Tsunami Travel Time Research Articles

Solving the puzzle of the 1996 Biak, Indonesia tsunami

On February 17, 1996, an earthquake (Mw=\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${M}_{\ ext{w}}=$$\\end{document} 8.2) occurred northeast of Biak Island, Indonesia, and generated a tsunami. Interestingly, the tsunami runup on the southwest side of Biak Island, which did not face the epicenter, was higher than that on the side of the island facing the epicenter. It was earlier suggested that the earthquake triggered submarine landslides. However, this hypothesis remains unexplored and unconfirmed. In this study, tsunami arrival times obtained from eyewitness accounts were used to perform backward tsunami travel time modeling. Based on the backward tsunami travel time results and multibeam bathymetry, five submarine landslide candidates were identified: three located to the southwest of Biak Island and two to the south of the island. Our analysis indicates that tsunamis from a large submarine landslide off the southwest coast of Biak Island (SL 2) and a small submarine landslide off the south side of Biak Island (SL 4) contributed to the 1996 Biak tsunami event and came earlier than the main tsunami from the earthquake fault. Tsunami sources were earlier modeled only by fault parameters without considering submarine landslide sources. As a result, the models could not explain the observed runup and eyewitness tsunami arrival times for the southwest and south of Biak Island. To address this problem, we propose an approach that combines a submarine landslide model with a modified version of a previously proposed fault model. Our combined model explains the observed runup and eyewitness tsunami arrival times well (Aida’s index values of the model are K = 1.00 and κ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\kappa$$\\end{document} = 1.44).Graphical abstract

Identification and ranking of subaerial volcanic tsunami hazard sources in Southeast Asia

Abstract. Tsunamis caused by large volcanic eruptions and flanks collapsing into the sea are major hazards for nearby coastal regions. They often occur with little precursory activity and are thus challenging to detect in a timely manner. This makes the pre-emptive identification of volcanoes prone to causing tsunamis particularly important, as it allows for better hazard assessment and denser monitoring in these areas. Here, we present a catalogue of potentially tsunamigenic volcanoes in Southeast Asia and rank these volcanoes by their tsunami hazard. The ranking is based on a multicriteria decision analysis (MCDA) composed of five individually weighted factors impacting flank stability and tsunami hazard. The data are sourced from geological databases, remote sensing data, historical volcano-induced tsunami records, and our topographic analyses, mainly considering the eruptive and tsunami history, elevation relative to the distance from the sea, flank steepness, hydrothermal alteration, and vegetation coverage. Out of 131 analysed volcanoes, we found 19 with particularly high tsunamigenic hazard potential in Indonesia (Anak Krakatau, Batu Tara, Iliwerung, Gamalama, Sangeang Api, Karangetang, Sirung, Wetar, Nila, Ruang, Serua) and Papua New Guinea (Kadovar, Ritter Island, Rabaul, Manam, Langila, Ulawun, Bam) but also in the Philippines (Didicas). While some of these volcanoes, such as Anak Krakatau, are well known for their deadly tsunamis, many others on this list are lesser known and monitored. We further performed tsunami travel time modelling on these high-hazard volcanoes, which indicates that future events could affect large coastal areas in a short time. This highlights the importance of individual tsunami hazard assessment for these volcanoes, the importance of dedicated volcanological monitoring, and the need for increased preparedness on the potentially affected coasts.

Method for Tsunami Wave Kinematics Modeling in a Gridded Area

The new method for the tsunami travel times calculation to the nodes of rectangular grid was developed and tested. The algorithm is based on constructing of the wave front segment inside the grid cell using tsunami arrival times to the cell corners. Testing the method proposed shows the better quality of the wave-front line approximation as compared to the existing method developed by the author earlier.

