Probabilistic Tsunami Hazard Research Articles

An improvement of tsunami hazard analysis in Central Chile based on stochastic rupture scenarios

ABSTRACT Central Chile is exposed to tsunami hazard, and large earthquakes and tsunamis have occurred over the last 500 years. Tsunami hazard analysis in Chile has been traditionally implemented by means of a deterministic approach, which is based on historical events and uniform slip distribution. The objective of the present study is to improve tsunami hazard analysis in central Chile (30°S to 38°S). To encompass the purpose, stochastic earthquake scenarios of magnitude 8.8 to 9.2 were generated. Two different sets of stochastic tsunami scenarios were selected by means of the Stochastic Reduced Order Model (SROM), which were applied to Quintero bay to perform a Probabilistic Tsunami Hazard Analysis (PTHA). The results showed that PTHA of Quintero bay from stochastic tsunami scenarios agrees with paleotsunami records in the bay, while a deterministic tsunami scenario underestimated the hazard. Two sets (50 and 100 scenarios, respectively) give similar results when smaller return periods are analyzed. However, for larger return periods (2000 yr) the set of 100 scenarios show better results consistent with previous paleoseismological findings. The methodology implemented here can be replicated in other seismic regions in Chile as well as in other active subduction zones, thus, both near field and far field events can be analyzed.

Uncertainty of probabilistic tsunami hazard assessment of Zihuatanejo (Mexico) due to the representation of tsunami variability

ABSTRACT This study conducts a probabilistic tsunami hazard assessment (PTHA) and compares two approaches to representing earthquake source variability in the PTHA. The target region is the coast of Zihuatanejo in the State of Guerrero, Mexico. First, numerous synthetic fault slip distributions are generated using a stochastic random-phase process. The moment magnitude ranges from 7.8 to 8.6. A numerical tsunami simulation is implemented for each earthquake fault slip. The result of the Monte Carlo simulation indicates the tsunami heights at the nearshore of city areas tend to be higher. Then, the exceedance probabilities of tsunami height are estimated and compared using two different PTHA approaches: the random phase approach and the logic tree approach. The logic tree can generally incorporate many types of uncertainty, but this study focuses on the earthquake source uncertainty for comparison. The comparison result indicates significant differences between the two tsunami hazard models. Additionally, the logic tree approach is used to investigate the possible ranges in tsunami heights for extreme events by assuming that a sizable epistemic uncertainty exists in a given region. The tsunami heights for a 1,000-year event vary significantly when the weighting values for the paths in the logic tree are changed.

Probabilistic tsunami hazard analysis for Tuzla test site using Monte Carlo simulations

Abstract. In this study, time-dependent probabilistic tsunami hazard analysis (PTHA) is performed for Tuzla, Istanbul, in the Sea of Marmara, Turkey, using various earthquake scenarios of Prince Island Fault (PIF) within the next 50 and 100 years. The Monte Carlo (MC) simulation technique is used to generate a synthetic earthquake catalogue, which includes earthquakes having moment magnitudes between Mw6.5 and 7.1. This interval defines the minimum and maximum magnitudes for the fault in the case of an entire fault rupture, which depends on the characteristic fault model. Based on this catalogue, probability of occurrence and associated tsunami wave heights are calculated for each event. The study associates the probabilistic approach with tsunami numerical modeling. The tsunami numerical code NAMI DANCE was used for tsunami simulations. According to the results of the analysis, distribution of probability of occurrence corresponding to tsunami hydrodynamic parameters is represented. Maximum positive and negative wave amplitudes show that tsunami wave heights up to 1 m have 65 % probability of exceedance for the next 50 years and this value increases by 85 % in the Tuzla region for the next 100 years. Inundation depth also exceeds 1 m in the region with probabilities of occurrence of 60 % and 80 % for the next 50 and 100 years, respectively. Moreover, probabilistic inundation maps are generated to investigate inundated zones and the amount of water penetrated inland. Probability of exceedance of 0.3 m wave height ranges between 10 % and 75 % according to these probabilistic inundation maps, and the maximum inundation distance calculated in the entire earthquake catalogue is 60 m in this test site. Furthermore, synthetic gauge points are selected along the western coast of Istanbul by including Tuzla coasts. Tuzla is one of the areas that shows high probability exceedance of 0.3 m wave height, which is around 90 %, for the next 50 years while this probability reaches up to more than 95 % for the next 100 years.

