Future Earthquakes Research Articles

Backprojection Imaging of the 2020 Mw 5.5 Magna, Utah, Earthquake Using a Local Dense Strong-Motion Network

Abstract We present the application of a backprojection method for imaging the detailed rupture of the 2020 Mw 5.5 Magna, Utah, earthquake. This is the first time that this method is applied to an earthquake smaller than Mw 6 in a local scale using a dense strong-motion network. The 2020 Magna earthquake occurred in a very well instrumented area, the Salt Lake valley, with tens of strong-motion seismic stations. We use envelopes of high-frequency S waves recorded on the transverse component at 45 seismic stations that are located at distances up to 100 km from the epicenter. The nearest station is ∼4.5 km. Backprojection resolves the epicentral location of the mainshock with an absolute error of less than 1 km, whereas the depth resolution is within the centroid depth range of multiple moment tensor solutions. Spatial distribution of the imaged subevents shows an up-dip unilateral west-northwest–east-southeast rupture with a length of ∼10 km, consistent with the distribution of early aftershocks. The average rupture speed is between 2.9 and 3.2 km/s for the first 2 and 3 s, respectively. The shallow dip (∼35°) of the Wasatch fault at depth, which failed during the Magna earthquake, combined with the up-dip unilateral rupture, indicates that ground-motion scenarios for future larger earthquakes in the Salt Lake Valley should be re-evaluated. This study underlines the need for instrumenting metropolitan areas of high seismic risk and adopting backprojection techniques in the near-real-time network products immediately after a strong earthquake.

Characteristic of Northern Thailand Seismic Stations from Horizontal-to-Vertical Spectral Ratios (HVSR) Analysis

Several major cities in Northern Thailand are located on a sedimentary basin, which could amplify ground motion from future earthquakes as they lie along several active faults. To study the seismic response and natural periods of these basins, a Horizontal to Vertical Spectral Ratio (HVSR) for each seismic station in Northern Thailand has been proposed. Several observed ground motion from moderate to small seismic events in and around Northern Thailand were used in this analysis. Several seismometers (TSA-100S, Trillium-120, PA-23, S-13 and KS 2000) of the Department of Mineral Resources (DMR) and Thai Meteorological Department (TMD) with triaxial digital accelerometer data were used. The 3 axis digital accelerometers (2-horizontal and vertical) were converted to Fourier amplitude spectral (FAS) in order to find basin natural period by Horizontal to Vertical Spectral Ratio (HVSR). This research investigates 6 stations in Northern Thailand with at least 10 observed ground motions for each station. We found that the natural period of three stations (CRAI, PAYA and PHRA) showed strong site amplification effect at low natural period (between 0.1 - 0.2 s with an amplitude larger than 2). The natural period of CMMT and MHIT stations were insignificant since CMMT and MHIT were located on the rocks. Lastly, we observed long natural period for CMCA station located in Chiang Mai basin around 2.50 s with an amplitude larger than 3. Furthermore, the computed site natural periods were compared with the average top 30 m shear wave velocity (Vs30) based on the data from the Shuttle Radar Topography Mission (SRTM) and Multichannel Analysis of Surface Wave (MASW) to find the type of soil in each area.

Viaduct maintenance for future traffic demands and earthquakes

The Tokyo Metropolitan Expressway in Japan has been in operation for more than half a century. Recently, serious damages in the network have been reported in many of the old routes. However, the Metropolitan Expressway has little-to-no of experience in managing such a situation so far. Thus, developing an appropriate management strategy focusing on maintenance is critical to the expressway. The emphasis of this study is placed on the maintenance improvement of steel viaducts, and the project aims to evaluate their marginal maintenance cost and identify the influences on the cost from uncertainties such as earthquakes and future traffic demand from an econometric perspective. The study reveals that the traffic volume of passenger cars can be identified as a significant factor, while the effect of earthquake events on the cost is not clearly pronounced. Based on the analyses, it is found that the current maintenance approach is capable of dealing with fluctuations in traffic volume, which is the most influential factor. Furthermore, an increase in the amount of maintenance works could possibly lower the maintenance costs due to economies of scale. The results also indicate that the efficiency of the current maintenance method could be improved.

