Seismic Liquefaction Risk Assessment of Critical Facilities in Kathmandu Valley, Nepal

Article Seismic Liquefaction Risk Assessment of Critical Facilities in Kathmandu Valley, Nepal

Prabin Acharya 1 , Keshab Sharma 2,* and Indra Prasad Acharya 1

1 Department of Civil Engineering, Pulchowk Campus, IoE, Tribhuvan University, Lalitpur 44700, Nepal; [email protected] (P.A.); [email protected] (I.P.A.) 2 BGC Engineering Inc., Fredericton, NB E3C 0A9, Canada * Correspondence: [email protected]; Tel.: +1-587-938-6767

Abstract: Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the region. The most recent was the Gorkha Nepal earthquake, measuring 7.8 Mw. Past earthquakes caused soil liquefaction in the valley with severe damages and destruction of existing critical infrastructures. As for such infrastructures, the road network, health facilities, schools and airports are considered. This paper presents a liquefaction susceptibility map. This map was obtained by comput- ing the liquefaction potential index (LPI) for several boreholes with SPT measurements and clustering the areas with similar values of LPI. Moreover, the locations of existing critical infrastructures were reported on this risk map. Therefore, we noted that 42% of the road network and 16% of the airport area are in zones of very high liquefaction susceptibility, while 60%, 54%, and 64% of health facilities, schools and colleges are in very high liquefaction zones, respectively. This indicates that most of the critical facilities in the valley are at serious risk of liquefaction during a major earthquake and therefore should be retroﬁtted for their proper functioning during such disasters.

Citation: Acharya, P.; Sharma, K.; Keywords: critical facilities; Kathmandu Valley; liquefaction; liquefaction potential index; seis- Acharya, I.P. Seismic Liquefaction mic hazards Risk Assessment of Critical Facilities in Kathmandu Valley, Nepal. GeoHazards 2021, 2, 153–171. https:// doi.org/10.3390/geohazards2030009 1. Introduction Nepal lies in one of the most active tectonic zones of the world, making the region Academic Editor: Filippo Santucci de extremely vulnerable to earthquakes. The Gorkha Nepal earthquake showed that the Magistris country experiences an earthquake of more than 7.0 Mw every 80–100 years [1]. Kathmandu, the capital city, also forming the central part of the country, is regarded as one of the most Received: 29 March 2021 Accepted: 13 July 2021 seismically vulnerable zones [2], prone to liquefaction. In recent times, the ﬁrst liquefaction Published: 15 July 2021 was reported during the 1934 Nepal–Bihar earthquake (Figure1) in the form of ground ﬁssures, cracks, subsidence, and sand boil up to the height of 4 to 5 m in Kathmandu

Publisher’s Note: MDPI stays neutral Valley [3]. The most recent one, manifested in 2015 by the Gorkha, Nepal earthquake with regard to jurisdictional claims in resulted in minor to major liquefaction in various locations of the valley (Figures2 and3). published maps and institutional afﬁl- Liquefaction occurred in several parts of the valley, the surface manifestations of which iations. were visible (Figure2) at more than 20 sites in the form of sand boils, cracks on the ground surface, and bearing capacity failure in buildings [4–9]. The liqueﬁed sites are presented in Figure3. Herein, it is important to note that the 2015 Gorkha earthquake occurred in the dry season, wherein the peak ground acceleration (PGA) recorded was 0.18 g, much

Copyright: © 2021 by the authors. lower than expected (i.e., 0.30 g) [4,5,8,10–13]. However, the liquefaction suggested that Licensee MDPI, Basel, Switzerland. the soil in the valley is highly prone to it, and the situation could have been worse if an This article is an open access article earthquake with higher PGA had occurred in the rainy season (monsoon period). Several distributed under the terms and studies (e.g., [14–16]) reported a signiﬁcant increment of the ground water table in the rainy conditions of the Creative Commons season. Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

GeoHazards 2021, 2, 153–171. https://doi.org/10.3390/geohazards2030009 https://www.mdpi.com/journal/geohazards GeoHazards 2021, 2 154 GeoHazards 2021, 2, x FOR PEER REVIEW 2 of 19 GeoHazards 2021, 2, x FOR PEER REVIEW 2 of 19

FigureFigure 1. 1.Liquefaction Liquefaction and and ground ground ﬁssures fissures in in the the (a) ( Tundhikhela) Tundhikhel and and (b) Nayabazar(b) Nayabazar areas area durings during the Figure 1. Liquefaction and ground fissures in the (a) Tundhikhel and (b) Nayabazar areas during the 1934 Nepal–Bihar earthquake (Adapted from ref. [3]). 1934the Nepal–Bihar1934 Nepal–Bihar earthquake earthquake (Adapted (Adapted from ref.from [3 ref.]). [3]). (b) (a(a)) (b)

11 mm

Lateral spreading of road embankment RoadRoad settledsettled upup toto 11 m,m, LokanthaliLokanthali Lateral spreading of road embankment (c) (e) (c) (d)(d) (e)

Figure 2. Ground liquefaction, settlement, and ground fissures: (a) road settlement at Lokanthali, Figure 2. Ground liquefaction, settlement, and ground fissures: (a) road settlement at Lokanthali, FigureBhaktpur 2. Ground; (b) lateral liquefaction, spreading settlement, of road embankment, and ground Lalitpur ﬁssures:; (c (a) )liquefaction road settlement in Bungamati, at Lokanthali, Lalit- Bhaktpur; (b) lateral spreading of road embankment, Lalitpur; (c) liquefaction in Bungamati, Lalit- Bhaktpur;pur; (d) liquefaction (b) lateral spreading-induced offissures road embankment, in Mulpani, Lalitpur;and (e) tilted (c) liquefaction building d inue Bungamati, to adjacent Lalitpur; ground pur; (d) liquefaction-induced fissures in Mulpani, and (e) tilted building due to adjacent ground (dsettlement) liquefaction-induced during the 2015 ﬁssures Gorkha in Mulpani,, Nepal, andearthquake. (e) tilted building due to adjacent ground settlement settlement during the 2015 Gorkha, Nepal, earthquake. during the 2015 Gorkha, Nepal, earthquake. The world at large has witnessed several pieces of evidence of liquefaction during The world at large has witnessed several pieces of evidence of liquefaction during someThe of the world most at devastating large has witnessed earthquakes several [17,18 pieces]. For ofinstance, evidence the of liquefaction liquefaction due during to the some of the most devastating earthquakes [17,18]. For instance, the liquefaction due to the someNiigata, of theJapan most, earthquake devastating in earthquakes1964 resulted [ 17in ,severe18]. For foundation instance, thefailure liquefaction of buildings due and to Niigata, Japan, earthquake in 1964 resulted in severe foundation failure of buildings and thebridges, Niigata, while Japan, also earthquakedamaging roads, in 1964 railroads, resulted and in severe airport foundation areas [19]. failureAs another of buildings example, bridges, while also damaging roads, railroads, and airport areas [19]. As another example, andone bridges,may consider while the also Tangshan damaging earthquake roads, railroads, in China and in July airport 1976, areas whereby [19]. the As anotherliquefac- one may consider the Tangshan earthquake in China in July 1976, whereby the liquefac- example,tion recorded one may covered consider over the2400 Tangshan km2 area, earthquake resulting in in a Chinalarge-scale in July ground 1976, unsettlement, whereby the tion recorded covered over 2400 km2 area, resulting in a large-scale ground unsettlement,