Tsunami inundation hazard across Japan

Japan faces the world's highest tsunami hazard and risk due to its tectonic environment, high population density and exposure concentration along its coastlines. It is therefore of paramount interest to quantify and differentiate absolute and relative tsunami hazard and risk on a countrywide scale. We quantify tsunami hazard in terms of inundation depth for the entire Japanese coastline with a probabilistic tsunami hazard assessment utilizing the earthquake source information of the 2017 Japanese seismic hazard model. We simulate a stochastic event set for offshore earthquake sources and generate, for each single source with MW ≥ 7.5, non-uniform finite-fault slip models. We calculate elastic seafloor and landmass deformations that serve as initial conditions to high-resolution numerical modelling of tsunami wave propagation and coastal inundations by solving the non-linear shallow water equation. Variable land surface roughness based on land cover data is used to simulate accurate hydraulics of coastal inundation.We differentiate tsunami hazard by inundation depth hazard curves and inundation depth return period maps aggregated to city ward polygons as meaningful administrative boundaries. We find mega-thrust events on the subduction interfaces constituting the largest hazard. However, events down to MW = 7.5 can contribute to substantial hazard in several regions along the coast. In particular for city wards within the Tokyo bay area, we find that earthquakes occurring on the Sagami trough and not the largest mega-thrust events on the Nankai trough, contribute to the highest inundation hazard. Our results also illustrate that tsunami hazard on the western Japanese coast is not negligible.

Probabilistic tsunami hazard assessment with simulation-based response surfaces

This paper proposes a novel response surface-based method for probabilistic tsunami hazard assessment (PTHA). Although recent advancements in numerical simulation have enabled the accurate characterization of tsunami hazards, the high computational cost of numerical simulation often prohibits its broad application to probabilistic hazard analysis. The proposed method addresses this challenge by constructing the response surface (RS) of a target output using the results of high-fidelity tsunami simulations. The proposed method quantifies uncertainties in key simulation variables and propagates those uncertainties to the target output through the RS in a computationally efficient Monte Carlo simulation (MCS). We illustrate and validate the proposed method through a case study of the tsunami induced by the 2011 Great East Japan earthquake. The case study focuses on Sendai, Ishinomaki, and Kamaishi in Japan as the target locations. The proposed method estimates coastal tsunami heights while considering uncertainties in the fault slip and rake as well as the modeling error associated with the numerical simulation. The MCS allows us to estimate the probability density functions of the tsunami height at the target locations. The proposed method quantifies the contribution of each source of uncertainty to the overall uncertainty in the target output and thus facilitates engineering decision-making.

Multisource Bayesian Probabilistic Tsunami Hazard Analysis for the Gulf of Naples (Italy)

AbstractA methodology for a comprehensive probabilistic tsunami hazard analysis is presented for the major sources of tsunamis (seismic events, landslides, and volcanic activity) and preliminarily applied in the Gulf of Naples (Italy). The methodology uses both a modular procedure to evaluate the tsunami hazard and a Bayesian analysis to include the historical information of the past tsunami events. In the the submarine earthquakes and the submarine mass failures are initially identified in a gridded domain and defined by a set of parameters, producing the sea floor deformations and the corresponding initial tsunami waves. Differently volcanic tsunamis generate sea surface waves caused by pyroclastic density currents from Somma‐Vesuvius. In the the tsunami waves are simulated and propagated in the deep sea by a numerical model that solves the shallow water equations. In the the tsunami wave heights are estimated at the coast using the 's amplification law. The selected tsunami intensity is the wave height. In the the probabilistic tsunami analysis computes the long‐term comprehensive Bayesian probabilistic tsunami hazard analysis. In the prior analysis the probabilities from the scenarios in which the tsunami parameter overcomes the selected threshold levels are combined with the spatial, temporal, and frequency‐size probabilities of occurrence of the tsunamigenic sources. The probability density functions are integrated with the derived from the historical information based on past tsunami data. The probability density functions are evaluated to produce the hazard curves in selected sites of the Gulf of Naples.