Structure Response Analysis of the Seismic Isolated Buildings in Bucharest City

The paper intends to evaluate and analyze the accelerometric data recorded on certain buildings located in the Bucharest metropolitan area, one of the most exposed in Europe, with three strong earthquakes with magnitude MW>7 in the last century. Starting from information comprised by databases for soils and buildings existing in Bucharest, certain types of structures were selected, according to their specificity (old buildings, retrofitted, etc.) and being continuously seismic monitored. The selected three buildings are equipped with seismic isolators and viscous dampers. The response of these structures, at the ground level, subjected to medium intensity earthquakes will be discussed in terms of peak accelerations and spectral accelerations. Based on the currently accepted standpoint that the dynamic response of certain structures subjected to earthquakes is strongly dependent of the ratio between the natural period of the structure and the dominant period at the construction site, a comparative analysis against free-field data is presented. There would be presented the improvement of seismic response of isolated buildings in Bucharest and the reason these buildings were protected choosing this method. The aim is to provide warnings regarding the severity of seismic events, by means of characteristics of the ground motion, gathered from the response spectra, which may be given soon after the seismic event took place. All the data recorded on instrumented structures during two seismic events (MW = 5.5 and MW = 4.8), together with the subsequent analysis, can represent a reference study for future earthquakes with similar magnitude. The integration of near-realtime seismology with performance-based earthquake engineering allows for providing the information useful for earthquake engineers and decision makers and can enhance the mitigation of seismic risk.

Static Source Properties of Slow and Fast Earthquakes

AbstractThe source characteristics of slow and fast earthquakes provide a window into the mechanical properties of faults. In particular, the average stress drop controls the evolution of friction, fault slip, and event magnitude. However, this important source property is typically inferred from the analysis of seismic waves and is subject to many epistemic uncertainties. Here, we investigate the source properties of 53 earthquakes and 17 slow‐slip events on thrust and strike‐slip faults in various tectonic settings using slip distributions constrained by geodesy in combination with other data. We determine the width, potency, and potency density of slow and fast earthquake sources based on static slip distributions. The potency density, defined conceptually as the ratio of average slip to rupture radius, is a measure of anelastic deformation with limited bias from rigidity differences across depths and tectonic settings. Strike‐slip earthquakes have the highest potency density, varying from 20 to 500 microstrain. The potency density is on average lower on continental thrust faults and megathrusts, from 10 to 200 microstrain, with an algebraic decrease with centroid depth, indicative of systematic changes in dominant rupture processes with depth. Slow slip events represent an end‐member style of rupture with low potency density and large rupture width. Significant variability in potency density of slow‐slip events affects their moment‐duration scaling. The variations of source properties across tectonic settings, depth, and rupture styles can be used to better constrain numerical simulations of seismicity and to assess the source characteristics of future earthquakes and slow slip events.

Effects of Killari earthquake on the paleo-channel of Tirna River Basin from Central India using anisotropy of magnetic susceptibility

