Potential Tsunami Research Articles

The formation and growth mechanisms of young back-arc spreading ridges from high-resolution bathymetry: The Marsili Seamount (Tyrrhenian Sea, Italy)

The formation and growth mechanisms of Mid-Ocean Ridges (MOR) are relatively well known, whereas those of back-arc spreading ridges are comparatively less known because geophysical, geochemical, and morphological data are scarce and of low density. Here we present a high-resolution bathymetry of the Marsili Seamount (MS; 1 Ma − 3 ka), which represents the inflated spreading ridge of the 2 Ma old Marsili back-arc basin associated to the subduction of the Ionian Sea below the Calabrian Arc and Tyrrhenian Sea. MS is 70 km long, 30 km wide, and its height reaches about 3000 m from surrounding seafloor. Our new digital bathymetric model has a 5 m grid cell size resolution and covers the MS bathymetry from −1670 mbsl to the top at −491 mbsl. We conduct morphometric and morphological analyses of the bathymetry and recognize landforms due to volcanic, tectonic, hydrothermal and gravity processes. MS consists of volcanoes related to fissural and central-type activity, this latter located at the northern and southern tips of the main dike swarms. Dike swarms represent the surface expression of different ridge segments whose strikes are controlled by the larger scale back-arc spreading processes and by the local occurrence of an active hydrothermal field. This latter develops in a flat area between two partly overlapping ridge segments where historical volcanism and extensional processes concentrate. Such ridges represent the embryonic stage of the formation of transform-like faults. Central volcanoes, the northern of which is characterized by a caldera, form at the tips of MS because the decrease in width of the major volcanic fissures promotes vent localization associated with the formation of sill-like reservoirs from which central-type vents may develop. Gravity processes affecting the MS flanks are due to shallow seafloor sliding. Caldera collapses affecting the northernmost central-type polygenic volcano must be included in the evaluation of the hazard related to potential tsunami. Inward dipping faults characterize the MS eastern flank suggesting a moderately asymmetric growth of the spreading ridge possibly associated with the eastward opening of the Marsili back-arc.The Marsili back-arc spreading rate is similar to those of MOR slow spreading ridges. However, the MS morphology resembles that of fast spreading ridges. These two features also characterize more extended back-arc spreading ridges (e.g. the Mariana in Western Pacific). We conclude that, independently from the spatial scale, the increase in the ridge accretion rate is related to the progressive addition of a subduction-related component to a pure spreading mantle source.

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.

Evaluation of reduced computational approaches to assessment of tsunami hazard and loss using stochastic source models: Case study for Tofino, British Columbia, Canada, subjected to Cascadia megathrust earthquakes

Probabilistic tsunami hazard and risk analyses are important decision support tools in developing tsunami risk reduction strategies and actions for coastal communities. A stochastic source modeling method facilitates the consideration of uncertainties associated with earthquake rupture processes. However, the computational costs are high when inland tsunami inundation and building damage need to be evaluated accurately. To develop a practical solution by keeping the computational requirements at a manageable level, probabilistic tsunami hazard analysis based on low-resolution tsunami simulations but considering a wide range of possible earthquake ruptures can be used to identify smaller sets of stochastic rupture models for target probability levels. These identified stochastic rupture models can be used to obtain the estimates of tsunami building loss by running high-resolution tsunami inundation simulations. A case study is set up for Tofino, British Columbia, Canada, under the potential tsunami threat from the Cascadia megathrust earthquakes to investigate the correlation between the maximum modeled tsunami wave amplitudes at offshore locations and the tsunami building loss. A practical solution is proposed to obtain the tsunami risk estimates based on a limited number of high-resolution tsunami inundation simulations, thus reducing the computational costs for the probabilistic tsunami risk analysis. The effectiveness of the approach is demonstrated by comparing the median value of the tsunami risk estimates from 20 stochastic rupture model simulations that are selected based on probabilistic tsunami hazard analysis for a representative offshore location using the low-resolution tsunami simulations (i.e. 270 m grids) with the full probabilistic tsunami risk analysis of the target building portfolio based on the 1200 high-resolution tsunami simulations (i.e. 5 m grids).

