Nepal Earthquake Research Articles

Understanding the impacts of floods on learning quality, school facilities, and educational recovery in Indonesia.

This research is among the first pieces of work to use the comprehensive school safety (CSS) framework to assess the impacts of floods on quality learning and education infrastructure. The CSS framework is employed here to identify the level of disruption to education services following floods in Jakarta, Indonesia, in 2013. The paper poses three key questions, concerning: (i) disruption to children's access to quality education during the flood emergency in 2013 and the early recovery phase; (ii) the impact of the floods on a school's physical infrastructure; and (iii) the effectiveness and level of success of the 2013 flood responses by relevant stakeholders. Combining quantitative and qualitative strategies, the paper examines the experiences of 100 schools in Jakarta. The findings suggest that the CSS framework offers a more nuanced approach to assessing post-disaster education needs. Moreover, it is also relevant for examining the relationship between the COVID-19 pandemic and relative losses in the education sector.

Response of reinforced concrete structures designed before and after 2015 Nepal earthquake

Response of reinforced concrete structures designed before and after 2015 Nepal earthquake

Modelling post‐earthquake cascading hazards: Changing patterns of landslide runout following the 2015 Gorkha earthquake, Nepal

AbstractCoseismic landslides represent the first stage of a broader cascading sequence of geohazards associated with high‐magnitude continental earthquakes, with the subsequent remobilization of coseismic landslide debris posing a long‐term post‐seismic legacy in mountain regions. Here, we quantify the controls on the hazard posed by landslide remobilization and debris runout, and compare the overlap between areas at risk of runout and the pattern of post‐seismic landslides and debris flows that actually occurred. Focusing on the 2015 Mw 7.8 Gorkha earthquake in Nepal, we show that the extent of the area that could be affected by debris runout remained elevated above coseismic levels 4.5 years after the event. While 150 km2 (0.6% of the study area) was directly impacted by landslides in the earthquake, an additional 614 km2 (2.5%) was left at risk from debris runout, increasing to 777 km2 (3.2%) after the 2019 monsoon. We evaluate how this area evolved by comparing modelled predictions of runout from coseismic landslides to multi‐temporal post‐seismic landslide inventories, and find that 14% (85 km2) of the total modelled potential runout area experienced landslide activity within 4.5 years after the earthquake. This value increases to 32% when modelled runout probability is thresholded, equivalent to 10 km2 of realized runout from a remaining modelled area of 32 km2. Although the proportion of the modelled runout area from coseismic landslides that remains a hazard has decreased through time, the overall runout susceptibility for the study area remains high. This indicates that runout potential is changing both spatially and temporally as a result of changes to the landslide distribution after the earthquake. These findings are particularly important for understanding evolving patterns of cascading hazards following large earthquakes, which is crucial for guiding decision‐making associated with post‐seismic recovery and reconstruction.

Correction to: Seismically active structures of the Main Himalayan Thrust revealed before, during and after the 2015 Mw 7.9 Gorkha earthquake in Nepal

Correction to: Seismically active structures of the Main Himalayan Thrust revealed before, during and after the 2015 Mw 7.9 Gorkha earthquake in Nepal

The impact of Nepal's earthquake on the health status of rural children

AbstractWe study the impact of Nepal's 2015 earthquake on the health status of children aged 0–5 years. Using a difference‐in‐differences approach we find that the earthquake decreased height‐for‐age z‐scores (HAZ) and that this effect is largely driven by females, who experienced an average decline of −0.763 standard deviations in their HAZ. Further, we find that females in the 0–3 years age group and in the least wealthy households are the most vulnerable. This is particularly unfortunate, as the first 3 years of life can impact long‐term health and well‐being, and female undernutrition contributes to the intergenerational transmission of poverty and ill health.

Managing Postdisaster Reconstruction after the 2015 Gorkha, Nepal Earthquake and Lessons Learned

The 2015 Gorkha earthquake was one of the most devastating earthquakes in Nepal in this century. Postdisaster reconstruction is a complex and highly challenging process, especially concerning developing countries like Nepal, as it involves several well-coordinated plans and working activities. Due to the large scale of devastation, the Nepal government created a separate body, the National Reconstruction Authority (NRA), to manage and oversee recovery and reconstruction activities. This paper briefly discusses organizations typically involved in postdisaster reconstruction processes and the multifaceted roles they play. Document analysis on research papers, collected reports from the NRA, governmental departments, and many other organizations involved in the reconstruction was carried out. This study provides a comprehensive review of the reconstruction process after the 2015 Gorkha, Nepal, earthquake, whereas previous studies have covered a specific issue. The reconstruction works are presented structurally in detail. Similarly, the crucial steps and lesson learned for managing expectations and building back better are highlighted. This study may help to develop effective organization and policies in future postdisaster reconstruction.

