Overview of the Large 25 April 2015 Gorkha, Nepal, Earthquake from Accelerometric Perspectives

Bhattarai, Madhusudan; Adhikari, Lok Bijaya; Gautam, Umesh; Laurendeau, Aurore; Labonne, Claire; Hoste-Colomer, Roser; Sèbe, Olivier; Hernandez, B.

doi:10.1785/0220150140

Cited by 41 publications

(29 citation statements)

References 21 publications

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“…Rapid dissemination of geological field investigation, accelerometric interpretation, some geotechnical effects, rapid seismo-tectonic characterization, structural performance and other aspects of Gorkha earthquake are reported by several researchers (e.g. Angster et al 2015;Bhattarai et al 2015;Hayes et al 2015;Martin et al 2015;Moss et al 2015;Ahmad & Singh 2016;Dutta et al 2016;Gautam & Chaulagain 2016;Gautam et al 2016a;Rai et al 2016;Gautam 2017) and some site-specific reconnaissance reports can be found elsewhere.…”

Section: Introductionmentioning

confidence: 94%

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Gautam¹

2017

Geomatics, Natural Hazards and Risk

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Gorkha earthquake (M W 7.8) of 25 April 2015 struck central, eastern and western Nepal and neighbouring areas. Enormous losses during Gorkha earthquake were attributed to collapse of 498,852 buildings, 446 public health facilities and partial damage of 256,697 buildings, 765 health facilities as well as severely affected 2900 cultural and historical sites. Anomalies were in particular observed in terms of localized damage and recurrent damages during 1833, 1934, 1988 and 2015 earthquakes. This paper reports geotechnical earthquake engineering observations noted during field reconnaissance conducted in affected areas. Damage reports from historical as well as recent Gorkha earthquakes are mapped in this paper. To depict lessons, forensic interpretations are presented considering 1833, 1934, 1988 and 2015 earthquakes.

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Section: Introductionmentioning

confidence: 94%

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Gautam¹

2017

Geomatics, Natural Hazards and Risk

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“…Only this M L 6.8 earthquake has power there and the long period response is observed, but its reliability does not seem enough due to the poor S/N in the frequency range lower than 0.3 Hz in DMG and KKA. A drastic site effect in the frequency range lower than 0.5 Hz has been shown during the 2015 Gorkha, Nepal earthquake (Bhattarai et al 2015), not only in DMG but also in other stations (Takai et al 2016;Kubo et al 2016). However, further studies on additional strong motion records, among them on records of the main shock and aftershocks of the 2015 Gorkha earthquake, will be required to understand and quantify its effect.…”

Section: Discussionmentioning

confidence: 99%

“…1). During the 2015 Gorkha, Nepal earthquake (e.g., Kobayashi et al 2015;Kubo et al 2016) clear predominant period around 0.2 Hz was observed at the DMG station (Bhattarai et al 2015), in KATNP site maintained by USGS (Dixit et al 2015) and also in some temporary stations in Kathmandu valley (Takai et al 2016). These show necessity of further studies by geological and geophysical survey and strong motion and earthquake observations, especially on underground velocity structure and on the shape of hard bedrock that shall be used for seismic hazard assessment.…”

Section: Introductionmentioning

confidence: 97%

Establishing a reference rock site for the site effect study in and around the Kathmandu valley, Nepal

Bhattarai¹,

Adhikari²,

Gautam³

et al. 2016

Earth Planets Space

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We propose a reference site for the site effect study in and around the Kathmandu valley, Nepal. The used data were the accelerograms recorded at two stations, DMG and KKA, and velocity seismograms co-recorded at the PKIN station during nine shallow local and regional earthquakes of local magnitude equal to or greater than 5.0. The DMG station is located on the thick sediments of the Kathmandu valley, whereas the others are rock sites. The KKA station is located on the granite and gneisses of the Shivapuri Lekh about 10 km northwest of the capital, and the PKIN station is in the tunnel of an old iron mine on the southern slope of the Phulchauki Hill about 15 km southeast. The spectral ratios of the ground motion records of the DMG station compared to those of the PKIN station, for all considered earthquakes, confirm that the DMG station has amplification ranging from 1 to 10 in the frequency range of 0.5-10 Hz, and spectral ratios of the KKA station referenced by the PKIN station show that the KKA station has significant amplification in the frequency range of 4-10 Hz and the peak value of the spectral ratio is at most over 25. Therefore, the site amplification in and around Kathmandu valley would be significantly underestimated in the frequency range from 4 to 10 Hz if the records of the KKA station were used as a proxy for input seismic motions to the sediment. Based on the above analysis, we propose that the PKIN station should be considered as a reliable reference site for the assessment of seismic hazards in and around the Kathmandu valley.

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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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Overview of the Large 25 April 2015 Gorkha, Nepal, Earthquake from Accelerometric Perspectives

Cited by 41 publications

References 21 publications

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Establishing a reference rock site for the site effect study in and around the Kathmandu valley, Nepal

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

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Overview of the Large 25 April 2015 Gorkha, Nepal, Earthquake from Accelerometric Perspectives

Cited by 41 publications

References 21 publications

Unearthed lessons of 25 April 2015 Gorkha earthquake (MW 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (MW 7.8): geotechnical earthquake engineering perspectives

Establishing a reference rock site for the site effect study in and around the Kathmandu valley, Nepal

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

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Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives