Time-averaged shear wave velocity over the upper 30 m of the earth’s surface (VS30) is a key parameter for estimating ground motion amplification as both a predictive and a diagnostic tool for earthquake hazards. The first-order approximation of VS30 is commonly obtained through a topographic slope–based or terrain proxy due to the widely available nature of digital elevation models. However, better-constrained VS30 maps have been developed in many regions. Such maps preferentially employ various combinations of VS30 measurements, higher-resolution elevation models, lithologic, geologic, geomorphic, and other proxies and often utilize refined interpolation schemes. We develop a new hybrid global VS30 map database that defaults to the global slope-based VS30 map, but smoothly inserts regional VS30 maps where available. In addition, we present comparisons of the default slope-based proxy maps against the new hybrid version in terms of VS30 and amplification ratio maps, and uncertainties in assigned VS30 values.
AllenTIWaldDJ (2009) On the use of high-resolution topographic data as a proxy for seismic site conditions (Vs30). Bulletin of the Seismological Society of America99: 935–943.
DanielsonJGeschD (2011) Global multi-resolution terrain elevation data 2010 (GMTED2010). U.S. Geological Survey Open-File Report 2011–1073. Available at: https://pubs.usgs.gov/of/2011/1073/ (last accessed January 2020).
4.
DestegulUDellowGHeronD (2009) A ground shaking amplification map for New Zealand. Bulletin of the New Zealand Society for Earthquake Engineering42: 122–128.
5.
ErasoJ (2015) Cálculo del promedio de velocidad de onda de corte a 30 metros de profundidad (Vs30) en Colombia como una aproximación a la estimación de los efectos sísmicos de sitio a escala nacional, p. 28. Colombia: Bogota.
6.
KarimzadehSFeizizadehBMatsuokaM (2017) From a GIS-based hybrid site condition map to an earthquake damage assessment in Iran: Methods and trends. International Journal of Disaster Risk Reduction22: 23–36.
7.
KwokOLAStewartJPKwakDYSunP-L (2018) Taiwan-specific model for Vs30 prediction considering between-proxy correlations. Earthquake Spectra34: 1973–1993.
McPhersonA (2017) A Revised Seismic Site Conditions Map for Australia. Canberra, ACT, Australia: Geoscience Australia.
10.
MatsuokaMWakamatsuKFujimotoKMidorikawaS (2006) Average shear-wave velocity mapping using Japan engineering geomorphologic classification map. Structural Engineering/Earthquake Engineering23: 57s–68s.
11.
MicheliniAFaenzaLLaucianiVMalagniniL (2008) ShakeMap implementation in Italy. Seismological Research Letters79: 688–697.
12.
PetersenMDShumwayAMPowersPMMuellerCSMoschettiMPFrankelADRezaeianSMcNamaraDELucoNBoydOSRukstalesKSJaiswalKSThompsonEMHooverSMClaytonBSFieldEHZengY (2019) The 2018 update of the US National Seismic Hazard Model: Overview of model and implications. Earthquake Spectra36: 5–41.
13.
SchulteSMMooneyWD (2005) An updated global earthquake catalogue for stable continental regions: Reassessing the correlation with ancient rifts. Geophysical Journal International161: 707–721.
14.
SeyhanEStewartJP (2014) Semi-empirical nonlinear site amplification from NGA-West2 data and simulations. Earthquake Spectra30: 1241–1256.
15.
SeyhanEStewartJPAnchetaTDDarraghRBGravesRW (2014) NGA-West2 site database. Earthquake Spectra30: 1007–1024.
16.
StewartJPKlimisNSavvaidisATheodoulidisNZargliEAthanasopoulosGPelekisPMylonakisGMargarisB (2014) Compilation of a local Vs profile database and its application for inference of Vs30 from geologic-and terrain-based proxies. Bulletin of the Seismological Society of America104: 2827–2841.
17.
StewartJPParkerGAHarmonJAAtkinsonGMBooreDMDarraghRBSilvaWJHashashYM (2017) Expert panel recommendations for ergodic site amplification in central and eastern North America. PEER Report 2017/04. Berkeley, CA: Pacific Earthquake Engineering Research Center.
18.
ThompsonEMWaldDJ (2012) Developing Vs30 site-condition maps by combining observations with geologic and topographic constraints. In: The 15th World, Conference, Earthquake, Engineering, Lisbon, Portugal, 24–28 September.
19.
ThompsonEMWaldDJWordenC (2014) A Vs30 map for California with geologic and topographic constraints. Bulletin of the Seismological Society of America104: 2313–2321.
20.
ThompsonEMWaldDJ (2016) Uncertainty in Vs30-based site response. Bulletin of the Seismological Society of America106: 453–463.
21.
WaldDJAllenTI (2007) Topographic slope as a proxy for seismic site conditions and amplification. Bulletin of the Seismological Society of America97: 1379–1395.
22.
WesselPSmithWHScharrooRLuisJWobbeF (2013) Generic mapping tools: Improved version released. Eos, Transactions American Geophysical Union94: 409–410.
23.
WillsCClahanK (2006) Developing a map of geologically defined site-condition categories for California. Bulletin of the Seismological Society of America96: 1483–1501.
24.
WordenCWaldDAllenTLinKGarciaDCuaG (2010) A revised ground-motion and intensity interpolation scheme for ShakeMap. Bulletin of the Seismological Society of America100: 3083–3096.