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.

Prediction of shelter needs based on simulation results of evacuees choosing evacuation facilities due to a potential tsunami earthquake in Padang, Indonesia

Tsunami disasters are predicted to occur in the West Sumatra region due to earthquakes. To deal with the tsunami hazard that will hit Padang City, the government has built several shelters and evacuation routes. At present, the number of evacuation facilities is still limited, this will cause community vulnerability in facing tsunami hazards. To overcome this vulnerable condition, it is necessary to determine the number of shelters needed to accommodate evacuees. In this study, the determination of the required number of shelters is done by simulating the number of evacuees who choose shelters during evacuation. The model of evacuee generation from 5 tsunami-prone zones in Padang City was created using a linear regression method. The model for selecting the type of evacuation facility in each zone uses a binary logit model. Prediction of shelter needs is carried out for minimum, normal and maximum conditions that may occur. From the simulation results, the number of evacuees who choose the shelter as a means of evacuation is obtained. The number of shelters needed in Padang City is a minimum of 6 units, normal 23 units and maximum 50 units.

Numerical Study of Tsunami Force on Superstructure of Offshore Rigid Frame Box Girder Bridge

Offshore bridges need to bear complex wave and current loads and face the threat of extreme loads such as tsunamis. Potential tsunamis will have disastrous effects on coastal areas. Compared with conventional beam bridges, there are few studies on rigid frame box girder bridges. In this paper, based on a continuous rigid frame box girder bridge in the offshore area, the parameters of tsunami impact force are analyzed. First, based on Stoke theory and water level in the storage area, the water level in the static water area and quasi stable area in the dam break wave working conditions are obtained, and 12 kinds of dam break wave working conditions are preliminarily proposed to be used for the background bridge. Then, according to the determined simulation working conditions, the box girder dam break impact numerical model is simulated. According to the calculated results, the stress characteristics of the box girder under the tsunami impact are described in the way of time history stage division, and on this basis, The stress mechanism is analyzed from the whole level and local level. The results show that on the whole level, the variation of horizontal force and vertical force with time can correspond to the variation of dam break flow around the box girder. At the local level, the horizontal wall boundary bears the vertical force, the vertical wall boundary bears the horizontal force, and the inclined wall boundary bears both the horizontal force and the vertical force. In addition, negative pressure is the cause of suction on the wall boundary. It provides a reference for the calculation and analysis of tsunami load of offshore rigid frame box girder bridges, the identification of bridge failure modes and the formulation of protective measures.

Assessing tsunami vertical evacuation processes based on probabilistic tsunami hazard assessment for west coast of Aceh Besar, Indonesia