Prediction of Building Damage Caused by Earthquake with Machine Learning

Estimating structural damage after an earthquake remains crucial in preventing loss of lives and properties. Conventional methods of damage estimation require a large amount of time and financial resources. For this reason, in recent years, machine learning algorithms that produce faster and more economical results have become the research topics of interest in damage estimation. Within the scope of this study, machine learning models that predict the damage level of the structure after the earthquake have been developed. In the models created, data sets containing structural and demographic information collected in 11 regions after the 2015 Gorkha, Nepal earthquake were used. Three classes of repair levels labeled by the engineers were chosen as the estimate label. The models were divided into Random Forest and XGBoost according to the classification algorithm they used, and models with and without demographic features according to the data they used. When the general accuracy rates of the models were compared, the models containing demographic information were more successful. The most successful result is the random forest model with an accuracy rate of 70.83% and the highest damage class recall value of 76.36%.

Seismic Performance of base isolated structure for Nepal Earthquake

Increased earthquakes have caused massive destruction and collapse of structures around the world in recent decades as a result of inadequate seismic design. In this way, creative work has received special attention with a focus on constructing the structure in such a way that harm to the structures is minimized. The goal is to construct structures that are safe, longlasting and durable for future generations. Active protective systems, hybrid protective systems and passive protective systems have all evolved as earthquake protection systems. The passive protection system keeps the structure elastic during large earthquakes and has a fundamental frequency that is lower than the predetermined base frequency of ground movement. The passive protective system includes base isolation as a component. Base isolation is currently the most innovative solution for seismic building protection in earthquake-prone areas. It has been successfully used for earthquake protection in a variety of buildings and other structures around the world. The purpose of this study is to investigate the performance of a G+8 building constructed of RCC and equipped with a high-damping rubber bearing and a lead rubber bearing isolation system. Two models are depicted in the work. The first model shows a conventional structure whereas the second model represents a base isolation structure. The goal is to use Time history in the ETABS-2017 software to compare the seismic response of a fixed base and base separated structure. The ground motion data from the Nepal earthquake of 2015 is used to do time history analysis.

Rahat-Sahayog (relief support): examining disaster emergency response in the aftermath of the Nepal Earthquake 2015

PurposeThis paper aims to critically examine the post-disaster emergency response amongst marginalised and disadvantaged social groups following the 2015 Nepal Earthquake (7.8 Mw).Design/methodology/approachA qualitative research method was employed by conducting interviews with disaster survivors from marginalised and ethnic social groups, humanitarian aid workers and government officials in the four districts worst hit by the 2015 Nepal Earthquake.FindingsThis research found that community members demonstrated remarkable cooperation in the aftermath of the disaster; however, caste-based discrimination still manifested in post-earthquake emergency environments. Further, this research showed that the engagement of government and local and international humanitarian organisations was noteworthy in the earthquake emergency response in Nepal as it localised relief packages and adapted the assistance corresponding to the fast-changing post-disaster environments. However, some relief materials were culturally inappropriate and climatically unsuitable. This paper also shows that the poor dissemination of relief distribution plans, resource duplication and ineffective targeting disproportionately impacted the oppressed and marginalised households in receiving humanitarian assistance.Originality/valueStudies have been undertaken on the emergency response to the 2015 Nepal Earthquake, however, few have focussed on the lived experience of marginalised and disadvantaged social groups. Further, this research builds on, and contributes to, the humanitarian mobile sovereignty discourse.

Improving Landslide Recognition on UAV Data through Transfer Learning

As a frequent geological disaster, landslides cause serious casualties and economic losses every year. When landslides occur, rapid access to disaster information is the premise of implementing disaster relief and reduction. Traditional satellite remote sensing may not be able to timely obtain the image data from the disaster areas due to orbital cycle and weather impacts. Visual interpretation of remote sensing data and machine learning methods need to be improved the detection efficiency. This paper studies landslide recognition based on the UAV remote sensing image. The affected area of the Zhangmu Port region in Tibet by the Nepal earthquake occurred on 25 April 2015 was selected to carry out the landslide investigation. Aiming at the problem of insufficient training sample data of landslides, we adopt the transfer learning method. The evaluation indexes show that the proposed method can automatically identify landslide disasters. Comparing with the SSD model, our new approach has better detection performance, providing thus accurate data support for scientific decision-making of disaster rescue.