The Killari Earthquake (Moment magnitude 6.1) of September 30, 1993, occurred in the state of Maharashtra, India, has an epicenter (18°03′ N, 76°33′ E) located at ~ 40 km SSW of Killari Town. The ~ 125 km long basin of Tirna River, close to the Killari Town, currently occupies the area that has witnessed episodic intra-cratonic earthquakes, including the Killari Earthquake, during last 800 years. The anisotropy of magnetic susceptibility (AMS) study was performed on ~ 233 soft sedimentary core samples from six successions located in the upper to lower stream of the Tirna River basin in the present study in order to evaluate the effects of earthquake on the river flow dynamics and its future consequence. The AMS Kmax orientations of the samples from the upper reach of the river section suggest that the sedimentation in this part of the river was controlled by a N–S to NNW–SSE fluvial regime with a low or medium flow velocity. In the middle reaches of the basin, an abrupt shift in the palaeo-flow direction occurred to W–E with low velocity flow. However, a NW–SE higher palaeo-flow regime is identified in the following central part of the basin in down-stream direction, followed by a low-velocity palaeo-flow regime at the lower reach of the Tirna basin. We attribute the sudden high flow velocity regime in the central part of the river basin to an enhanced gradient of the river that resulted from the reactivation of a NW–SE fault transecting the Tirna River basin at the Killari Town. As the NW–SE faulting in regional scale is attributed as the main cause of Killari Earthquake, the reactivation of this fault, thus, could enhance the further possibility of an earthquake in near future, and hence leading to devastating flood in the almost flat-lying downstream part of the Tirna River.

Multisegment Rupture Hazard Modeling along the Xianshuihe Fault Zone, Southeastern Tibetan Plateau

AbstractThe Xianshuihe fault is a remarkable strike-slip fault characterized by high slip rate (∼10 mm/yr) and frequent strong historical earthquakes. The potential for future large earthquakes on this fault is enhanced by the 2008 Mw 7.9 Wenchuan earthquake. Previous works gave little attention to the probabilities of multisegment ruptures on the Xianshuihe fault. In this study, we build five possible multisegment rupture combination models for the Xianshuihe fault. The fault slip rates and historical earthquakes are used as input constraints to model the future seismicity on the fault segments and test whether the rupture combination models are appropriate. The segment combination model, based essentially on historical ruptures, has produced the seismicity rates most consistent with the historical records, although the model with ruptures on both the entire northern section and southern section should also be considered. The peak ground acceleration values with a return period of 475 yr calculated using the modeled rates on the Xianshuihe fault for both two models are on average larger than the values of the China Seismic Ground Motion Parameters Zonation Map.

Two global ensemble seismicity models obtained from the combination of interseismic strain measurements and earthquake-catalogue information

SUMMARYGlobal seismicity models provide scientific hypotheses about the rate, location and magnitude of future earthquakes to occur worldwide. Given the aleatory variability of earthquake activity and epistemic uncertainties in seismicity forecasting, the veracity of these hypotheses can only be confirmed or rejected after prospective forecast evaluation. In this study, we present the construction of and test results for two updated global earthquake models, aimed at providing mean estimates of shallow (d ≤ 70 km) seismicity for seismic hazard assessment. These approaches, referred to as the Tectonic Earthquake Activity Model (TEAM) and the World Hybrid Earthquake Estimates based on Likelihood scores (WHEEL) model, use the Subduction Megathrust Earthquake Rate Forecast (SMERF2), an earthquake-rate model for subduction zones constrained by geodetic strain measurements and earthquake-catalogue information. Thus, these global ensemble seismicity models capture two independent components necessary for long-term earthquake forecasting, namely interseismic crustal strain accumulation and sudden lithospheric stress release. The calibration period for TEAM and WHEEL extends from 1977 January 1 to 2013 December 31. Accordingly, we use m ≥ 5.95 earthquakes recorded during the 2014–2019 period to pseudo-prospectively evaluate the forecasting skills of these earthquake models, and statistically compare their performances to that of the Global Earthquake Activity Rate (GEAR1) model. As a result, GEAR1 and WHEEL are the most informative global seismicity models during the pseudo-prospective test period, as both rank with the highest information scores among all participant earthquake-rate forecasts. Nonetheless, further prospective evaluations are required to more accurately assess the abilities of these global ensemble seismicity models to forecast long-term earthquake activity.

