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Abstract <p>Raxaul, located in the East Champaran district of Bihar, India, and adjacent to Birgunj city in Nepal, is a region with significant seismic risk. Due to the substantial seismic hazard posed by earthquakes in this area, it is essential to comprehend the subsurface conditions. We gathered ambient noise data to compute horizontal-to-vertical spectral ratio (H/V), using a short-period seismometer, at thirty-four different locations in Raxaul. The predominant frequency in the area lies between 0.50 and 1.40 Hz. Rayleigh wave ellipticity inversion is used to estimate the shear wave velocity profiles. The soil’s Vs30 varies from ~125 to ~260 m/s in the region, and the site falls in classes D and E, suggesting a possibility of soil amplification and liquefaction. Additionally, the area’s seismic vulnerability index was determined using both the amplitude and predominant frequency data. Over 75% of the land is susceptible to liquefaction in the study region. This information is crucial for determining the area’s seismic risk and developing effective mitigation plans by the National Disaster Management Authorities (NDMA) and the Geological Survey of India (GSI) in order to create seismic microzonation maps in the East Champaran area and improve methods for reducing and preparing for seismic hazard.</p> Research highlights <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Ambient noise H/V spectral ratio analysis is performed for Raxaul (India), where predominant frequencies vary between 0.5 and 1.4 Hz.</p> </ItemContent> <ItemContent> <p>The region shows high liquefaction susceptibility, with class E soils posing the greatest seismic risk.</p> </ItemContent> <ItemContent> <p>The low Vs values (130–260 m/s) indicate thick alluvial sediments and risk of high seismic wave amplifications.</p> </ItemContent> </UnorderedList></p>

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Evaluating the seismic site conditions in the Raxaul Region, Bihar, India: Strategic analysis for risk mitigation

  • 期刊论文

  • 发表日期：

    2026年7月7日

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  • Gautam Chaurasia,
  • Mohit Agrawal,
  • Ravindra K Gupta

摘要

Abstract

Raxaul, located in the East Champaran district of Bihar, India, and adjacent to Birgunj city in Nepal, is a region with significant seismic risk. Due to the substantial seismic hazard posed by earthquakes in this area, it is essential to comprehend the subsurface conditions. We gathered ambient noise data to compute horizontal-to-vertical spectral ratio (H/V), using a short-period seismometer, at thirty-four different locations in Raxaul. The predominant frequency in the area lies between 0.50 and 1.40 Hz. Rayleigh wave ellipticity inversion is used to estimate the shear wave velocity profiles. The soil’s Vs30 varies from ~125 to ~260 m/s in the region, and the site falls in classes D and E, suggesting a possibility of soil amplification and liquefaction. Additionally, the area’s seismic vulnerability index was determined using both the amplitude and predominant frequency data. Over 75% of the land is susceptible to liquefaction in the study region. This information is crucial for determining the area’s seismic risk and developing effective mitigation plans by the National Disaster Management Authorities (NDMA) and the Geological Survey of India (GSI) in order to create seismic microzonation maps in the East Champaran area and improve methods for reducing and preparing for seismic hazard.

Research highlights

Ambient noise H/V spectral ratio analysis is performed for Raxaul (India), where predominant frequencies vary between 0.5 and 1.4 Hz.

The region shows high liquefaction susceptibility, with class E soils posing the greatest seismic risk.

The low Vs values (130–260 m/s) indicate thick alluvial sediments and risk of high seismic wave amplifications.