Assessing future uncertainties: earthquake tsunami hazard in the Java trench, Indonesia.

The uncertain tsunamigenic potential of the Makran Subduction Zone (MSZ) has made it an interesting natural laboratory for tsunami-related studies. This study aims to review the recent activities on tsunami hazard in the Makran subduction zone with a focus on deterministic and probabilistic tsunami hazard assessments. While almost all studies focused on tsunami hazard from the Makran subduction thrust, other local sources such as splay faults and landslides can be also real threats in the future. Far-field tsunami sources such as Sumatra-Andaman and Java subduction zones, commonly lumped as the Sunda subduction zone, do not seem to pose a serious risk to the Makran coastlines. The tsunamigenic potential of the western segment of the MSZ should not be underestimated considering the new evidence from geological studies and lessons from past tsunamis in the world. An overview of the results of tsunami hazard studies shows that the coastal area between Kereti to Ormara along the shoreline of Iran-Pakistan and the coastal segment between Muscat and Sur along Oman’s shoreline are the most hazardous areas. Uncertainties in studying tsunami hazard for the Makran region are large. We recommend that future studies mainly focus on the role of thick sediments, a better understanding of the plates interface geometry, the source mechanism and history of extreme-wave deposits, the contribution of other local tsunamigenic sources and vulnerability assessment for all coastlines of the whole Makran region.

The tsunami hazard posed by the Flores backarc thrust, which runs along the northern coast of the islands of Bali and Lombok, Indonesia, is poorly studied compared to the Sunda megathrust, situated ~250 km to the south of the islands. However, the 2018 Lombok earthquake sequence demonstrated the seismic potential of the western Flores Thrust when a fault ramp beneath the island of Lombok ruptured in two Mw 6.9 earthquakes. Although the uplift in these events mostly occurred below land, the sequence still generated 1–2.5 m-high local tsunamis along the northern coast of Lombok (Wibowo et al., 2021). Historical records show that the Flores fault system in the Lombok and Bali region has generated at least six ≥ Ms 6.5 tsunamigenic earthquakes since 1800 CE. Hence, it is important to assess the possible tsunami hazard represented by this fault system. Here, we focus on the submarine fault segment located between the islands of Lombok and Bali (below the Lombok Strait). We assess modeled tsunami patterns generated by fault slip in six earthquake scenarios (slip of 1–5 m, representing Mw 7.2–7.9+), with a focus on impacts on the capital cities of Mataram, Lombok and Denpasar, Bali, which lie on the coasts facing the strait. We use a geologically constrained earthquake model informed by the Lombok earthquake sequence (Lythgoe et al., 2021), together with a high-resolution bathymetry dataset developed by combining direct measurements from GEBCO with sounding measurements from the official nautical charts for Indonesia. Our results show that fault rupture in this region could trigger a tsunami reaching Mataram in < 8 minutes and Denpasar in ~10–15 minutes, with multiple waves. For an earthquake with 3–5 m of coseismic slip, Mataram and Denpasar experience maximum wave heights of ~1.3–3.3 m and ~0.7 to 1.5 m, respectively. Furthermore, our earthquake models indicate that both cities would experience coseismic subsidence of 20–40 cm, exacerbating their exposure to both the tsunami and other coastal hazards. Overall, Mataram city is more exposed than Denpasar to high tsunami waves arriving quickly from the fault source. To understand how a tsunami would affect Mataram, we model the associated inundation using the 5 m slip model and show that Mataram is inundated ~55–140 m inland along the northern coast and ~230 m along the southern coast, with maximum flow depths of ~2–3 m. Our study highlights that the early tsunami arrival in Mataram, Lombok gives little time for residents to evacuate. Raising their awareness about the potential for locally generated tsunamis and the need for evacuation plans is important to help them respond immediately after experiencing strong ground shaking.

Kapanewon Temon, the location of New Yogyakarta International Airport (NYIA), is projected to become a new economic center but is vulnerable to tsunami hazards due to its proximity to the southern Java subduction zone. Mitigation efforts are necessary to prepare for the worst-case scenarios. This study assesses tsunami hazard potential based on a worst-case scenario using a geophysical approach through numerical simulations with the COMCOT software. The data used include bathymetry, topography, administrative boundaries, land cover, and fault parameters. Simulation results indicate potential tsunami inundation up to 20 meters in key areas such as Congot Beach, the southern coast of NYIA, and Glagah Beach, with an estimated arrival time of 0.6-0.63 hours. These findings are expected to serve as a reference for spatial planning and disaster risk mitigation efforts in Kapanewon Temon, Kulon Progo Regency.

