Potential Tsunami Hazard Research Articles

Study on earthquake and tsunami hazard: evaluating probabilistic seismic hazard function (PSHF) and potential tsunami height simulation in the coastal cities of Sumatra Island

This study uses integrated geological, geodesy, and seismology data to assess the potential tsunami and Probabilistic Seismic Hazard Function (PSHF) near Sumatra’s coastal cities. It focuses on estimating the possible level of ground shaking due to the seismic activity within the Sumatran Fault Zone (SFZ) and subduction zone. It uses the Peak Ground Acceleration (PGA) as a measure. An amplification factor that is based on the previous study is used. It is calculated through the Horizontal-Vertical Spectral Ratio (HVSR), which measures possible surface ground shaking. The Seismic Hazard Function (SHF) is calculated considering magnitudes 6.5 to 9.0 for subduction sources and 6.5 to 7.8 for SFZ sources. Also, the PGA based on the Maximum Possible Earthquake (MPE) magnitude is estimated, and tsunami heights are simulated to assess the possible hazard risk. The tsunami source model in this study is characterized by considering the possibility of the long-term perspectives on giant earthquakes and tsunamis that might occur in subduction zones around the off-coast of southern Sumatra Island. The potentiality source zone is characterized based on the utilization of the cross-correlation of correlation dimension (DC) based on the shallow earthquake catalog of 2010 to 2022 and the SHmax-rate of surface strain rate. Based on the MPE, the relatively high estimated PGA at the base rock was found around Mentawai and Pagai Utara islands at about 0.224 g and 0.328 g, with the largest estimated PGA based on the MPE at the surface with values of about 0.5 g and 0.6 g. The possible maximum tsunami height (Hmax) estimated based on source scenarios position around the west coast of Sumatera Island, such as for Kota Padang and Kota Bungus, reaches up to 12.0 m and 22.0 m, respectively. The findings provide valuable insight into seismic and tsunami hazards, benefiting future mitigation strategies.

Assessing the potential tsunami source of the Manila trench at the Bengkayang nuclear power plant site in Kalimantan using topographical details

Tsunamis pose a significant threat to the construction of Nuclear Power Plants. Therefore, it is necessary to carry out a comprehensive study regarding the potential threat of tsunamis and mitigation measures using detailed data at prospective locations. This assessment is a prerequisite for effective environmental impact planning and analysis. To determine the suitability of a prospective location, careful consideration of natural factors, including earthquakes as triggers for tsunamis, is essential. The main objective of this tsunami research is to assess the level of safety of potential locations against tsunami hazards and develop appropriate mitigation strategies. This research uses the Cornell Multigrid Coupled Tsunami (COMCOT) tsunami modeling technique. This modeling approach utilizes topographic and bathymetric data obtained through extensive field surveys. In addition, this research aims to determine the maximum tsunami height in the inundation area and identify potential tsunami hazards arising from various scenarios related to the active tectonic potential of the Philippine Manila Trench. The Bengkayang Gosong Beach area and West Kalimantan are among the candidate locations that may be affected with the estimated tsunami height being between 0.48 meters and 0.62 meters. The tsunami arrival time was between 9 hours 10 minutes to 9 hours 24 minutes. These findings play an important role in conducting comprehensive risk assessments for nuclear power plant development, ensuring that necessary steps are taken to reduce potential hazards associated with tsunamis.

3D NUMERICAL MODELLING OF FIVE SUBMARINE LANDSLIDE SCENARIOS IN PERTH CANYON, AUSTRALIA TO ASSESS TSUNAMIGENIC HAZARD

Submarine canyons have been identified on nearly all margins around the world (Urlaub et al., 2013). Their configuration and morphology has been attributed to several factors including geology, tectonism, sea-level variations, and sediment supply to the region (Laursen and Normark, 2002) with processes occurring over varying temporal and spatial scales driving complex morphologies (Drexler, et al., 2006). A common process in submarine canyons is the mass wasting of sediment in the form of submarine landslides (SMLS) (Brothers, et al., 2013). A SMLS is a displacement of sediment or debris driven by gravity where the downslope forces are greater than the forces that are acting to resist the mass-failures (Mountjoy and Micallef, 2018). The potential tsunami hazard posed by these SMLS was assessed by Buller et al. (2021) using empirical calculations which showed that these SMLSs posed a tsunami threat to the adjacent coastline with calculated wave amplitudes ranging from 2.13 – 15.90 m. However, the tsunami risk assessed in their study was a conservative initial assessment and did not consider how local bathymetry influenced tsunami propagation.

Analysis of Airport Officers' Preparedness at Yogyakarta International Airport in Facing Potential Tsunami Hazards

Indonesia is a country that has a geological location where three plates meet and two oceans meet. Because of its geological location, Indonesia is a country that is vulnerable to disasters such as the tsunami disaster. Therefore, preparedness is needed to deal with these potential hazards. Preparedness is a series of activities carried out to anticipate disasters through appropriate and efficient steps. Preparedness is emphasized on the ability to take preparatory actions to face disaster emergencies quickly and precisely. At airports that are located in disaster-prone areas, of course, the preparedness of airport officers is of utmost concern. This preparedness can be in the form of training such as simulations and outreach. In addition to preparedness, preparation for disaster mitigation is also needed. This disaster mitigation can be in the form of constructing disaster-resistant buildings, installing evacuation signs and also making policies that are carried out when a disaster occurs. This study uses qualitative methods with data collection techniques through interviews, observation, and documentation. Then proceed with data analysis techniques, namely data reduction, data presentation, and drawing conclusions. The results shown in this study are that the preparedness of airport officers at Yogyakarta International Airport has been very well prepared, namely by conducting training with related parties and also local residents. In addition, work instructions were also prepared so that they could be used as guidelines in the event of a tsunami disaster. Yogyakarta International Airport has prepared structural and non-structural disaster mitigation. This structural mitigation is in the form of building a building that can withstand an earthquake of 8.8 magnitude and a tsunami of 12 meters, making green belts, installing evacuation route signs, and activating an early warning system. The non-structural mitigation set at this airport is making policies that regulate how to mobilize resources during and after a disaster occurs and data on the amount of available resources. After the disaster, how the airport will be operated will be seen how big the impact is on the airport area.

Potential tsunami hazard of the southern Vanuatu subduction zone: tectonics, case study of the Matthew Island tsunami of 10 February 2021 and implication in regional hazard assessment

Abstract. The Vanuatu subduction zone (VSZ) is known to be seismically very active, due to the high convergence rate between the Australian and Pacific tectonic plates for the majority of the margin. However, this is not the case on its southernmost part south of latitude 22.5∘ S and east of longitude 170∘ E, which is neither highly tectonically active nor has it produced large tsunamis over the past 150 years. It has also not been widely studied. On the 11 February 2021 (10 February UTC), a magnitude Mw 7.7 earthquake triggered a tsunami warning in New Caledonia and Vanuatu 20 min after midnight (local time). With an epicentre located close to the volcanic islands of Matthew and Hunter, this shallow reverse-faulting rupture (< 30 km depth) was able to deform the seabed and produce a tsunami. This was confirmed 45 min later by the coastal gauges of the Loyalty and the south Vanuatu islands, which recorded the first tsunami waves. Showing a typical recorded amplitude of less than 1 m, with a maximum of ∼ 1.5 m in Lenakel (Tanna, Vanuatu), it was observed on most coastal gauges and DART stations in the south-west Pacific region as far as Tasmania to the south and Tuvalu to the north at distances of ∼ 3000 and ∼ 1800 km from the epicentre. In this study, the tsunamigenic potential of the southernmost part of the VSZ and the implications in terms of regional hazard assessment are discussed through (1) the presentation of the complex tectonic settings of this “transition zone” between the Solomon–Vanuatu and the Tonga–Kermadec trenches, (2) the case study of the 10 February 2021 tsunami at a south-west Pacific regional scale using three different tsunami generation scenarios computed with the COMCOT modelling code on a set of 48 nested bathymetric grids, and (3) the simulation of a plausible Mw 8.2 scenario encompassing the active part of this “transition zone”. The validation of the Mw 7.7 parameters for tsunami modelling provides the means to further assess the hazard from potential tsunamis triggered by higher magnitude earthquakes in this region. Tsunami records highlight that > 28 cm wave amplitudes were recorded at eight different coastal gauges, including one with an amplitude of more than 1 m (Lenakel, Tanna, Vanuatu). The tsunami threat at that location would be large enough to warrant an onshore evacuation. Finally, it helps to highlight the significant role played by the numerous submarine features in the region, the Norfolk Ridge being the most important, which acts like a waveguide from the north to the south.