Scenario-based tsunami hazard assessment for the coast of Vietnam from the \(109^{o}\) Meridian fault zone

Located on the continental shelf and stretching approximately 1,000 km along the Central and Southern Central coasts of Vietnam, the 109o Meridian Fault system has long been recognized as seismically active. Empirical evidence of the seismic, volcanic, and submarine landslide activities also suggests that this fault might be capable of originating near-field tsunamis, which can harm the Vietnamese coastal zone. This paper investigates the possibility of the near-field tsunamis from the 109o Meridian Fault and their impact on the Vietnamese coasts. Location and segmentation of the 109o Meridian fault were determined using seismological, geophysical data, and geomorphologic evidence. The fault’s seismotectonic and geodynamic characteristics were used to model the tsunami source. The COMCOT model was used for simulating three worst-case tsunami scenarios excited by earthquakes with Mw = 8.0 originated in two different segments of the 109o Meridian Fault source. The relationship between tsunami wave height and the source-to-coast travel time is investigated in detail at the virtual sea-level stations distributed along the Vietnamese coastline. The simulation results are presented in the deep-ocean tsunami amplitude maps for the entire East Vietnam Sea region and the coastal tsunami amplitude maps for the Vietnamese coasts. The simulation results show the highest tsunami hazards concentrated along the Central and Southern Central Vietnam coastal zones (from Quang Nam province to Ba Ria-Vung Tau province), with the highest tsunami waves not exceeding 4 m observed off-shore the Quang Ngai, Phu Yen and Ninh Thuan provinces. The shortest tsunami travel time from the source to the Southern Central coast is 35 minutes. Due to its strike-slip mechanism, there is a low possibility of the 109o Meridian fault generating earthquake-triggered tsunamis. Moreover, even if they occurred, the near-field tsunamis generated from the 109o Meridian fault source can hardly cause severe damage and losses for the coastal zones of Vietnam, as shown by the simulation results. Nevertheless, the worst-case scenarios simulation results provide the highest risk that the near-field tsunamis from the 109o Meridian fault source might affect the Vietnamese coasts, which is helpful for the national tsunami warning and response purpose.

The January 15th, 2022 Hunga Tonga-Hunga Ha’apai eruption recorded in Brazil

Extreme events affect societies all around the world. A recent example is the submarine volcano Hunga Tonga-Hunga Ha'apai in the South Pacific Ocean, which erupted on January 15, 2022 at approximately 0415 UTC, expelling ash up to 39 kilometers high. Instruments around the world recorded both the initial atmospheric shock wave and the subsequent tsunami signal. The aim of this work is to report the record from tide gauges and barometers of this event along the Brazilian coast. For this, the tsunami travel time to Brazil was calculated, and spikes in atmospheric pressure data and noise in the tide gauge records were identified. The arrival of the tsunami waves was clearly observed in tidal records from three stations located in Imbituba, Arraial do Cabo, and Salvador. In addition, in Belém and Santana, the signal-to-noise ratio was too low or there was no signal at all. Surprisingly, the atmospheric signal was less observable. The shock wave signature was evident in the Fortaleza atmospheric pressure data, while at the Imbituba and Belém stations the signal only appeared after filtering the data by calculating the highest and lowest pressure difference within the hour. The weaker, or absence of, barometric signal is likely associated with the supposed attenuation, or blocking, of the signal by the Andes Mountains.

The Modeling of Tsunami Wave Run-Up and Vulnerability Zone Analysis In Cipatujah, Tasikmalaya District

Cipatujah is a sub-district in Tasikmalaya Regency, West Java Province, Indonesia, which is one of the areas affected by significant damage due to tectonic activity in the southern region of Java, namely an earthquake with a magnitude of 7.7 magnitude and West Java tsunami in 2006 after Nusa Kambangan and PangandaranThe purpose of this study is to estimate the tsunami travel time, wave heights distribution, coverage areas, and vulnerability zone based on the Java 17 July 2006 earthquake scenario in Cipatujah, Tasikmalaya Regency. The method used in this study is quantitative and requires bathymetry data, high points, earthquake parameters of July 17, 2006, tidal data, RBI maps, and land use data. Tsunami modeling with numerical simulations using COMCOT v 1.7 and MATLAB software, also Arc Map for mapping tsunami coverage and vulnerability zone areas. Based on data processing, it was found that the maximum wave speed of 3.92 m/s. In the 27th minute, the waves had reached the Cipatujah region, with a maximum run-up height of 6.115 meters and a maximum tsunami range on the land of 1.891 meters. The area affected by the tsunami based on the processing of tsunami coverage data in Cipatujah totals 11.64 km2. Whereas for tsunami vulnerability zone in Cipatujah, it is divided into 3 categories, namely low hazard zone, medium hazard zone, and high hazard zone. This indicates that the Cipatujah region is included in a high tsunami-prone zone. Based on the results of verification and validation with an RSR value of 0,073, then it is assumed that the height of the run-up model is sufficient by the run-up data that occurred during the event.