Tsunami hazard assessment in the Makran subduction zone

The lack of offshore seismic data caused uncertainties associated to understating the behavior of future tsunamigenic earthquakes in the Makran Subduction Zone (MSZ). Future tsunamigenic events in the MSZ may trigger significant near-field tsunamis. Run-up heights in the near-field are controlled by the heterogeneity of slip over the rupture area. Considering a non-planar geometry for the Makran subduction zone, a range of random k^{-2} slip models were generated to hypothesize rupturing on the fault zone. We model tsunamis numerically and assess probabilistic tsunami hazard in the near-field for all synthetic scenarios. The main affected areas by tsunami waves are the area between Jask and Ormara along the shorelines of Iran and Pakistan and the area between Muscat and Sur along the Oman coastline. The maximum peak-run-up along the shores of Iran and Pakistan is about 16 m and about 12 m for the Oman shoreline. The slip distributions control the run-up along the Makran coastlines. The dependency of run-up to the heterogeneity of slip is higher in the most impacted areas. Those areas are more vulnerable to tsunami hazard than other areas.

Sensitivity Analysis According to Fault Parameters for Probabilistic Tsunami Hazard Curves

Sensitivity Analysis According to Fault Parameters for Probabilistic Tsunami Hazard Curves

Tsunami risk perception in southern Italy: first evidence from a sample survey

Abstract. The Italian Tsunami Alert Centre of the Istituto Nazionale di Geofisica e Vulcanologia (Centro di Allerta Tsunami, hereinafter CAT-INGV) supported a computer-assisted telephone interview (CATI) survey to investigate tsunami risk perception in two pilot regions of southern Italy. The survey was carried out on a stratified sample of 1021 interviewees representing about 3.2 million people living in 183 coastal municipalities of the two regions, namely Calabria and Apulia. The main goal of this research is to verify whether and how people's perception of tsunami hazard compares to the results of (PTHA) – probabilistic tsunami hazard assessment (TSUMAPS-NEAM project; Basili et al., 2018). As shown by the results of this project, both investigated regions are characterised by high tsunami hazard. Nonetheless, the long return time of such events could lead people to consider the occurrence of a tsunami in the Mediterranean Sea to be very unlikely. The survey results reveal that people's risk perception is low: for almost half of the whole sample the occurrence of a tsunami in the Mediterranean Sea is considered quite unlikely, with a clear difference between Apulia and Calabria. In the latter region the risk perception is much higher than in the former, probably due to the shorter time elapsed since the last event. Also, belonging to different coastal areas1 appears to have a significant influence on the way tsunami hazard is conceived, having a stronger effect on risk characterisation: the interviewees of Tyrrhenian Calabria are indeed more likely to associate tsunami risk with volcanoes than the Ionian citizens. This is coherent considering the presence of active volcanoes and related tsunami precedents in the Tyrrhenian. Television emerged as the most relevant source of knowledge for almost 90 % of the sample, and the influence of media also results in the way tsunami risk is characterised. In particular, the survey showed that people's perception and understanding of tsunamis are affected by media accounts of large events, such as the 2004 Sumatra and the 2011 Japan tsunamis. At the same time, it is evident that the risk posed by smaller events is underrated. Furthermore, the survey's results show that the word “tsunami” occupies a different semantic space in comparison to the Italian traditional headword maremoto, with differences among sample strata. In other words, the same physical phenomenon would be understood in two different ways by younger, educated people and elders with a low education level. The results of this study, although limited to two regions, provide a first assessment of tsunami risk perception in Italy, also entailing important consequences for both risk communication practice and mitigation policies.

Tsunami hazard mapping methodology and its implementation for the Far Eastern coast of the Russian Federation

The overview maps of tsunami hazard for the Far East coast of Russian Federation are created. The methodological basis of the PTHA (Probabilistic Tsunami Hazard Assessment) approach are discussed, as well as the problems of constructing seismotectonic models of the main tsunamigenic zones, mathematical models and algorithms for calculating probability estimates of tsunami hazard, and some problems of applying the RTHA methodology both related to the lack of observation data and with the complexity of performing a large amount of scenario calculations. Examples of overview tsunami hazard maps for various recurrence intervals, constructed using the PTHA methodology and presented using the WTMap application, are given.

A Methodology for Mapping Tsunami Hazards and Its Implementation for the Far Eastern Coast of the Russian Federation

Overview maps of tsunami hazards for the Far Eastern coast of the Russian Federation are created. The methodological principles of the PTHA (Probabilistic Tsunami Hazard Assessment) approach are discussed, as are the problems of constructing seismotectonic models of the main tsunamigenic zones, mathematical models and algorithms for calculating probability estimates of tsunami hazards, and some problems of applying the PTHA methods related both to the lack of observation data and the complexity in performing a large volume of numerical scenario simulations. Examples of overview maps of tsunami hazards for various recurrence intervals, constructed using the PTHA methodology and presented using the “WTMap” application, are given.