Evaluation of tsunami disaster risk for a coastal region requires reliable estimation of tsunami hazard, for example, wave amplitude close to the shore. Observed tsunami data are scarce and have poor spatial coverage, and for this reason probabilistic tsunami hazard analysis (PTHA) traditionally relies on numerical simulation of “synthetic” tsunami generation and propagation toward the coast. Such an approach has been extensively studied in the past and it is widely recognized as an important disaster‐risk mitigation tool. PTHA can not only provide less uncertain and spatially coherent hazard estimates in comparison with classical empirical data analysis which is restricted at the tide gauge stations, but also local inundation information. In this paper, we explore a purely statistical alternative to traditional PTHA for evaluation of tsunami amplitude hazard. Here, we use tide gauge measurements of tsunami amplitude along the western United States, specifically California and Oregon, and develop a spatial Bayesian hierarchical model (BHM) to assess tsunami hazard from far‐field earthquake sources at various recurrence intervals. The configuration of our model incorporates latent Gaussian fields that utilize information on the distance between tide gauges as well as on the continental shelf width, that is, a covariate linked to potential dissipative effects on wave energy as the tsunami travels over shallow water. Through our BHM, we produce spatially continuous probabilistic maps of far‐field tsunami hazard which can aid comprehensive tsunami disaster risk reduction and management.

The past 100 years have seen the occurrence of five earthquakes and 94 earthquakes. Here we assess the potential for future great earthquakes using inferences of interseismic subduction zone coupling from a global block model incorporating both tectonic plate motions and earthquake cycle effects. Interseismic earthquake cycle effects are represented using a first‐order quasistatic elastic approximation and include of interacting fault system area across the globe. We use estimated spatial variations in decadal‐duration coupling at 15 subduction zones and the Himalayan range front to estimate the locations and magnitudes of potential seismic events using empirical scaling relationships relating coupled area to moment magnitude. As threshold coupling values increase, estimates of potential earthquake magnitudes decrease, but the total number of large earthquakes varies non‐monotonically. These rupture scenarios include as many as 14 recent or potential earthquakes globally and up to 18 distinct events associated with a single subduction zone (South America). We also combine estimated slip deficit rates and potential event magnitudes to calculate recurrence intervals for large earthquake scenarios, finding that almost all potential earthquakes would have a recurrence time of less than 1,000 years.

Tsunamis pose a significant threat to the Jailolo coastal area in North Maluku, Indonesia, because of its proximity to the Maluku Sea subduction zone, where seismic activity has historically triggered destructive waves. This study aims to map tsunami hazards in the Jailolo coastal area by integrating the Structure-from-Motion (SfM) photogrammetry method with numerical calculations. The SfM photogrammetry method involves using an unmanned aerial vehicle (UAV) to produce digital elevation model (DEM) data in the form of digital terrain model and digital surface model, as well as orthomosaic data. In addition, tsunami wave propagation simulation modelling was carried out using the Cornell Multi-Grid Coupled Tsunami computational program, with input data including Manning’s coefficient data and fault parameters. The aerial photography resulted in DEMs with a vertical accuracy of LE90 of 0.15 metres and an orthomosaic with a horizontal accuracy of CE90 of 0.5 metres. The tsunami simulation revealed tsunami waves reaching 5.8–17.4 metres, with a hazard zone of approximately 119.31 hectares and an inundation distance of about 700 metres from the coast. The affected areas include settlements, agriculture and mangrove forests. In conclusion, the integration of UAV-based SfM photogrammetry and numerical simulations effectively produces high-precision tsunami hazard maps. Contribution: This study provides a significant contribution to disaster mitigation and evacuation planning by providing an accurate and efficient method for mapping tsunami hazards. The precise data can support decision-making in high-risk coastal areas such as Jailolo.

