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Douglas Channel is the principal shipping route between the town of Kitimat and the Pacific Ocean. Prediction of near-surface currents is crucial for safe tanker navigation and cleaning-up oil spills. Three years of current velocity data were collected at two moorings located 30 km apart. Spectral, wavelet, and harmonic analysis of measured currents throughout the upper (40-m) and lower (50–358 m) water columns indicated the predominant influence of semidiurnal (SD) tidal currents. In the upper layer, wind and density flows resulted in considerable seasonal and interannual variability of these currents. Analysis of the SD variance reveals three major components: barotropic, coherent baroclinic, and random baroclinic. The predictability of near-surface currents depends on the relative contribution and stability of the first two components. Tidal constants estimated for one year were used to predict currents for two other years; we found that at the mooring closer to the entrance of Douglas Channel, 80 to 89% of the SD energy in the upper layer and 89–93% in the lower layer can be forecasted, while closer to the two channel head, these numbers are smaller: 55–70% and 79–89%, respectively.

The eruption of the Tonga–Hunga underwater volcano in the Central Pacific on 15 January 2022 generated pronounced atmospheric pressure waves that circumvented the globe several times during the next five days. Propagating with a sound speed of ~10 spherical degrees/hour, the pressure waves forced substantial tsunami waves in the Atlantic Ocean that impacted the East Coast of the United States. Almost simultaneously, on 16-17 January 2022, a deep midlatitude cyclone crossed the East Coast. The cyclone, which formed over the northern part of the Gulf of Mexico, began to rapidly intensify as it moved northward. When it reached 40° N, the system produced a pressure change of 36 hPa/24 hours, classifying the cyclone as a “bomb cyclone”. Strong high-frequency (period

Two prominent near-field tsunamis impacted the nearby coasts of Mexico. The first tsunami was generated by a major (Mw 8.2) intraplate normal-fault earthquake on 8 September 2017 in the Gulf of Tehuantepec (Chiapas, Mexico). Tsunami waves from this event were measured by a large number of high-resolution coastal tide gauges located along the coasts of California, Mexico and Central America, by three open-ocean DART stations anchored offshore from the affected region and by several distant DARTs. The second tsunami was produced by a thrust fault Mw 7.6 earthquake on 19 September 2022 within the coastal zone of Michoacán, Mexico. The 2022 tsunami was recorded by six coastal tide gauges and a single offshore DART station. All seven instruments were located within 250 km of the source. No tsunami was detected at larger distances along the coasts of North and Central America, but the tsunami signal was detected at the Hawaii and Samoa islands. All available coastal and open-ocean data were used for comprehensive analyses of these two events. Maximum trough-to-crest wave heights for the 2017 tsunami were recorded at Puerto Chiapas (351 cm), Salina Cruz (209 cm), Acapulco (160 cm) and Huatulco (137 cm), while for the 2022 tsunami they were observed at Manzanillo (172 cm) and Zihuatanejo (102 cm). For both events, the “strengths” of the recorded tsunami waves were mostly determined by distance from the source rather than by the specific resonant characteristics of individual sites. Estimates of the frequency content (“colour”) of the two tsunami events revealed that the 2017 tsunami was mostly long-period (“reddish”), with 87% of the total tsunami energy at periods >35 min, while the 2022 tsunami was short-period (“bluish”) with 91% of energy at periods

The major (Mw 8.2) intraplate normal-fault earthquake of 8 September 2017 in the Gulf of Tehuantepec (Chiapas, Mexico) generated a strong tsunami that severely impacted the nearby coasts of Mexico and Central America. Tsunami waves in the near-field area were measured by seventeen high-resolution coastal tide gauges and by three open-ocean DART stations anchored offshore from the affected region. Data from these sites, together with those from four distant DARTs, were used for comprehensive analyses of the 2017 event. De-tided sea level time series were examined to determine the statistical and spectral characteristics of the 2017 tsunami waves along the Mexican and Central American coastline. The characteristics of the recorded waves from this near-field event were compared with those from two great far-field events: the 2010 Chile and the 2011 Tohoku tsunamis. Maximum trough-to-crest wave heights for the 2017 tsunami were recorded at Puerto Chiapas (351 cm), Salina Cruz (209 cm), Acapulco (160 cm), Huatulco (137 cm) and Acajutla, El Salvador (118 cm). While maximum 2010 and 2011 tsunami waves were observed at specific “hot spots” (sites with a high Q-factor and pronounced resonant properties, such as Manzanillo and Acapulco), the “strengths” of the recorded 2017 tsunami waves were mostly determined by distance from the source. Contrary to the maximum wave heights, the general spectral properties of the tsunami signals for all three events were highly similar at a given coastal site and mainly resemble the spectral structure of background oscillations at the same site. This similarity indicates that the frequency properties of the tsunami waveforms for a steady-state tsunami signal are mainly determined by local topographic features rather than by the source parameters. Estimates of the “colour” of an event (i.e., the open-ocean tsunami frequency content) show that the 2017 Chiapas tsunami was mostly “reddish” (long-period), with 68% (DART 43413) to 87% (DART 43412) of the total tsunami energy related to waves with periods > 35 min. In contrast, the 2010 and 2011 tsunamis were “reddish-blue”, with 48–57% associated with long-period waves (> 35 min) and 52–43% with short-period waves (2–35 min). The dominant periods of the tsunami waves were mostly linked to the shape, length, and width of the source region: the larger the source and the shallower its depth, the longer the periods of the generated tsunami waves. The complicated structure of the source explains the saturated and wide frequency-band character of the tsunami spectra. Our analysis also reveals an anisotropic nature to the 2017 tsunami waves; waves that propagated northeastward along the mainland coast of North America and southeastward along the Central American coast were significantly different from those that propagated southwestward, normal to the source orientation. This aspect of the wave field appears to be related to two distinct types of waves; “trapped (edge) waves” retained on the shelf (which plays the role of a “wave guide”), and “leaky waves” that radiate into the open ocean.