Coastal Hazard Modeling in Indonesia Small Island: Case Study of Ternate Island

Indonesia’s small islands have a high potential for multi coastal hazards, including tsunami and coastal floods due to sea-level rise and tidal waves. Meanwhile, most small island populations live in coastal areas, which increases the potential for disaster risk. Hazard assessment is one of the essential stages and bases in disaster management. This study focuses on tsunami and coastal flood hazards modeling in Ternate Island and analyzing the potential impact on coastal land use. This research combined detailed remote sensing data and geographic information system methods to assess the coastal hazard models. A very detailed resolution remote sensing imagery of Pleiades and detail resolution imagery of SPOT 7 are used as input for physical parameter extraction. DEMNAS (Digital Elevation Models Nasional) data as a topographic parameter is used in potential tsunami and coastal flood hazard area coverage. A numerical model is applied to assess the tsunami hazard model using surface roughness, slope, and run-up scenarios based on historical data. At the same time, the coastal flood model integrates sea level rise parameters and average tidal waves. The research results are believed to contribute as important input data for disaster management based on the sister island concept in Indonesia.

Submarine Landslide Susceptibility Mapping in Recently Deglaciated Terrain, Glacier Bay, Alaska

Submarine mass wasting events have damaged underwater structures and propagated waves that have inundated towns and affected human populations in nearby coastal areas. Susceptibility to submarine landslides can be pronounced in degrading cryospheric environments, where existing glaciers can provide high volumes of sediment, while cycles of glaciation and ice-loss can damage and destabilize slopes. Despite their contribution to potential tsunami hazard, submarine landslides can be difficult to study because of limited access and data collection in underwater environments. Here we present a method to quantify and map the submarine landslide susceptibility of sediment-covered slopes in Glacier Bay, Glacier Bay National Park and Preserve, Alaska, using multibeam-sonar bathymetric digital elevation models (DEMs) and historical maps of glacial extents over the last ∼250 years. After mapping an inventory of >7,000 landslide scarps in submarine sediments, we filtered the inventory by size to account for limitations in DEM resolution and spatial scales relevant to tsunami hazards. We then assessed landslide concentration, accounting for the age of the initial exposure of submarine slopes by deglaciation. We found a positive correlation between landslide concentration and deglaciation age, which we interpreted as a mean landslide accumulation rate over the period of record. Local deviations from this rate indicated differences in susceptibility. Additionally, we accounted for some of the effect of material and morphometric properties by estimating the submarine bedrock-sediment distribution using a morphometric model and assessing the relationship between slope angle and landslide incidence. Finally, we supplemented our susceptibility assessment with a geomorphic component based on the propensity of active submarine fans and deltas to produce landslides. Thus, our map of submarine landslide susceptibility incorporates three components: age-adjusted landslide concentration, slope angle, and geomorphology. We find that areas of mapped high susceptibility correlate broadly with areas of high sediment input and availability, locations of fans and deltas, and steep sediment-covered glacially carved fjords and troughs. Areas of high submarine landslide susceptibility in Glacier Bay moderately correspond with locations of known high-hazard subaerial slopes, but more research on submarine and subaerial landslides in degrading cryospheric environments would be beneficial to better understand landslide and tsunami hazards.

Deterministic tsunami hazard assessment and zoning approach using far-field and near-field sources: Study of Cixi County of Zhejiang Province, China

Investigating the potential tsunami hazard for coastal regions is helpful for urban development and emergency evacuation. In this paper, we present a deterministic method for tsunami hazard assessment (DTHA) in terms of tsunami amplitude and tsunami-induced currents. 21 extreme far-field transoceanic tsunami sources located in the Pacific Rim and, 14 near-field sources in Ryukyu Trough and Manila Trench are suggested. The Digital Elevation Model (DEM) data of 50 m combined with coastal breakwater data is adopted. The tsunami hazard is analyzed based on tsunami amplitude and tsunami-induced velocity. The coastal risk of Cixi County is presented and discussed. The results highlight the necessity of combining the tsunami amplitude and tsunami-induced currents in hazard assessment with the protective role of breakwaters. Further study manifests the effects of astronomical tide on tsunami hazard. The submarine topography consisted of ridges and trenches could trap tsunami energy and change propagation direction. The heterogeneous effect of slip distribution on tsunami hazard assessment is investigated, indicating the feasibility of using uniform slip source in DTHA. This study provides a comprehensive and quantitative assessment method incorporating tide, DEM, breakwater, and multiple sources to evaluate the tsunami risk for hazard reduction and urban planning.