Investigation of damage to the water network of Uki City from the 2016 Kumamoto earthquake: derivation of damage functions and construction of infrastructure loss scenarios

The 2016 Kumamoto earthquake (main-shock: Mw 7.0, April 16th) has induced a widespread disruption of lifeline systems across the affected area. In Uki City (Kumamoto prefecture, Japan), water supply had been intermittently cut off for several days: as a result, around 50 repair operations on various locations of the underground pipeline system have been carried out by municipal services. In order to better constrain the vulnerability of such infrastructure with respect to future earthquakes, the collected empirical data is exploited to derive repair-rate functions for ductile pipelines (ductile iron and polyvinyl chloride) of small diameter (less than 100 mm). Due to the relatively low number of data points over a limited range of seismic intensity, the derivation of purely empirical damage function appears to be subject to significant statistical biases. Therefore, a Bayesian updating framework is adopted, where prior information on the parameters of the repair-rate function is estimated from existing damage functions from the literature. Moreover, the uncertainty related to the characterization of the Peak Ground Velocity at the location of the pipelines is taken into account by: (i) the generation of shake-maps with different assumptions on ground-motion prediction equations or fault models, and (ii) the inclusion of a spatially correlated field of the intra-event shake-map error term (i.e., modelling of the inherent variability of the seismic intensity). The results show that the derived repair-rate equation is consistent with some existing functions for ductile and earthquake-resistant pipeline segments. The effect of specific land conditions (e.g., topographic/geological factors) is also investigated, with the possibility to further parametrize the repair-rate function. Finally, the developed damage functions are applied to stochastic simulations of the seismic performance of the water network, while keeping track of various sources of uncertainties and quantifying their impact on the system’s loss distribution.

Effect of variation in design acceleration spectrum on the seismic resilience of a building

Past studies have shown that the ground motion is of a highly random nature. It was found in past literature that there exist large variations in ground motion characteristics at other sites for the same earthquake, as well as for the same site from other earthquakes. These large variations in ground motion characteristics illustrate the difficulties in accurately predicting demands of future earthquakes which always leads us to the challenge in identifying the design ground motions that gives a reasonable probability of having credible design provisions. The present study is focused on finding the effect of variations in ground motions on an important design parameter, seismic resilience of a building. The change in ground motion characteristics has been considered through the design acceleration spectrum of the Indian Standard code IS:1893–2016 (Part-1) which depends on several factors viz. Zone factor (Z), importance factor (I) and response reduction factor (R). An existing reinforced concrete building of G + 10 storey with I = 1.5 and R = 5 was considered. The behavior of the building was examined for the six combinations of I/R ratio and corresponding drop down in the functionality and the seismic resilience was evaluated. The result shows the existing building has a significant increase in the demand displacement, demand ductility and loss in seismic resilience at the combination I = 1.5 and R = 3 with increase in the cumulative damage probability of exceedance corresponding to the “Extreme” and “Collapse” state. This was due to the sudden increase in future seismic acceleration (Ah) when compared with designed seismic acceleration.

Continuum of earthquake rupture speeds enabled by oblique slip

Earthquake rupture speed can affect ground shaking and thus seismic hazard. Seismological observations show that large earthquakes span a continuum of rupture speeds, from slower than Rayleigh waves up to P wave speed, and include speeds that are predicted to be unstable by 2D theory. This discrepancy between observations and theory has not yet been reconciled by a quantitative model. Here we present numerical simulations that show that long ruptures with oblique slip (both strike-slip and dip-slip components) can propagate steadily at various speeds, including those previously suggested to be unstable. The obliqueness of slip and the ratio of fracture energy to static energy release rate primarily control the propagation speed of long ruptures. We find that the effects of these controls on rupture speed can be predicted by extending the 3D theory of fracture mechanics to long ruptures with oblique slip. We propose that this model provides a quantitative framework to interpret supershear earthquakes, to constrain the energy ratio of faults based on observed rupture speed and rake angle, and to relate the potential rupture speed and size of future earthquakes to the observed slip deficit along faults.

