Understanding potential flow velocities during high-energy marine inundation events is crucial for coastal risk assessment. However, modelling struggles to simulate wave energy dissipation across atoll island coastlines. Here, we examined coral reefblocks transported by past tropical cyclones to calculate the minimum flow velocities (MFVs) responsible. Fieldwork on 6 atolls in the Tuamotu archipelago (South Pacific) examined 196 reefblocks, some megaclasts exceeding 300 cubic metres in size. These blocks are scattered between the oceanside reef edge and the atoll lagoon over several hundred metres and suggest flow velocities much higher than those modelled in an assumed ‘extreme reference scenario’ (HS = 12 m). Through U/Th dating and by studying archives and historical aerial photos, the cyclones that moved these reefblocks were identified. Inundation flows generated by two recent cyclones (March and April 1983), two historical cyclones (1903 AD and 1906 AD) and one prehistorical cyclone (54–80 AD) were calculated (storms with swells 10–18.5 m in height). Calculations reveal that previous modelling underestimates flow velocities across atoll islands (inhabited areas) for two reasons: the underestimation of extreme swell heights and the unaccounted-for degradation of shoreline rubble ramparts. During a supercyclone (HS > 15 m), flows can exceed 3 m/s at 350 m from the reef edge and are capable of transporting 20-ton coral blocks. Findings have a wider significance to tropical coral reef coastlines beyond these atolls studied, where the presence of reefblocks can allow hindcasting of the characteristics of prehistorical cyclone inundations.

Coral reefs are integral components of tropical coastal marine ecosystems that have considerable capacity to mitigate extreme flows and marine floods caused by storms and tsunamis. However, limited studies on coral reef efficacy in reducing such flows, coupled with variable roughness coefficient characteristics, hinder their broader utilization in sustainable engineering applications for societal benefit. In this study, we conducted comprehensive experimental investigations to examine flow–coral interactions and the flow energy reduction capabilities of coral reefs. Three-dimensional-printed coral reefs were used to simulate actual coral reefs, providing a scalable and environmentally responsible approach for studying nature-based coastal protection systems. Flow characteristics within the coral reef were investigated through flow depth and velocity measurements taken at the front of, over, and behind the reef. Analysis was performed considering nondimensional parameters, i.e., the Froude number (Fr), the depth effect (DE; ratio of flow depth to coral height), and the size effect (SE; ratio of coral length to coral height), to assess the flow energy reduction under different coral combinations and flow conditions. Spatial variations in flow depth over the reef showed that fast and shallow flows exhibited a reduction gradient toward the back of the reef. The findings revealed a substantial reduction in flow depth and velocity, reaching up to 27.5% and 25%, respectively, at the back boundary of the coral. Two-layered velocity analyses showed that the velocity over the top of corals could be six times higher than that through the coral reef structure for deep flows. Manning’s roughness coefficient varied considerably from 0.03 to 0.26. Overall, this study contributes to sustainable coastal engineering by demonstrating how bio-inspired coral reef structures can be applied to reduce flow energy and enhance coastal resilience in an environmentally adaptive manner.

Triggered by earthquakes along the Hellenic and Calabrian arcs, submarine landslides and eruptions of active volcanoes in Italy and Greece, the Mediterranean Sea has experienced significant tsunamis in the past. Nonetheless, the patterns of these tsunamis in terms of timing, frequency, intensities and the dominant triggering mechanisms remain poorly understood. The unique position of the Maltese Islands in the Central Mediterranean makes Malta vulnerable to tsunami risks from various directions in the surrounding seascape. However, in contrast to many other Mediterranean coastlines, no onshore sediments associated with tsunamis have yet been reported in the Maltese archipelago, except for boulder deposits that face limitations with age-dating and correlation with known historical events. This study reveals hitherto unrecognized sand-grade sediments deposited within karst pockets (solution hollows), typical of exposed limestone terrain on the L-A & hstrok;rax Peninsula (northern Malta Island). These karst pockets (>10 m above sea-level) are ideal repositories for the preservation of tsunami deposits because, once washed in, sediments are protected from removal by natural forces. The sediments comprise shelly sands overlying terra rossa lining the base of the hollows. Through their retrieval, examination and interpretation, this study presents the first detailed description of tsunami sediments in Malta, characterizing their granulometric properties, sedimentary structures and micro-faunal assemblages that together indicate a marine origin for the sands. Relative age-dating was achievable from the detection of Amphistegina lobifera, locally an alien foraminifer species, but which is known to have invaded the Mediterranean Sea with the opening of the Suez Canal in 1869. The frequent occurrence of karst pocket sand deposits in juxtaposition with boulder deposits atop steep cliffs suggests a probable palaeotsunami origin, shedding new light on the coastal hazard exposure of the Central Mediterranean.