Seismically active structures of the Main Himalayan Thrust revealed before, during and after the 2015 Mw 7.9 Gorkha earthquake in Nepal

SUMMARY The Mw 7.9 2015 April 25 Gorkha earthquake is the latest of a millenary-long series of large devastating Himalayan earthquakes. It is also the first time a large Himalayan earthquake and its aftershocks were recorded by a local network of seismic stations. In the 5 yr following the main shock, more than 31 000 aftershocks were located by this permanent network within the ruptured area, including 14 362 events with ML greater than 2.5, 7 events with ML > 6, including one large aftershock with Mw 7.2 on 2015 May 12. In 2020, 5 yr after the main shock, the seismicity rate along the ruptured fault segments was still about 5 times higher than the background seismicity before the Gorkha earthquake. Several bursts of earthquakes, sometimes organized in clusters, have been observed from a few days to several years after the main shock. Some of these clusters were located at the same place as the clusters that happened during the decades of interseismic stress build-up that preceded the large earthquake. They also happened in the vicinity of the high frequency seismic bursts that occurred during the main shock. These heterogeneities contribute to a persistent segmentation of the seismicity along strike, possibly controlled by geological structural complexities of the Main Himalayan Thrust fault. We suggest that these pre-2015 clusters revealed the seismo-geological segmentation that influences both the coseismic rupture and the post-seismic relaxation.

Recent large and strong earthquakes in the eastern Himalayas: An appraisal on seismotectonic model

Since 1934, two great earthquakes (Mw ≥8.0) and some eight large/strong earthquakes (Mw 6.5–7.8) occurred in the eastern Himalayas, from eastern Nepal to the Eastern Himalayan Syntaxis (EHS) Zone. All these events are instrumentally recorded by local as well as by the global network. From west to east these events are the 2015 two large/devastating earthquakes (Mw 7.8 and 7.3, respectively) in eastern Nepal, the 1934 and 1988 Bihar–Nepal earthquakes (Mw 8.1 and 6.8, respectively), the 2011 Sikkim (Mw 6.9), the 1967 and 2009 Bhutan (Mw 6.5 and 6.3, respectively), 1964 and 1947 Arunachal–Tibet (Mw 6.5 and 7.0, respectively), and the 1950 Assam–Tibet great (Mw 8.4) earthquakes. Most recently, on 28 April 2021, an earthquake Mw 6.1 occurred in the Assam foredeep. These events are documented as shallow (0–20 km) Main Himalayan Thrust (MHT) earthquakes in the International Seismological Center and National Earthquake Information Center—USGS catalogues. With the advent of local digital seismic networks and better precision of hypocentre locations, the eastern Himalayan earthquake source zones are found to be much different; these are not typically MHT events. Precise hypocentre locations indicate bimodal seismicity at shallower (0–20 km) as well as at deeper depths (40–70 km) in the eastern Himalayas. Seismic cross‐sections and fault plane solutions of the earthquakes do not support a uniform seismotectonic model for the entire Himalayas. All the instrumentally recorded past great earthquakes in the Himalayas and the recent destructive earthquakes in the eastern Himalayas study region are critically examined in view of the known seismotectonic model, and we suggest that each large/great earthquake occurred in its own unique complex tectonic environment. The transverse structures play a major role in generating the deeper earthquakes in the eastern Himalayas and the EHS; the shallower MHT may be flattened.

Investigation of microtremors observed at historic masonry townhouse buildings after Nepal earthquake

The Gorkha earthquake in 2015 was a recent large-scale earthquake that caused severe damage to many historic masonry buildings in the Kathmandu Valley, Nepal. The authors conducted a visual inspection survey of seismically damaged buildings after the earthquake in the historic town district of Bhaktapur in the Kathmandu Valley. The first part of this paper reports the distribution of the historic masonry buildings for each damage level in the surveyed area. A concentrating zone of severely-damaged buildings was explicitly found in the damage-level distribution map. Almost half of all the surveyed buildings were severely damaged during the earthquake, and most of these were historic masonry townhouse buildings. In the second part, the ambient vibration characteristics of the conventional historic masonry buildings in Bhaktapur are investigated. Typical dwelling houses in a historic town district in Nepal, which generally formed terraced houses built around a courtyard, were targeted for the measurement. Thus, the influence of adjacent buildings, which makes it difficult to identify the predominant natural frequencies from building vibration measurements, was also observed. Microtremor measurements using two accelerometers were conducted at 11 historic masonry buildings to investigate the discrimination degree for identifying the predominant natural frequency of conventional townhouse buildings. The estimated primary natural frequencies of these buildings were compared with the results of the screening model analysis. The advantages of using the proposed screening model analysis to improve the uncertainty of the first natural frequency identification by the microtremor measurement are discussed. Additional measurements of the microtremors at 4 of the 11 measured buildings were conducted using a different location combination of the two acceleration sensors. The sensors were placed between two different floors, and the transfer functions of each floor were investigated to observe the predominant vibration components on the floors in the entire building. Moreover, the coherence values observing the in-plane correlation of the floor responses were also analyzed for the dataset measured at two points separated on the same floor. Finally, an effective method for measuring the microtremors is discussed to improve the assessment of the vibration characteristics of conventional historic masonry buildings in Nepal.