Liquefaction susceptibility maps for the Aqaba–Elat region with projections of future hazards with sea-level rise

The cities of Aqaba, Jordan and Elat, Israel are vulnerable to seismic damage because they are built over the active faults of the Dead Sea Transform that are the source of historically destructive earthquakes. A liquefaction susceptibility map was generated for the Aqaba–Elat region. Borehole data from 149 locations and the water table depth were used to calculate effective overburden stress in the Seed–Idriss simplified method. The liquefaction analysis was based on applying a cyclic loading scenario with horizontal peak ground acceleration of 0.3 g in a major earthquake. The liquefaction map, compiled using a GIS platform, shows high and moderate liquefaction susceptibility zones along the northern coast of the Gulf of Aqaba that extend 800 m inland from the shoreline. In Aqaba, several hotels, luxury apartment complexes, archaeological sites, ports and commercial districts are located within high and moderate liquefaction zones. In Elat, the seaport and the coastal hotel district are located within a high susceptibility zone. Most residential areas, schools and hospitals in both cities are located within zones not susceptible to liquefaction based on the methods of this study. The total area with the potential to be liquefied along the Gulf of Aqaba is c. 10 km 2 . Given predictions for global sea-level, we ran three liquefaction models utilizing projected water table rises of 0.5, 1 and 2 m. These models yielded an increase in the area of high liquefaction ranging from 26 to 49%. Given the high potential of future earthquakes, our liquefaction susceptibility maps should help inform city officials for hazard mitigation planning.

Assessing seismic resilience of school educational sector. An attempt to establish the initial conditions in Calabria Region, southern Italy

School education constitutes one of the strategic functions to be recovered after an earthquake. The structural improvement of school buildings together with the strengthening of the administrators' capacity to react positively following an earthquake are key factors that contribute to social vulnerability's reduction. Nevertheless, in Italy, the issue of risk reduction policies related to school sector is not yet consolidated in the institutional agendas. Observing the last major Italian earthquakes what remains predominant is school buildings' damage degree with consequent interruption of the system functionality. Among the causes: the building heritage vulnerability and the lack of risk mitigation policies, capable of building a resilient community for future earthquakes. That of resilience is considered a relevant paradigm to address the issue of how to strengthen the school sector's capacity to ensure the buildings physical safety and to guarantee the maintenance of the school function, looking at pre and post-event phases.The paper proposes a set of indicators and a methodology for a preliminary assessment of the educational sector's seismic resilience, in terms of initial conditions. The method has been tested on a first case study: Calabria Region, Southern Italy. The results show that spatial differences in the educational sector's seismic resilience are evident. Except for some large urban areas, the less resilient areas are grouped mainly in the southern part of the Region, while the most resilient ones are located mostly in the central-northern sector. The ambition is to identify a repeatable approach, useful as guidelines for school seismic prevention policies.

Seismic responses of the densely distributed caves of the Mogao Grottoes in China

Some of the largest and best-preserved Buddhist art treasure houses in the world, namely the Mogao Grottoes, are located at the northwest edge of the region of the Qinghai-Tibet plateau and are adjacent to the Altun and Qilian mountains, where the geotectonic activity is intense and large earthquakes have occurred. Future earthquakes are one of the major threats to the caves of the Mogao Grottoes; therefore, it is important that their dynamic performance is studied when an earthquake occurs. To understand the dynamic performance of the densely distributed caves under the effect of earthquakes, as well as the long-term stability of the Mogao Grottoes, the stress distribution, deformation characteristics, and peak-acceleration amplification factor were analysed under rare-earthquake conditions using a finite-difference element. The numerical study revealed that the most dangerous state of the caves is the initial time when an earthquake occurs. The obvious tensile stress concentration appeared at the top and the bottom of the caves of the middle floor; the main damage was caused by the shear failure towards the direction of the free face and not by the tensile failure. A large permanent horizontal displacement of the caves occurred after an earthquake, mostly at the densely distributed caves of the middle floor. The acceleration amplification effect of the middle-floor caves was significant; the Fourier amplitudes of the acceleration (which were monitored in all caves) were significantly magnified at the frequencies of 3 ~ 4 Hz and 7 ~ 9 Hz, whereas the Fourier amplitudes of the acceleration which were monitored in the middle-floor caves were almost amplified within the entire frequency range. Although the maximum stress was within the allowed limit and no tensile failure occurred, great permanent inhomogeneous horizontal displacements and large accelerations could have a negative effect on the stability of caves and the preservation of wall paintings. Moreover, it was assumed that the calculation results could serve as a type of guidance and as advice on the preventive protection of the Mogao Grottoes.