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deformation,liquefaction recorded sliding, and covered sand over boiling, 2400 coupled km2 area, with resulting severe indamages a large-scale to buildings, ground roads, unset- farmlands,tlement, deformation, and bridges sliding, [20]. The and liquefaction sand boiling, during coupled thewith 1998 severe Adana damages–Ceyhan to earthquake buildings, inroads, Turkey farmlands, displaced and and bridges fractured [20 ].the The foundations liquefaction of several during homes, the 1998 ruptured Adana–Ceyhan sewers, waterearthquake pipelines, in Turkey and irrigation displaced andcanals, fractured and damaged the foundations small concrete of several bridges homes, and ruptured pave- mentssewers, [21 water]. The pipelines, widespread and liquefaction irrigation canals, during and the damaged 2001 Bhuj, small India concrete, earthquake bridges in andthe meizoseismalpavements [21 area]. The resulted widespread in sand liquefaction boils, craters, during and the lateral 2001 Bhuj, spreading India, earthquake[22]. Further, in Ayothiramanthe meizoseismal et al. area [23] resulted in this regard in sand reported boils, craters, that the and liquefaction lateral spreading covered [22 an]. Further,area of moreAyothiraman than 15,000 et al. m [232 during] in this the regard 2001 reportedBhuj earthquake, that the liquefaction causing significant covered andamage. area of Later more, inthan 2011, 15,000 the mliquefaction2 during the recorded 2001 Bhuj in earthquake,the Tohoku causingregion and significant Kanto region damage. covered Later, an in 2011,area ofthe over liquefaction 70 km2, including recorded Ibaragi, in the Tohoku Chiba, and region Tokyo and due Kanto to the region great covered east Japan an areaearthquake of over [2470– km262]., Even including the Christchurch Ibaragi, Chiba, earthquake and Tokyo in due 2011 to resulted the great in east ground Japan distortion, earthquake fissures, [24–26]. largeEven settlements, the Christchurch and lateral earthquake ground in movements, 2011 resulted severely in ground disrupting distortion, the fissures,city’s lifelines large suchsettlements, as road and networks lateral ground[27]. Most movements, of the damage severely during disrupting the 2018 the Sulawesi city’s lifelines earthquake, such as Indonesiaroad networks, was [due27]. to Most a liquefaction of the damage-induced during lateral the 2018spreading Sulawesi event earthquake, [28]. Indonesia, was dueThe toliquefaction a liquefaction-induced potential index lateral (LPI) spreading has been event widely [28 adopted]. in liquefaction hazard mapping,The liquefaction urban planning, potential and index assessing (LPI) has liquefaction been widely risk adopted to infrastructure in liquefactions [29– haz-31]. Liquefactionard mapping, can urban affect planning, and cause and damage assessing to infrastructures liquefaction risk such to as infrastructures buildings, pipelines, [29–31]. roadsLiquefaction in many can different affect andways. cause In this damage regards, to infrastructures liquefaction potential such as analysis buildings, of soil pipelines, using availableroads in manygeotechnical different information ways. In this is imperative regards, liquefaction to mitigate potential the potential analysis damage of soil caused using byavailable liquefaction. geotechnical Several information studies have is been imperative carried to out mitigate to evaluate the potential the seismic damage liquefaction caused riskby liquefaction. for critical infrastructures Several studies by have using been a various carried simplified out to evaluate method. the Mian seismic et al. liquefaction [32], Tang etrisk al. for [31] critical, Maurer infrastructures et al. [33] and by Meslem using a variouset al. [34] simplified evaluated method. liquefaction Mian-induced et al. [32 ],loss Tang at theet al. critical [31], Maurerinfrastructure et al. [ 33scale] and by Meslemusing several et al. parameters [34] evaluated such liquefaction-induced as LPI, Liquefaction lossSe- verityat the criticalNumber infrastructure (LSN), and Probability scale by using of Liquefaction several parameters (PL). Phule such and as LPI, Choudhury Liquefaction [35] andSeverity D’Apuzzo Number et (LSN),al. [36] andconducted Probability a liquefaction of Liquefaction risk assessment (PL). Phule of and transportation Choudhury sys- [35] temsand D’Apuzzo by using a et simplified al. [36] conducted approach. a liquefactionSimilarly, Paolella risk assessment et al. [37] of, Mosavat transportation et al. [38] systems, and Coelhoby using and a simplified Costa [39] approach. assessed Similarly,the liquefaction Paolella risk et al.to [building37], Mosavat structures. et al. [38 As], andmost Coelho of the buildingsand Costa in [39 Nepal] assessed have thebeen liquefaction constructing risk with to building shallow structures.foundations As [12], most the of same the build- sim- plifiedings in approach Nepal have can been be used constructing to evaluate with the shallow liquefaction foundations risk to road [12],s, theairport sames, and simplified buildings.approach Past canstudies be usedshowed to evaluate that liquefaction the liquefaction is highly risk vulnerable to roads, airports,to shallow and foundation buildings.s [37,40Past studies]. showed that liquefaction is highly vulnerable to shallow foundations [37,40].

Figure 3. EngineeringEngineering geological geological map map of of Kathmandu Kathmandu Valley Valley (modified (modiﬁed after after Sakai Sakai (Adapted (Adapted from from ref.ref. [ 41])])).).