Identifikasi Pendekatan Shallow Water Equation Dalam Simulasi 2D Gelombang Tsunami di Pantai Keburuhan Purworejo

Kabupaten Purworejo merupakan salah satu dari lima daerah yang terkena dampak run-up tsunami Jawa 17 Juli 2006. Berdasarkan hasil Rapid Survey oleh BPDP dan BPPT, sepanjang Pantai Keburuhan merupakan lokasi terjadinya run-up tsunami di Kabupaten Purworejo di koordinat 109.912 LS -7.85 BT sebesar 1,7 meter. Tujuan dari penelitian ini adalah memperkirakan waktu tempuh tsunami, distribusi tinggi gelombang tsunami dan daerah jangkauan tsunami akibat dampak gempa tsunami Jawa 17 Juli 2006 di Pantai Keburuhan, Purworejo. Metode yang digunakan adalah metode deskriptif analitis dengan pendekatan kuantitatif. Data yang digunakan pada penelitian ini adalah titik tinggi, batimetri, parameter gempa, peramalan pasang surut wilayah perairan Pantai Keburuhan, data citra Geo Eye 1, dan kelerengan pantai. Pemodelan tsunami menggunakan perangkat lunak COMCOT v1.7 dengan kejadian gempa Jawa 17 Juli 2006. Berdasarkan pengolahan data, diketahui bahwa kecepatan gelombang maksimal sebesar 3.8788 m/s. Pada menit ke- 40, amplitudo awal gelombang tsunami sebesar 1.644 meter telah mencapai Pantai Keburuhan. Daerah jangkauan tsunami terluas dan jarak jangkauan maksimum terjauh terjadi di Pantai Keburuhan adalah 1,23 km2 dan 1,4 km. Berdasarkan hasil verifikasi dengan nilai RSR sebesar 0,26. Hasil validasi simulasi tsunami menggunakan COMCOT v1.7 diketahui bahwa tinggi run-up tsunami model sudah cukup sesuai dengan data run-up yang terjadi saat kejadian, dengan nilai RSR sebesar 0,29 dan CF sebesar 1,63.

Оперативный прогноз локальных цунами по данным ближайших к очагам глубоководных станций, содержащим шумы сейсмического происхождения

Reliable short-term tsunami forecast on the Kuril Islands when earthquakes occur in the Kuril-Kamchatka Trench is the most difficult. Forecasting by the traditional magnitude method often leads to false tsunami alarms. Based on the examples of the events of 2006, 2007 and 2020 on the Kuril Islands, as well as the event of 2018 in Alaska, it was shown that according to the data of the ocean level measuring stations closest to the tsunami source (tsunami travel time is 10–20 minutes) it is possible to adequately predict the tsunami near the coast. Calculations of tsunami waveforms near the coast from data containing seismic noise have shown that the resulting waveforms contain high-frequency oscillations. However, these fluctuations do not interfere with the assessment of the real waveform and the danger of the expected tsunami. In contrast to forecast methods based on the magnitude criterion, the applied method of short-term tsunami forecast makes it possible to calculate the waveform: the amplitudes of the first, maximum waves, their arrival time at a given point and the estimated duration of the tsunami. The proposed method can become a tool that will improve the quality of operational tsunami warning, significantly reducing the number of false tsunami alarms.

