The Kathmandu Valley is within a seismically active region with only few recorded strong-motion data. Geophysical information in the Valley is also sparse. In addition, the absence of an open database which compiles in situ geophysical tests, borehole records, and geotechnical laboratory data is affecting the advancement of knowledge in the region. This article presents SAFER/GEO-591 database, named after the Engineering and Physical Science Research Council (EPSRC)-funded project Seismic Safety and Resilience of Schools in Nepal (SAFER). SAFER/GEO-591 contains data from groundwater wells and boreholes originally commissioned for research and commercial purposes. This work describes (1) the quality assessment and harmonization process conducted on the dataset, (2) the variation of shear-wave velocity (V_S) measurements and geotechnical parameters with depth and elevation in the Valley, (3) the current understanding of the Valley sediment/bedrock topography, and finally (4) new geological cross sections. A companion article presents an updated V_(S30) map across the Valley based on the contributions of this article. The database can be downloaded from the University of Bristol repository via DOI: https://doi.org/10.5523/bris.3gjcvx51lnpuv269xsa1yrb0rw

Asimaki, Domniki

De Luca, Flavia

De Risi, Raffaele

Gilder, Charlotte E. L.

Maskey, Prem Nath

Pokhrel, Rama Mohan

Sextos, Anastasios

Vardanega, Paul J.

Werner, Maximilian J.

English

The Kathmandu Valley is within a seismically active region and only few recorded strong motion data are available for the region. Geophysical information in the valley is very sparse. Additionally, the absence of an open database which compiles in situ geophysical tests, borehole records and geotechnical laboratory data is preventing the advancement of knowledge in the region. This paper presents SAFER/GEO-591 database, named after the EPSRC funded project Seismic Safety and Resilience of Schools in Nepal (SAFER). SAFER/GEO-591 contains data from groundwater wells and boreholes originally commissioned for research and commercial purposes. This work discusses (i) the quality assessment and harmonization process conducted on the dataset, (ii) shear-wave velocity (Vs) measurements and geotechnical parameters with depth and elevation in the Valley, (iii) a review of the current understanding of the Valley sediment/bedrock topography, and lastly (iv) new geological cross sections. A companion paper presents an updated VS30 map across the Valley based on the contributions of this paper. The database can be freely downloaded from the University of Bristol Repository via DOI:https://doi.org/10.5523/bris.2d5fji307ihtm28492er663bwf<br/

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The SAFER Geodatabase for the Kathmandu Valley:geotechnical and geological variability

El Gilder, Charlotte

Caltech Authors - Main

APPENDIX A to “The SAFER geodatabase for the Kathmandu Valley: geotechnical and 
geological variability”. 
 
Figure A1. Database geotechnical parameters with depth (m below ground level). Vs = shear wave 
velocity (m/s); SPT-N = uncorrected SPT value in number of blows; w = moisture content (%); wL = 
liquid limit (%) (number of non-plastic samples is 65); wPL = plastic limit (%); 𝜌 = bulk density (g/cm³); 
𝜌𝑝𝑎𝑟 = particle density (g/cm³); cv = coefficient of consolidation(cm
2/sec). Geotechnical strength values 
from unconsolidated undrained triaxial tests, cu = undrained shear strength (kPa). c' = effective cohesion 
(kPa) and ' = effective angle of friction (deg). Data for Made Ground is included. 
 
Figure A2. SPT-N with elevation separated by material types. Elevation categories informed from 
Sakai (2001) cross-section and provides possible separation by geological formation; Te = terrace 
deposits, G = Gokarna Formation, T = Thimi Formation, P = Patan Formation and K = Kalimati 
Formation. 35 points are not included due to unknown locations. 
 
Figure A3. Database geotechnical parameters with shear wave velocity (m/s). Plot is separated for 
material type. SPT-N values represent the average values over each geophysical interval. Other plots 
provide duplicate values if more than one test is in each geophysical layer. The SPT-N with Vs plot is 
showing there is not a statistically meaningful relationship between these parameters using the empirical 
equation 𝑉𝑠 = 𝑐1𝑁
𝐶2 with the data currently available. 
 