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Kathmandu Valley has many perennial rivers flowing through it, and most parts haveKathmandu a young sandy Valley silt hasto silty many sand perennial layer in riversthe upper ﬂowing bound. through The presence it, and mostof a young parts haveloose asaturated young sandy sand silt deposit to silty makes sand layerthe valley’s in the uppersoil vulnerable bound. The to presenceliquefaction of a even young in loose saturated sand deposit makes the valley’s soil vulnerable to liquefaction even in earthquakes during the dry season, such as those of 1934 and 2015. Soil liquefaction po- earthquakes during the dry season, such as those of 1934 and 2015. Soil liquefaction tential in the valley has been determined in the past by different researchers [9,42,43]; potential in the valley has been determined in the past by different researchers [9,42,43]; however, the effects of liquefaction on critical facilities of the valley have not been studied however, the effects of liquefaction on critical facilities of the valley have not been studied yet. The ability to respond and recover from a disaster such as an earthquake is directly yet. The ability to respond and recover from a disaster such as an earthquake is directly related to the condition of critical facilities during those disasters. Moreover, in earlier related to the condition of critical facilities during those disasters. Moreover, in earlier studies, limited borehole data were used, while in this study more than 500 boreholes up studies, limited borehole data were used, while in this study more than 500 boreholes up to to depths of 20.0 m from 143 locations were considered (Figure 4). Furthermore, most of depths of 20.0 m from 143 locations were considered (Figure4). Furthermore, most of the the previous studies were confined to determining the safety factor against liquefaction, previous studies were conﬁned to determining the safety factor against liquefaction, rather rather than the liquefaction potential index (LPI). Notably, the factor of safety against liq- than the liquefaction potential index (LPI). Notably, the factor of safety against liquefaction atuefaction a given at depth a given does depth not necessarilydoes not nec provideessarily anyprovide clear any information clear information on the severity on the se- of liquefaction;verity of liquefaction; however, however, in this study, in this we study, calculated we calculate LPI at eachd LPI borehole at each site. borehole site.

FigureFigure 4.4. BoreholesBoreholes consideredconsidered inin thethe study.study.

Thus,Thus, thethe objectiveobjective ofof thisthis studystudy isis toto predictpredict thethe effectseffects ofof liquefactionliquefaction onon selectedselected criticalcritical facilitiesfacilities ofof KathmanduKathmandu ValleyValley usingusing LPI.LPI. Further,Further, thethe criticalcritical facilitiesfacilities chosenchosen forfor thisthis studystudy includeinclude roadroad networks,networks, healthhealth facilities,facilities, airports,airports, schools,schools, andand colleges.colleges. ThisThis studystudy wouldwould bebe beneﬁcialbeneficial inin citycity planning,planning, asas wellwell asas forfor mitigationmitigation activitiesactivities forfor criticalcritical infrastructuresinfrastructures in in the the valley, valley, making making it betterit better prepared prepared to tackleto tackle such such disasters disasters in the in future.the fu- Theture. results The results from thisfrom study this canstudy be can used be only used for only desk, fo preliminaryr desk, preliminary and feasibility and feasibility studies. Similarstudies. studiesSimilar canstudies be carried can be carried out for out other for critical other critical facilities facilities such as such ﬁre as and fire emergency and emer- responsegency response systems, system polices, andpolice other and security other security stations, stations, electrical electrical facilities, facilities, etc., and etc. also, and in otheralso in major other cities major of cities the country of the country such as such Pokhara as Pokhara and Butwal. and Butwal.

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2. Earthquake History and Scenario Kathmandu Valley is located in the center of the Himalayan concave chain. The Himalayan arc, which marks an active boundary between the Indian and Eurasian plates, has caused numerous large earthquakes, both in recent and historical times. Kathmandu Valley is surrounded by three major tectonic zones, namely the Main Central Thrust (MCT), Main Boundary Thrust (MBT) and Main Frontal Thrust (MFT) [10,44]. Many active faults are distributed along these major tectonic boundaries, clearly highlighting the seismic hazard in this region. The first documented earthquake event in the country dates back to 7 June 1255. Over recent centuries, earthquakes in 1803, 1833, 1897, 1905, 1934, 1950, 2001, and 2005 have occurred in the Himalayan region and resulted in a large number of casualties and extensive damages to structures [17,18,45,46]. The most recent major earthquake in Nepal is the 2015 Gorkha earthquake. Though there have been numerous earthquakes larger than Mw 7.0 in the past, the 2015 Gorkha earthquake is the most recent and well-documented earthquake in the region. Several probabilistic seismic hazard assessments have been conducted for Kathmandu Valley. Seismic hazard analysis for Kathmandu Valley has been largely confined to similar sources and resulted from similar earthquake scenarios, i.e., magnitude and PGA [13,47]. Probabilistic seismic hazard assessments conducted by JICA [13] considering seismic source zone models based on improved earthquake catalogues and modern ground motion models have been widely used [10,12]. JICA [13] estimated the ground motion of Kathmandu Valley after analyzing three different scenario earthquakes. Three scenario earthquakes (Central Nepal South Scenario Earthquake, Far-Mid Wester Nepal Scenario Earthquake, and Western Nepal Scenario Earthquake) were selected considering the fault, seismo-tectonic and geological condition around Kathmandu Valley. The 1934 Bihar–Nepal earthquake was considered as a verification earthquake. One-dimensional ground response analysis was carried out for the ground amplification. The ground model for response analysis was prepared from typical column data by conducting several field investigations for soil type and shear wave velocity (Vs). An attenuation formula was considered to get the peak ground acceleration at the bedrock. The bedrock was considered to be the layer at which the minimum Vs is 400 m/s, which exists almost at a depth of 100 m from the ground surface. JICA [13] reported a PGA of 0.30 g for scenario earthquake of 8.0 Mw with a 10% probability of exceedance in 50 years (i.e., return period of 475 years) in Kathmandu Valley.

3. Study Area The critical facilities of Kathmandu Valley, the capital of Nepal, were studied, and the effects of liquefaction were predicted. The region around the valley has high hills with steep slopes; shallow bedrocks were also noted in areas around the hills. The geological map of the valley is shown in Figure3. The study area was decided on after excluding the area with bedrock in shallow depth from the specific areas of the valley. Generally, the most common soils in the valley are clayey silt and grey to dark silty sand. Additionally, poorly graded, and silty sands can be observed along the river, which is highly susceptible to liquefaction. Organic clay, fine sand beds, and peat layers may also be found in the surface layer up to 1 m [48]. Many perennial rivers flow through the valley, which effectively helps the groundwater table to remain high.