Complex rupture dynamics on an immature fault during the 2020 Mw 6.8 Elaz\u0131\u011f earthquake, Turkey

Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding of earthquake physics and the assessment of earthquake hazards. Here we use a laboratory-derived fault-friction law and high-quality strong-motion seismic recordings of the 2020 Elazığ earthquake, Turkey, to reveal the complex rupture dynamics. We discover an initial Mw 5.8 rupture stage and explain how cascading behavior of the event, involving at least three episodes, each of M > 6, caused it to evolve into a large earthquake, contrarily to other M5+ events on this part of the East Anatolian Fault. Although the dynamic stress transfer during the rupture did not overcome the strength of the uppermost ~5 kilometers, surface ruptures during future earthquakes cannot be ruled out. We foresee that future, routine dynamic inversions will improve understanding of earthquake rupture parameters, an essential component of modern, physics-based earthquake hazard assessment.

Crustal deformation rates in Kashmir valley and adjoining regions from continuous GPS measurements from 2008 to 2019

We present GPS velocities in Kashmir valley and adjoining regions from continuous Global Positioning System (cGPS) network during 2008 to 2019. Results indicate total arc normal shortening rates of ~ 14 mm/year across this transect of Himalaya that is comparable to the rates of ~ 10 to 20 mm/year reported else-where in the 2500 km Himalaya Arc. For the first time in Himalayas, arc-parallel extension rate of ~ 7 mm/year was recorded in the Kashmir valley, pointing to oblique deformation. Inverse modeling of the contemporary deformation rates in Kashmir valley indicate oblique slip of ~ 16 mm/year along the decollement with locking depth of ~ 15 km and width of ~ 145 km. This result is consistent with the recorded micro-seismicity and low velocity layer at a depth of 12 to 16 km beneath the Kashmir valley obtained from collocated broadband seismic network. Geodetic strain rates are consistent with the dislocation model and micro-seismic activity, with high strain accumulation (~ 7e−08 maximum compression) to the north of Kashmir valley and south of Zanskar ranges. Assuming the stored energy was fully released during 1555 earthquake, high geodetic strain rate since then and observed micro-seismicity point to probable future large earthquakes of Mw ~ 7.7 in Kashmir seismic gap.

Constructing the Seismograms of Future Earthquakes in Yunnan, China, Using Compressed Sensing

Abstract The ability to calculate the seismogram of an earthquake at a local or regional scale is critical but challenging for many seismological studies because detailed knowledge about the 3D heterogeneities in the Earth’s subsurface, although essential, is often insufficient. Here, we present an application of compressed sensing technology that can help predict the seismograms of earthquakes at any position using data from past events randomly distributed in the same area in Jinggu County, Yunnan, China. This first data-driven approach for calculating seismograms generates a large dataset in 3D with a volume encompassing an active fault zone. The input number of earthquakes comprises only 1.27% of the total output events. We use the output data to create a database intended to find the best-matching waveform of a new event by applying an earthquake search engine, which instantly reveals the hypocenter and focal-mechanism solution.