Nearly Instantaneous Tsunamis Following the Mw 7.5 2018 Palu Earthquake

AbstractThe tsunami observations produced by the 2018 magnitude 7.5 Palu strike‐slip earthquake challenged the traditional basis underlying tsunami hazard assessments and early warning systems. We analyzed an extraordinary collection of 38 amateur and closed circuit television videos to show that the Palu tsunamis devastated widely separated coastal areas around Palu Bay within a few minutes after the mainshock and included wave periods shorter than 100 s missed by the local tide station. Although rupture models based on teleseismic and geodetic data predict up to 5‐m tsunami runups, they cannot explain the higher surveyed runups nor the tsunami waveforms reconstructed from video footage, suggesting either these underestimate actual seafloor deformation and/or that non‐tectonic sources were involved. Post‐tsunami coastline surveys combined with video evidence and modeled tsunami travel times suggest that submarine landslides contributed to tsunami generation. The video‐based observations have broad implications for tsunami hazard assessments, early warning systems, and risk‐reduction planning.

Reanalysis of the 1761 transatlantic tsunami

Abstract. The segment of the Africa–Eurasia plate boundary between the Gloria Fault and the Strait of Gibraltar has been the setting of significant tsunamigenic earthquakes. However, their precise location and rupture mechanism remain poorly understood. The investigation of each event contributes to a better understanding of the structure of this diffuse plate boundary and ultimately leads to a better evaluation of the seismic and tsunami hazard. The 31 March 1761 event is one of the few known transatlantic tsunamis. Macroseismic data and tsunami travel times were used in previous studies to assess its source area. However, no one discussed the geological source of this event. In this study, we present a reappraisal of tsunami data to show that the observations data set is compatible with a geological source close to Coral Patch and Ampere seamounts. We constrain the rupture mechanism with plate kinematics and the tectonic setting of the area. This study favours the hypothesis that the 1761 event occurred in the southwest of the likely location of the 1 November 1755 earthquake in a slow deforming compressive regime driven by the dextral transpressive collision between Africa and Eurasia.

Tsunamis generated by subaqueous volcanic explosions in Taal Caldera Lake, Philippines

Volcanic subaqueous explosions can generate hazardous tsunamis, especially in lakes. In this paper, we simulate different scenarios of subaqueous explosions and related tsunamis in Taal Caldera Lake (Luzon, Philippines). Taal volcano is one of the most active volcanoes in Southeast Asia, and eruptive processes are mostly explosive. We test different energies of explosions at eight different explosion sites in the lake. The initial water surface displacement (ƞ0) generated by the explosion is estimated as a function of explosion energy at a given depth. We estimate the tsunami travel times, maximum wave heights, and wave periods at the shoreline. This type of hazard is typically neglected and our work has important implications for hazard assessment around Taal Lake. Due to fast propagation of tsunamis in the lake (waves typically crossing the lake in less than 10 min), there is only a short time available for issuing a warning. For ƞ0 ≤ 50 m, wave heights at the shoreline are less than 2 m with a non-dispersive numerical model, and less than 0.5 m with a dispersive model, whatever the explosion depth and location. Powerful explosions with ƞ0 > > 100 m generate wave heights greater than 2 m all around the lake and local peaks higher than 10 m.

An Evaluation of Modelled Tsunami Arrival Times

The Joint Australian Tsunami Warning Centre provides forecasts of tsunami arrival times based on the Tsunami Travel Times (TTT) software. In this work, travel times from a pre-computed scenario database and TTT are evaluated through comparison with observed arrival times at tide gauges and tsunameters. It is found that travel times from the scenario database are at least as accurate as those from TTT and in most cases, more accurate. The ‘best’ scenario-based method is Tp20—the time of arrival of the first peak that is at least 20% of the maximum amplitude at that point.

The prediction of tsunami travel time to Mataram City Indonesia based on North Lombok earthquake as the initial condition

The past earthquake records in North Lombok show the high level of earthquake hazard in this area. The maximum magnitude of the earthquake was 6.4 Mw on May 30th, 1979. But, there were no tsunami events records due to those earthquakes. Nevertheless, this area is very close to Mataram City (province capital city) and tourism area. Therefore, the assessment of tsunami hazard is very important. The tsunami simulation was conducted by using COMCOT Model, which is based on the North Lombok Earthquake as the initial condition. The simulation result shows the prediction of tsunami travel time is about 18 ~ 20 minutes from the source location to Mataram City. The height of the tsunami wave is 0.13 ~ 0.20 meters due to the earthquake magnitude is about 6 Mw.