4. Critical Facilities The objective of this research is to predict the effects of liquefaction on critical facilities of Kathmandu Valley. The data of critical facilities of Kathmandu Valley were collected from the department of survey (Nepal), available topographical sheets, google earth images, and open street map (OSM) data. Though there are several critical facilities in the region, the ones considered include the road networks, airport, hospitals, schools, and colleges, the details of which are presented below. GeoHazards 2021, 2, x FOR PEER REVIEW 6 of 19

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4.1. Road Network 4.1. RoadThe Networkroadway is the only means of transport within Kathmandu Valley; under normal circumstances, the airway is not used for goods transport, which effectively makes road- The roadway is the only means of transport within Kathmandu Valley; under normal ways the only means to import goods required for Kathmandu. Road networks are circumstances, the airway is not used for goods transport, which effectively makes road- thereby critical structures that need to withstand disasters such as earthquakes, particu- ways the only means to import goods required for Kathmandu. Road networks are thereby larly seismic hazards such as liquefaction. The Nepal Road Standard [49] has classified critical structures that need to withstand disasters such as earthquakes, particularly seismic roads into four categories; these include (i) the national highway, (ii) feeder roads, (iii) hazards such as liquefaction. The Nepal Road Standard [49] has classiﬁed roads into four district roads, and (iv) urban roads. For simplicity, we have renamed the urban roads and categories; these include (i) the national highway, (ii) feeder roads, (iii) district roads, and smaller streets as ‘other roads’. The total length of the entire road network (Figure 5) used (iv) urban roads. For simplicity, we have renamed the urban roads and smaller streets as ‘otherin this roads’. study is The about total 1974.1 length km, of theout entireof which road the network length (Figureof the national5) used inhighway this study is 55.6 is aboutkm, the 1974.1 feeder km, road out is of 58.1 which km, the the length district of the road national is 189.3 highway km, and is other 55.6 km, road the is feeder 1671.0 road km. isThe 58.1 national km, the highways district road are isthe 189.3 main km, roads and that other connect road is the 1671.0 entire km. country, The national while highwaysthe feeder areroads the are main more roads localized that connect in nature, the entire serving country, the community while the feeder’s interest, roads and are connecting more localized dis- intrict nature, headquarters, serving the major community’s economic interest,centers, and and tourism connecting centers district. District headquarters, roads serve major the economicproduction centers, and market and tourism areas, while centers. urban District roads roads serve serve to connect the production the people and within market the areas,urban whilemunicipalities. urban roads serve to connect the people within the urban municipalities.

FigureFigure 5.5. Road network and airportairport inin KathmanduKathmandu Valley.Valley.

4.2.4.2. Airport TribhuvanTribhuvan InternationalInternational AirportAirport (TIA)(TIA) isis thethe onlyonly internationalinternational airportairport inin thethe countrycountry andand thethe onlyonly airportairport inin thethe capitalcapital city.city. ThisThis makesmakes thethe TIATIA aa pivotalpivotal centercenter toto receivereceive aa rapidrapid responseresponse fromfrom thethe internationalinternational communitycommunity andand reachreach regionsregions outsideoutside thethe valleyvalley duringduring disastersdisasters suchsuch asas earthquakes.earthquakes. The totaltotal area of TIATIA (shown(shown inin FigureFigure5 5)) used used for for zoningzoning inin thisthis studystudy isis 2.7682.768 Sq.Sq. km.km.

4.3. Health Facility Health facilities need to withstand disasters and serve people during emergencies; in effect, these infrastructures need to be extra strong, and special attention during construc-

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GeoHazards 2021, 2 4.3. Health Facility 159 Health facilities need to withstand disasters and serve people during emergencies; in effect, these infrastructures need to be extra strong, and special attention during construc- tiontion shouldshould bebe given. given. TheThe healthhealth facilitiesfacilities includeinclude hospitals,hospitals, criticalcritical carecare facilities,facilities, clinics,clinics, andand otherother facilitiesfacilities thatthat provideprovide emergencyemergency healthhealth responses,responses, especiallyespecially duringduring aa disaster.disaster. AA total total of of 263 263 health health facilities facilities (Figure (Figure6 )6 inside) inside the the valley valley have have been been categorized categorized according according toto their their locations locations in in the the liquefaction liquefaction susceptibility susceptibility zone. zone.

Figure 6. Health facilities in Kathmandu Valley. Figure 6. Health facilities in Kathmandu Valley.

4.4.4.4. SchoolSchool andand CollegeCollege UnderUnder normal normal circumstances, circumstances, schools schools and and colleges colleges are are not not considered considered critical critical facilities. facili- However,ties. However, there there is minimal is minimal open open land land in Kathmandu,in Kathmandu, which which is is very very critical critical during during an an emergency.emergency. In In that that regard, regard, schools schools and and colleges colleges in in the the valleyvalley havehave beenbeen consideredconsidered critical,critical, oftenoften servingserving as a temporary shelter shelter during during disaste disasters.rs. A Atotal total of of1973 1973 schools schools and and 404 404col- collegesleges (Figure (Figure 77) )of of Kathmandu Kathmandu have have been been considered forfor thisthis research.research. ItIt is is seen seen that that the the densitydensity ofof schoolsschools andand collegescolleges inin thethe centralcentral partpart ofof KathmanduKathmandu ValleyValley is is high high while while this this valuevalue is is quite quite low low in in the the countryside countryside of of the the valley. valley.

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FigureFigure 7.7. SchoolsSchools andand collegescolleges inin KathmanduKathmandu Valley.Valley.