Empirical seismic fragility models for Nepalese school buildings

Empirical vulnerability models are fundamental tools to assess the impact of future earthquakes on urban settlements and communities. Generally, they consist of sets of fragility curves that are derived from georeferenced post-earthquake damage data. Following the 2015 Nepal earthquake sequence, the World Bank, through the Global Program for Safer Schools, conducted a Structural Integrity and Damage Assessment (SIDA) of about 18,000 school buildings in the earthquake-affected area. In this work, the database is utilized to identify the main structural characteristics of the Nepalese school building stock. For the first time, extended SIDA school damage data is processed to derive fragility curves for the main structural typologies. Data sets for each structural typology are used for a Bayesian updating of existing fragilities to obtain regional models for Nepalese schools. These fragility estimates can be adopted to assess potential seismic losses of the school infrastructure in Nepal. Additionally, they can be used for calibrating loss assessment studies in the wider Himalayan region where the structural typologies are similar.

Seismic vulnerability assessment of reinforced concrete school building in Nepal

The school building built with reinforced concrete in Nepal confront high seismic risk during past seismic events. The vast extent structural damage and loss of human life’s and property was due to the poor enforcement of the standards, lack of ductile detailing and poor construction materials and practices in Nepal. The effect of earthquake excitation on buildings was ignored after the latest earthquake in 2015. Most of the school structures were used in full-fledged without performing any seismic evaluation. Seeing these situations, especially in Nepal, a vulnerability assessment of such school structures is essential. The seismic risk owing to future earthquake can be minimize by proper vulnerability assessment of the school structures. To this end, the purpose of the study is to evaluate seismic performance of school structure through both vulnerability and fragility assessment. The main research issues are explored through analytical method. For this, structural response parameters are analytically studied through linear and non-linear analyses by finite element program-based software. In dynamic analysis, numerical building models were subjected to three synthetic earthquakes Gorkha, El-Centro and Kobe. The fragility function of case study building structure was plotted with the probability of failure at every 0.1 g interval of PGA, which provided technical base for seismic vulnerability assessment of school buildings. The result indicates that the selected school building is found to be vulnerable compared with the standard international guidelines. The results of this study are more useful for different governmental authorities, emergency response organization who are directly involved for proper planning and implementation.

Mapping of liquefaction risk on road network based on relationship between liquefaction potential and liquefaction-induced road subsidence

On March 11, 2011, a large earthquake of Mw 9.0 shook north-eastern Japan and caused severe liquefaction-induced damage over a wide area of reclaimed lands along the coast of Tokyo Bay. Although regional mapping of the liquefaction hazard had been performed in many automounts bodies in Japan, it seems that the maps were not effectively used on all fronts of disaster-prevention management, because the maps only provide liquefaction susceptibilities and little quantitative information on how seriously the ground might deform in a scenario earthquake, which is absolutely necessary information for discussing what-if scenarios. Konagai et al. (2013) conducted air-borne LiDAR surveys to obtain liquefaction-induced ground deformations over the north-eastern stretch of the Tokyo Bay shore area, including Urayasu City, where approximately 85% of the city area was heavily liquefied. Meanwhile, the authors have developed a geotechnical database for liquefaction risk assessments, compiling all the available borehole logs and soil testing data provided by Urayasu City (2012). Given the potential risk of re-liquefaction in a future scenario earthquake, it is an overriding priority to develop a knowledge-sharing liquefaction hazard map reflecting precise records from the past, such as liquefaction-induced ground subsidence and liquefaction-related damage. This paper attempts to assess the liquefaction-induced damage risk on road network, examining the relationship between the liquefaction potential index and the actual ground subsidence. For this purpose, firstly, the spatial distribution of the liquefaction potential (PL) was estimated over Urayasu City based on the above-mentioned geotechnical database developed by the authors. Secondly, the spatial distribution of the PL values and the actual liquefaction-induced road subsidence confirmed through air-born LiDAR surveys were compared to develop an empirical rule for estimating the potential road subsidence in a scenario earthquake. This empirical rule was found to describe the actual damage to roads and manholes in a satisfactory manner. Therefore, it is expected that a risk map, developed on the basis of this empirical rule, will not only help to assess liquefaction-induced damage, but also to design countermeasures against the what-if scenarios of liquefaction.