Abstract Ocean-bottom pressure gauges of wide and dense ocean-bottom observation networks around Japan, S-net DONET, observed ocean waves caused by the Tonga eruption that started at approximately 13:00 JST (UTC + 0900) on January 15, 2022. We scrutinized waveform records arriving to evaluate their nature found two significant disturbances between 20:00 21:00 after 22:00. The first disturbance with a positive-polarity pulse dominated long-period components (1000–3000 s) arrived DONET...

Abstract Although most tsunamis are generated by the sea‐bottom deformation caused earthquakes, some excited sea‐surface pressure changes. This study theoretically investigated changes and derived solutions in three‐dimensional (3‐D) space, whereas past studies employed two‐dimensional equations. Using solutions, we simulated visualized tsunami generation a growing change. Negative change made sea surface uplifted inside source region negative leading waves were radiated from region. We also...

Abstract This study reports an ocean‐bottom pressure gauge (OBP) network, S‐net, which captured meteotsunamis with amplitudes as small a few cm, and investigates its validity limitation for meteotsunami research studies through data analyses numerical simulations. On July 1, 2020, S‐net recorded tsunami‐like signals, although no earthquake was reported. These waves, propagating northward velocity of ∼110 m/s, were explained by atmospheric low maximum amplitude −0.5 ± 0.1 hPa moving...

Offshore ocean bottom pressure gauges (OBPs) are often used to estimate the spatial distribution of initial sea-surface height associated with offshore earthquakes (the tsunami source model). However, sensors sometimes record changes that neither related tsunamis nor seafloor coseismic displacements non-tsunami components) due sensor rotation or tilt ground shaking long-term mechanical drift. These components can be a error when accurately estimating model and thus need removed provide...

Abstract Tsunamis with amplitudes of up to 40 cm, related the M w 7.1 normal‐faulting earthquake off Fukushima, Japan, on November 21, 2016, were clearly recorded by a new offshore wide and dense ocean‐bottom pressure gauge network, S‐net, high azimuthal coverage located closer focal area. We processed S‐net data found some stations included tsunami‐irrelevant drift step signals. analyzed infer tsunami source distribution. A subsidence region narrow spatial extent (∼40 km) large peak (∼200...

It is important to advance preparation for a tsunami disaster, one of the great concerns in Japan. Forecasting inundation such solution, which contributes perceiving danger tsunami, as directly linked with damage. Therefore, we developed new real-time forecast system, aimed at rapidly and accurately forecasting on land, based offshore data observed by seafloor observation network along Japan Trench, S-net. The system takes database approach. A called scenario bank was constructed assuming...

Abstract Recent developments of ocean‐bottom pressure gauges (PG) have enabled us to observe various waves including seismic and tsunami covering periods T ∼ 10 0 –10 3 s. To investigate the quality for broadband observation, this study examined PG records (sampling rate 1 Hz) around Japan associated with 2010 Chile earthquake. We identified three distinct wave trains, attributed body waves, Rayleigh tsunamis. Clear dispersive features in tsunamis were explained by theories elastic gravity...

SUMMARY We applied ambient noise cross-correlation analysis to the cabled ocean bottom seismic network offshore northeast Japan (Seafloor observation for earthquakes and tsunamis along Trench: S-net) extract surface waves propagating in area of forearc region. found two types peculiar pulses functions (CCFs) records: periodic mainly every minute sharp around lag time zero. These strongly contaminate wave signals CCFs at frequencies below ∼0.1 Hz. The originate from instrument noises, while...

S-net is the online and real-time seafloor observation network of 150 observatories for earthquakes tsunamis along Japan Trench. It covers focal region 2011 off Pacific coast Tohoku earthquake its vicinity regions. was established to enhance reliability early warnings tsunami after occurrence earthquake. Full-scale operation has started since April 2017. The data from are being transferred center at NIED on a basis, then verification integrity carried out. Obtained reveal that can observe...

Abstract To assess the risk of tsunamis from outer‐rise earthquakes, we carried out tsunami simulations using 33 simple rectangular fault models with 60° dip angles based on marine seismic observations and surveys Japan Trench. The largest resulting these models, produced by a M w 8.7 normal‐faulting event 332 km long, had maximum height 27.0 m. We tested variations predictions due to uncertainties in assumed parameters. Because actual Trench faults range 45° 75°, calculated earthquakes 45°,...

Abstract The southern Kuril Trench is one of the most seismically active regions in world. In this study, marine surveys and observations were performed to construct fault models for possible outer-rise earthquakes. Seismic seafloor bathymetric indicated that dip angle was approximately 50°–80°, with a strike slightly oblique axis Trench. maximum length estimated be ~ 260 km. Based on these findings, we proposed 17 models, moment magnitudes ranging from 7.2 8.4. To numerically simulate...

Abstract Although tsunamis are dispersive water waves, hazard maps for earthquake-generated neglect effects because the spatial dimensions of much greater than depth, and generally small. Furthermore, calculations that include non-dispersive tend to predict higher ones effects. models may overestimate tsunami height, this conservative approach is acceptable in disaster management, where goal save lives protect property. However, we demonstrate offshore frequency dispersion amplifies caused...

The detailed understanding of tsunami hazard risk using numerical simulations requires a model that can accurately predict inundation phenomena on land. In such models, the structural effects are indirectly considered variation bottom roughness as proxy for differences in building densities. Only few studies have conducted intermodel tests to investigate complex coastal urban cities. During analysis hackathon held September 2020, eight research groups met discussion current problems. this...

Researchers have developed tsunami inundation models based on nonlinear shallow water equations to estimate propagation and inundation. However, their empirical results are not in perfect agreement with those of other research institutes, even though the same governing used. Therefore, we quantitatively evaluated variability simulations this study. Several institutes conducted under input conditions using adopted for hazard assessment, resulting a certain degree among them. By examining...

Abstract Long-term continuous observation of seafloor pressure is effective for detecting vertical deformations that are associated with transient tectonic phenomena such as slow slip events. Since the aseismic event prior to 2011 Tohoku earthquake, several discoveries have been made on spontaneous events and various other types earthquake along Japan Kuril Trenches. Seafloor network earthquakes tsunamis Trench (S-net) expected provide invaluable information activities via geodetic signals...

We have investigated the real-time forecasting method for meteorological tsunamis. Forecasting tsunamis is difficult because, unlike storm surges, suddenly strike in clear and calm ocean. Although it becoming that source mechanism atmospheric pressure changes far field, generation propagation processes not been verified because to observe offshore region. In Japan, Abiki Kyushu region has known a long time. On other hand, tsunami caused by an wave generated huge eruption near Tonga Islands...

In Japan, hazard maps for tsunami risks are shown by many sites of organizations disaster prevention, and known well public, recently. The truly meaning reality damages, however, do not seem to be recognized correctly. particular, second damages inundation, which occurrence debris, the drift, fire so on, could severe local residents. Therefore, we have considered debris as one important factors evaluation reconstruction. We combined our technologies real-time prediction system showing...

Tsunamis have been known to result from a wide range of phenomena, such as earthquakes, volcanic eruptions, submarine mass failures, and meteorite impacts. Of earthquake-generated tsunamis, those arising strike-slip mechanisms are less common, with the 1994 Mindoro tsunami in Philippines among few examples. The followed M w 7.1 earthquake along right-lateral Aglubang River Fault. affected coasts surrounding Verde Island Passage, one Philippines’ insular seas located between islands Luzon...