5.5. SPT-BasedSPT-Based LiquefactionLiquefaction AssessmentAssessment InIn Nepal, Nepal, most most of of the the geotechnical geotechnical investigations investigations thus thus far far have have been been limited limited to standardto stand- penetrationard penetration tests tests to a depthto a depth of 15 of to 15 20 to m 20 because m because other other in situ ingeotechnical situ geotechnical investigations, investiga- suchtions, as such cone as penetration cone penetration tests (CPTs) tests and(CPT shears) and wave shear velocity wave tests, velocity have test beens, have sparsely been used.sparsely Although used. Although more modern more approaches modern approaches for liquefaction for liquefaction analysis using analysis the CPT, using shear the waveCPT, shear velocity, wave and velocity cyclic, loading and cyclic tests loading have beentests developedhave been developed and provide and more provide accurate more results,accurate the results, liquefaction the liquefaction potential potential assessment assessment in the valley in the has valley mostly has reliedmostly on relied SPT-N on valuesSPT-N and values borehole and borehole data [9,42 data]. Several [9,42]. methodsSeveral methods are available are available for liquefaction for liquefaction assessment as- ofsessment soil (e.g., of [ 50soil–57 (e.g.]) and, [50 estimating–57]) and settlementestimating and settlement lateral displacement and lateral displacement of soil (e.g., [56 of,58 soil]) due(e.g. to, [56,58 liquefaction.]) due to In liquefaction. this study, theIn this method study, suggested the method by Idriss suggested and Boulanger by Idriss and [50] Bou- was adoptedlanger [50 to] was perform adopted an analysis to perform of the an analysis factor of of safety the factor (FS) withof safety respect (FS) to with liquefaction. respect to Thisliquefaction. method hasThis been method modified has been several modified times, several as per thetimes liquefaction, as per the case liquefaction studies from case thestudies past from earthquakes, the past and earthquakes uses the SPT, and data uses and the geotechnical SPT data and properties geotechnical of the properties soil profile of tothe predict soil profile the factor to predict of safety the factor against of the safety liquefaction against the for liquefaction each layer [for50]. each Additionally, layer [50]. weAdditionally, also adopted we Iwasaki also adopted et al.’s Iwasaki [59] method et al. to’s calculate[59] method the Liquefactionto calculate the Potential Liquefaction Index (LPI)Potential of the Index sites, (LPI) using of FS the against sites, using liquefaction FS against on each liquefaction layer. As on already each layer. mentioned, As already the liquefactionmentioned, analysisthe liquefaction was performed analysis considering was performed an earthquake considering scenario an earthqua of 8.0 keMw scenariowith a PGA of 0.30 g. of 8.0 Mw with a PGA of 0.30 g. In this method, the FS with respect to liquefaction can be calculated using Equa- In this method, the FS with respect to liquefaction can be calculated using Equation tion (1) [50]. The property of the soils to resist liquefaction is defined as the cyclic resistance (1) [50]. The property of the soils to resist liquefaction is defined as the cyclic resistance ratio (CRR), and the stress (loading) that results in liquefaction is termed the cyclic stress ratio (CRR), and the stress (loading) that results in liquefaction is termed the cyclic stress ratio (CSR). ratio (CSR). CRR FS = 7.5 MSF (1) CSR퐶푅푅7.5 퐹푆 = 푀푆퐹 (1) where CRR7.5 is the cyclic resistance ratio calibrated퐶푆푅 for the earthquake of magnitude 7.5. ThewhereCRR CRR7.5 can7.5 isbe the modified cyclic resistance using the ratio magnitude calibrated scaling for the factor earthquake (MSF) for of anmagnitude earthquake 7.5. havingThe CRR different7.5 can be magnitudes; modified usingMSF accountsthe magnitude for the scaling effects offactor the number(MSF) for of an cycles earthquake during having different magnitudes; MSF accounts for the effects of the number of cycles during

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the earthquake or earthquake duration. The value of MSF for the considered scenario earthquake was calculated using Equation (2) [50]:

− Mw MSF = 6.9e 4 − 0.058 (≤ 1.8) (2)

Equation (3) [50] was used for determining the CRR for a cohesionless soil with any ﬁnes content. ! (N ) (N ) 2 (N ) 3 (N ) 4 CRR = exp 1 60cs + 1 60cs − 1 60cs + 1 60cs − 2.8 (3) 7.5 14.1 126 23.6 25.4

where (N1)60cs is an equivalent clean-sand SPT blow count. The following equations (Equations (4) and (5)) are used to calculate (N1)60cs [50]:

(N1)60cs = (N1)60 + ∆(N1)60 (4) ! 9.7 15.7 2 ∆(N ) = exp 1.63 + − (5) 1 60 FC + 0.01 FC + 0.01

where (N1)60 is the corrected SPT-N value and FC is the ﬁnes content in the soils obtained from sieve analysis of soil collected using a split spoon. The measured SPT-N value was corrected using Equation (6):

(N1)60 = NCNCECBCRCS (6)

where (N1)60 is the SPT blow count normalized to the atmospheric pressure of 100 kPa and a hammer efﬁciency of 60%, N is the measured SPT blow count, and CN, CE, CB, CR and CS are the correction factors for the overburden stress, hammer energy ratio, borehole diameter, rod length and samplers with or without liners, respectively. The CSR is calculated by Equation (7) [50]:

τmax σvc amax CSR = 0.65 0 = 0.65 0 rd (7) σ vc σ vc g

where τmax is the earthquake-induced maximum shear stress, amax is the peak horizontal acceleration at the ground surface, g is the gravitational acceleration, σvc and σ’vc are the total overburden stress and effective overburden stress, respectively, and rd is the stress reduction coefﬁcient given by Equation (8) [50]: h z z i r = exp −1.012 − 1.126sin + 5.133 + M 0.106 + 0.118sin + 5.142 (8) d 11.73 w 11.28 where z is the depth of the soil layer in meters. A typical soil proﬁle, SPT-N value, and FS is shown in Figure8. A sample calculation of FS and LPI is shown in Table1.

Liquefaction Potential Index (LPI) The factor of safety against liquefaction at a given depth does not provide clear information on the severity of the potential ground deformation. For predicting the severity of liquefaction at a site through considering the soil proﬁle in the top 20 m, the LPI was calculated using Equations (9)–(13) [59]:

Z z LPI = F(z)W(z)dz (9) 0 where F(z) = 1 − FS For FS < 1 (10) F(z) = 0 For FS ≥ 1 (11) GeoHazards 2021, 2 162 GeoHazards 2021, 2, x FOR PEER REVIEW 10 of 19

W(z) = 10 − 0.5z For z < 20 (12) 18 26.20 Saturated 5 344.25 211.82 0.84 0.27 0.88 0.87 0.32 0.25 0.92 0.12 W(z) = 0 For z ≥ 20 (13) 20 25.16 Saturated 5 383.25 231.20 0.82 0.26 0.88 0.86 0.29 0.22 0.84 0.00 Based on the LPI value, liquefaction susceptibility of the site can be classiﬁed into four7.96

categories as (Table* overburden2): very low, correction low, high, factor and. very high [59].

FigureFigure 8. TypicalTypical soil soil profile, proﬁle, SPT SPT-N-N value, value, and and FSFS withwith depth depth at at(a) ( aManamaiju) Manamaiju,, (b) (bImadol) Imadol,, (c) (Ramkotc) Ramkot,, and and (d) ( dBungamati.) Bungamati.

LiquefactionTable 1. Sample Potential calculation index of(LPI)FS and LPI for a typical borehole.