On November 21, 2020, at the age of 70, one of the world’s largest specialists in the science of tsunami, Doctor of Physical and Mathematical Sciences, Chief Researcher of the Tsunami Laboratory in the Shirshov Institute of Oceanology, the Russian Academy of Sciences, Evgueny Arkadievich Kulikov, suddenly passed away. From 1980 to 1986 he was the Head of the Ocean Physics Laboratory in the Tsunami Department of the Sakhalin Complex Research Institute / Institute of Marine Geology and Geophysics, Far East Scientific Center of the USSR Academy of Sciences (Yuzhno-Sakhalinsk). From 2004 to 2018, E.A. Kulikov headed the Tsunami Laboratory of the Shirshov Institute of Oceanology, Russian Academy of Sciences. E.A. Kulikov had students and colleagues all over the world – in Russia from Sakhalin to Moscow, in Europe, Canada, and the U.S.A. He left a bright mark in oceanology, in the science of tsunami, as well as in the memory of numerous friends and colleagues around the world as a remarkable scientist, teacher, and wonderful person. The presented article describes the main scientific stages of E.A. Kulikov.

Copyright © The Author(s) 2020. Two hazardous typhoons, Lionrock (August 2016) and Jebi (September 2018), destructively affected the coast of Japan and produced extreme sea level variations. The results of field surveys in the impacted regions showed that multiple deaths and extensive floods were caused by the combined effect of low-frequency sea level raise (storm surges) and intensive high-frequency (HF) tsunami-like waves (meteotsunamis). The data from ten tide gauges for the 2016 event and eight gauges for the 2018 event were used to examine the properties of the observed sea levels, to estimate the relative contribution of the two sea level components and to evaluate their statistical characteristics (maximum wave heights, amplitudes and periods of individual components, etc.). For the 2016 event, we found that the surge heights were from 12 to 35 cm and that the mean contribution of surges into the total observed sea level heights was ~ 39%; the meteotsunami amplitudes were from 22 to 92 cm, and they contributed 61% of the total height. For the 2018 event, storm surges were significantly stronger, from 46 to 170 cm, while HF amplitudes were from 38 to 130 cm; their relative inputs were 67% and 33%, respectively. Combined, they formed total flood heights of up to 120 cm (2016 event) and 288 cm (2018 event). Previously, the contribution of storm seiches (meteotsunamis) in coastal floods had been underestimated, but results of the present study demonstrate that they can play the principal role. What is even more important, they produce devastating currents: according to our estimates, current speeds were up to 3 knots (1.5 m/s) during the Lionrock event and more than 5 knots (2.6 m/s) during Jebi; these strong currents appear to be the main reason for the resulting damage of coastal infrastructure. The most important characteristic of the recorded meteotsunamis is their trough-to-crest maximum height. During the 2016 event, these heights at three stations were > 1 m: 171 cm at Erimo, 109 cm at Hachijojima and 102 cm at Ayukawa. The 2018 event was stronger; maximum meteotsunami wave heights were 257 cm at Gobo, 138 cm at Kushimoto, 137 cm at Kumano and 128 cm at Murotomisaki. The 2018 Gobo height of 257 cm is much larger than historical non-seismic seiche maxima for the Pacific coast of Japan (140–169 cm) estimated by Nakano and Unoki (1962) for the period of 1930–1956. Russian State Assignment of IORAS 928 #0149-2019-0005; the Royal Society, the United Kingdom

The major (Mw 7.9) earthquake that struck the Gulf of Alaska near Kodiak Island on 23 January 2018 was a rare, mid-plate strike-slip event that triggered a minor trans-Pacific tsunami. An analysis of the simultaneous measurements of tsunami waveforms at 21 open-ocean sites (including three independent arrays of stations) and 27 coastal tide gauges in the Gulf of Alaska and along the coast of North America has enabled us to examine properties of the 2018 tsunami, its transformation over the continental slope and shelf, and its amplification as the waves approached the coast. Results show that the tsunami wave variance decreased monotonically along the west coast from northern British Columbia to southern Oregon. Based on the variance structure, the mean amplification factor for Tofino on the west coast of Vancouver Island (a “beacon” site with a long time series), was $$A_{RMS}^{Tof}$$ = 5.3, in good agreement with corresponding estimates for four major past events; 4.5 (2009 Samoa), 4.3 (2010 Chile), 6.3 (2011 Tohoku) and 5.2 (2012 Haida Gwaii). This variance-derived amplification for Tofino was greater than the amplification factor based on the amplitude ratio ($$A_{{}}^{Tof}$$ = 3.2). Spectral analysis of the records showed that the tsunami had a relatively large high-frequency content (i.e., was “blueish”), with nearly 90% of the total energy in the open ocean at frequencies > 1.7 cph (periods

Typhoon Maysak (Julian in the Philippines) was a powerful tropical cyclone that strongly impacted coastal regions of the Sea of Japan on 2–4 September 2020. Destructive winds, violent storm waves, and intense rainfall occurred in Japan, on the Korean Peninsula, and in Far-Eastern Russia. Devastating coastal floods caused severe damage to coastal infrastructure and to ships and boats anchored in harbours and were responsible for numerous deaths. Our study indicates that the main reason for the destructive floods was the superposition of storm surge, extreme seiches (meteorological tsunamis), and surf beats. At various sites, different types of sea level oscillations prevailed depending on the atmospheric forcing, local topographic properties, and resonant shelf/coastal zone features. The principal forcing factors of these oscillations were atmospheric pressure and wind stress, but the exact generation mechanism of each specific type of oscillation was strongly site dependent. The uniqueness of the sea level response at each site is the main challenge in our understanding of the generation process and to the mitigation of the hazardous consequences of possible future events.