BackgroundTsunamis are rare events compared to other disasters but have devastating consequences. In the last 100 years, more than 24 tsunamis and more than 235,000 fatalities have occurred globally. Indonesia has a high risk of a tsunami disaster. Since the devastating 2004 tsunami in the Indian Ocean, much research and preparatory work have been done to reduce the impact of future tsunamis in Indonesia, including in the province of Aceh, especially along the western coast where West Aceh is located. This coastal area was destroyed by a tsunami as high as 15–30 m, resulting in the loss of life, housing, tourist areas, industrial areas, and other public facilities. Given that tsunami disasters are rare and sometimes occur long in advance, human memory and awareness are reduced, making research on the level of tsunami awareness of disasters a challenging task.MethodProbabilistic Tsunami Hazard Assessment (PTHA) is a method that has been developed to predict tsunami hazards with a return period of hundreds to thousands of years, beyond the limited availability of historical data. The PTHA method can provide important information that supports tsunami risk management measures. This study aims to estimate recurrence period-based tsunami risk on the west coast of the district of Aceh Besar using the PTHA method. In this study, the source of the tsunami is caused by fault activity at sea. Seven tsunami scenarios based on fault parameters (earthquakes of magnitudes Mw 8.0 to 9.2 with interval 0,2) with the fault location focusing on the Aceh-Andaman Mega Thrust Segment, as applied in this study. This segment was a similar source to the 2004 Indian Ocean tsunami that created a rupture area along a distance of 1155 km, with six parts of the fault.ResultThe maximum inundation distance reached 6 km for the flat area, with a flow depth of 13 m. The site has a cliff that is close to the shoreline, with an inundation distance shorter than the distance across the flat area. With an arrival time of less than 25 min, it is recommended to have an evacuation building and evacuation road in a wide inundated area, and an arrangement of hills close to the beach as an evacuation area, in order to reduce the number of casualties. For 100 years return period or exceedance probability rate 0.01, the average flow depth on the coast may exceed 5 m, and the maximum flow depth for a 1000-year return period or annual probability of 0.001 is 12 m. With the potential tsunami in the future, continuous tsunami drills and tsunami education are needed so that people can maintain an awareness of the threat posed by tsunamis.

Tsunami Risk Change Analysis for Qidong County of China Based on Land Use Classification

Tsunamis can cause high numbers of casualties, as well as direct and indirect economic losses to coastal regions. The huge destructiveness of tsunamis requires us to study tsunami risk and its temporal change. We adopt the tsunami scenarios of the Ryukyu Trench as an example to analyze the temporal change in tsunami risk. According to the tsunami numerical model results, the tsunami inundation in the worst tsunami scenario covered an area of 82.83 km2. Satellite data including Landsat 8 images from July 2013 and Landsat 9 images from March 2022 were used with the random forest (RF) method to analyze land use and tsunami vulnerability in 2013 and 2022. The tsunami risk and its temporal change were analyzed by integrating tsunami hazard and tsunami vulnerability. The tsunami risk change analysis results show that the area of tsunami risk level 1 increased by 4.57 km2, and the area of tsunami risk level 4 decreased by 7.31 km2. By analyzing changes in land use and land cover (LULC) and tsunami risk, we concluded that the expansion of constructed land and the increase in coastal population were responsible for the increase in tsunami risk. The results of tsunami risk change analysis will help us understand the current tsunami risk and predict possible future risk change. In addition, it is necessary to prepare tsunami prevention measures in advance and produce tsunami emergency response plans for Qidong County and other regions under potential tsunami threat.

Tsunami scenario triggered by a submarine landslide offshore of northern Sumatra Island and its hazard assessment

Abstract. Near the northern border of Sumatra, the right-lateral strike–slip Sumatran fault zone splits into two branches and extends into the offshore, as revealed by seismic sounding surveys. However, due to its strike–slip faulting characteristics, the Sumatran fault zone's activity is rarely believed to cause tsunami hazards in this region. According to two reprocessed reflection seismic profiles, the extended Sumatran fault zone is strongly associated with chaotic facies, indicating that large submarine landslides have been triggered. Coastal steep slopes and new subsurface characteristics of submarine landslide deposits were mapped using recently acquired high-resolution shallow bathymetry data. Slope stability analysis revealed some targets with steep morphology to be close to failure. In an extreme hypothetical case, an earthquake of Mw 7 or more occurred, and the strong ground shaking triggered a submarine landslide off the northern shore of Sumatra. Based on a simulation of tsunami wave propagation in shallow water, the results of this study indicate that a potential tsunami hazard from several submarine landslide sources triggered by the strike–slip fault system can generate a tsunami as high as 4–8 m at several locations along the northern coast of Aceh. The landslide tsunami hazard assessment and early warning systems in this study area can be improved on the basis of this proposed scenario.

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.