Corrected The factor of safety against liquefaction at a given depth does not provide clear in- Depth Soil FC σ σ’ MSF for CRR for M = 7.5 SPT-N formation vcon the severityvc r ofCSR the potential groundK * deformation. For predictingCRR FSthe severity LPI (m) Saturation (%) (kPa) (kPa) d Sand σ and σ ’ = 1 atm Value of liquefaction at a site through considering the soil profilevc in the top 20 m, the LPI was 1.5 11.90 Unsaturatedcalculated7 27.00 using 27.00 Equation 1.00s 0.19(9)–(13)0.88 [59]: 1.10 0.13 n.a. 0.00 3 20.90 Unsaturated 7 54.00 54.00 0.99 0.19 0.88푧 1.09 0.22 n.a. 0.00 4.5 27.14 Unsaturated 7 81.00 81.00 0.98 0.19 0.88퐿푃퐼 = ∫ 1.04퐹(푧)푊(푧)푑푧 0.36 n.a. 0.00(9) 6 13.43 Saturated 7 110.25 95.54 0.97 0.22 0.880 1.01 0.14 0.13 0.58 4.36 7.5 18.27 Saturatedwhere 9 139.50 110.07 0.95 0.24 0.88 0.99 0.19 0.17 0.71 2.69 9 26.50 Saturated 5 168.75 124.61 0.94 0.25 0.88 0.96 0.33 0.28 1.12 0.00 10.5 27.67 Saturated 5 198.00 139.14 0.93 0.26F(z) 0.88= 1 − FS 0.94 For FS 0.37 < 1 0.31 1.19 0.00(10) 12 30.05 Saturated 5 227.25 153.68 0.91 0.26 0.88 0.91 0.49 0.39 1.49 0.00 13.5 24.41 Saturated 5 256.50 168.21 0.89 0.27F(z)0.88 = 0 0.92 For FS 0.28 ≥ 1 0.22 0.84 0.79(11) 15 27.98 Saturated 5 285.75 182.75 0.88 0.27 0.88 0.89 0.38 0.30 1.12 0.00 16.5 27.06 Saturated 5 315.00 197.28 0.86 0.27W(z)0.88 = 10 – 0.5 0.88z For z 0.35< 20 0.27 1.00 0.00(12) 18 26.20 Saturated 5 344.25 211.82 0.84 0.27W(z)0.88 = 0 0.87 For z 0.32≥ 20 0.25 0.92 0.12(13) 20 25.16 Saturated 5 383.25 231.20 0.82 0.26 0.88 0.86 0.29 0.22 0.84 0.00 Based on the LPI value, liquefaction susceptibility of the site can be classified7.96 into four categories as* overburden(Table 2): correctionvery low factor., low, high, and very high [59].

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Table 2. Liquefaction potential classification (Adapted from ref. [59]). Table 2. Liquefaction potential classiﬁcation (Adapted from ref. [59]). LPI Susceptibility 0 LPI VerySusceptibility low 0 < LPI ≤0 5 Low Very low 5 < LPI0 < ≤LPI 15≤ 5High Low 5 < LPI ≤ 15 High LPI LPI> 15> 15Very Very high high

6. Results and Discussion 6. Results and Discussion The occurrence of liquefaction vis a vis its severity was evaluated based on the clas- The occurrence of liquefaction vis a vis its severity was evaluated based on the sification proposed by Iwasaki et al. [59]. According to Iwasaki et al. [59], no evidence of classification proposed by Iwasaki et al. [59]. According to Iwasaki et al. [59], no evidence liquefaction phenomena is expected where LPI is zero, while low and high liquefaction of liquefaction phenomena is expected where LPI is zero, while low and high liquefaction potential is expected where LPI values range between 0 and 5, and 5 and 15, respectively. potential is expected where LPI values range between 0 and 5, and 5 and 15, respectively. Notably, a very high potential of liquefaction is expected when the LPI is greater than 15. Notably, a very high potential of liquefaction is expected when the LPI is greater than Figure 9 shows the distribution of liquefaction susceptibility based on the LPI value at 15. Figure9 shows the distribution of liquefaction susceptibility based on the LPI value each borehole considered in this study. The LPI histogram shown in Figure 10 reveals that at each borehole considered in this study. The LPI histogram shown in Figure 10 reveals thatsignificant significant portions portions of the of area the in area the invalley the valleyare susceptible are susceptible to liquefaction to liquefaction.. The liquefac- The liquefactiontion hazard hazardmap based map on based LPI onis shownLPI is shownin Figure in Figure11, which 11, reflects which reflectsthat about that 60% about of 60%Kathmandu of Kathmandu Valley Valleyis highly is highlysusceptible, susceptible, while about while about24% is24% not issusceptible not susceptible to an earth- to an quake scenario of 8.0 Mw with PGA 0.30 g during the monsoon period (rainy season). Im- earthquake scenario of 8.0 Mw with PGA 0.30 g during the monsoon period (rainy season). Importantly,portantly, the the increase increase in inthe the thickness thickness of ofsoft soft soil soil deposits deposits and and shallow shallow groundwater groundwater ta- tablesbles at at the the center center of of the the valley valley was was observed observed to to be be more susceptible to liquefaction,liquefaction, whilewhile lowlow toto veryvery lowlow potentialpotential ofof liquefactionliquefaction waswas observedobserved atat thethe edgesedges of of the the valley. valley.

FigureFigure 9.9. LPILPI forfor eacheach boreholeborehole consideredconsidered inin thisthis study.study.

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FigureFigure 10. 10.The The histogramhistogram ofof liquefactionliquefaction potential potential index index values. values. Figure 10. The histogram of liquefaction potential index values.

FigureFigure 11. 11.Liquefaction Liquefaction susceptibilitysusceptibility map map of of Kathmandu Kathmandu Valley. Valley. Figure 11. Liquefaction susceptibility map of Kathmandu Valley. InIn addition,addition, thethe effectseffects ofof liquefactionliquefaction onon criticalcritical facilities,facilities, asas discusseddiscussed inin SectionSection4 4,, werewereIn thoroughlythoroughly addition, the analyzed effects using usingof liquefaction the the liquefaction liquefaction on critical susceptibility susceptibility facilities, asmap mapdiscussed (Figure (Figure 11in ).11Section The). Thecrit- 4, criticalwereical facilities thoroughly facilities were were analyzed overlaid overlaid usingin the in thethe map, map,liquefaction and and the the corresponding susceptibility corresponding numbermap number (Figure or area or 11 area ).falling The falling crit- un- undericalder facilitieseach each category category were overlaidof ofliquefaction liquefaction in the map,susceptibility susceptibility and the correspondingwas was found. found. As numberAsmentioned mentioned or area earlier, earlier, falling the the un-liq- liquefactionderuefaction each category susceptibility susceptibility of liquefaction of ofthe the site, site,susceptibility where where the thecritical was critical infrastructuresfound. infrastructures As mentioned are located are earlier, located,, were the were clas- liq- classiﬁeduefactionsified into intosusceptibility four four categories categories of the such suchsite, as where as very very low,the low, critical low, low, high, high,infrastructures and and v veryery highare located basedbased , on onwere thethe clas-LPI LPI value.sifiedvalue. into Moreover,Moreover, four categories the the critical critical such facilities facilities as very that that low, can can low, be be affected affected high, and by by liquefaction liquefactionvery high based were were quantiﬁed onquantified the LPI andvalue.and havehave Moreover, beenbeen discussed discussed the critical below. below. facilities that can be affected by liquefaction were quantified and have been discussed below.

