Structural performance and associated lessons to be learned from world earthquakes in Nepal after 25 April 2015 (MW 7.8) Gorkha earthquake

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

“…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.…”

“…Some of the urban areas like Kathmandu Valley in Nepal are situated in the alluvial deposits with highly interlayered clay and silts and sometimes gravels or mixture of all. These alluvial deposits are known to be the most affected sites in terms of damage concentration due to geological condition, population concentration and structural vulnerability (Gautam & Chaulagain 2016). The majority locations of Sub-Himalaya and Higher Himalaya have steep slopes leading to rock falls or landslides during earthquakes.…”

“…The peak ground acceleration (PGA) during the 25 April 2015 earthquake was recorded »0.25g, thus surface manifestations of liquefaction are justified according to the PGA threshold criteria set by Santucci de Magistris et al (2013Magistris et al ( , 2014. Partly the damage was also attributed to structural deficiencies (details can be found in Gautam & Chaulagain 2016;Gautam et al 2016b;Gautam 2017) however, many failure evidences were related to foundation slides in Balaju. Immediate vicinity of tributaries, shallow depth of groundwater table and prevalence of sand in upper 30-m strata undergird the possibility of liquefaction, thus surface manifestations were not observed in Balaju.…”

Seismic vulnerability of vernacular Newari buildings in Nepal: observations and analysis of damage due to 1934, 1988, 2011, and 2015 earthquakes

“…The epicenter of Gorkha earthquake was located ~78 km N-NE of Kathmandu valley in Barpak village of Gorkha district. Several factors like local amplification and construction technology responsible for structural damage and the accounts of building damage in regional scale are presented by and Gautam and Chaulagain (2016). In the case of Bhaktapur, almost 80% building stocks were the vernacular Newari houses and most of 20 remaining buildings were the substandard RC buildings (for details see: Chaulagain et al (2013).…”

“…In the case of Bhaktapur, almost 80% building stocks were the vernacular Newari houses and most of 20 remaining buildings were the substandard RC buildings (for details see: Chaulagain et al (2013). During Gorkha earthquake, relatively lower value of PGA and short duration of shaking may have altered the damage scenario and hence previous loss estimation models depicted by Chaulagain et al (2016) was not able to represent the actual damage scenario.…”