2015년 네팔 지진과 여성

This study aims to analyze the earthquake experiences of 10 women from Dalit villages in Sindhupalchok District, which suffered severe damage from the 2015 earthquake in Nepal, from an intersectional perspective of gender, caste, and class. In the absence of husbands due to their international labor migration, Dalit women were exposed to multiple socio-economic, health and hygiene vulnerabilities due to the intersectionality of caste, class, and gender factors. This study shows that the husband’s continued labor migration without returning home can be understood as a survival strategy and the only hope for the poor Dalit households to receive material support for recovery from earthquake damage.

Strong ground motion data of the 2015 Gorkha Nepal earthquake sequence in the Kathmandu Valley

Strong-motion records of earthquakes are used not only to evaluate the source rupture process, seismic wave propagation and strong ground motion characteristics, but also to provide valuable data for earthquake disaster mitigation. The Kathmandu Valley, Nepal, which is characterised by having soft sediments that have been deposited in an earthquake-prone zone, has experienced numerous earthquakes. We have operated four strong-motion stations in the Kathmandu Valley since 2011. These stations recorded the 2015 magnitude 7.8 Gorkha Nepal earthquake that occurred in the Himalayan continental collision zone. For several months after the mainshock, we deployed four additional temporary stations. Here, we describe the seismic data for 18 earthquakes over magnitude 5.0 collected by this array, including the 2015 magnitude 7.3 Dolakha earthquake of maximum aftershock and three large aftershocks of magnitude 6-class. These data are essential for validating the sedimentary structure of the basin and for evaluating the hazard and risk of future earthquakes in the Kathmandu Valley.

From goods to goats: examining post-disaster livelihood recovery in the aftermath of the Nepal earthquake 2015

Disasters can have substantial impacts on people’s livelihoods in developing countries. Further, if the need for livelihood interventions is ignored or delayed, the crisis may trigger unexpected harmful consequences in the affected households in the aftermath. Therefore, restoring livelihoods should remain a priority in the post-disaster recovery process. However, such recoveries in rural contexts and developing countries, like Nepal, are complex as the livelihood restoration process is affected by serious spatial, socio-economic, and political factors. We employed qualitative research methods in four highly affected districts in the 2015 Nepal Earthquake (7.8 Mw) to examine post-disaster livelihoods recovery. Our paper critically assesses the humanitarian response based on the narratives and lived experiences of affected households. The findings show that humanitarian assistance was crucial in addressing several unmet needs of disaster-affected rural households in resource-poor settings in Nepal. However, the interventions were generally fragmented, insufficient, neoliberal led (forcing market dependencies), and largely business-as-usual in their orientation. Previous studies in Nepal paid insufficient attention to the goods provided to affected households in the name of recovery. Therefore, our paper scrutinises selected humanitarian objects, such as power tillers, and unpacks their political economy and effectiveness in local contexts. Further, our findings show that some livelihood policies reinforced the gap between the haves and have-nots, thereby reproducing pre-disaster inequalities in the post-disaster field.

Kathmandu Basin as a local modulator of seismic waves: 2-D modelling of non-linear site response under obliquely incident waves

SUMMARYThe 2015 Mw 7.8 Gorkha, Nepal earthquake is the largest event to have struck the capital city of Kathmandu in recent times. One of its surprising features was the frequency content of the recorded ground motion, exhibiting a notable amplification at low frequencies (<2 Hz) and a contrasting depletion at higher frequencies. The latter has been partially attributed to the damper behaviour of the Kathmandu basin. While such weak high-frequency ground motion helped avoiding severe damage in the city, the catastrophic outcomes of earlier earthquakes in the region attest to a contrasting role of the Kathmandu basin as a broad-band amplifier, in addition to possible source effects. Given the possibility of future strong events in the region, our main objective is to elucidate the seismic behaviour of the Kathmandu basin by focusing on site effects. We numerically model 2-D P–SV wave propagation in a broad frequency band (up to 10 Hz), incorporating the most recent data for the Kathmandu basin geometry, soil stratigraphy and geotechnical soil properties, and accounting for the non-linear effect of multidimensional soil plasticity on wave propagation. We find that: (1) the Kathmandu basin generally amplifies low frequency ground motion (<2 Hz); (2) waves with large incidence angles relative to vertical can dramatically amplify the high frequency ground motion with respect to bedrock despite the damping effect of soil non-linearity and (3) the spatial distribution of peak ground motion amplitudes along the basin is highly sensitive to soil non-linearity and wave incidence (angle and direction), favouring larger values near the basin edges located closer to the source, as observed during the 2015 event. Our modelling approach and findings can support the ongoing resilience practices in Nepal and can guide future seismic hazard assessment studies for other sites that feature similar complexities in basin geometry, soil stratigraphy and dynamic soil behaviour.