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6.1.6.1. RoadRoad NetworkNetwork TheThe spatialspatial distributiondistribution ofof liquefactionliquefaction alongalong thethe roadroad networknetwork waswas computed computed using using GIS.GIS. TheThe resultsresults obtainedobtained areare shownshown inin FigureFigure 12 12 and and TableTable3 .3 A. A total total of of 1974.1 1974.1 km km of of the the roadsroads inin thethe valleyvalley werewere analyzed. analyzed. TheThe totaltotal lengthlength ofof thethe highwayhighway withinwithin thethe studystudy area area waswas foundfound toto bebe 55.655.6 km,km, outout ofof whichwhich onlyonly 0.2%0.2% ofof thethe highwayhighway waswas foundfound toto bebe inin nono liquefactionliquefaction zone,zone, whilewhile 61%61% waswas inin a a very very high high liquefaction liquefaction susceptible susceptible zone. zone. OutOut ofof the the remainingremaining length length of of highways, highways, 32% 32% was was found found in in a highlya highly susceptible susceptible zone, zone, whereas whereas 7% 7 of% theof the road road network network was was in ain low a low liquefaction liquefaction zone. zone. The The second second category category of of roads roads studied studied werewere feederfeeder roads.roads. Out of 58.1 km km of of feeder feeder roads roads in in the the valley, valley, 1%, 1%, 28%, 28%, 37 37%,%, and and 34 34%% of ofthe the feeder feeder road roadss were were found found to be to bein very in very low, low, low, low, high, high, and and very very high high liquefaction liquefaction sus- susceptibilityceptibility zone zones,s, respectively. respectively. Similarly, Similarly, about about 43% 43% of of district district roads roads and 41% 41% of of other other roadsroads were were found found to to be be inin aa veryvery highhigh liquefactionliquefaction zones.zones. Importantly,Importantly, if if we we are are to to consider consider thethe totaltotal lengthlength ofof roadsroads inin thethe valley,valley, 42% 42% of of the the roads roads are are estimated estimated toto bebe in in very very high high liquefactionliquefaction risk risk zones, zones, whereas whereas about about 5% 5% are are in in very very low low liquefaction liquefaction zones. zones.

FigureFigure 12.12.Liquefaction Liquefaction susceptibilitysusceptibility mapmap withwith roadroad networknetwork and and airport airport of of Kathmandu Kathmandu Valley. Valley.

TableTable 3.3.Liquefaction Liquefaction susceptibilitysusceptibility ofof thethe roadroad network network in in Kathmandu Kathmandu Valley. Valley. Highways Feeder Roads District Roads Other Roads Total LPI Highways Feeder Roads District Roads Other Roads Total LPI km % km % km % km % km % km % km % km % km % km % Very low 0.1 0.2 ≈ 0 0.6 1 12.7 7 79.8 5 93.3 5 Very low 0.1 0.2 ≈ 0 0.6 1 12.7 7 79.8 5 93.3 5 Low Low3.6 7 3.6 16.5 7 16.528 2828.7 28.715 15365.3 365.3 22 22414.0 414.0 21 High High18.0 32 18.0 21.2 32 21.237 3766.7 66.735 35538.3 538.3 32 32644.3 644.3 32 Very highVery high33.9 61 33.9 19.8 61 19.834 3481.2 81.243 43687.6 687.6 41 41822.5 822.5 42 Total Total55.6 100 55.6 58.1 100 58.1100 100189.3 189.3100 1001671.0 1671.0 100 100 1974.1 1974.1 100

FigureFigure 1212 shows shows thatthat mostmost ofof thethe roadsroads inin thethe studystudy areaarea werewere inin highhigh toto veryvery highhigh liquefactionliquefaction susceptible susceptible zones, zones, thereby thereby indicating indicating that that a a larger larger road road network network is is liable liable to to be be affected due to liquefaction during a major earthquake. It is notable that the central part

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affected due to liquefaction during a major earthquake. It is notable that the central part of the valley has a higher liquefaction potential and the road network in the central region is also higher. It was also found that major road networks of the valley that have higher importance and major roles in rapid response during a disaster are also centrally located. This goes on to suggest that major roads in the valley in high to very high susceptible zones need to be specially strengthened to minimize liquefaction effects. 6.2. Airport The liquefaction susceptibility of the Tribhuvan International Airport (TIA) located in the central part of the valley covering nearly a 3 sq. km area is shown in Figure 12. The percentage of the area falling under each category of liquefaction was estimated and is presented in Table4.

Table 4. Liquefaction susceptibility of Tribhuvan International Airport in Kathmandu Valley.

Airport Liquefaction Susceptibility Area (Sq. m) Percentage (%) Very low 0 0 Low 0.16 6 High 2.16 78 Very high 0.44 16 Total 2.76 100

It can be seen that out of the total area of TIA, no portion of the airport was in a very low liquefaction zone. Only a small portion (i.e., about 6%) of the airport area on the northern part was estimated to have a low liquefaction zone. On the other hand, 78% of the airport’s area is in the high liquefaction zone and 16% is in the very high susceptibility zone. This indicates that the risk of liquefaction during a major earthquake in and around the airport area is on the higher side; thus, a detailed soil investigation and countermeasures of soil liquefaction are needed for the proper functioning of the airport during a major earthquake.

6.3. Health Facility Major health facilities in the capital city such as hospitals, clinics, and health posts were mapped, and the possibility of liquefaction effects on these facilities was evaluated (Figure 13). Table5 shows the number of health facilities falling in different categories of liquefaction susceptibility. Figure 13 indicates that a large number of health facilities are in the central part of the valley, where most of the buildup area lies. As discussed earlier, the liquefaction susceptibility in the central region of the valley is higher. The total percentage of health facilities in a very high liquefaction zone was observed to be 60%, while this was 32% in a high liquefaction zone. This indicates that more than 92% of health facilities have been in high to a very high zones of liquefaction susceptibility in the valley. Additionally, the health facilities in very low zones make up a mere 1%, while 7% are in low liquefaction zones. The higher percentage of health facilities in high to very high liquefaction zone highlights the importance of detailed soil investigations in these areas, which effectively should be followed by remedial and countermeasures against liquefaction.

Table 5. Health facilities in the valley falling on a different zone of liquefaction susceptibility.

Health Facility Liquefaction Susceptibility Number Percentage (%) Very low 2 1 Low 18 7 High 84 32 Very high 159 60 Total 263 100 GeoHazards 2021, 2 167 GeoHazards 2021, 2, x FOR PEER REVIEW 15 of 19

FigureFigure 13. 13.Liquefaction Liquefaction susceptibility susceptibility map map with with health health facilities facilities of of Kathmandu Kathmandu Valley. Valley.