The Mediterranean Sea has experienced extreme waves (including large tsunamis) in the past. However, the pattern of timing, frequency and magnitudes of these events, and the relative importance of possible storm and tsunamigenic mechanisms (undersea earthquakes, volcanic eruptions, major landslides) are not so well understood. The Maltese archipelago is uniquely situated for extreme wave research in the Mediterranean Sea, since this group of small islands is exposed to waves approaching from any direction. Previous studies in Malta investigating sediment deposits from Holocene palaeotsunamis have tended to focus on the hydrodynamic characteristics of large coastal boulders. This study adopts an alternative approach. In the Aħrax area on the northernmost peninsula of Malta Island, we examined ‘karst pockets’ (solution hollows) that pockmark the exposed limestone terrain at elevations of up to 10-12 m asl. Deposited in the pockets are shelly marine sands. Lined by insoluble terra rossa soils, the pockets act as sediment traps during inundation by wave flow and are excellent repositories from which the accumulated marine sands cannot easily be removed.This presentation describes the sampling methods, some challenges and results of subsequent laboratory analysis. Findings show the moderately-sorted sands contain a rich microfossil assemblage of mostly benthic species, comprising foraminifera, gastropods, echinoidea, serpulidae and bryozoa. Wave-abraded forms occur alongside well-preserved forms. Sediment stratigraphy within the karst pockets suggests various depositional episodes, contrasted by differing grain sizes, microfossil contents, colours and erosional contacts, while the cliff-top elevations of 10-12 m require consideration of the potential of both storm waves and tsunamis and their respective capabilities with regard to the exposed coastal geomorphology.

In Hawai`i, tsunamis are often described in orally transmitted legends (mo`olelo). This study examines sedimentary evidence of a possible local submarine landslide-generated tsunami, described in a legend from the south east coast of Maui which originated between the 15th Century CE and the first arrival of Europeans in 1778 CE. Physical evidence for a tsunami, found at the Nu'u Refuge, Maui, is primarily comprised of an extensive coral clast deposit (found 8.5 m above msl and 251 m inland from the shoreline) together with waterworn cobbles which form fracture-embedded wedge clasts in a local basalt escarpment (at up to 8 m above msl). U/Th dating of the coral clasts gives a maximum tsunami deposit age of 1671 CE for the event that may have inspired the local mo`olelo. This depositional sequence is used to characterize the nature of the assumed tsunami in terms of inundation distance, maximum wave runup and minimum flow velocities. A numerical model developed using GeoClaw matches well with the physical evidence. The data and modeling presented here suggest that locallygenerated tsunamis from submarine landslides warrant further research attention as sources of destructive high energy marine inundation events.

Few constructional features of coastal geomorphology have been investigated at the northernmost extremity of the Gulf of Thailand (GoT), with a view to establishing the position (height) of local relative sea level (RSL) during the marine regression following the regional mid-Holocene highstand (MHH) that occurred at approximately 6.5 ka BP. Here, the work investigates a 2 m thick exposure of marine gravels on the coast of Ko Khang Khao islet in the eastern Bay of Bangkok. At an elevation of 3.3-5.3 m above modern sea level, the sequence is interpreted to represent a Holocene raised beach. The unlithified sediments comprise rounded quartz and mylonite pebbles and cobbles, oriented predominantly NE-SW, supported by fossiliferous sands that are rich in marine shells, coral fragments and occasional terrestrial gastropods. The juxtaposition of the marine and nonmarine gastropoda of contemporaneous ages makes a compelling story for a coastal storm deposit, thrown up either by a winter monsoon storm, or by a palaeotyphoon that managed to penetrate the upper Gulf. Overlapping results of C14 and OSL age-dating of shell material and mineral sands suggest the raised (storm) beach formed between 3.5 and 4.0 ka BP, i.e. 2.5-3.0 ka after the MHH peak, at a height of 1.3-3.3 m above the local RSL position at that time (according to glacial isostatic adjustment modelling). Given the otherwise paucity of data from the upper GoT, the Ko Khang Khao raised beach provides new information that expands our current understanding of geographical variations in RSL across Southeast Asia during the Late Holocene.

The Oceania region has often been overlooked in fundamental hydrological research owing to assumptions that cultural complexities hinder such efforts. However, this perspective is somewhat na & iuml;ve. Substantial evidence demonstrates that Pacific Islanders actively engage in research, contributing both local Indigenous knowledge and expert capabilities in "island hydrology." Numerous projects and publications by Pacific Island scholars showcase this expertise. To enhance self-reliance in smaller Pacific nations, it is crucial to improve access to advanced hydrology education and secure funding to support it. Overcoming these challenges is essential to unlocking the full potential of future hydrological research in the Pacific Islands.