Testing machine learning models for seismic damage prediction at a regional scale using building-damage dataset compiled after the 2015 Gorkha Nepal earthquake

Assessing post-seismic damage on an urban/regional scale remains relatively difficult owing to the significant amount of time and resources required to acquire information and conduct a building-by-building seismic damage assessment. However, the application of new methods based on artificial intelligence, combined with the increasingly systematic availability of field surveys of post-seismic damage, has provided new perspectives for urban/regional seismic damage assessment. This study analyzes the effectiveness and relevance of a number of machine learning techniques for analyzing spatially distributed seismic damage after an earthquake at the regional scale. The basic structural parameters of a portfolio of buildings and the post-earthquake damage surveyed after the Nepal 2015 earthquake are analyzed and combined with macro-seismic intensity values provided by the United States Geological Survey ShakeMap tool. Among the methods considered, the random forest regression model provides the best damage predictions for specified ground motion intensity values and structural parameters. For traffic-light-based damage classification (three classes: green-, amber-, and red-tagged buildings based on post-earthquake damage grade), a mean accuracy of 0.68 is obtained. This study shows that restricting learning to basic features of buildings (i.e. number of stories, height, plinth area, and age), which could be readily available from authoritative databases (e.g. national census) or field-surveyed databases, yields a reliable prediction of building damage (4 features/3 damage grade accuracy: 0.64).

Effectiveness of PNL technique in disaster damage assessment: evidence from selective case studies

Natural disasters often cause large scale infrastructural damage and disruption of services. In such cases, a rapid damage assessment technique might prove beneficial to assist the disaster management efforts. Percent of normal light (PNL) can be one such technique. In this study, we test the effectiveness of PNL technique in rapid damage assessment from four selected case studies, namely the 2014 cyclone Hudhud, 2015 Gorkha (Nepal) earthquake, 2016 Central Italy earthquake, and the 2018 flood in Kerala. The dataset used has been taken from the Visible Infrared Imaging Radiometer Suite–Day/Night Band (VIIRS-DNB) scan data from the Joint Polar Satellite System (JPSS-1). The change in radiance values from the VIIRS-DNB dataset enables PNL computation to map the disaster affected regions. The results depict that PNL can be a viable alternative for rapid damage assessment.

Hybrid Broadband Ground Motion Simulation for 2015 Mw 7.9 Nepal Earthquake

The present study aims at simulating broadband ground motions in the epicentral region of the 2015[Formula: see text]Mw 7.9 Nepal event, using hybrid broadband technique. The spectral element method is used to simulate the low-frequency ground motion. The three-dimensional material property variation and the basin geometry at the Kathmandu basin are incorporated in the spectral element model. High frequency synthetics are simulated using scattering Green’s function approach by consistently using the source and medium model of low frequency simulation. The simulated Low Frequency (LF) (0–0.3[Formula: see text]Hz) results are combined with high-frequency scatterograms to generate broadband ground motions (0–10[Formula: see text]Hz). The scattering parameters for broadband ground motion simulation are estimated from the recorded data of Nepal mainshock. These parameters are used further for simulating the ground motions over a grid of stations at 2[Formula: see text]km [Formula: see text] 2[Formula: see text]km spacing at the epicentral region. The simulated results are shown as peak ground acceleration (PGA), peak ground velocity, and spectral acceleration contours plots. The maximum PGA in the horizontal and vertical directions are 0.35[Formula: see text]g and 0.32[Formula: see text]g in the epicentral region. Also, the acceleration time histories and corresponding response spectra are presented for some of the selected cities in the region where no records are available. These simulated outcomes are used for analyzing the validity of Indian seismic codal provisions at the near-field of large Himalayan earthquakes. The results show the significant underestimation of near-field hazard by the codal provisions at the Himalayan region.