6.4.6.4. School School and and College College AA total total of of 1973 1973 schools schools and and 404 404 colleges colleges in in the the valleyvalley havehave beenbeen analyzedanalyzed (Figure(Figure 14 14).). TheThe schools schools and and colleges colleges falling falling under under a differenta different category category of liquefactionof liquefaction are are presented presented in Tablein Table6. 6. The plot of schools and colleges in the liquefaction susceptibility map indicates that schoolsTable 6. andSchools colleges and colleges in very of high Kathmandu liquefaction Valley susceptibility falling in a different zoned zone were of 54%liquefaction and 64%, sus- respectively.ceptibility. This might be attributed to a large number of schools and colleges in the central part of the valley, which is highly prone to liquefaction. The very low and low School College liquefactionLiquefaction zones Susceptibility are located along the edges of the valley where a smaller number of Number Percentage (%) Number Percentage (%) schools and colleges can be seen. Thus, only 2% of schools and 0.5% of colleges were effectivelyVery in very low low liquefaction43 zones, while a higher2 percentage2 of schools0.5 and ≈ colleges0 were in highLow to very high liquefaction232 zones. 12 15 4 High 629 32 130 32 Table 6. Schools and colleges of Kathmandu Valley falling in a different zone of liquefaction suscepti- Very high 1069 54 257 64 bility. Total 1973 100 404 100 Liquefaction School College Susceptibility Number Percentage (%) Number Percentage (%) Very low 43 2 2 0.5 ≈ 0 Low 232 12 15 4 High 629 32 130 32 Very high 1069 54 257 64 Total 1973 100 404 100

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FigureFigure 14.14.Liquefaction Liquefaction susceptibilitysusceptibility mapmap withwith schoolsschools andand collegescolleges of of Kathmandu Kathmandu Valley. Valley.

7. ConclusionsThe plot of and schools Recommendations and colleges in the liquefaction susceptibility map indicates that schoolsA liquefaction and colleges potential in very maphigh ofliquefaction the subsurface susceptibility geological zone materialsd were of 54% Kathmandu and 64%, Valleyrespectively. was prepared This might for an be earthquake attributed scenario to a large having number a magnitude of schools of and 8.0 M collegesw with 0.30in the g PGA.central The part category of the ofvalley very, high which and is high highly susceptibility prone to liquefaction. for liquefaction The was very observed low and at thelow centralliquefaction part of zones the valley, are located while lowalong to the very edges low potentialof the valley of liquefaction where a smaller was observed number atof theschools edge and of the colleges valley. can The be effects seen. of Thus, liquefaction only 2% on of critical schools facilities and 0.5% of the of valleycolleges have were been ef- evaluatedfectively in using very thelow liquefaction liquefaction potentialzones, while map. a higher The critical percentage facilities of schools chosen and to evaluate colleges seismicwere in soil high liquefaction to very high effects liquefaction included zones. the road network, airport, health facilities, schools and colleges. For an earthquake of 8.0 Mw, PGA 0.30 g and groundwater conditions for the7. Conclusions monsoon period, and Recommendations it was seen that 60% of the hospitals and about 64% of colleges in the valleyA liquefaction are in very potential high-risk map zones of the of liquefaction.subsurface geological Similarly, materials 54% of the of schoolsKathmandu and 42%Valley of thewas road prepared network for inan theearthquake valley are scenario in a very having high liquefactiona magnitude zone,of 8.0 while Mw with 78% 0.3 of0 theg PGA. airport The area category is in the of very high-risk high and zone high of liquefaction susceptibility occurrence. for liquefaction This goes was onobserved to show at thatthe central the percentage part of the of criticalvalley, while facilities low falling to very in low the potential very high-risk of liquefaction zone of liquefaction was observed is certainlyat the edge on of the the higher valley. side. The Importantly, effects of liquefaction the central on part critical of the facilities valley, whichof the valley has a highhave chancebeen evaluated of liquefaction using occurrence,the liquefaction also potential has a higher map. percentage The critical of facilities critical facilities, chosen to which eval- highlightsuate seismic the soil possibility liquefaction of greater effects liquefaction included the effects road in network, that region. airport, health facilities, The existing critical infrastructures such as hospitals, schools, colleges, airport, and schools and colleges. For an earthquake of 8.0 Mw, PGA 0.30 g and groundwater condi- roadtions facilities for the monsoon located on period, weak subsoilsit was seen that that may 60% liquefy of the under hospitals moderate and about shaking 64% should of col- beleges retrofitted in the valley to meet are thein very requirement high-risk ofzone maintainings of liquefaction. their functionsSimilarly, after54% of earthquakes. the schools Inand addition 42% of to,the theroad facilities network used in the in thisvalley study, are in other a very critical high servicesliquefaction such zone, as emergency while 78% responseof the airport services, area is telecommunication in the high-risk zone services, of liquefaction financial occurrence. institutions, This and goes major on to indus- show trial/commercial facilities located in very high-risk zones of liquefaction should also be that the percentage of critical facilities falling in the very high-risk zone of liquefaction is relocated or retrofitted. The development of all these facilities should be carried out consid- certainly on the higher side. Importantly, the central part of the valley, which has a high ering appropriate land use guided by the liquefaction risks to mitigate potential loss and chance of liquefaction occurrence, also has a higher percentage of critical facilities, which proper functioning after earthquakes. This study can help in urban planning, preliminary highlights the possibility of greater liquefaction effects in that region. studies, feasibility studies, and land-use policies. This research also assists the government The existing critical infrastructures such as hospitals, schools, colleges, airport, and road facilities located on weak subsoils that may liquefy under moderate shaking should

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authority and the geotechnical engineers beforehand to plan the comprehensive seismic microzonation based on the provided liquefaction map. The results from this study can be used only for preliminary studies and desk study. A more detailed site-speciﬁc study is recommended before developing any critical infrastructures in Kathmandu Valley.

Author Contributions: Conceptualization, P.A. and K.S.; methodology, P.A. and K.S.; software, P.A.; validation, P.A., K.S. and I.P.A.; formal analysis, P.A.; resources, P.A. and K.S.; data curation, P.A.; writing—original draft preparation, P.A.; writing—review and editing, P.A., K.S. and I.P.A.; supervi- sion, K.S. and I.P.A. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Borehole log data and test results were collected from different geotechnical laboratories working in the Kathmandu valley. These data are available on request. Data used to present critical facilities were extracted to QGIS from OSM (Open Street Map); additional data as required were collected from the Department of Survey, Nepal. Some data were digitized by the authors using topographical sheets and google earth imagery. These digitized data are also available on request. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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