Optimal deployment of seafloor observation network for tsunami data assimilation in the South China Sea

We propose an optimal deployment scheme of the Seafloor Observation Network (SON) in the South China Sea (SCS), aiming at early warning of potential tsunami hazards based on the data assimilation approach. The SON is composed of offshore bottom pressure gauges (OBPGs). We design the initial location of OBPGs along the isobaths of 500, 1000, and 2000 m. The energy distribution of the tsunami wavefield based on Empirical Orthogonal Function (EOF) analysis is used as a reference. Then, synthetic tsunamis generated by stochastic slip sources along the Manila Trench are adopted to evaluate the performance of the SON. The OBPGs at a depth of 1000 m can make an accurate early warning based on tsunami data assimilation at a reasonable engineering cost. Finally, based on the quantitative evaluation, the optimal deployment scheme of the SON is suggested. Our results indicate that at least three stations are required to cover the coast along southern China to forecast the tsunami in the SCS successfully. We note that our method could also be applied to other regions to design the SON against potential tsunami hazards.

Rapid assessment of tsunami source impacts on low-lying coastal areas using offshore wave superposition and static sweep of onshore terrain

ABSTRACT Tsunami source impacts in coastal areas should be investigated thoroughly; however, investigating the associated source uncertainties can incur large computational costs. This study presents a technique for rapid assessment of the impacts and their uncertainties based on a combination of the linear wave superposition for Green’s functions and a static sweep algorithm for onshore terrain. A waveform from a tsunami source is quickly estimated at a shore based on the aforementioned superposition of single-point sources simulated by a linearized Boussinesq model. The maximum water surface elevation change in the waveform, the maximum tsunami elevation, is then determined. In addition, a digital elevation model for onshore terrain that can be inundated by a tsunami is scanned using the sweep algorithm to statically compare the tsunami and ground elevations. As a result, areas with lower ground elevation than the tsunami are quickly identified as potential tsunami hazard zones. This combined analysis is applied to assess potential tsunami sources in the Japan Sea, and the source impacts are comprehensively investigated for Sakata and Akita cities in Japan. Our analysis successfully and quantitatively indicates source impacts while considering their great uncertainty. Additionally, critical areas for expanding tsunami inundation are quickly and efficiently identified.

Spatial modeling of tsunami for evacuation planning in Ciletuh Bay, Sukabumi, West Java

Indonesia is a country located at the meeting of three tectonic plates. This condition makes Indonesia a disaster-prone region, especially caused by the movement of tectonic plates, one of which is the tsunami. Several tsunami occurs were recorded in Indonesia. Tsunami occur on a large scale and causes losses, both environmental damage and fatalities. Therefore, evacuation planning is needed to minimize the number of fatalities when a tsunami occurs. This study aims to find out the potential threat of tsunami hazard in Ciletuh Bay and analyze evacuation planning in the region. The method used in this research is the spatial modeling method which is divided into tsunami inundation modeling, population distribution, and estimated evacuation travel time. The result of this study is that potential tsunami hazard in Ciwaru Village id found in two hamlets with an area of 104.63 Ha. A total of 590 exposed residents can evacuate within 0 – 15 minutes. The selection of evacuation routes with the fastest travel time is needed so that residents can reach the evacuation collection point before the tsunami arrives. The availability of road access in the hamlet makes it easier for residents in tsunami-exposed areas to reach evacuation gathering points.