Meteorological tsunamis (“meteotsunamis”) are hazardous tsunami-like waves of atmospheric origin. They have typical periods from a few minutes to about 3 h and typical spatial scales from a few hundred meters to approximately 100–150 km. The waves have different local names in different regions of the world: “rissaga” in the Balearic Islands (Spain), “marrobbio” in Sicily (Italy), “sciga” in the Adriatic Sea (Croatia), “milghuba” in Malta, and “abiki” in Japan. Meteotsunamis have markedly different generation mechanisms than storm surge or rogue waves, and are mainly produced by direct air pressure forcing. Several recent destructive meteotsunami events have attracted considerable attention to the phenomenon. The present paper is one of the first attempts to classify and overview the strongest events. A total of 51 selected events over the past 27 years are examined and described. Some of these events are well known (e.g. the events of 4 July 1992 Daytona Beach, Florida, 15 June 2006 Ciutadella Harbour, Spain, and 13 June 2013 East Coast of USA), while others have only been mentioned in the media and on the Internet. The list of events includes those that have occurred in the Mediterranean, the Black Sea, Japan, South Korea, Australia, the Great Lakes, South Africa, the USA, Canada, Brazil, the Netherlands and other countries and regions. All meteotsunami events are separated into four groups: “Good-weather harbour”, “Good-weather open-coast”, “Bad-weather harbour (storm seiches)” and “Bad-weather open-coast”. “Good-weather” meteotsunamis are most typical for the Mediterranean region, while “bad-weather” events mainly occur on the Atlantic coasts of the USA and Europe.

The five great trans-Pacific tsunamis of the 20th century that occurred in 1946, 1952, 1957, 1960 and 1964 were accurately recorded by analogue tide gauges on the coast of British Columbia. All available pen-and-paper records of these events were collected, digitised, de-tided and analysed. The 1946 Aleutian Islands event was recorded at two stations, Tofino and Victoria, where maximum trough-to-crest tsunami wave heights were 55 and 27 cm, respectively. These two gauged stations, as well as Prince Rupert, Alert Bay and Kitimat, also recorded the 1952 Kamchatka tsunami, which generated a maximum wave height of 77 cm at Tofino. The 1957 Andreanof Islands tsunami was recorded at six primary stations and the 1960 Chile tsunami by 17 primary and temporary tide gauges. For both of these events, the maximum tsunami wave heights also occurred at Tofino: 48 cm (1957) and 132 cm (1960). The 1964 Alaska tsunami remains the strongest tsunami yet instrumentally recorded on the coast of British Columbia. Our examination of 16 records from this event shows that maximum wave heights at eight stations were higher than 1 m, including Port Alberni (770 cm), Ocean Falls (376 cm), Tofino (237 cm) and Alert Bay (222 cm). We also find that the maximum wave at all stations for this event was among the first three waves. Subsequent wave heights rapidly attenuated following this group of waves. Frequency-time (f–t) analyses of the tsunami waveforms reveal that, for each station, the dominant frequencies of the waves and their evolution with time were very similar for different tsunamis, but differed considerably among sites for a particular tsunami, indicating the strong influence of local/regional topography on the incoming waves. From the latter point of view, the 1964 tsunami was exceptional. The epicentre of the 1964 Alaska earthquake was located much closer to the BC coast than for the other events and, therefore, the influence of the source was much stronger. The “ringing” of this tsunami was substantially shorter (

Two hazardous typhoons, Maysak and Haishen, in September 2020 produced extreme sea level oscillations in the Sea of Japan. These typhoons generated three different types of sea level variations: 1) storm surges (with typical periods from several hours to 1.5 days), 2) extreme seiches (with periods from a few minutes to several tens of minutes), and 3) storm-generated infragravity waves (with periods up to 3-5 min). The data from eleven tide gauges on Russian, Korean, and Japanese coasts were used to examine the properties of these oscillations. The relative contribution of the three separate sea level components and their statistical characteristics (duration, wave heights, and periods) were estimated. The periods of the main eigen modes of individual bays and harbours in the Sea of Japan were estimated based on spectral analysis of longterm background records at the corresponding sites. The results of wavelet analysis show the frequency properties and the temporal evolution of individual sea level components. We found that high-frequency sea level oscillations at stations Preobrazheniye and Rudnaya Pristan have a “white noise” spectrum, caused by the dominance of infragravity waves. A high correlation was detected between the variance of high-frequency sea level oscillations at these stations and the significant wind wave height evaluated from ERA5 for this water area.

Tsunami-like sea level oscillations recently recorded by tide gauges located along the coasts of British Columbia (Canada) and Washington State (USA) have been identified as meteorological tsunamis. Globally, such events can create hazardous conditions in coastal areas, including the possible loss of life, and need to be taken into account in any assessment of risk to nearshore infrastructure. On 1 November 2010, a significant meteotsunami occurred in the southern Strait of Georgia, British Columbia. To examine this event, we have used all available sea level and air pressure data, including 1-min records from five Canadian Hydrographic Service and five USA National Oceanic and Atmospheric Administration tide gauges, as well as high-resolution time series from two Ocean Network Canada VENUS bottom pressure recorders and from 132 air pressure sensors within the Victoria School-Based Weather Station Network of southern British Columbia. The oceanic responses to four well-defined atmospheric disturbances (labelled D1–D4) were selected for analysis. Disturbance D3, which propagated toward ~ 100° True (eastward) at a speed of ~ 20 m/s, appears to have been responsible for generating the meteotsunami observed in the southern Strait of Georgia, while disturbance D4 that moved toward ~ 55° True at a speed of 24 m/s appears to have produced the meteotsunami observed in Juan de Fuca Strait that separates Vancouver Island from Washington State. We used the physical parameters derived for the four disturbances to force numerical simulations of the events and compared the results to observations from selected tide gauge sites. The numerical experiments revealed strongly individual sea level responses at each site to changing air pressure disturbance speed, direction and intensity, such that each location has its own set of “site-specific” air pressure characteristics that produce the strongest sea level response. Differences in the local topography and coastline geometry appear to be responsible for the different responses among sites.

