Current regional seismic risk assessment methods do not take into account either ground motion directionality or building orientation. A recent study examined the combined effect of ground motion directionality and building orientation for a testbed of imaginary buildings with the same height, structural material, lateral resisting system, and underlain soil properties. That study concluded that future urban seismic risk analyses should consider the combined effects of ground motion directionality and building orientation, and indicated that further research was warranted to conduct this type of assessment in real-world conditions. This investigation specifically examines the combined effects of ground motion directionality and urban layout on the seismic responses and damages of 150 tall buildings in San Francisco’s Financial District during the 1989 Loma Prieta earthquake, using an advanced probabilistic regional seismic risk framework previously developed by the authors. Building responses and damages were computed for three scenarios: (1) buildings in their current orientations, (2) buildings rotated so that one principal axis is aligned with the RotD100 orientation during the Loma Prieta earthquake in downtown San Francisco, and (3) buildings rotated so that both building principal axes are 45° from the RotD100 orientation. The results indicate that peak building responses and damages can vary by up to 30% and 100%, respectively, depending on changes in the urban grid layout. However, responses and damages at individual building stories can change by much more than 30% and 100%, respectively. Larger responses and damages are expected to occur when the city has an orthogonal grid layout and the orientation of RotD100 aligns with the city’s street grid. These findings, which highlight the combined impact of urban layout and ground motion directionality on building responses and damages, have important implications for city officials, planners, insurers, reinsurers, and other stakeholders involved in regional seismic risk assessments.
Alonso-RodríguezAMirandaE (2016) Dynamic behavior of buildings with non-uniform stiffness along their height assessed through coupled flexural and shear beams. Bulletin of Earthquake Engineering14(12): 3463–3483.
2.
ArnadóttirTSegallP (1994) The 1989 Loma Prieta earthquake imaged from inversion of geodetic data. Journal of Geophysical Research: Solid Earth99(B11): 21835–21855.
3.
ATC-119 (2018) San Francisco tall buildings study. Report for Applied Technology Council, December. Redwood City, CA: Applied Technology Council.
4.
BantisJMirandaE (2025) Effect of damping on response spectral ordinates of ground motions recorded on soft soils in the San Francisco bay area. Soil Dynamics and Earthquake Engineering196: 109449.
5.
BantisJHeresiPPoulosAMirandaE (2025a) Framework for regional seismic risk assessments of groups of tall buildings. Earthquake Engineering and Structural Dynamics54(3): 833–850.
6.
BantisJMirandaEHeresiP (2025b) Simplified site response analysis for regional seismic risk assessments. Soil Dynamics and Earthquake Engineering188: 109022.
7.
BantisJMirandaEHeresiP (2025c) Regional damage estimation of tall pre-Northridge steel moment-resisting frame buildings in San Francisco during the Loma Prieta earthquake. Earthquake Spectra41: 2060-2088.
8.
BantisJMirandaEHeresiP (2025d) Impact of hypocenter location of different Mw7.0 earthquakes on the Hayward fault on the seismic response of tall buildings in San Francisco. Earthquake Engineering and Structural Dynamics54: 1975–1991.
9.
BantisJCMirandaE (2023) Evaluation of random-vibration procedures to estimate response spectral ordinates on soft soil sites from Fourier amplitude spectra. Soil Dynamics and Earthquake Engineering166: 107776.
10.
BerozaGC (1991) Near-source modeling of the Loma Prieta earthquake: Evidence for heterogeneous slip and implications for earthquake hazard. Bulletin of the Seismological Society of America81(5): 1603–1621.
11.
BoeingG (2019) Urban spatial order: Street network orientation, configuration, and entropy. Applied Network Science4(1): 1–19.
12.
BooreDM (2010) Orientation-independent, nongeometric-mean measures of seismic intensity from two horizontal components of motion. Bulletin of the Seismological Society of America100(4): 1830–1835.
13.
BozorgniaYAbrahamsonNAAtikLAAnchetaTDAtkinsonGMBakerJWBaltayABooreDMCampbellKWChiouBSJDarraghR (2014) NGA-West2 research project. Earthquake Spectra30(3): 973–987.
14.
ByerlyPHesterJMarshallK (1931) The natural periods of vibration of some tall buildings in San Francisco. Bulletin of the Seismological Society of America21(4): 268–276.
15.
ChernyRW (1995) City commercial, city beautiful, city practical: The San Francisco visions of William C. Ralston, James D. Phelan, and Michael M. O’Shaughnessy. California History73(4): 297–337.