Insights on the origin of multiple tsunami events affected the archaeological site of Ognina (south-eastern Sicily, Italy)

South-eastern Sicily is one of the most seismically active areas of the Mediterranean Sea, marked by a high level of crustal seismicity, causing major earthquakes (up to Mw ∼7). As a consequence, this area is prone to earthquake-generated tsunamis, which affected the Ionian coast of Sicily in historical times. These tsunamis left geomorphic and sedimentary imprints, such as large boulders or high-energy deposits, along the coasts. One of these was reported by previous works along the coast of Ognina, a small residential area located 20 km south of Siracusa. The deposits fill the back edge of a ria incised into Miocene limestones, are composed of three main stratigraphic units and were attributed to several tsunami and storm events that occurred along the coasts of south-eastern Sicily since the IV century Common Era (CE). Here, we use numerical models to simulate the impact of these extreme marine events, at the time of their occurrence, along the Ognina coastal sector, with the aim to: i) better define the tsunamigenic sources responsible for the events found in the deposits, ii) verify if some units could be related to a storm event, iii) investigate constrains on the paleogeography of the studied area at the time of tsunami and storm occurrence. We reconstructed the morphology of ancient local landscapes using geological and historical information, together with a detailed topographic and geoelectrical survey. We implemented a modelling chain (composed of Delft Dashboard, Delft 3d-FLOW and XBeach) to simulate the tsunami and storm wave propagation upon the ancient landscapes. Our results demonstrate that the use of advanced modeling tools, combined with in situ geological evidence and geophysical survey, has the potential to support the attribution of coastal geomorphic imprints to specific tsunami or storm events, the better definition of the paleo-landscapes, and the identification of the most likely tsunamigenic sources. This last aspect plays a fundamental role in providing more reliable characteristics of the tsunami propagation as well as in the assessing of potential tsunami hazard and related coastal impacts.

Numerical study on impacts of a concurrent storm-tide-tsunami event in Macau and Hong Kong

Intensified activities of tropical cyclones in the Western North Pacific have imposed increasing threats to coastal cities in the context of global climate change. A storm surge superimposed with astronomical high tide, i.e., a storm-tide event, often causes severe flooding in many coastal cities in South China Sea (SCS) region. Meanwhile, the potential tsunami hazard associated with the megathrust in Manila subduction zone has become a serious concern in this region. These two kinds of coastal hazard have been studied independently in the past since they are caused by different physical mechanisms in nature. However, there is no scientific reason to rule out the possibility of concurrence of a storm-tide-tsunami event, which is admittedly rare. This study simulates a group of synthetic events assuming that tsunami waves are generated by a Mw 9 earthquake in the Manila subduction zone during a typhoon, which has the same characteristics as the 2017 Typhoon Hato. A numerical model package originally developed for storm-tide calculation has been modified to simulate a concurrent storm-tide-tsunami event. A variety of scenarios are considered as the tsunamis are superimposed at different phases of the storm-tide event. Their compound impacts on Macau and Hong Kong in Pearl River Delta, China, are investigated. Specifically, the results of water level, arrival time of the maximum water level, flow velocity, and inundation depth are discussed. The worst-case scenarios have been identified at Macau and Hong Kong, respectively. The scenario with tsunami being initiated at 07:00 on 23-Aug-2017 leads to an inundated area of 12.0 km2 in Macau. On the other hand, the scenario with tsunami being started at 08:10 on the same day generates an inundation area of 8.9 km2 in the vicinity of Kai Tak terminal region in Hong Kong. In addition, the efficacy of the linear superposition of results obtained separately for each hazard (i.e., typhoon and tsunamis) is also discussed. Generally speaking, the differences between the linearly superimposed solutions and fully coupled results vary temporally and spatially and could be either positive or negative. However, the linearly superimposed solutions consistently underestimate the maximum water elevation and yield delays on the arrival times of peak flooding stage in the Pearl River estuary. It is concluded that for coastal protection and hazard mitigation planning in this region, these extreme situations need to be considered. A fully coupled numerical model package is now available for conducting such studies.

Analysis of Tsunami Disaster Risk for a Petroleum Refinery Plant at Tsunami Prone Area

A Petroleum Refinery Plant is located in the tsunami prone area at the southern coast of Central Java, Indonesia. The potential mega thrust earthquake, along subduction zone of southern coast of Java, has been identified to have moment magnitude as maximum as Mw = 8.7. The worst scenario due to this earthquake will potentially generate 5.3m to 8.6m tsunami height along the coast within 30 minutes and will inundate one to two kilometres inland of the refinery complex. In this regard, a comprehensive investigation on potential tsunami hazard, level of vulnerability, and tsunami risk potential were carried out. The investigation includes collection and analysis data of detailed topography, bathymetry, land covering and land use, availability of protective structure as well as disaster contingency plan, field ground check data verification, awareness questionnaire, etc. The investigation output includes numerical tsunami inundation simulation, tsunami hazard index, vulnerability index, capacity index, and tsunami risk index for all area of refinery unit. It is concluded that: 1) the main location of refinery complex with considerable numbers of tanks is vulnerable to high tsunami hazard index, and 2) the capacity index in all area are mostly between low to mid-level.