Probabilistic Tsunami Hazard Assessment for Local and Regional Seismic Sources Along the Pacific Coast of Central America with Emphasis on the Role of Selected Uncertainties

Historical data indicate that the Middle America subduction zone represents the primary tsunamigenic source that affects the Central American coastal areas. In recent years, the tsunami potential in the region has mainly been assessed using maximum credible earthquakes or historical events showing moderate tsunami potential. However, such deterministic scenarios are not provided with their adequate probability of occurrence. In this study, earthquake rates have been combined with tsunami numerical modeling in order to assess probabilistic tsunami hazard posed by local and regional seismic sources. The common conceptual framework for the probabilistic seismic hazard assessment has been adapted to estimate the probabilities of exceeding certain tsunami amplitudes along the Central American Pacific coast. The study area encompasses seismic sources related to the Central America, Colombia and Ecuador subduction zones. In addition to the classical subduction inter-plate events, this study also incorporates sources at the outer rise, within the Caribbean crust as well as intra-slab sources. The study yields conclusive remarks showing that the highest hazard is posed to northwestern Costa Rica, El Salvador and the Nicaraguan coast, southern Colombia and northern Ecuador. In most of the region it is 50 to 80% likely that the tsunami heights will exceed 2 m for the 500 year time exposure (T). The lowest hazard appears to be in the inner part of the Fonseca Gulf, Honduras. We also show the large dependence of PTHA on model assumptions. While the approach taken in this study represents a thorough step forward in tsunami hazard assessment in the region, we also highlight that the integration of all possible uncertainties will be necessary to generate rigorous hazard models required for risk planning.

Tsunami hazard assessment at Mediterranean coast of Egypt

Possibilities of forecasting of a tsunami characteristics for areas with small base of historical tsunami are discussed. The PTHA method (Probabilistic Tsunami Hazard Assessment), which cornerstone the statistical analysis of real and predictive earthquakes which number is rather big, with the subsequent calculation of waves of a Tsunami from possible earthquakes is for this purpose used. This method for assessment of long-term tsunami danger on the Mediterranean coast of Egypt is used. It is shown that the predicted wave heights change along the coast that is caused by heterogeneity of topography of a coastal zone and features of the chart of radiation of a tsunami in the sea. The predicted wave heights for 1000 years change within 0.83.4 m.

Probabilistic tsunami hazard assessment and its application to southeast coast of Hainan Island from Manila Trench

Tsunami is one of the most destructive natural disasters and the probabilistic tsunami hazard assessment (PTHA) has become increasingly popular in both academic and engineering field. However, most methods to carry out PTHA cannot avoid large number of scenario simulations generated by comprehensive assessment of the uncertainties of all seismic parameters. In order to balance the accuracy and feasibility in PTHA, we propose a more efficient approach. Based on the linear assumption of tsunami waves in deep water, the computation of tsunami wave propagation is given by the linear superposition of waves caused by unit sources of water level disturbance, which transforms a large number of seismic tsunami scenarios simulations into a limited number of simulations on wave propagating from each unit source. By placing 5,438 unit sources in Gaussian-shaped waveform with the interval of 0.1° around Manila Trench to approximate the initial water level disturbance under any combination of seismic parameters, we have evaluated 1,380,000 potential seismic scenarios in the Manila trench area. The water level fluctuation process of each target point along 100 m isobaths in every scenario is calculated to estimate whether the maximum wave height of the leading wave exceeds a specific critical value. Combining the probability density of each seismic parameter, the exceedance probabilities of specific wave heights and hazard curves at all target points are given.

Tsunami Hazard Assessment on the Egyptian Coast of the Mediterranean

Tsunami forecast possibilities for areas with a small base of historical tsunamis have been discussed using the Probabilistic Tsunami Hazard Assessment (PTHA) method, which is based on a statistical analysis of a sufficiently large number of real and predictive earthquakes with a subsequent calculation of possible tsunami waves. This method has been used for a long-term tsunami hazard assessment on the Mediterranean coast of Egypt. The predicted wave heights have been shown to vary along the coastline due to the inhomogeneity of the coastal topography and specific features of the tsunami radiation pattern in the sea. The predicted wave heights for 1000 years vary in the range between 0.8 and 3.4 m.