Meteorological tsunamis are frequently destructive tsunami-like waves generated by small-scale atmospheric disturbances. Several devastating events occurred recently in various regions of the world oceans, including the Balearic Islands, Sicily, the Adriatic and Black seas, the Great Lakes, the west coast of South Korea, the Netherlands and the Persian Gulf. Although this phenomenon has been actively studied for more than 25 years, the exact mechanism (or mechanisms) responsible for producing these extreme events remains a puzzle. One of the major problems making it difficult to determine the physical process generating meteotsunamis is the absence of a network of simultaneously working precise tide gauges and microbarographs in the affected region. A unique set of high-resolution atmospheric data from the meteorological “school network” of 132 school stations became available for 2008-2019 for the area of southern Vancouver Island and nearby Gulf Islands located in the Strait of Georgia. These data, combined with 1-min sea level data from Canadian Hydrographic Service (CHS) and USA National Oceanic and Atmospheric Administration (NOAA) tide gauges, has enabled us to examine both the spatial and temporal features of mesoscale atmospheric disturbances and coincident properties of the associated sea level oscillations. The data analyses, supported by a series of numerical experiments, has made it possible to reconstruct observed events and to determine the specific atmospheric parameters producing the strongest sea level response in the southern part of the Strait of Georgia. These experiments have helped us to recognize the most effective (and hence, most hazardous) directions and speeds of propagating atmospheric disturbances and to identify “hot spots” along the coast that are under the highest risk of large meteotsunamis.

Ocean Networks Canada (ONC; http://www.oceannetworks.ca/) operates the multidisciplinary NEPTUNE and VENUS cabled ocean observatories off the west coast of Canada and an increasing number of miniat...

Tides in the Adriatic Sea are anomalously strong in comparison with most of other parts of the Mediterranean Sea. Consequently, tides play a fundamental role in the hydrodynamics of this sea and in the formation of destructive floods in its northernmost part. The resonant character of the Adriatic tides is evident, but the exact mechanism of their formation has never been thoroughly examined. In the present study, we used multidecadal tide gauge data from 10 stations located along the basin's coastline to examine the spectral properties of the Adriatic Sea and to provide high‐resolution tidal analysis. Our results demonstrate that both diurnal and semidiurnal tidal harmonics are resonantly amplified due to the proximity of tidal periods to the periods of the fundamental (21.5 hr) and first (10.9 hr) Adriatic eigen modes, respectively. The constructed resonance models were found to closely describe specific features of the observed tides in the Adriatic Sea, including both major and minor harmonics, and therefore help to explain the dominant physical mechanism driving the floods in the northernmost part of the basin, including the Venice Lagoon.

A major tsunami-like event, locally known as ‘marrobbio’, impacted the southwestern coast of Sicily on 25–26 June 2014. The event was part of a chain of hazardous episodes in the Mediterranean and Black seas during the last week of June 2014 resulting from an anomalous atmospheric system (“tumultuous atmosphere”) propagating eastward over the region. The synoptic patterns and vertical structure of the atmosphere over Sicily at the time of the event indicate that atmospheric wave ducting was responsible for the generation of tsunamigenic air pressure disturbances that produced especially high sea level responses (“meteotsunamis”) at certain sites along the Sicilian coast. The strongest sea level oscillations were observed at Mazara del Vallo, where a 1-m meteotsunami bore, propagating upstream in the Mazaro River, was generated. The combined effects of external resonance (Proudman resonance on the western Sicilian shelf) and internal resonant conditions (bathymetric and topographic characteristics of specific sites) were found to be the key factors that caused the meteotsunami (marrobbio phenomenon) on the coast of Sicily and the meteobore at Mazara del Vallo.

On 27 June, a 1–2-m high wave struck the beaches of Odessa, the third largest Ukrainian city, and the neighbouring port-town Illichevsk (northwestern Black Sea). Throughout the day, prominent seiche oscillations were observed in several other ports of the Black Sea. Tsunamigenic synoptic conditions were found over the Black Sea, stretching from Romania in the west to the Crimean Peninsula in the east. Intense air pressure disturbances and convective thunderstorm clouds were associated with these conditions ; right at the time of the event, a 1.5-hPa air pressure jump was recorded at Odessa and a few hours earlier in Romania. We have utilized a barotropic ocean numerical model to test two hypotheses: (1) a tsunami-like wave was generated by an air pressure disturbance propagating directly over Odessa (‘‘Experiment 1’’) ; (2) a tsunami-like wave was generated by an air pressure disturbance propagating offshore, approximately 200 km to the south of Odessa, and along the shelf break (‘‘Experiment 2’’). Both experiments decisively confirm the meteorological origin of the tsunami- like waves on the coast of Odessa and imply that intensified long ocean waves in this region were generated via the Proudman resonance mechanism while propagating over the northwestern Black Sea shelf. The ‘‘Odessa tsunami’’ of 27 June 2014 was identified as a ‘‘beach meteotsunami’’, similar to events regularly observed on the beaches of Florida, USA, but different from the ‘‘harbour meteotsunamis’’, which occurred 1–3 days earlier in Ciutadella (Baleares, Spain), Mazara del Vallo (Sicily, Italy) and Vela Luka (Croatia) in the Mediterranean Sea, despite that they were associated with the same atmospheric system moving over the Mediterranean/Black Sea region on 23–27 June 2014.

Twenty-five papers on the study of tsunamis are included in Volume I of the PAGEOPH topical issue ‘‘Global Tsunami Science: Past and Future’’. Six papers examine various aspects of tsunami probability and uncertainty analysis related to hazard assessment. Three papers relate to deterministic hazard and risk assessment. Five more papers present new methods for tsunami warning and detection. Six papers describe new methods for modeling tsunami hydrodynamics. Two papers investigate tsunamis generated by non-seismic sources: landslides and meteorological disturbances. The final three papers describe important case studies of recent and historical events. Collectively, this volume highlights contemporary trends in global tsunami research, both fundamental and applied toward hazard assessment and mitigation.

