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Fragility Assessment of Slope Stability for Producing Probabilistic Seismic Landslide Hazard Maps
Using Nonlinear Incremental Dynamic Analysis〇Dongliang HUANG, Hiroyuki GOTO, Chenlin XIANG

1. Introduction
Landslides

The distributions of regional slope height and angle
triggeredbyearthquakes

havewere extracted through slope-unit division using ademonstrated their devastating potential to damage

digital elevation model (DEM). By employing bivariate

essential infrastructure during previous seismic events.

sampling procedures, we constructed 50 finite element

Evaluating the capacity of slopes to withstand varying

models of slope samples with a classic soil-bedrock

degrees of ground shaking in anticipation of future

structure. Nonlinear dynamic simulations of Mohr-earthquakes remains a critical concern. The fragility

Coulomb material

curve method, coupled with the nonlinear incremental

subsequently

dynamic analysis (IDA) approach, stands out as a well-displacements, utilizing 28 representative groundestablished strategy in the field of earthquake

motions from the global PEER NGA-West2 Databaseengineering, making it an ideal choice for addressingscaled to five cumulative square acceleration (CSA)

this issue (Baker 2015). This preference is attributed tolevels (Fig. 2). Parameters are from Jibson et al. (2000).

(Huang et al. 2024) wereconductedtoobtainresidual

key considerations such as the selection of seismic
records, waveform scaling, and nonlinear simulation.
In this study, we conducted a fragility assessment ofclassic

coseismic

landslides

duringthe1994

Northridge earthquake (Jibson et al. 2000) using thenonlinear incremental dynamic analysis method.
Regional slope models, incorporating variations inslope heights and angles, were subjected to the
influence of globally representative records from pastearthquakes. The resultant probabilistic fragility curves

Fig. 1 Study area DEM and landslide polygons.

offer valuable insights into predicting slope failure
ratios across diverse intensity levels of futureearthquakes. The method not only demonstrates
theoretical reliability but also holds clear physicalsssignificance, rendering it applicable to the productionof probabilistic seismic landslide hazard maps.
2. Methodology
The study area, occupying an 856×856 square meter
space, is positioned adjacent to a highway, with anotable concentration of landslides (Fig. 1).

Fig. 2 Displacement histories of 120m_29° slope.

3. Results
The simulation results formed diverse IDA curves,considering variations in slope height, slope angle,
CSA level, and seismic records (Figs. 3 and 4).
Generally, with the increase in CSA values, the slope
residual displacement tends to rise. Slope collapse
threshold is set to the displacement over 0.3 m tocalculate the theoretical slope collapse ratios atdifferent CSA levels. Subsequently, fragility curves foreach slope model were estimated using the Maximum
Likelihood method, as outlined in Baker (2015). TheFig. 3 IDA curves of 50 slope samples with theresulting fragility curves demonstrate the robust

variations of slope height and angle under the action

calculation of the proposed workflow (Fig. 5). Inof the scaled RSN57_SFERN_ORR021.AT2 records.

comparison to the observed collapse ratio of 0.69 at aCSA value of 28.12 m2/s3, the predicted collapse
probability reaches 0.76. A comprehensive discussion
on slope sampling, displacement threshold, seismicintensity measure, seismic intensity level, and theselection of representative records is needed for futurestudies.
Acknowledgments
Financial supports for this study were provided bytheChinese

ScholarshipCouncil(CSC,Nos.

202106370143, 202107000093).
References
Baker J.W., 2015. Efficient Analytical Fragility Function

Fig. 4 IDA curves of 54m_35° slope using 28 records(CSA histogram attached) scaled at five CSA levels.

Fitting Using Dynamic Structural Analysis. Earthq
Spectra. 31, 579–599.
Huang D., Goto H., Xiang C., 2024. Controlling role ofground motion time histories on the north ‒ south
difference in coseismic landslide distribution during the2018 Hokkaido Eastern Iburi earthquake. In: The 8thinternational conference on earthquake geotechnicalengineering. Osaka, Japan. 1–6.
Jibson R.W., Harp E.L., Michael J.A., 2000. A method for
producing digital probabilistic seismic landslide hazard
maps. Eng Geol. 58, 271–289.
Ancheta T.D., Darragh R.B., Stewart J.P., 2013. PEER
NGA-West2 Database.

Fig. 5 The probabilistic fragility curve generated in thisstudy and the corresponding observed damage ratio
derived from 20 failed slope units (yellow) thatcovered by landslide polygons (red).