Sensitivity of Probabilistic Tsunami Hazard Assessment to Far-Field Earthquake Slip Complexity and Rigidity Depth-Dependence: Case Study of Australia

Probabilistic Tsunami Hazard Assessment (PTHA) often proceeds by constructing a suite of hypothetical earthquake scenarios, and modelling their tsunamis and occurrence-rates. Both tsunami and occurrence-rate models are affected by the representation of earthquake slip and rigidity, but the overall importance of these factors for far-field PTHA is unclear. We study the sensitivity of an Australia-wide PTHA to six different far-field earthquake scenario representations, including two rigidity models (constant and depth-varying) combined with three slip models: fixed-area-uniform-slip (with rupture area deterministically related to magnitude); variable-area-uniform-slip; and spatially heterogeneous-slip. Earthquake-tsunami scenarios are tested by comparison with DART-buoy tsunami observations, demonstrating biases in some slip models. Scenario occurrence-rates are modelled using Bayesian techniques to account for uncertainties in seismic coupling, maximum-magnitudes and Gutenberg-Richter b-values. The approach maintains reasonable consistency with the historical earthquake record and spatially variable plate convergence rates for all slip/rigidity model combinations, and facilitates partial correction of model-specific biases (identified via DART-buoy testing). The modelled magnitude exceedance-rates are tested by comparison with rates derived from long-term historical and paleoseismic data and alternative moment-conservation techniques, demonstrating the robustness of our approach. The tsunami hazard offshore of Australia is found to be insensitive to the choice of rigidity model, but significantly affected by the choice of slip model. The fixed-area-uniform-slip model produces lower hazard than the other slip models. Bias adjustment of the variable-area-uniform-slip model produces a strong preference for ‘compact’ scenarios, which compensates for a lack of slip heterogeneity. Thus, both heterogeneous-slip and variable-area-uniform-slip models induce similar far-field tsunami hazard.

Differences between heterogenous and homogenous slip in regional tsunami hazards modelling

Summary The homogenous slip finite fault model is commonly used in tsunami hazards for a variety of applications. These include early warning and short-term forecasts of tsunami amplitudes, scenario ruptures for risk assessments, and probabilistic tsunami hazard analysis (PTHA). Over the last decade, however, it has become feasible to calculate stochastic slip models which reflect the expected spatial statistics of slip observed in real events. In this paper we examine the impacts of the homogenous slip model when compared to stochastic slip distributions and ask whether, in light of these technical advancements, the homogenous slip assumption remains a reasonable one. We employ a simplified subduction zone geometry, free of complex path and site effects, and study simulated tsunamis from earthquakes in the magnitude 7 to magnitude 9 range. We find that homogenous slip models have lower tsunami potential energies and frequently underpredict the peak tsunami amplitudes and the resulting tsunami hazard, particularly at low probabilities of exceedance. This finding has important implications for all tsunami hazards applications. Calculating a suite of realistic stochastic slip distributions is now within reach of tsunami scientists, thus, we conclude that use of heterogeneous slip models for tsunami hazards applications is preferable

Introduction to “Twenty Five Years of Modern Tsunami Science Following the 1992 Nicaragua and Flores Island Tsunamis, Volume I”

Following the first volume (PAGEOPH, 2019, 176, No. 7), twenty-four papers on tsunamis are included in the PAGEOPH topical issue “Twenty five years of modern tsunami science following the 1992 Nicaragua and Flores Island tsunamis: Volume II,” reporting on the frontiers of tsunami science and research. The first two papers overview meteorological tsunamis, discussing progress since the 1992 Daytona event, and examining the March 2017 Persian Gulf destructive event. The next four papers review historical tsunami events, starting with a paper providing statistics for the last 120 years. The 2018 Kodiak event is investigated in the following two papers. A set of five papers discusses tsunami-warning methodologies specifically for the Australia and Nankai (Japan) regions, and general tsunami warning approaches. Probabilistic tsunami hazard assessment including case studies for two Australian coasts and the Pacific Coast of Central America, as well as discussion regarding the effect of shallow slip amplification uncertainty, and tsunami hazard assessment for the Port of Ensenada, Baja California, are presented in the next five papers. Two papers discuss tsunami tide interaction, and the following two investigate landslide-generated tsunamis, specifically a tsunami landslide scenario study for the Maltese Islands, and the 1694 Ambon, Indonesia tsunami. Tsunami hydrodynamics studies investigating shoaling on steep continental slopes and transmission of long surface, and tsunami-like waves are presented in the last two papers.