The Tohoku (East Japan) earthquake of 11 March 2011 (M w 9.0) generated a great trans-oceanic tsunami that spread throughout the Pacific Ocean, where it was measured by numerous coastal tide gauges and open-ocean DART (Deep-ocean Assessment and Reporting of Tsunamis) stations. Statistical and spectral analyses of the tsunami waves recorded along the Pacific coast of Mexico have enabled us to estimate the principal parameters of the waves along the coast and to compare statistical features of the tsunami with other tsunamis recorded on this coast. We identify coastal “hot spots”—Manzanillo, Zihuatanejo, Acapulco, and Ensenada—corresponding to sites having highest tsunami hazard potential, where wave heights during the 2011 event exceeded 1.5–2 m and tsunami-induced currents were strong enough to close port operations. Based on a joint spectral analysis of the tsunamis and background noise, we reconstructed the spectra of tsunami waves in the deep ocean and found that, with the exception of the high-frequency spectral band (>5 cph), the spectra are in close agreement with the “true” tsunami spectra determined from DART bottom pressure records. The departure of the high-frequency spectra in the coastal region from the deep-sea spectra is shown to be related to background infragravity waves generated in the coastal zone. The total energy and frequency content of the Tohoku tsunami is compared with the corresponding results for the 2010 Chilean tsunami. Our findings show that the integral open-ocean tsunami energy, I 0, was ~2.30 cm2, or approximately 1.7 times larger than for the 2010 event. Comparison of this parameter with the mean coastal tsunami variance (451 cm2) indicates that tsunami waves propagating onshore from the open ocean amplified by 14 times; the same was observed for the 2010 tsunami. The “tsunami colour” (frequency content) for the 2011 Tohoku tsunami was “red”, with about 65% of the total energy associated with low-frequency waves at frequencies 35 min). The “red colour” (i.e., the prevalence of low-frequency waves) in the 2011 Tohoku, as well as in the 2010 Chile tsunamis, is explained by the large extension of the source areas. In contrast, the 2014 and 2015 Chilean earthquakes had much smaller source areas and, consequently, induced “bluish” (high-frequency) tsunamis.

Long-term hourly data from 12 tide gauge stations were used to examine the character of tidal oscillations in the Caspian Sea. Diurnal and semidiurnal tidal peaks are well-defined in sea level spectra in the Middle and South Caspian basins. High-resolution spectral analysis revealed that the diurnal sea level oscillations in the Middle Caspian Basin have a gravitational origin, while those in the South Caspian Basin are mainly caused by radiational effects: the amplitude of diurnal radiational harmonic S1 is much higher than those of gravitational harmonics О1, P1, and K1. In the North Caspian Basin, there are no gravitational tides and only weak radiational tides are observed. A semidiurnal type of tide is predominant in the Middle and South Caspian basins. Harmonic analysis of the tides for individual annual series with subsequent vector averaging over the entire observational period was applied to estimate the mean amplitudes and phases of major tidal constituents. The amplitude of the M2 harmonic reaches 5.4 cm in the South Caspian Basin (at Aladga). A maximum tidal range of 21 cm was found at the Aladga station in the southeastern part of the Caspian Sea, whereas the tidal range in the western part of the South Caspian Basin varies from 5 to 10 cm.

Sea level changes with a period of 14 months ( P 14 ) are usually associated with the pole tide, which is the oceanic response to the Chandler wobble in the Earth's axis of rotation. The amplitudes of these changes in the Baltic Sea are anomalously large, much larger than follows from the equilibrium pole tide theory. It appears that the oscillations are related to meteorological forcing rather than to pole motions. To examine the P 14 properties, we used long-term (48–213 years) tide gauge records from 77 stations located in the Baltic Sea and adjacent area of the North Sea. High-resolution sea level spectra revealed a cluster of peaks with periods from 410 to 450 days. The temporal variations in the P 14 sea level amplitudes and peak frequencies are found to be considerable and poorly correlated with the modulation of the Earth's pole motions. In contrast, our findings for 1871–2011 demonstrate strong resemblance between temporal (year-to-year) variations of the P 14 peak and zonal wind, confirming earlier results of Ekman (1996) and O’Connor et al. (2000) , who indicated the major role of the zonal wind in formation of the 14-month oscillations in the Baltic and North seas. The integral amplitudes of the P 14 oscillations in the Baltic Sea gradually increase eastward from the entrance (the Danish straits) to the farthest ends of the sea with the largest amplitudes (up to 6.5 cm) observed at the very head of the Gulf of Finland. Similar P 14 amplification toward the west coast of Denmark is also observed along the south coast of the North Sea. The geographical distribution of the P 14 in these two regions are almost the same as of the seasonal sea level oscillations, indicating presumably similar formation mechanisms. Extensive shallow-water areas in the Baltic Sea and southeastern part of the North Sea, combined with intense meteorological forcing, appear to be two key factors responsible for the formation of anomalously strong 14-month oscillations in these regions.

Twenty-two papers on tsunamis are included in the Pure and Applied Geophysicstopical issue Twenty five years of modern tsunami science following the 1992 Nicaragua and Flores Island tsunamis: Volume I, reporting on the frontiers of tsunami science and research. The first three papers overview significant tsunamis of 1992-2018 and discuss the problems of tsunami cataloguing. The main focus of the next four papers is on specific details of historical tsunami events and field surveys. First, three papers are related to thorough analyses of several historical events based on macroseismic, seismological, and tsunami observations, tide gauge data, and modelling results: the 1907 Sumatra tsunami earthquake, the 1941 Andaman Islands earthquake, and five great tsunamis in the Pacific Ocean (1946, 1952, 1957, 1960 and 1964). The last paper of the section concerns results of the field survey of the 2017 Bodrum-Kos tsunami. The reconstruction of the tsunami sources is the main target of the four following papers, with four events examined in detail: the historical 1810 Baja California, 1992 Flores Island, 2012 Haida Gwaii and 2015 Chilean (Illapel) tsunamis. A set of three papers address problems associated with landslide-generated tsunamis in three different regions: a modelling of the 2017 landslide and tsunami at Karrat Fjord, Greenland; a probabilistic analysis of the hazard from the Indus Canyon in the NW Indian Ocean; and a study of the landslide-induced tsunami hazard along the US East Coast. The next section, including three papers, reports on comparisons between different types of tsunami models, on numerical modelling of tsunami waves in the Caspian Sea, and on the modelling of magnetic signals at Easter Island, following the 2010 and 2015 Chilean tsunamis. The last group of five papers discusses tsunami hazard assessment and warning for various regions of the world oceans, including Alaska, the eastern and western Mediterranean, Australia, the Northeast Atlantic and the entire Pacific Ocean; one specific aspect of these studies is the compilation and efficient application of observed data, in particular, from DARTs.