The 2004 Sumatra tsunami in the Southeastern Pacific Ocean: New Global Insight from Observations and Modeling

AbstractThe 2004 Sumatra tsunami was an unprecedented global disaster measured throughout the world oceans. The present study focused on a region of the southeastern Pacific Ocean where the “westward” circumferentially propagating tsunami branch converged with the “eastward” branch, based on data from fortuitously placed Chilean DART 32401 and tide gauges along the coast of South America. By comparison of the tsunami and background spectra, we suppressed the influence of topography and reconstructed coastal “spectral ratios” that were in close agreement with a ratio at DART 32401 and spectral ratios in other oceans. Findings indicate that even remote tsunami records carry spectral source signatures (“birth‐marks”). The 2004 tsunami waves were found to occupy the broad frequency band of 0.25–10 cph with the prominent ratio peak at period of 40 min related to the southern fast‐slip source domain. This rupture “hot‐spot” of ∼350 km was responsible for the global impact of the 2004 tsunami. Data from DART 32401 provided validation of model results: the simulated maximum tsunami wave height of 2.25 cm was a conservative approximation to the measured height of 2.05 cm; the computed tsunami travel time of 25 h 35 min to DART 32401, although 20 min earlier than the actual travel time, provided a favorable result in comparison with 24 h 25 min estimated from classical kinematic theory. The numerical simulations consistently reproduced the wave height changes observed along the coast of South America, including local amplification of tsunami waves at the northern stations of Arica (72 cm) and Callao (67 cm).

Scenario-Based Tsunami Evacuation Analysis: A Case Study of Haimen Town, Taizhou, China

In current tsunami prevention and mitigation, evacuation is the most important method of saving people’s lives. Tsunami evacuation is analyzed for a given travel time and a specific inundation area. Before evacuation analysis, the tsunami inundation and tsunami travel time are first calculated by numerical modeling. This paper analyzes the tsunami evacuation of Haimen Town, Jiaojiang District, Taizhou City, China, under the hypothesis of a magnitude 9.0 earthquake scenario in the Ryukyu Trench. The Cornell multi-grid coupled tsunami (COMCOT) model and Tsunami Travel Time (TTT) model are used to calculate the tsunami inundation and tsunami travel time, respectively. GIS techniques are used to solve the evacuation problem. Both horizontal and vertical evacuations are adopted based on the Chinese community characteristics, disaster prevention facilities, land use, and other practical conditions. A cost raster is used to analyze the arrival cost of each grid in the study area. The location allocation and cost allocation methods are used to solve shelter selection and coverage problems, respectively. The network analyst is applied to provide evacuation routes for each community. The evacuation analysis results can provide a scientific reference for the development of tsunami evacuation plans.

Teaching fundamental concepts of coastal engineering using excel spreadsheet

ABSTRACTA Microsoft‐Excel spreadsheet was developed using Visual Basic for Applications (VBA) functions to calculate fundamental wave properties using linear wave theory, simple wave transformations, tidal elevations, tsunami travel time, wind wave growth parameters, design wave heights using Raleigh's probability distribution, breakwater dimensions, and longshore sediment transport rates. This spreadsheet was used in teaching an undergraduate coastal engineering course. The students were found to be motivated to study the subject matter with the help of VBA functions and develop their own applications in coastal engineering. This spreadsheet may be helpful to the practicing engineers as well for calculations relevant to some important wave parameters that are used in the design of coastal structures. © 2017 Wiley Periodicals, Inc. Comput Appl Eng Educ 25:304–310, 2017; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21798

Estimate of tsunami source using optimized unit sources and including dispersion effects during tsunami propagation: The 2012 Haida Gwaii earthquake

AbstractWe apply a genetic algorithm to find the optimized unit sources using dispersive tsunami synthetics to estimate the tsunami source of the 2012 Haida Gwaii earthquake. The optimal number and distribution of unit sources gives the sea surface elevation similar to that from our previous slip distribution on a fault using tsunami data, but different from that using seismic data. The difference is possibly due to submarine mass failure in the source region. Dispersion effects during tsunami propagation reduce the maximum amplitudes by up to 20% of conventional linear longwave propagation model. Dispersion effects also increase tsunami travel time by approximately 1 min per 1300 km on average. The dispersion effects on amplitudes depend on the azimuth from the tsunami source reflecting the directivity of tsunami source, while the effects on travel times depend only on the distance from the source.