Figure A4. Model b+g raster displayed as a function of depth. Orange region is showing where bedrock 
is outcropping at the surface so is a zone where depth = 0 m. 
 
Table A1. List of VS30 values derived from downhole measurements 
ID (1) Source reference Database record 
Measurement 
final depth 
(m bgl) 
VS30 (m/s) (3) 
Calculated Inferred 
B1 
B2 
B3 
B4 
B5 
JICA (2002) R_JICA_2002 BH1 
BH2 
BH3 
BH4 
BH5 
30 180 
231 
219 
198 
216 
- 
- 
- 
- 
- 
B6 Industrial (2) IND_Bakh_2006 BH1 
BH3 
30 135 
146 
- 
- 
B7 IND_Bans_2007 BH3 
BH5 
BH8 
30 
18 
30 
236 
- 
265 
- 
261 
- 
B8 
B9 
B10 
B11 
B12 
J-RAPID (2016) R_JRAP_2016 BH1 
BH2 
BH3 
BH4 
BH5 
11 
15 
13 
15 
9 
- 
- 
- 
- 
- 
140 
203 
147 
139 
170 
B13 
B14 
Pokhrel (2006) RES_Pokh_2006 BH6 
BH7 
30 
88 
237 
207 
- 
- 
B15 Gilder et al. (2019) RES_Safe_2018 BH1 30 257 - 
(1) ID’s correspond to map locations in De Risi et al. (2019). 
(2) Industrial references are mainly via personal communication due to confidentiality on data (see database 
manual at the datasets DOI for more details). 
(2) VS30 values calculated according to Eurocode 8 (CEN 2004), from geophysical intervals as 
recommended for direct downhole seismic methods described in Kim et al (2004). The values listed as 
inferred are corrected using Boore (2004) so are the result of extrapolation. Where 9m depth was reached 
the regression co-efficient for 10m was used. 
Table A2. Material properties by elevation and soil type in Kathmandu Valley from laboratory testing 
Soil Type 
(1) 
Elevation 
category 
(m OD)  
Stats (2) 
Soil Properties (3) 
w wL wPL  cu c' ' 
Clay 
>1386 
min 18.9 37.0 20.4 2.48 8.2 - - 
max 62.5 42.6 24.6 2.59 17.4 - - 
 32.3 39.9 22.8 2.55 12.8 - - 
n 13 11 8 14 2 - - 
 11.8 2.0 1.8 0.03 6.5 - - 
1386 - 
1310  
min 25.2 43.1 29.4 
2.49 
- 2.0 6.2 
max 36.6 52.2 34.5 - 24.7 23.0 
 30.0 47.7 32.6 - 10.5 15.0 
n 3 2 4 1 - 7 7 
 5.9 6.4 2.3 - - 7.2 6.4 
<1310 
min 16.2 26.2 13.7 1.97 8.5 0.0 8.0 
max 115.8 82.0 53.1 2.72 74.1 29.0 40.0 
 47.8 45.8 30.1 2.48 43.7 13.4 21.2 
n 83 48 47 26 13 40 40 
 24.4 13.7 9.3 0.26 16.5 7.4 8.4 
Silt 
>1386 
min 
31.9 39.5 22.0 2.58 
- - - 
max - - - 
 - - - 
n 1 1 1 1 - - - 
1386 - 
1310  
min 24.9 30.4 22.0 2.55 
36.2 
4.7 9.9 
max 65.1 67.0 41.2 2.73 27.0 33.0 
 37.6 45.3 30.9 2.67 13.7 20.0 
n 6 13 10 10 1 8 8 
 15.2 12.4 6.0 0.07 - 7.3 8.7 
<1310 
min 5.4 24.6 20.0 2.17 1.3 0.0 7.0 
max 108.5 95.9 63.8 2.88 60.4 57.2 69.0 
 55.0 49.3 34.5 2.60 35.8 9.9 23.1 
n 68 95 84 59 15 34 34 
 22.0 16.2 12.5 0.14 17.0 10.7 10.7 
Sand 
1386 - 
1310  
min 10.0 35.0 - 1.89 - 0.0 11.8 
max 47.1 42.0 - 3.26 - 16.0 38.0 
 24.1 38.5 - 2.61 - 9.8 23.0 
n 129 2 - 67 - 6 6 
 7.0 4.9 - 0.22 - 5.8 11.9 
<1310 
min 10.5 26.5 - 2.61 - 0.0 18.0 
max 39.4 47.0 - 2.76 - 27.7 38.4 
 24.8 36.4 - 2.65 - 7.0 28.7 
n 14 6 - 10 - 8 8 
 10.0 7.6 - 0.05 - 10.6 6.8 
 (1) Unknown soil types are not included in table but spread of this data can be deduced from Fig 3.  
(2) min = minimum; max = maximum, µ = mean, n = number of tests, σ = standard deviation. 
(3) w = moisture content (%); wL = liquid limit (%); wPL = plastic limit (%); Vs = shear wave velocity (m/s); 𝜌 = 
bulk density (g/cm³). Values from unconsolidated undrained triaxial test, cu in kPa. c' in kPa and ' in degrees. 
For elevation >1386 this is no sand data. 
 