On 19 March 2017, destructive tsunami-like waves impacted the northeast shore of the Persian Gulf (PG). The maximum surveyed runup of about 3 m was observed at Dayyer in southern Iran, where damaging waves inundated the land for a distance of * 1 km and resulted in the deaths of five people. Because the PG has always been considered safe from extreme oceanic waves, the event was totally unexpected. In this study, we examined sea level data from 12 stations across the PG and a variety of meteorological information, including satellite imagery, high-altitude isohypse maps and high-resolution air pressure records from 47 instruments along the PG. Our results show that the event was very local, with recorded maximum trough-to-crest wave heights of 197 cm at Dayyer and 234 cm at Asaluyeh, near field cities in Iran located * 80 km apart. The dominant wave periods were in the range of 15–20 min. At all distant tide gauges, the observed wave heights were \ 35 cm. No earthquakes or landslides were evident at the time of the event. On the other hand, atmospheric processes during 18–22 March were very active and 10 distinctive tsunamigenic air pressure disturbances were observed propagating over the PG, suggesting that the event of 19 March 2017 was a ‘‘meteorological tsunami’’. Atmospheric conditions over the PG were highly favourable for the generation of meteotsunamis and very similar to those that caused a chain of strong meteotsunamis in the Mediterranean and Black Sea regions during 23–27 June 2014. Based on the 500 hPa wind, we evaluated that the disturbances had propagation speeds of 21–38 m/s, with the disturbance at Dayyer having a speed of ~ 26 m/s toward 77º True. The Froude number, Fr (estimated as the ratio of the air disturbance speed to the long wave speed), on 19 March 2017 in the Dayyer/Asaluyeh region was close to resonance, Fr ~ 0.9 to 1.1, which is highly favourable for meteotsunami generation. Our findings indicate that the Dayyer/Asaluyeh area is a ‘‘hot spot’’ that is highly vulnerable to extreme, weather-induced tsunami-like waves. Brunel University London, Russian State Assignment, FCT, Croatian Science Foundation

The three great earthquakes off the coast of Chile on 27 February 2010 (Maule, Mw 8.8), 1 April 2014 (Iquique, Mw 8.2) and 16 September 2015 (Illapel, Mw 8.3) generated major transoceanic tsunamis that spread throughout the Pacific Ocean and were measured by numerous coastal tide gauges and open-ocean DART stations. Statistical and spectral analyses of the tsunami waves from the events recorded on the Pacific coast of Mexico enabled us to estimate parameters of the waves along the coast and to compare statistical features of the events. We also identified three coastal “hot spots” (sites having maximum tsunami risk): Puerto Angel, Puerto Madero and Manzanillo. Based on the joint spectral analyses of the tsunamis and background noise, we have developed a method for using coastal observations to determine the underlying spectrum of tsunami waves in the deep ocean. The “reconstructed” open-ocean tsunami spectra are in close agreement with the actual tsunami spectra evaluated from direct analysis of the DART records offshore of Mexico. We have further used the spectral estimates to parameterize the energy of the three Chilean tsunamis based on the total open-ocean tsunami energy and frequency content of the individual events.

Time series observations from instruments sited in the deep ocean and along coastal margins of the Pacific during major tsunami events in the years since 2010 were systematically processed. Examination of these records during four events, 2010 Chile (Maule), 2011 East Japan (Tohoku), 2012 Haida Gwaii and 2014 Chile (Iquique), show the prevalence of a small negative phase leading the first major positive tsunami wave, a phase that is not typically reproduced by current modelling approaches. We present leading negative phase signatures in examples from the more than 40 deep-ocean bottom pressure and approximately 200 tide gauge records investigated for this study. High sampling rate time series (15-s) were given greater weight in our investigation than the more readily available 1-min series. Careful investigation of tsunami arrival at each deep-ocean site highlights the role filtering techniques may play in misleading researchers or masking specific tsunami features such as the leading negative phase that is the basis of this study. The main focus of this investigation is to characterise the scale and repeatability of the phenomenon in support of recent similar findings rather than to provide a definitive explanation as to the cause. In general, our findings are in good agreement with and support the theoretical results of Watada et al. (J Geophys Res Solid Earth 119:4287–4310, 2014).

The tides in the Baltic Sea are weak but unmistakably recognizable in sea-level spectra. Multiyear hourly tide gauge series enable us to examine specific tidal properties in detail and to identify some unexpected effects. Two nearby stations on the southeastern coast of the sea, namely Baltiysk, located in the strait connecting the Vistula Lagoon to the Baltic Sea, and Otkrytoe, on the coast of the Curonian Lagoon, are found to have very different character of tidal motions. Based on 13 years of simultaneous observations at these stations we constructed high-resolution spectra of sea level fluctuations that demonstrated that the tidal spectrum at Baltiysk is “classical” with sharp peaks corresponding to the major tidal constituents: M2, S2, N2, K1, O1, and P1. Unlike at Baltiysk, the main tidal peak at Otkrytoe is at the S1 frequency; the K1, P1, and S2 tidal harmonics also have significant peaks, while the other harmonics (including M2 and O1) are undistinguishable. Further analysis indicated that the tides at Baltiysk are generated by ordinary gravitational tidal forces, while at Otkrytoe they are induced by solar radiation, specifically by the breeze winds creating wind setups and setdowns in the Curonian Lagoon. Moreover, our findings demonstrate that the observed K1 and P1 peaks at Otkrytoe are related not to gravitational forces but to the seasonal modulation of the S1 radiational tidal constituent. The separate analysis of the “summer” and “winter” sea level spectra at Otkrytoe reveals prominent radiational tidal peaks (S1 and S2) in summer and the absence of these peaks in winter. The results of the analysis support the assumption that these motions are generated by the breeze winds associated with the sea/land temperature contrasts, which are substantial during the warm (ice-free) season but vague during the cold season when ice cover diminishes these contrasts.

Deep-ocean tsunami measurements play a major role in understanding the physics of tsunami wave generation and propagation, and in improving the effectiveness of tsunami warning systems. This paper provides an overview of the history of tsunami recording in the open ocean from the earliest days, approximately 50 years ago, to the present day. Modern tsunami monitoring systems such as the self-contained Deep-ocean Assessment and Reporting of Tsunamis and innovative cabled sensing networks, including, but not limited to, the Japanese bottom cable projects and the NEPTUNE-Canada geophysical bottom observatory, are highlighted. The specific peculiarities of seafloor longwave observations in the deep ocean are discussed and compared with observations recorded in coastal regions. Tsunami detection in bottom pressure observations is exemplified through analysis of distant (22,000 km from the source) records of the 2004 Sumatra tsunami in the northeastern Pacific.

A major (M w 7.7) earthquake occurred on October 28, 2012 along the Queen Charlotte Fault Zone off the west coast of Haida Gwaii (formerly the Queen Charlotte Islands). The earthquake was the second strongest instrumentally recorded earthquake in Canadian history and generated the largest local tsunami ever recorded on the coast of British Columbia. A field survey on the Pacific side of Haida Gwaii revealed maximum runup heights of up to 7.6 m at sites sheltered from storm waves and 13 m in a small inlet that is less sheltered from storms (Leonard and Bednarski 2014). The tsunami was recorded by tide gauges along the coast of British Columbia, by open-ocean bottom pressure sensors of the NEPTUNE facility at Ocean Networks Canada’s cabled observatory located seaward of southwestern Vancouver Island, and by several DART stations located in the northeast Pacific. The tsunami observations, in combination with rigorous numerical modeling, enabled us to determine the physical properties of this event and to correct the location of the tsunami source with respect to the initial geophysical estimates. The initial model results were used to specify sites of particular interest for post-tsunami field surveys on the coast of Moresby Island (Haida Gwaii), while field survey observations (Leonard and Bednarski 2014) were used, in turn, to verify the numerical simulations based on the corrected source region.

With this volume of the Pure and Applied Geophysics (PAGEOPH) topical issue “Tsunamis in the Pacific Ocean: 2011–2012”, we are pleased to present 21 new papers discussing tsunami events occurring in this two-year span. Owing to the profound impact resulting from the unique crossover of a natural and nuclear disaster, research into the 11 March 2011 Tohoku, Japan earthquake and tsunami continues; here we present 12 papers related to this event. Three papers report on detailed field survey results and updated analyses of the wave dynamics based on these surveys. Two papers explore the effects of the Tohoku tsunami on the coast of Russia. Three papers discuss the tsunami source mechanism, and four papers deal with tsunami hydrodynamics in the far field or over the wider Pacific basin. In addition, a series of five papers presents studies of four new tsunami and earthquake events occurring over this time period. This includes tsunamis in El Salvador, the Philippines, Japan and the west coast of British Columbia, Canada. Finally, we present four new papers on tsunami science, including discussions on tsunami event duration, tsunami wave amplitude, tsunami energy and tsunami recurrence.

The pole tide, which is driven by the Chandler Wobble, has a period of about 14 months and typical amplitudes in the World Ocean of ∼0.5 cm. However, in the Baltic Sea the pole tide is anomalously high. To examine this effect we used long-term hourly sea level records from 23 tide gauges and monthly records from 64 stations. The lengths of the series were up to 123 years for hourly records and 211 years for monthly records. High-resolution spectra revealed a cluster of neighboring peaks with periods from 410 to 440 days. The results of spectral analysis were applied to estimate the integral amplitudes of pole tides from all available tide gauges along the coast of the Baltic Sea. The height of the pole tide was found to gradually increase from the entrance (Danish Straits, 1.5–2 cm) to the northeast end of the sea. The largest amplitudes—up to 4.5–7 cm—were observed in the heads of the Gulf of Finland and the Gulf of Bothnia. Significant temporal fluctuations in amplitudes and periods of the pole tide were observed during the 19th and 20th centuries.

[1] Tsunamis triggered by powerful earthquakes cause extensive damage and loss of life within many regions of the World Ocean. Although coastal inundation from major tsunamis is becoming increasingly well understood, we know little about the broader aspects of such events on distal marine systems. Here we use time series from moored oceanic sensors to show that the Tohoku tsunami generated by the magnitude 9.0 earthquake off eastern Japan in March 2011 caused days of surge-like currents and turbulent mixing in the inner basin of an anoxic Canadian fjord located over 7000 km from the seafloor rupture zone. Mixing, combined with the inflow of more oxygen-rich water from the adjoining outer basin, led to abrupt changes in the hydrodynamics, bottom sedimentation, and zooplankton behavior in the basin. These findings help define mechanisms by which major transoceanic tsunamis can significantly alter coastal marine environments located far from the source area.

An underwater landslide located in the central partof the eastern slope of Sakhalin Island was found andmapped during investigations under the auspices ofthe Korean–Russian Project Sakhalin Slope GasHydrates (SSGH) [1, 2]. The study region was confined to a depression oriented in the northeasterlydirection (Fig. 1a). The research in this region [1–4]demonstrated that closed depressions with round andslightly elongated forms in the northeasterly directionare characteristic peculiarities of the morphology ofthis depression (Fig. 1b). The slope angles of theirwalls are 7–10°, while the sizes are in the rangebetween 600 m and 10 km. They are located at depthsfrom 20 to 150 m. One of the largest depressions has anotable morphology. Its northern edge is quite flat(~7°), while the southern edge is steep (25–30°). Itconsists of one or a few cliffs with a total height up to100 m (Fig. 2).Two types of the sedimentary sections were foundwithin the study region. The first one is common. It ischaracterized by numerous reflecting levels that provide evidence about the layered structure of the sedimentary column. The second type of seismic section isobserved only in the southernmost depression crossedby seismic profile LV5603 (Fig. 2). Here, we distinguish a sedimentary body whose cover has a hillystructure, while the foot corresponding to a highamplitude reflecting level cuts off the underlyingreflectors. The body is acoustically transparentbecause there are no reflecting layers. Slope boundaries and diffracted reflections are seen on the highresolution section of seismic profiler SES2000DS,which is caused by the chaotic internal structure of thissedimentary body.The abovementioned peculiarities of the sedimentary cover structure together with the morphology ofthe depression give grounds to think that this sedimentary formation is a landslide. A section made usingseismic profiler SES2000DS with a resolution on theorder of 10 cm [4] does not demonstrate that the roofof the landslide is covered with horizontally locatedsediments. Taking into account that the rate of sediment deposition in this region during the Holocenewas 33 cm over 1000 years [2], the age of the landslideis less than 300 years. The breakoff wall of the landslide is very steep (25–30°). In some regions it consistsof two cliffs. Its form is undulating, and its length is22 km (Fig. 1b). The area occupied by the landslide is42 km@2, and its volume is approximately 4 km

Long-term hourly data from 35 tide gauge stations, including 15 stations in the Gulf of Finland, were used to examine tidal sea level oscillations of the Baltic Sea. High-resolution spectral analysis revealed the well-defined fine structure of tidal peaks with diurnal peaks at most stations being higher than semidiurnal. At some stations (e.g., Narva, Daugava, and Wladyslawowo), high frequency radiational tidal peaks with periods multiple of the solar day (3, 4, 5, 6, and 8 cpd) were detected; the respective oscillations are supposed to be caused by seabreeze winds. Harmonic analysis of tides for individual yearly sea level series followed by vector averaging over the entire observational period was used to estimate the amplitudes and phases of 16 tidal constituents. The maximum tidal oscillations of 17–19 cm were found to be observed in the Gulf of Finland and, first of all, in Neva Bay (in the head of the gulf). Diurnal or mixed diurnal tides are predominant in almost the entire Baltic Sea. The comparison of the observed tides with those theoretically computed showed that the existing numerical models of the main tidal harmonics generally quite accurately reproduce the structure of the tides in the Baltic Sea except for some regions of the Gulf of Bothnia.

The generation mechanism of meteotsunamis, which are meteorologically induced water waves with spatial/temporal characteristics and behavior similar to seismic tsunamis, is poorly understood. We quantify meteotsunamis in terms of seasonality, causes, and occurrence frequency through the analysis of long-term water level records in the Laurentian Great Lakes. The majority of the observed meteotsunamis happen from late-spring to mid-summer and are associated primarily with convective storms. Meteotsunami events of potentially dangerous magnitude (height > 0.3 m) occur an average of 106 times per year throughout the region. These results reveal that meteotsunamis are much more frequent than follow from historic anecdotal reports. Future climate scenarios over the United States show a likely increase in the number of days favorable to severe convective storm formation over the Great Lakes, particularly in the spring season. This would suggest that the convectively associated meteotsunamis in these regions may experience an increase in occurrence frequency or a temporal shift in occurrence to earlier in the warm season. To date, meteotsunamis in the area of the Great Lakes have been an overlooked hazard.

The understanding of meteotsunamis - significant atmospherically generated long ocean waves in the tsunami frequency band - has advanced considerably during the last two decades. Scientists and specialists use near-field in situ data and remote observations, as well as atmospheric and ocean modelling, to study destructive events. The phenomenon has been reported and investigated worldwide, indicating its relevance within other marine natural hazards and demonstrating the urgent need for meteotsunami warning systems for certain countries. In this paper we summarize the present knowledge of the phenomenon, identify particular research gaps, and propose near-future critical components of meteotsunami research. We emphasize a potential concept of merging yet-to-be-developed meteotsunami warning systems and existing tsunami or multi-hazard early warning systems.

Twenty-one papers on the 2011 Tohoku, Japan tsunami are included in Volume I of the PAGEOPH topical issue “Historical and Recent Catastrophic Tsunamis in the World.” Two papers discuss seismological aspects of the event with an emphasis on tsunami generation and warning. Five papers report the impacts and effects in Japan through field surveys of tsunami heights, building damage, and tsunami deposits or analysis of satellite data. Eight papers report the tsunami effects on other Pacific coasts, including the Kuril Islands, the USA, French Polynesia, the Galapagos Islands, Australia, and New Zealand. Three papers report on analyses of the instrumental records of the 2011 Tohoku tsunami, and two more papers report their modelling efforts of the tsunami. Several of the above papers also compare the 2011 Tohoku and 2010 Chile tsunamis.

Eighteen papers on past and recent destructive tsunamis are included in Volume II of the PAGEOPH topical issue “Historical and Recent Catastrophic Tsunamis in the World.” Three papers discuss deep-sea (DART) and coastal tsunami observations, warning systems and risk management in the Pacific Ocean. Four papers examine the 1755 Lisbon, 1964 Alaska, 2003 Algeria, and 2011 Haiti tsunamis. Four more papers, as well as some papers in Volume I, report on various aspects of the 2010 Chile tsunami. Two papers present some results of field survey and modelling investigation of the 2010 Mentawai, Indonesia, tsunami. Three papers report on modelling efforts of tsunami generation by earthquake and landslide, and of tsunami propagation. Finally, two papers discuss hazard assessment using a probabilistic approach.