RISK COMMUNICATION STRATEGY IN DEALING WITH THE TSUNAMI DISASTER

Umang Beach Club Private Island Resort is located in Sumur village, Pandeglang, Banten. Has a unique location, located at two potential tsunami sources. The first is Seismic, which is at the center of the Sunda Strait megathrust. The second, namely Unsesmic, is located at a distance of about 70km from Mount Anak Krakatu. This study aims to find a risk communication strategy in dealing with the tsunami natural disaster. This study used a qualitative descriptive method and collected data by interviews, documentation and observation. Interviews were conducted with informants, namely local governments and disaster-related institutions. The results of the study found that risk communication strategies in dealing with tsunamis were initiated by common perceptions of the tsunami hazard, setting goals, developing messages, face-to-face communication.

Analysis of the Availability of Mosque Sanitation Facilities in the Tsunami Green Area as an Alternative Place for The Final Evacuation of the Tsunami Disaster in Padang City

The city of Padang as one of the areas in West Sumatra which is in a coastal area is very prone to tectonic earthquakes with the potential for tsunamis, it is verynecessary to have high preparedness to deal with it. One of the things that must be prepared is the evacuation site the end, which is a temporary residence for disaster victims. One alternative that can be used as a final evacuation site is a mosque. This study aims to prepare mosque sanitation facilities in the tsunami green area. The measurement of the preparedness of mosque sanitation facilities is seen from observations, in the form of a checklist table that will be filled out by researchers in 29 mosques that are the object of study. With a descriptive type of research, to see an overview of the condition of mosque sanitation facilities. Based on the results of research and discussion, it can be concluded that from the 29 mosques studied, all mosques were obtained in the category of sanitation, construction, toilets and latrines, lighting and ventilation conditions of mosques in the city of Padang. While 17 mosques (58.6%) are located close to Jalan Raya, there are 25 mosques (86.2%) with courtyards in good condition, there are 28 mosques (96.6%) with good waste management, 13 mosques (44.8%) using water sources from PDAM and there are 28 mosques (96.6%) that have wastewater disposal in good condition. This can be used as an evacuation site, so the main thing that must be done is the maintenance of the sanitary condition of the mosque so that it is maintained and can become a proper evacuation site.

Tsunami Potential Prediction with Artificial Neural Network

Natural disasters are caused by biological factors such as earthquakes, tsunamis, and landslides. One of the destructive natural disasters that can cause considerable losses in terms of casualties and the economy is the tsunami. A tsunami is a series of tall or long waves in shallow seas. Various tsunami triggers include earthquakes, volcanic activity, and underwater landslides. This study aims to predict tsunamis with an Artificial Neural Network, which is a part of Machine Learning. Artificial Neural Network (ANN) is a model that has the same characteristics as biological neural networks. The process resembles the work of a neural network, which processes incoming information through neurons—using Multi-Layer Perceptron with five input parameters, two hidden layers, and one output. The ANN model can predict a tsunami potential in a country by 81%.

The tsunamigenic potential of landslide-generated tsunamis on the Vavilov seamount

The investigation of submarine volcanoes and the tsunamigenic potential of possible movements on their flanks is arduous. In most cases, the lack of specific information about the eruptions' history and their consequences does not allow a comprehensive analysis in terms of hazard. Nevertheless, useful clues on the possible occurrence of mass movements on seamounts can be obtained from a series of research fields. These account for morphological studies, observations of hydrothermal activity, collection of geophysical data (for example, detailed DEM, seismic profiles, magnetic data), etc. In this context, this study presents new bathymetric data of the Vavilov submarine volcano (Tyrrhenian Sea, Italy) and a detailed morphological analysis of the structure. The latter allows the identification of zones potentially prone to mass movements and the development of numerical scenarios to investigate the tsunami potential associated to these movements on the Vavilov flanks. Results prove that the waves generated by the mass displacements in the proposed scenarios (involving sliding volumes between 0.32 km3 and 1.7 km3) reach maximum values in the order of centimetres, not considering dispersive effects. Eventually, a scenario involving the partial collapse of the west flank of the Vavilov Seamount is simulated, although the occurrence of such an event in the past is still debated due to the uncertainties related to the origin and development of the volcano dome. In this scenario, water elevation as high as 10 m are found in large portions of the Tyrrhenian coasts: waves are large enough to emplace sizeable tsunami deposits onshore, that could have been preserved until today in some specific stretches of the coast and could be detected by a finalised geological search. This study belongs to a series of works devoted to the submarine structures of the Tyrrhenian Sea aiming to disclose the tsunamigenic potential of submarine mass movements on their flanks.

Tsunami debris analysis to support blue economy development in Tasikmalaya, West Java

In many coastal and marine environments, the blue economy is being developed to enhance community welfare. The possibility of a tsunami disaster, which could destroy the infrastructure supporting the blue economy, is one of the development challenges. The Sindangkerta beach and the Pamayang harbor in Tasikmalaya, West Java, Indonesia, are the two locations where this study discusses the possibility of tsunami debris occurring. Infrastructure that supports life may be threatened by tsunami debris. To ascertain the origin of the debris, a field survey was used in the study. When a tsunami is approaching, beachfront houses and fishing boats are easily swept towards land. The number and mass of houses and boats are counted. In order to calculate the magnitude of the tsunami impact force, the material stiffness of the two types of objects was also examined. The potential tsunami debris's runup and rundown directions are also estimated. The study's findings show that houses that serve as restaurants and shops for tourists predominate at the Sindangkerta tourist destination while fishing boats serve as the primary source of debris at the Pamayang fishing port. In addition, the debris dispersal area due to run-up and run-down is also depicted.

Tsunami scenario triggered by the activity of the Mentawai Fault Zone offshore western Sumatra Island

Subduction zones worldwide pose tsunami risks, mainly linked to megathrust activity near subduction trenches. However, tsunamis can originate from various sources, including marine volcanic eruptions, submarine landslides, and strike-slip earthquakes. In the Sumatra subduction zone, a seismic gap in the Mentawai region heightens the tsunami risk. This region’s tectonics are complex due to the oblique subduction of the India-Australia oceanic plate beneath the Eurasian continental plate, leading to the sliver faults system of Mentawai Fault Zone (MFZ) and Sumatra Fault Zone (SFZ). The SFZ on Sumatra Island has limited tsunami potential, except at its northern and southern offshore extensions. In contrast, the MFZ, situated in the marine Northern Bengkulu basin, holds a higher tsunami-generation potential. This study aims to assess the MFZ activity in generating tsunamis, estimate the maximum wave height, and analyze propagation, and arrival times at several crucial sites in Western Sumatra Province. We utilized the COMCOT tsunami model to simulate scenarios with two fault mechanisms, i.e., strike-slip and back thrust, and two magnitudes (Mw 7.6, and 8.2). The results indicate that the most hazardous tsunami, generated by a strike-slip fault with Mw 8.2, produces a 2-meter tsunami on the east coast of Siberut Island and the west coast of Padang City, West Sumatra. The scenarios reveal that Mentawai Island’s eastern part lacks evacuation time, with an almost instantaneous tsunami arrival. In contrast, western Sumatra, including Pariaman and Padang City, has 13 to 20 minutes for evacuation planning. Thus, disaster risk reduction strategies in these locations should consider these findings.