The Vanuatu Trench hosts tsunamigenic earthquakes exceeding magnitude 7. For these source locations, current tsunami early warning systems in Aotearoa - New Zealand are based on earthquake point-source parameters and as tsunamis propagate, initial forecasts are refined by DART (Deep-ocean Assessment and Reporting of Tsunamis) sea-level analysis. This study, which is part of the R-CET (The Rapid Characterization of Earthquakes and Tsunami) project led by GNS Science, aims to seismologically characterize the spatio-temporal behavior of the regional tsunamigenic ruptures in near real-time. This transition from basic point sources to 4-D rupture propagation could enhance the accuracy of initial tsunami threat maps and hazard response. A new array of broadband seismic stations, designated as the R-CET array, has been strategically deployed in New Zealand to support this analysis for events in the South Pacific.In this proof-of-concept study, we applied a beamforming array seismological technique to analyze the R-CET array recordings from a recent tsunamigenic earthquake (Mw 7.7) in the Vanuatu region, the Loyalty Islands, on May 19, 2023. We use sliding window fk-analysis beamforming, which can simultaneously measure backazimuth and slowness. Incorporating the sliding window, in conjunction with the fk diagrams, helps to observe temporal azimuthal changes, which facilitates tracking the rupture length and direction over time. Preliminary results showed the azimuthal and temporal variation of the rupture is in alignment with post-processing estimates of the finite fault solution for this event reported by USGS. We test the utility of this analysis in tsunami forecasts by comparing threat maps generated from the beamforming source and initial response maps used in real-time response on the day. We further compare our results to actual measured coastal cancellation gauges (tide gauges) and DART observations. We show that this analysis has the potential to improve initial tsunami forecasts prior to the onset of tsunami waves at deep ocean tsunamimeters. We further present the technique as an enticing path to meet UN Ocean Decade tsunami warning goals within our framework of ensemble and time-dependent forecasting.

Se revisa la literatura sobre la sismicidad (IMM≥VI en Oaxaca y/o daños en otra localidad de Oaxaca) ocurrida en el estado de Oaxaca durante el período 1542-1988. La información macrosísmica se utiliza para agrupar los temblores en familias de eventos semejantes. Basándose en el conocimiento actual sobre los procesos sismotectónicos en la región, se sugiere la definición de 8 zonas sismogenicas. En un catalogo se presentan los datos, indicando las fuentes y nuestra interpretación. Los 68 eventos mayores (mb ≥6.5, Ms≥7.0) son asignados a cada una de las zonas sísmicas; para éstas se analizan los tiempos de recurrencia y se seleccionan los sismos máximos esperados. Los resultados principales son: - En la zona de subducción pueden ocurrir terremotos de gran magnitud (Ms Ì´Í‚ 8.5), como el de marzo de 1787. - En la zona de subducción, en el periodo 1928-1988, han ocurrido once sismos (Ms ≥ 7.0), cuatro en la mitad este y siete en la oeste. En los 56 años precios a 1928 se presento un periodo de calma sísmica (Ms≥7.0); en la región de ocurrencia del gran terremoto de 1787 sólo vuelve a temblar (Ms ≥ 7.0) en 1928, después de 141 años de calma sísmica. - En 1928, en un lapso de 8 meses, ocurren cuatro eventos de subducción (Ms≥7.4); en el mismo período ocurren dos temblores intraplaca importantes (mb = 7.7) en la parte norte. En enero de 131 ocurre otro intraplaca (Ms = 8.0) en la parte sur. Este patrón de liberación de energía sísmica en un corto periodo de tiempo refuerza la afirmación de que en Oaxaca deben esperarse terremotos de gran magnitud por ruptura simultánea de varias unidades sismogénicas. - Las zonas "Huajuapan" y "Mixe" son afectadas por eventos de profundidad intermedia y falla normal (60≤H≤ 120 km, mb Ì´Í‚ 7.0-7.7) con tiempos de recurrencia bastante regulares (95 ± 11 años y 80 ± 16 años, respectivamente). - En la zona "valle" ocurren sismos someros de falla normal (25≤H≤50, Ms Ì´Í‚ 8.0) en periodos de tiempo también muy regulares (82±16 años). Posiblemente en la zona "Mixteca Media", al oeste de la anterior, también ocurren eventos de este tipo; en este caso la zona "Mixteca Media" presentaría un potencial sísmico muy alto (156 ± 22 años, ultimo temblor en 1854). - Para la zona "Istmo" se concluye que, en general, su actividad sísmica de profundidad intermedia es de magnitud moderada (mb ≤ 6.5). de especial interés es el evento de diciembre 29, 1917 (Ms = 7.1); nuestra relocalización indica que su epicentro esta situado en el Golfo de Tehuantepec, en una brecha sísmica cuyo potencial sísmico es difícil de evaluar. - El análisis de la actividad sísmica (mb ≥6.5, Ms≥7.0) ocurrida en los últimos 480 años surgiere que estudios basados en los catálogos de los últimos 150 años pueden conducir a conclusiones erróneas sobre la sismotectónica de la región, subestimar los sismos máximos y definir periodos de recurrencia con escasa información.

