 46 sites across eastern and central Nepal. The network spanned a region approximately 210 km along strike by 110 km across strike with a station spacing of 20–25 km. In this article, we report lessons learned from this deployment as well as details of the publicly accessible dataset including data recovery, data quality, and potential for future research.

scholarly journals The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

2015 ◽  
Vol 49 (1) ◽  
pp. 1-5
Author(s):  
Sudhir Rajaure ◽  
Megh Raj Dhital ◽  
Lalu Prasad Paudel
Keyword(s):  
Source Zone ◽  
Great Earthquake ◽  
Kathmandu Valley ◽  
Main Central Thrust ◽  
Gorkha Earthquake ◽  
Ground Acceleration ◽  
Low Frequencies ◽  
High Frequencies ◽  
Nepal Earthquake ◽  
2015 Gorkha Earthquake

The Gorkha Earthquake occurred on the gently dipping part of the Main Himalayan Thrust (MHT), close to the Main Central Thrust (MCT). This earthquake possibly occurred in the source zone of the 1833 Nepal Earthquake (Mw 7.6), which occurred after 182 years. The region between the 1905 Kangra Earthquake and 1934 Bihar-Nepal Earthquake has not produced any great earthquake since the last 500 years and still remains a potential site for great earthquake(s) in future. The Kathmandu Valley witnessed moderate ground acceleration and comparatively large velocity as recorded at Kantipath during the Mw 7.8, Gorkha Earthquake. The analysis of the records show that high frequencies were damped and low frequencies were dominant over the sedimentary basin, which can be attributed to the response of the sediments underneath. Because of damping of high frequencies, the engineered, low storey buildings were less damaged and resisted the ground shaking comparatively well. However, on the other hand, the historical monument 'Dharahara' collapsed completely and the high rise apartment buildings suffered more because of the dominance of low frequencies.

scholarly journals The Performance of Slender Monuments during the 2015 Gorkha, Nepal, Earthquake

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 321-343 ◽  
Author(s):  
Anjali Mehrotra ◽  
Matthew DeJong
Keyword(s):  
Ground Motion ◽  
Low Frequency ◽  
Kathmandu Valley ◽  
Discrete Element Modeling ◽  
Frequency Content ◽  
Gorkha Earthquake ◽  
Long Period ◽  
2015 Gorkha Earthquake ◽  
Long Period Ground Motion ◽  
2015 Gorkha Nepal Earthquake

This paper studies damage to a few specific monuments in the Kathmandu Valley that were either partially or completely destroyed during the 2015 Gorkha earthquake. Three of these structures—namely, the Basantapur Column, the Dharahara Tower, and the Narayan Temple—were modeled both analytically using rocking dynamics and computationally using discrete element modeling (DEM). The results emphasize the importance of large low frequency content within the ground motion, demonstrating that the Dharahara Tower could have collapsed due to the primary long-period ground motion pulse alone. In addition, comparison of analytical and computational modeling to the observed response enables evaluation of structural behavior, including discussion of the importance of elastic amplification and column embedment on performance during the earthquake.

scholarly journals Identifying archaeological evidence of past earthquakes in a contemporary disaster scenario: case studies of damage, resilience and risk reduction from the 2015 Gorkha Earthquake and past seismic events within the Kathmandu Valley UNESCO World Heritage Property (Nepal)

2019 ◽  
Vol 24 (4) ◽  
pp. 729-751 ◽  
Author(s):  
Christopher Davis ◽  
Robin Coningham ◽  
Kosh Prasad Acharya ◽  
Ram Bahadur Kunwar ◽  
Paolo Forlin ◽  
...  
Keyword(s):  
Risk Reduction ◽  
World Heritage ◽  
Lessons Learned ◽  
Kathmandu Valley ◽  
Gorkha Earthquake ◽  
Unesco World Heritage ◽  
2015 Gorkha Earthquake ◽  
Reduction Strategies ◽  
The Face ◽  
Disaster Scenario