 
 
 
References 
 
Boore, D. M., 2004. Estimating VS(30) (or NEHRP Site Classes) from Shallow Velocity Models 
(Depths <30 m). Bulletin of the Seismological Society of America, 94(2), 591 – 597. 
CEN (European Committee for Standardization), 2004. Eurocode 8: Design of structures for earthquake 
resistance – Part 1: General rules, seismic actions and rules for buildings. Brussels, Belgium. 
De Risi R., De Luca, F., Gilder, C. E. L., Pokhrel, R. M. and Vardanega, P. J., 2019. SAFER 
Geodatabase for the Kathmandu basin: Bayesian kriging as strategy in data scarce regions. 
Earthquake Spectra, under review. 
Gilder, C. E. L., Pokhrel, R. M., and Vardanega, P. J., 2019. A ground investigation to inform 
earthquake hazard assessment in the Kathmandu Valley, Nepal. 17th European Conference on Soil 
Mechanics and Geotechnical Engineering, (XVII ECSMGE-2019), Reykjavik, Iceland. 
Japan International Cooperation Agency (JICA), 2002. The Study on Earthquake Disaster Mitigation 
in the Kathmandu Valley. Final Report, Volume I-IV. 
J-RAPID., 2016. Japan-Nepal Urgent Collaborative Projects regarding the April 2015 Nepal earthquake 
within the J-Rapid Program: Investigation of foundation liquefaction susceptibility in the 
Kathmandu Valley, Final Report. 
Kim, D-S., Bang, E-S., and Kim, W-C., 2004. Evaluation of Various Downhole Data Reduction 
Methods for Obtaining Reliable Vs Profiles. Geotechnical Testing Journal 27(6), 585-597. 
Pokhrel, R. M., 2006. Determination of soil dynamic properties of Kathmandu Valley by using down 
the hole seismic method, Masters Dissertation, Central Department of Geology, Institute of Science 
and Technology, Tribhuvan University, Kathmandu, Nepal. 
Sakai, H., Fujii, R., Kawahara, Y., Upreti, B. N. and Shrestha, S. D., 2001. Core drilling of the basin-
fill sediments in the Kathmandu Valley for Palaeoclimatic study: preliminary results. Journal of 
Nepal Geological Society, 25 (Special Issue), 9-18. 
 


SAFER geodatabase for the Kathmandu Valley: Geotechnical and geological variability

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The SAFER Geodatabase for the Kathmandu Valley:geotechnical and geological variability

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