The high level of seismic activity and the potential for large earthquakes in the San Jacinto fault zone, southern California, make it desirable to have accurate locations and source parameters for as many previous events as possible. Prior to the installation of a dense seismic network in this region, earthquakes were located using only a few stations with generally poor azimuthal coverage resulting in considerable uncertainty in the locations. We relocate and obtain moment estimates for historic (pre-WWSSN) earthquakes in the western Imperial Valley by comparing the waveforms and travel times with recent earthquakes in the region. All the events are in the ML 5.5 to 6.5 range. The historic earthquakes of interest occurred in 1937, 1942, and 1954. We use the 1968 Borrego Mountain, 1969 Coyote Mountain, and 1987 Elmore Ranch earthquakes as calibration events. We employ regional and teleseismic data from continuously operating stations, with Pasadena, DeBilt, Berkeley, Ottawa, and St. Louis recording most of the events. The waveforms imply that all the events are almost pure strike-slip events on vertical or near-vertical faults. Approximate values for the strikes were obtained and are within the range of observed strikes for well-studied earthquakes in this region. The earthquakes are relocated by comparing S-P and surface-wave - S travel times of historic events with the presumably well-located recent events. The relocations require only a small change in location for the 1954 event and a larger adjustment in the 1942 epicenter. It also appears that the 1969 earthquake may have been mislocated. The moment estimates are obtained by direct comparison of the maximum amplitudes. The moment estimates imply that the 1968 and not the 1942 earthquake is the largest to have occurred in the region this century. Previous magnitude estimates suggested the 1942 event was larger.

<title>Abstract</title> The Lesser Sunda Islands (comprising Bali, West Nusa Tenggara, and East Nusa Tenggara) are situated between three seismic sources: the subduction zone, the fold-thrust back (FTB), and the back-arc thrust fault system in the north. The combined activity of these three sources makes the region highly vulnerable to tsunami hazards. The high population density in coastal areas and the presence of critical infrastructure in this region increase the urgency of conducting a tsunami hazard assessment. This study aims to analyze the tsunami hazard using a Probabilistic Tsunami Hazard Assessment (PTHA) based on a Green’s function approach, derived from simulations of the Shallow Water Equation (SWE). A total of 10,120 tsunami scenarios were developed from 9 fault sources using the stochastic slip distribution based on the Von Karman correlation function. All faults were divided into 108 subfaults to estimate the response of the tsunami wave at 255 observation points. The locations with the highest frequency per year for waves exceeding 1 m include Jembrana and Buleleng, northern and southern Sumbawa, as well as Sikka and west Manggarai. The tsunami hazard maps indicate that for a return period (RP) of 2475 years, more than 57% of the locations experience tsunami waves exceeding 3 m, with maximum heights reaching over 11 m. For the return period of 475 years, the rate is more than 0.4%, and for the return period of 72 years, there’s no location where the tsunami wave height exceeds 3 meters. The faults from the Bali subduction zone, the Sumbawa thrust, the Flores thrust, and the Timor FTB are the dominant contributors to the tsunami hazard in 20 strategic locations.

- Disasters such as floods, earthquakes, and cyclones pose significant threats to human life, infrastructure, and the environment. Timely preparedness and effective mitigation strategies are essential to minimize their impact. This study proposes an AI-based disaster preparedness and mitigation plan system that leverages advanced machine learning and data analytics techniques to predict, monitor, and respond to potential disasters. The system integrates real-time data from multiple sources such as satellite imagery, weather forecasts, and IoT sensors to enhance situational awareness. By utilizing predictive models and intelligent algorithms, the system identifies risk-prone areas, supports early warning mechanisms, and assists authorities in resource allocation and decision-making. Techniques such as data preprocessing, pattern recognition, and model optimization are applied to improve accuracy and reliability. Evaluation metrics including prediction accuracy, response time, and risk assessment efficiency are used to measure system performance. The results highlight the effectiveness of AI in improving disaster resilience, reducing losses, and enabling scalable and proactive disaster management solutions. Keywords: Disaster Management, Artificial Intelligence, Machine Learning, Early Warning Systems, Risk Prediction, Mitigation Planning.