Efektivitas Pelaksanaan Tsunami Safe Zone Terhadap Masyarakat KotaPadang

An earthquake with the potential for a tsunami is a disaster that needs to be anticipated, especially the city of Padang, which is an earthquake-prone area with the potential for a tsunami. Considering the potential for this very dangerous disaster, of course it is necessary to make efforts to reduce disaster risk in order to prevent or at least anticipate the number of victims, both property and human life. Efforts to reduce disaster risk for the safety of human life, when an earthquake with a potential tsunami occurs, tsunami evacuation instructions have been installed by the Padang City Regional Disaster Management Agency, one of which is by making a blue line (Tsunami Safe Zone). The blue line (Tsunami Safe Zone) is an estimate of the area classified as safe from a potential tsunami. This blue line will later indicate that if residents have crossed the line, they will be in a tsunami-safe area. Keywords: effectiviness, tsunami, safe zone

A Tsunami Generated by a Strike‐Slip Event: Constraints From GPS and SAR Data on the 2018 Palu Earthquake

AbstractA devastating tsunami struck Palu Bay in the wake of the 28 September 2018 Mw = 7.5 Palu earthquake (Sulawesi, Indonesia). With a predominantly strike‐slip mechanism, the question remains whether this unexpected tsunami was generated by the earthquake itself, or rather by earthquake‐induced landslides. In this study we examine the tsunami potential of the co‐seismic deformation. To this end, we present a novel geodetic data set of Global Positioning System and multiple Synthetic Aperture Radar‐derived displacement fields to estimate a 3D co‐seismic surface deformation field. The data reveal a number of fault bends, conforming to our interpretation of the tectonic setting as a transtensional basin. Using a Bayesian framework, we provide robust finite fault solutions of the co‐seismic slip distribution, incorporating several scenarios of tectonically feasible fault orientations below the bay. These finite fault scenarios involve large co‐seismic uplift (>2 m) below the bay due to thrusting on a restraining fault bend that connects the offshore continuation of two parallel onshore fault segments. With the co‐seismic displacement estimates as input we simulate a number of tsunami cases. For most locations for which video‐derived tsunami waveforms are available our models provide a qualitative fit to leading wave arrival times and polarity. The modeled tsunamis explain most of the observed runup. We conclude that co‐seismic deformation was the main driver behind the tsunami that followed the Palu earthquake. Our unique geodetic data set constrains vertical motions of the sea floor, and sheds new light on the tsunamigenesis of strike‐slip faults in transtensional basins.

Multi-hazard analysis of flood and tsunamis on the western Mediterranean coast of Turkey

Abstract. Flooding has always been a devastating hazard for social and economic assets and activities. Especially, lowland areas such as coastal regions can be more vulnerable to inundations. The combination of different natural hazards observed at the same time is definitely worsening the situation in the affected regions. The goal of this study is to conduct a distinctive multi-hazard analysis considering flood hazards with the contribution of potential earthquake-triggered tsunamis that might be observed throughout the Fethiye coastline and city center. For this purpose, tsunami hazard curves are generated based on Monte Carlo simulations. Comprehensive stochastic hazard analyses are performed considering the aleatory variability of earthquake-triggered tsunamis and epistemic uncertainty of floods having 10-, 50-, and 100-year return periods. Numerical simulations are conducted to combine the potential tsunamis and flood events that are able to adversely affect the selected region. The results of this study show that the blockage of stream outlets due to tsunami waves drastically increases the inundated areas and worsens the condition for the selected region.

Risk Communication Model in Facing Tsunami Disaster Through Stakeholder Engagement

Umang Beach Club Private Island Resort is located in Sumur village, Pandeglang district, Banten. It has a very unique location, located at two sources of potential tsunamis. The first is Seismic, which is at the center of the megathrust of the Sunda Strait. The second, namely Unsesmic, is located at a distance of about 70km from Mount Anak Krakatu. This study aims to find a risk communication model in dealing with tsunami natural disasters through stakeholder engagement. This research uses descriptive qualitative method and data collection by interview, documentation and observation. Interviews were conducted with Umang Beach Club Private Island Resort, local government and disaster-related institutions, Sumur village communities, disaster communities as well as tsunami and risk management experts. The results of the study found a risk communication model in dealing with tsunami natural disasters through stakeholder engagement. Risk communication needs to be carried out in a systematic and planned manner and integrated with all stakeholders involved with disasters to reduce disaster risk.