Seismic Microzonation of Densely Populated Area of Kathmandu Valley of Nepal using Microtremor Observations

Paudyal, Youb Raj; Bhandary, Netra Prakash; Yatabe, Ryuichi

doi:10.1080/13632469.2012.693242

Cited by 39 publications

(37 citation statements)

References 73 publications

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“…Similarly, there are two other peaks at 0.5 Hz and 1.5 Hz, respectively. The peak at 0.2 Hz, observed in this study, is not noticed in the report of Paudyal et. al.…”

Section: Discussioncontrasting

confidence: 82%

“…The amplifi cation factor is about 5 to 6 in the lacustrine area, between 2 to 3 in transitional area and between 1 and 2 in fl uviatile area. Paudyal et al (2012) applied horizontal-to-vertical ratio of Fourier spectra (H/V ratio technique) of ambient noise recorded at soil sites to estimate fundamental frequency at different parts of the Kathmandu Valley. They reported that the valley has fundamental frequencies in the range between 0.6 to 8.9 Hz in the central and northern part of the sedimentary basin.…”

Section: Previous Workmentioning

confidence: 99%

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The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

Rajaure¹,

Dhital

Paudel

2015

Journal of Nepal Geological Society

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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.

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“…Similarly, there are two other peaks at 0.5 Hz and 1.5 Hz, respectively. The peak at 0.2 Hz, observed in this study, is not noticed in the report of Paudyal et. al.…”

Section: Discussioncontrasting

confidence: 82%

Section: Previous Workmentioning

confidence: 99%

The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

Rajaure¹,

Dhital

Paudel

2015

Journal of Nepal Geological Society

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“…The high fatality rate in that urban community is of the same order of magnitude as the fatality rates recorded in the worst fatal meizoseismal areas which include the cities of Managua, Nicaragua, in 1972 (1 %), Spitak, Armenia, in 1988 (4.5 %), Avezzano andMessina, Italy, in 1915 and1908 (17 and20 %) (e.g., Beavers 2003, 2008) and has to be compared to the 30 % recorded in 1976 in areas of the city of Tangshan, China, exposed to total collapse of masonry buildings (Shiono 1995). This high fatality rate in Kathmandu valley is probably due to combined effects of the vulnerable multi-storys building stock, made of brick with mud mortar, its high concentration and of additional seismo-geological effects typical of the Kathmandu basin, including (1) very long solicitation of the structures due to trapping of the seismic waves (e.g., Bhattarai et al 2012;Chamlagain and Gautam 2015), (2) dominant seismic periods, related to the seismic source and sedimentary basin response, corresponding to the natural periods of multi-storys buildings (e.g., Paudyal et al 2012;Rajaure et al 2014;Goda et al 2015;Galetzka et al 2015;Bhattarai et al 2015) and (3) liquefactions (e.g., Gajurel et al 2000;Mugnier et al 2011). In comparison, mountainous areas of Bhojpur and Udaypur Gadhi fatality rates, on the hanging wall of the fault that ruptured, are of the order of one percent, which is low compared with the values observed in Kathmandu valley, but still very high for rudimentary buildings, woodframed with light roof material, usually safer when, in addition, established on the bedrock.…”

Section: Fatality Rate Collection and Analysismentioning

confidence: 99%

Fatality rates of the M w ~8.2, 1934, Bihar–Nepal earthquake and comparison with the April 2015 Gorkha earthquake

Sapkota¹,

Bollinger

Perrier

2016

Earth Planets Space

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Large Himalayan earthquakes expose rapidly growing populations of millions of people to high levels of seismic hazards, in particular in northeast India and Nepal. Calibrating vulnerability models specific to this region of the world is therefore crucial to the development of reliable mitigation measures. Here, we reevaluate the >15,700 casualties (8500 in Nepal and 7200 in India) from the M w ~8.2, 1934, Bihar-Nepal earthquake and calculate the fatality rates for this earthquake using an estimation of the population derived from two census held in 1921 and 1942. Values reach 0.7-1 % in the epicentral region, located in eastern Nepal, and 2-5 % in the urban areas of the Kathmandu valley. Assuming a constant vulnerability, we obtain, if the same earthquake would have repeated in 2011, fatalities of 33,000 in Nepal and 50,000 in India. Fast-growing population in India indeed must unavoidably lead to increased levels of casualty compared with Nepal, where the population growth is smaller. Aside from that probably robust fact, extrapolations have to be taken with great caution. Among other effects, building and life vulnerability could depend on population concentration and evolution of construction methods. Indeed, fatalities of the April 25, 2015, M w 7.8 Gorkha earthquake indicated on average a reduction in building vulnerability in urban areas, while rural areas remained highly vulnerable. While effective scaling laws, function of the building stock, seem to describe these differences adequately, vulnerability in the case of an M w >8.2 earthquake remains largely unknown. Further research should be carried out urgently so that better prevention strategies can be implemented and building codes reevaluated on, adequately combining detailed ancient and modern data.

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“…assessed seismic risk and mapped the seismic hazard across Nepal. Similarly, Paudyal et al (2012), Gautam and Chamlagain (2016), and Gautam et al (2017) performed local-scale hazard analyses and developed microzonation maps. In addition to this, performed a loss estimation assessment of earthquakes in Kathmandu Valley.…”

Section: Introductionmentioning

confidence: 99%

Assessment of social vulnerability to natural hazards in Nepal

Gautam¹

2017

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper investigates district-wide social vulnerability to natural hazards in Nepal. Disasters such as earthquakes, floods, landslides, epidemics, and droughts are common in Nepal. Every year thousands of people are killed and huge economic and environmental losses occur in Nepal due to various natural hazards. Although natural hazards are well recognized, quantitative and qualitative social vulnerability mapping has not existed until now in Nepal. This study aims to quantify the social vulnerability on a local scale, considering all 75 districts using the available census. To perform district-level vulnerability mapping, 13 variables were selected and aggregated indexes were plotted in an ArcGIS environment. The sum of results shows that only 4 districts in Nepal have a very low social vulnerability index whereas 46 districts (61 %) are at moderate to high social vulnerability levels. Vulnerability mapping highlights the immediate need for decentralized frameworks to tackle natural hazards in district level; additionally, the results of this study can contribute to preparedness, planning and resource management, inter-district coordination, contingency planning, and public awareness efforts.

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Seismic Microzonation of Densely Populated Area of Kathmandu Valley of Nepal using Microtremor Observations

Cited by 39 publications

References 73 publications

The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

Fatality rates of the M w ~8.2, 1934, Bihar–Nepal earthquake and comparison with the April 2015 Gorkha earthquake

Assessment of social vulnerability to natural hazards in Nepal

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