Assessment of tsunami hazard for coastal areas of Shandong Province, China

Two tsunami earthquakes occurred in the Java subduction zone within the last 12 years, providing multiple well‐recorded tsunami events for analysis. The June 2, 1994 Mw = 7.8 and July 17, 2006 Mw = 7.7 reverse mechanism earthquakes produced tsunami with locally large (&gt;8 m) runups, were deficient in high frequency energy relative to long period radiation, had primarily normal faulting aftershocks, and occurred near subducting seamounts. Previous models of the 1994 event and aftershocks suggested extension in the outer rise due to slip at depth at a subducted seamount. Here we relocate aftershocks for the 1994 and 2006 events and compare to slip distributions and bathymetry. Most 1994 aftershocks occurred within the slab updip of the mainshock, consistent with the extensional hypothesis, but the 2006 aftershocks have a more complex pattern. Regional subducting features as asperities and barriers may influence both events, but in different ways.

&amp;lt;p&amp;gt;The Tj&amp;amp;#246;rnes Fracture Zone (TFZ) in North Iceland is the largest and most complex zone of transform faulting in Iceland, formed due to a ridge-jump between two spreading centers of the Mid-Atlantic Ridge, the Northern Volcanic Zone and Kolbeinsey Ridge in North Iceland. Strong earthquakes (Ms&amp;gt;6) have repeatedly occurred in the TFZ and affected the North Icelandic population. In particular the large historical earthquakes of 1755 (Ms 7.0) and 1872 (doublet, Ms 6.5), have been associated with the H&amp;amp;#250;sav&amp;amp;#305;&amp;amp;#769;k-Flatey Fault (HFF), which is the largest linear strike-slip transform fault in the TFZ, and in Iceland. We simulate fault rupture on the HFF and the corresponding near-fault ground motion for several potential earthquake scenarios, including scenario events that replicate the large 1755 and 1872 events. Such simulations are relevant for the town of H&amp;amp;#250;sav&amp;amp;#305;&amp;amp;#769;k in particular, as it is located on top of the HFF and is therefore subject to the highest seismic hazard in the country. Due to the mostly offshore location of the HFF, its precise geometry has only recently been studied in more detail. We compile updated seismological and geophysical information in the area, such as a recently derived three-dimensional velocity model for P and S waves. Seismicity relocations using this velocity model, together with bathymetric and geodetic data, provide detailed information to constrain the fault geometry. In addition, we use this 3D velocity model to simulate seismic wave propagation. For this purpose, we generate a variety of kinematic earthquake-rupture scenarios, and apply a 3D finite-difference method (SORD) to propagate the radiated seismic waves through Earth structure. Slip distributions for the different scenarios are computed using a von Karman autocorrelation function whose parameters are calibrated with slip distributions available for a few recent Icelandic earthquakes. Simulated scenarios provide synthetic ground motion and time histories and estimates of peak ground motion parameters (PGA and PGV) at low frequencies (&amp;lt;2 Hz) for H&amp;amp;#250;sav&amp;amp;#237;k and other main towns in North Iceland along with maps of ground shaking for the entire region [130 km x 110 km]. Ground motion estimates are compared with those provided by empirical ground motion models calibrated to Icelandic earthquakes and dynamic fault-rupture simulations for the HFF. Directivity effects towards or away from the coastal areas are analyzed to estimate the expected range of shaking. Thick sedimentary deposits (up to &amp;amp;#8764;4 km thick) located offshore on top of the HFF (reported by seismic, gravity anomaly and tomographic studies) may affect the effective depth of the fault's top boundary and the surface rupture potential. The results of this study showcase the extent of expected ground motions from significant and likely earthquake scenarios on the HFF. Finite fault earthquake simulations complement the currently available information on seismic hazard for North Iceland, and are a first step towards a systematic and large-scale earthquake scenario database on the HFF, and for the entire fault system of the TFZ, that will enable comprehensive and physics-based hazard assessment in the region.&amp;lt;/p&amp;gt;

Tsunami hazard and risk zoning for Qurayyat in northeast Oman coast: Worst-case credible scenarios along the Makran Subduction Zone, Western Asia