Effect of Shallow Slip Amplification Uncertainty on Probabilistic Tsunami Hazard Analysis in Subduction Zones: Use of Long-Term Balanced Stochastic Slip Models

The complexity of coseismic slip distributions influences the tsunami hazard posed by local and, to a certain extent, distant tsunami sources. Large slip concentrated in shallow patches was observed in recent tsunamigenic earthquakes, possibly due to dynamic amplification near the free surface, variable frictional conditions or other factors. We propose a method for incorporating enhanced shallow slip for subduction earthquakes while preventing systematic slip excess at shallow depths over one or more seismic cycles. The method uses the classic k−2 stochastic slip distributions, augmented by shallow slip amplification. It is necessary for deep events with lower slip to occur more often than shallow ones with amplified slip to balance the long-term cumulative slip. We evaluate the impact of this approach on tsunami hazard in the central and eastern Mediterranean Sea adopting a realistic 3D geometry for three subduction zones, by using it to model ~ 150,000 earthquakes with M_{w} from 6.0 to 9.0. We combine earthquake rates, depth-dependent slip distributions, tsunami modeling, and epistemic uncertainty through an ensemble modeling technique. We found that the mean hazard curves obtained with our method show enhanced probabilities for larger inundation heights as compared to the curves derived from depth-independent slip distributions. Our approach is completely general and can be applied to any subduction zone in the world.

Construction of Logic Trees and Hazard Curves for Probabilistic Tsunami Hazard Analysis

지진해일 규모와 발생시기 예측의 ì–´ë ¤ì›€ìœ¼ë¡œ 인해 ê²°ì •ë¡ ì  방법으로 얻은 결과가 ì‹¤ì œ 재난을 반영하지 못하는 사례가 ë°œìƒí•˜ê³ ìžˆë‹¤. 따라서 지진해일의 불확실성을 í™•ë¥ ë¡ ì ìœ¼ë¡œ ì ‘ê·¼í•˜ëŠ” í™•ë¥ ë¡ ì  지진해일 재해도 분석(Probabilistic Tsunami Hazard Analysis) 연구의 중요성이 ì ì°¨ ì¦ê°€í•˜ê³ ìžˆë‹¤. 본 연구에서는 과거 동해안에 피해를 ìœ ë°œí•œ 동해 동연부 지진에 대하여 í™•ë¥ ë¡ ì  지진해일 재해도 분석을 위한 기초연구를 수행하였다. 초기수면변위와 í•´ì¼ê³ ë¶„í¬ì˜ 불확실성을 ê³ ë ¤í•˜ê¸° 위해 로직트리 기법을 사용하였으며, 우리나라에 내습하는 지진해일의 특성을 반영하여 분기를 구성하였다. 프랙타일 ê³¡ì„ ì„ 산출하는 ê³¼ì •ì—ì„œ 분기의 수가 증가하면 시간소요가 ë¹„ì„ í˜•ì ìœ¼ë¡œ 증가하므로 ëª¨ë“ ë¶„ê¸°ë¥¼ ê³ ë ¤í•˜ë©´ì„œë„ 계산시간을 줄일 수 있는 ê°œì„ ëœ 방법을 ì œì•ˆí•˜ì˜€ë‹¤. 새로 ì œì•ˆëœ 이산가중치분포법(Discrete Weight Distribution)ê³¼ ì •ë ¬ê¸°ë²• 및 ëª¬í Œì¹´ë¥¼ë¡œë²•ìœ¼ë¡œ 얻은 결과의 일관성과 소요시간을 비교하였다. 이산가중치분포법은 ì •ë ¬ê¸°ë²•ì„ ì ìš©í•œ 경우보다 계산시간이 짧아 íš¨ìœ¨ì ì¸ 것으로 평가되었으나, 다수의 분기나 세그먼트를 ê³ ë ¤í• ê²½ìš° ëª¬í Œì¹´ë¥¼ë¡œ 방법이 더 íš¨ìœ¨ì ì¸ 것으로 판단된다. 핵심용어: 지진해일 재해도 분석, 로직트리, í™•ë¥ ë¡ ì  모델링