New study on the 1941 Gloria Fault earthquake and tsunami

Abstract. The M ∼ 8.3–8.4 25 November 1941 was one of the largest submarine strike-slip earthquakes ever recorded in the Northeast (NE) Atlantic basin. This event occurred along the Eurasia–Nubia plate boundary between the Azores and the Strait of Gibraltar. After the earthquake, the tide stations in the NE Atlantic recorded a small tsunami with maximum amplitudes of 40 cm peak to through in the Azores and Madeira islands. In this study, we present a re-evaluation of the earthquake epicentre location using seismological data not included in previous studies. We invert the tsunami travel times to obtain a preliminary tsunami source location using the backward ray tracing (BRT) technique. We invert the tsunami waveforms to infer the initial sea surface displacement using empirical Green's functions, without prior assumptions about the geometry of the source. The results of the BRT simulation locate the tsunami source quite close to the new epicentre. This fact suggests that the co-seismic deformation of the earthquake induced the tsunami. The waveform inversion of tsunami data favours the conclusion that the earthquake ruptured an approximately 160 km segment of the plate boundary, in the eastern section of the Gloria Fault between −20.249 and −18.630° E. The results presented here contribute to the evaluation of tsunami hazard in the Northeast Atlantic basin.

Near‐ and far‐field tsunamigenic effects on the Z component of the geomagnetic field during the Japanese event, 2011

AbstractIn this work, we examine the vertical component (Z) of the geomagnetic field observed by ground‐based observatories during the tsunami event which happened on 11 March 2011. For this event, we have selected nine magnetic observatories distributed along the tsunami passage, covering up to 3000 km epicentral distance. The traveltime diagram of the magnetic disturbances is constructed and compared with the simulated tsunami traveltime diagram. From this comparison, we identify the amplified magnetic disturbances appearing during the tsunami arrival in the vicinity of these observatories. Moreover, mean absolute percentage error map is constructed to examine the cross correlations among different observatories and the amplified disturbances are found to be highly correlated. These features suggest that the amplified disturbances are tsunamigenic in nature. These results are in confirmation with the previous near‐field studies, and they shed new insight into the tsunamigenic magnetic disturbances on near‐ and far‐field distances from the epicenter.

A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

During the 1964 Great Alaska earthquake (Mw 9.2), several fjords, straits, and bays throughout southern Alaska experienced significant tsunami runup of localized, but unexplained origin. Dangerous Passage is a glacimarine fjord in western Prince William Sound, which experienced a tsunami that devastated the village of Chenega where 23 of 75 inhabitants were lost – the highest relative loss of any community during the earthquake. Previous studies suggested the source of the devastating tsunami was either from a local submarine landslide of unknown origin or from coseismic tectonic displacement. Here we present new observations from high-resolution multibeam bathymetry and seismic reflection surveys conducted in the waters adjacent to the village of Chenega. The seabed morphology and substrate architecture reveal a large submarine landslide complex in water depths of 120–360 m. Analysis of bathymetric change between 1957 and 2014 indicates the upper 20–50 m (∼0.7 km3) of glacimarine sediment was destabilized and evacuated from the steep face of a submerged moraine and an adjacent ∼21 km2 perched sedimentary basin. Once mobilized, landslide debris poured over the steep, 130 m-high face of a deeper moraine and then blanketed the terminal basin (∼465 m water depth) in 11±5 m of sediment. These results, combined with inverse tsunami travel-time modeling, suggest that earthquake-triggered submarine landslides generated the tsunami that struck the village of Chenega roughly 4 min after shaking began. Unlike other tsunamigenic landslides observed in and around Prince William Sound in 1964, the failures in Dangerous Passage are not linked to an active submarine delta. The requisite environmental conditions needed to generate large submarine landslides in glacimarine fjords around the world may be more common than previously thought.