Spatial Analysis on Tsunami Predictions in Pandeglang Regency

Pandeglang Regency is an area that has the potentiel to be hit by tsunamis. The plate subduction paths of Indo-Australia and Anak Krakatau Volcano make Pandeglang Regency a region with a high tsunami potential. One step that can be taken to overcome and minimize losses is to do spatial planning to protect it against potential tsunami damage. This research aimed to evaluate the spatial area of Pandeglang Regency based on the identification of potential tsunami hazards. The concept of modelling the tsunami inundation height developed by Berryman and based on Head Regulation No.4 of 2012 of the Indonesian National Board for Disaster Management has been used to identify potential tsunami hazards. The modelling was carried out by calculating the potential distribution of tsunami wave heights in coastal areas. Three scenarios were used to estimate the distribution. The results showed that the first scenario predicted a maximum tsunami height of 7.5 meters above sea level with the furthest tsunami inundation reaching 1,700.12 meters. Second scenario predicted maximum height of 15 meters, with the furthest tsunami inundation reaching 3,384.62 meters. Meanwhile, the last scenario was able to predict a height of 20 meters and showed the furthest tsunami inundation reaching 5.155,11 meters. These results proved that in all scenarios, the widest inundation would occur in Panimbang Regency. This is due to the relatively small variations in roughness and slope of the surface. The same condition also occurs in the last two scenarios, in which Sumur District was the area most ffected. Therefore, the spatial plan of Pandeglang Regency needs to be evaluated and the function of residential area changed to reduce and prevent large losses.

Stochastic Analysis of Tsunami Hazard of the 1945 Makran Subduction Zone Mw 8.1–8.3 Earthquakes

Historical records of major earthquakes in the northwestern Indian Ocean along the Makran Subduction Zone (MSZ) indicate high potential tsunami hazards for coastal regions of Pakistan, Iran, Oman, and western India. There are fast-growing and populous cities and ports that are economically important, such as Chabahar (Iran), Gwadar (Pakistan), Muscat (Oman), and Mumbai (India). In this study, we assess the tsunami hazard of the 1945 MSZ event (fatalities ≈300 people) using stochastic earthquake rupture models of Mw 8.1–8.3 by considering uncertainties related to rupture geometry and slip heterogeneity. To quantify the uncertainty of earthquake source characteristics in tsunami hazard analysis, 1000 stochastic tsunami scenarios are generated via a stochastic source modeling approach. There are main objectives of this study: (1) developing stochastic earthquake slip models for the MSZ, (2) comparing results of the simulation with the existing observations of the 1945 event, and (3) evaluating the effect of uncertain fault geometry and earthquake slip based on simulated near-shore wave profiles. The 1945 Makran earthquake is focused upon by comparing model predictions with existing observations, consisting of far-field tsunami waveforms recorded on tide gauges in Karachi and Mumbai and coseismic deformation along the Pakistani coast. The results identify the source model that matches the existing observations of the 1945 Makran event best among the stochastic sources. The length, width, mean slip, and maximum slip of the identified source model are 270 km, 130 km, 2.9 m, and 19.3 m, respectively. Moreover, the sensitivity of the maximum tsunami heights along the coastline to the location of a large-slip area is highlighted. The maximum heights of the tsunami and coseismic deformation results at Ormara are in the range of 0.3–7.0 m and −2.7 to 1.1 m, respectively, for the 1000 stochastic source models.

Physical assessment of wave forces on bridge girder impacted by potential tsunami hazard

ABSTRACT Bridges are one of the most susceptible structural elements that can be viciously impacted by tsunami disaster. During the latest few tsunami hazards, a number of bridges were affected severely due to the lack of proper incorporation of tsunami forces in design guidelines. Therefore, it becomes imperative to evaluate the stability of bridges through the analysis of tsunami-induced forces on bridge structures. In the present study, laboratory experiments were carried out to quantify the exerted tsunami forces on girder model. Broken waves along with unbroken waves were considered for the analysis purpose. The maximum horizontal forces were larger for the broken waves than the unbroken waves. Results showed that the initial impact forces were larger than the hydrodynamic forces for broken waves whereas the opposite was true for unbroken waves. Measured forces on girder model, located in higher position, were larger and increased with increasing wave height. Lower girder position showed better performance than higher girder position regardless of wave height. One predictive formula was proposed to estimate the horizontal wave pressure on the seaward side of girder using as input the wave height and girder height. The normalized wave pressure increased as tsunami wave height increased.