16.
ChevalierA (1911) The Chevalier commercial, pictorial and tourist map of San Francisco. Map. Available at: https://www.davidrumsey.com/maps6460.html (accessed 11 May 2025).
17.
CruzC (2017) Evaluation of damping ratios inferred from the seismic response of buildings. PhD Thesis, Department of Civil and Environmental Engineering, Stanford University, Stanford, CA.
18.
CruzCMirandaE (2017) Evaluation of the Rayleigh damping model for buildings. Engineering Structures138: 324–336.
Federal Emergency Management Agency (FEMA) (2012) Seismic performance assessment of buildings, vol. 1. Report No. FEMA P-58. Prepared by Applied Technology Council for the Federal Emergency Management Agency. Washington, DC: Federal Emergency Management Agency.
21.
FilippitzisFKohlerMDHeatonTHGravesRWClaytonRWGuyRGBunnJJChandyKM (2021) Ground motions in urban Los Angeles from the 2019 Ridgecrest earthquake sequence. Earthquake Spectra37(4): 2493–2522.
22.
Garcia-SuarezJAsimakiD (2020) On the fundamental resonant mode of inhomogeneous soil deposits. Soil Dynamics and Earthquake Engineering135: 106190.
23.
GaspariniDAVanmarckeEH (1976) Simulated earthquake motions compatible with prescribed response spectra. Report No. R76-4, MIT Department of Civil Engineering. Boston, MA: MIT Department of Civil Engineering.
24.
GirmayNMirandaEPoulosA (2024) Orientation and intensity of maximum response spectral ordinates during the December 20, 2022 Mw 6.4 Ferndale, California earthquake. Soil Dynamics and Earthquake Engineering176: 108323.
25.
GirmayNPoulosAMirandaE (2023) Directionality and polarization of response spectral ordinates in the 2023 Kahramanmaras, Türkiye earthquake doublet. Earthquake Spectra40(1): 486–504.
26.
Google Earth 7.3 (2014) Map showing downtown San Francisco. Available at: https://earth.google.com/web/ (accessed 5 February 2024).
HongHPGodaK (2007) Orientation-dependent ground-motion measure for seismic-hazard assessment. Bulletin of the Seismological Society of America97(5): 1525–1538.
29.
ParsonsCRCurrierI (1878) The city of San Francisco. Birds eye view from the bay looking south-west. Map. Available at: https://loc.gov/item/75693104/(accessed 11 May 2025).
30.
PetersenMDShumwayAMPowersPMMuellerCSMoschettiMPFrankelADRezaeianSMcNamaraDELucoNBoydOSRukstalesKS (2020) The 2018 update of the US National Seismic Hazard Model: Overview of model and implications. Earthquake Spectra36(1): 5–41.
31.
PoulosAMirandaE (2022a) Probabilistic characterization of the directionality of horizontal earthquake response spectra. Earthquake Engineering & Structural Dynamics51(9): 2077–2090.
32.
PoulosAMirandaE (2022b) Proposal of orientation-independent measure of intensity for earthquake-resistant design. Earthquake Spectra38(1): 235–253.
33.
PoulosAMirandaE (2023a) Effect of style of faulting on the orientation of maximum horizontal earthquake response spectra. Bulletin of the Seismological Society of America113(5): 2092–2105.
34.
PoulosAMirandaE (2023b) Modification of ground-motion models to estimate orientation-dependent horizontal response spectra in strike-slip earthquakes. Bulletin of the Seismological Society of America113(6): 2718–2729.
35.
PoulosAMirandaE (2024) Directionality characteristics of horizontal response spectra from the 2022 Mw 6.9 Chihshang, Taiwan earthquake. Earthquake Spectra40(3): 1683–1696.
36.
PoulosAMirandaE (2025) Accounting for ground motion directionality and building orientations in urban seismic risk analysis. Earthquake Spectra41(2): 1780–1800.
37.
RathjeEMKottkeAROzbeyMC (2005) Using inverse random vibration theory to develop input Fourier amplitude spectra for use in site response. In: 16th international conference on soil mechanics and geotechnical engineering: TC4 Earthquake geotechnical engineering satellite conference, Osaka, Japan, 12–16 September.
SchlockerJRadbruchDHBonillaMG (1954) Preliminary bedrock-surface map of the San Francisco City area, California (No. 54-274). US Geological Survey Open File Map. Available at: https://pubs.usgs.gov/of/1954/0274/plate-1.pdf (accessed 11 May 2025).