AbstractThe 2015 Gorkha Earthquake was a humanitarian disaster but also a cultural catastrophe that damaged and destroyed historic monuments across Nepal, including those within the Kathmandu Valley UNESCO World Heritage Property. In the rush to rebuild, traditionally constructed foundations are being removed and replaced with modern materials without assessments of whether these contributed to the collapse of a monument. Generally undertaken without scientific recording, these interventions have led to the irreversible destruction of earlier subsurface phases of cultural activity and the potential loss of evidence for successful traditional seismic adaptations and risk reduction strategies, with no research into whether modern materials, such as concrete and steel, would offer enhanced resilience. In response to this context, multidisciplinary post-disaster investigations were undertaken between 2015 and 2018, including archaeological excavation, geophysical survey, geoarchaeological analysis, linked to architectural and engineering studies, to begin to evaluate and assess the damage to, and seismic adaptations of, historic structures within Nepal’s Kathmandu Valley. Where possible, we draw on archaeoseismological approaches for the identification and classification of Earthquake Archaeological Effects (EAEs) at selected monuments damaged by the 2015 Gorkha Earthquake. Lessons learned from evidence of potential weaknesses, as well as historic ‘risk-sensitive tactics’ of hazard reduction within monuments, are now being incorporated into reconstruction and rehabilitation initiatives alongside the development of methods for the protection of heritage in the face of future earthquakes.

scholarly journals DAMAGE FROM THE APRIL-MAY 2015 GORKHA EARTHQUAKE SEQUENCE IN THE SOLUKHUMBU DISTRICT (EVEREST REGION), NEPAL

2016 ◽  
Author(s):  
David R. Lageson ◽  
◽  
Monique Fort ◽  
Roshan Raj Bhattarai ◽  
Mary Hubbard
Keyword(s):  
Earthquake Sequence ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake

Hydropower Infrastructure Performance after the 2015 Gorkha, Nepal, Earthquake Sequence

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 115-132 ◽  
Author(s):  
Menzer Pehlivan ◽  
Christopher Madden Madugo ◽  
Amy Macdonald ◽  
Deepak Rayamajhi ◽  
Youssef M. A. Hashash ◽  
...  
Keyword(s):  
Primary Source ◽  
Earthquake Sequence ◽  
Long Term Effects ◽  
Gorkha Earthquake ◽  
Hydro Power ◽  
2015 Gorkha Earthquake ◽  
Before And After ◽  
Short And Long Term ◽  
Infrastructure Performance

Hydropower infrastructure, the primary source of electricity in Nepal, experienced severe damage following the 2015 Gorkha earthquake sequence, resulting in a 15% loss in the country's energy production. The performance of hydropower infrastructure during and after the sequence was one of the unique focuses of the Geotechnical Extreme Events Reconnaissance (GEER) study. The GEER team visited damaged hydropower projects along the Trishuli and Sunkoshi rivers by road and on foot, along with the ongoing 465-MW Upper Tamakoshi hydropower project by helicopter. The primary cause of damage to the hydropower infrastructure was landslide and rockfall debris falling on powerhouses, penstocks, and dam structures. Moreover, landslides blocked road access to many sites, delaying necessary repairs to damaged structures and resumption of power generation. Power production in Nepal before and after the 2015 Gorkha earthquake sequence, seismic performance of visited hydropower projects, and short- and long-term effects, together with residual risks for Nepal's hydro-power infrastructure, are discussed in this paper.

Site Characteristics of Kathmandu Valley from Array Microtremor Observations

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 85-93 ◽  
Author(s):  
Nakhorn Poovarodom ◽  
Deepak Chamlagain ◽  
Amorntep Jirasakjamroonsri ◽  
Pennung Warnitchai
Keyword(s):  
Main Shock ◽  
Site Response ◽  
Horizontal Component ◽  
Response Analysis ◽  
Kathmandu Valley ◽  
Gorkha Earthquake ◽  
Velocity Models ◽  
Site Characteristics ◽  
2015 Gorkha Earthquake ◽  
Good Agreement

Array microtremor observations were conducted in Kathmandu Valley close to six seismic stations. Sedimentary layers from surface to deep basement rock were modeled according to the derived velocity structures for site response analysis. The records in horizontal component from the 2015 Gorkha earthquake main shock at deep sedimentary sites were compared with the predictions from analysis using the records from a shallow sedimentary site as input motions. Generally, the comparisons are in good agreement where spectral amplification at long periods and suppression at short periods could be justified by the velocity models.

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