Potential tsunami hazard along the southern Turkish coast

The aim of this study is to determine the tsunami potential of the southern Turkish coast through hypothetical earthquake scenarios developed for several critical coastal sites in the region. A well-known tsunami numerical model (MOST) is utilized to calculate the run-up and inundation of the subsequent tsunami waves. The coastal regions selected to realize the aim of the study are Akkuyu and Yeşilovacık from Mersin and Yumurtalık from Adana, which are chosen for their industrial and environmental importance. Time series of wave amplitudes at these three sites as well as contour plots presenting maximum wave amplitudes within the computational domain are generated for different earthquake moment magnitudes. Results obtained from the numerical model suggest that while earthquakes having magnitude smaller than 7.5 generate weak oscillations, earthquakes with magnitude greater than 7.5 result in significant waves reaching maximum wave height of a few meters at the selected coastal regions. Given the number and the magnitude scale of tsunamigenic earthquakes occurred in the region in the past, the modeling effort here indicates that hazard induced by tectonic tsunamis should seriously be taken into account by both the central and the local government authorities, who are responsible for pre- and post-disaster action planning. This issue is critical for minimizing the damage of a possible tsunami event. The proposed study is hoped to be used as a basis for future tsunami risk maps to be developed for the region.

Pandeglang regency spatial evaluation based on tsunami hazard potential

The coastal area of Pandeglang Regency is one area that has the potential to be affected by the tsunami. The existence of the Krakatau Anak Volcano and plate subduction paths in the Sunda Strait cause Pandeglang Regency to become one of the regions that has a tsunami potential. One of the steps to anticipate the tsunami disaster is to do spatial planning that has considered the potential tsunami hazard. The purpose of this research is to evaluate the spatial area of Pandeglang Regency based on the identification of potential tsunami hazards. The identification of potential tsunami hazards is done by modeling the potential distribution of tsunami wave heights in coastal areas using GIS modeling. The results of the identification of potential tsunami hazards on the coast of Pandeglang Regency showed that an area of 194.15 hectares of residential land and the location of existing activities had the potential to be affected by the tsunami. The total area of the coastal area of Pandeglang Regency which was potentially affected by the tsunami hazard reached 1483.26 hectares. The results of a review of the Pandeglang Regency's spatial plan showed that 488.22 hectares of land were found in the planned residential spatial patterns that were potentially affected by the tsunami. Therefore, the regional spatial plan of Pandeglang Regency in the study area needs to be evaluated by changing the function of residential land that has the potential to be affected by the tsunami hazard to the border of the beach or other open land.

Revised earthquake sources along Manila trench for tsunami hazard assessment in the South China Sea

Abstract. Seismogenic tsunami hazard assessments are highly dependent on the reliability of earthquake source models. Here in a study of the Manila subduction zone (MSZ) system, we combine the geological characteristics of the subducting plate, geometry, and coupling state of the subduction interface to propose a series of fault rupture scenarios. We divide the subduction zone into three rupture segments: 14–16, 16–19, and 19–21.7∘ N inferred from geological structures associated with the down-going Sunda plate. Each of these segments is capable of generating earthquakes of a magnitude between Mw=8.5+ and Mw=9+, assuming a 1000-year seismic return period as suggested by previous studies. The most poorly constrained segment of the MSZ lies between 19 and 21.7∘ N, and here we use both local geological structures and characteristics of other subduction zone earthquakes around the world, to investigate the potential rupture characteristics of this segment. We consider multiple rupture modes for tsunamigenic earthquake and megathrust-splay fault earthquakes. These rupture models facilitate an improved understanding of the potential tsunami hazard in the South China Sea (SCS). Hydrodynamic simulations demonstrate that coastlines surrounding the SCS could be devastated by tsunami waves up to 10 m if large megathrust earthquakes occur in these segments. The regions most prone to these hazards include west Luzon of Philippines, southern Taiwan, southeastern China, central Vietnam, and Palawan Island.