This work presents the first known application of a new approach to tsunami modelling, by linking a discrete cellular automata (CA) dynamic model of a submarine landslide to an off -the -shelf tsunami modelling package. This has the advantage of simulating the temporal evolution of the submarine landslide rather than as a single rigid sliding mass. We first tested that the coupled model was able to satisfactorily reproduce observed tsunami wave heights resulting from the flank collapse of the Anak Krakatau volcano in the Sunda Strait (Indonesia) in December 2018, before applying it to a speculative area of interest on the North Borneo (Continental) Shelf (NBS). The NBS has one of the thickest near -shore clastic sediment wedges known globally (12 km thickness) and a very long pre -history of submarine landsliding. We modelled a small slide (5 km3 volume) because this is far more likely to occur than a recurrence of the gigantic Brunei slide (1200 km3 volume). Results indicate that a 5 km3 submarine landslide generates multiple tsunami waves, the largest of which reached 8 m at the coast of nearby Balabac Island (The Philippines). Small tsunami waves also arrived on the central Vietnam coast, more than 900 km distant. A larger potential failure on the NBS therefore appears capable of causing a tsunami with greater runup heights, which could pose a risk to much of central and southern Vietnam, northern Borneo (Sabah, Brunei) and Palawan. Finally, we note that the South China Sea is fringed by a necklace of other thick offshore clastic sediment accumulations, most notably on the southern China continental margin, offshore southern Taiwan, and offshore central Vietnam. Given the proof -of -concept of our coupled CA-tsunami modelling approach described here, we recommend this also be applied in these areas to assess the risk posed by a wide range of submarine landslides to coastal populations and infrastructural assets (including nuclear power plants).

Many regions worldwide suffer from heavy air pollution caused by particulate matter (PM2.5) and nitrogen dioxide (NO2), resulting in a huge annual disease burden and significant welfare costs. Following the outbreak of the COVID-19 global pandemic, enforced curfews and restrictions on human mobility (so-called periods of ‘lockdown’) have become important measures to control the spread of the virus. This study aims to investigate the improvement in air quality following COVID-19 lockdown measures and the projected benefits for environmental health. China was chosen as a case study. The work projects annual premature deaths and welfare costs by integrating PM2.5 and NO2 pollutant measurements derived from satellite imagery (MODIS instruments on Terra and Aqua, and TROPOMI on Sentinel-5P) with census data archived by the Organization for Economic Co-operation and Development (OECD). A 91-day timeframe centred on the initial lockdown date of 23 January 2020 was investigated. To perform the projections, OECD data on five variables from 1990 to 2019 (mean population exposure to ambient PM2.5, premature deaths, welfare costs, gross domestic product and population) were used as training data to run the Autoregressive Integrated Moving Average (ARIMA) and multiple regression models. The analysis of the satellite imagery revealed that across the regions of Beijing, Hebei, Shandong, Henan, Xi’an, Shanghai and Hubei, the average concentrations of PM2.5 decreased by 6.2, 30.7, 14.1, 20.7, 29.3, 5.5 and 17.3%, while the NO2 decreased by 45.5, 54.7, 60.5, 58.7, 63.6, 50.5 and 66.5%, respectively, during the period of lockdown restrictions in 2020, as compared with the equivalent period in 2019. Such improvements in air quality were found to be beneficial, reducing in 2020 both the number of premature deaths by approximately 97,390 and welfare costs by over USD 74 billion.

Across the hyperarid Arabian Peninsula, preparing to face evolving risks of flash-flood hazards against projected scenarios for climate change requires both an understanding of the extreme rainfall events responsible and the implementation of appropriate mitigation/adaptation measures. In July 2022, torrential storms affected northeastern UAE. The damaging impacts prompted a broader consideration of flash-flood risks, especially for rapidly-urbanising arid landscapes. Occurring unexpectedly in mid-summer when rainfall is normally absent, the storms were produced by a combination of climatic and oceanic conditions: ITCZ position, unusual westward extension of a humid air mass from the Indian monsoonal trough, a cool sea-surface temperature anomaly that drove strong onshore moisture advection, and orographic precipitation enhancement by the coastal ranges. A foreign media suggestion that cloud seeding was partly responsible, however, is contested. Although flood emergency management was coordinated and effective, it is argued that various strategies may be strengthened to reduce future disaster risks. These include increased monitoring of mountain wadi systems to augment meteorological forecasts with hydrological information, and improved modelling to predict runoff-generation processes better in ungauged catchments. Greater capture of floodwaters to infiltrate and replenish groundwater aquifers also supports ongoing national efforts to develop sustainable solutions for addressing freshwater scarcity.

Cyclone Shaheen in the Arabian Sea during early October 2021 was an extremely rare climatic event (Figure 1). Although this cyclone was not as powerful as some other storms in the region over recent years, it followed an unusual east-to-west track across the far north of the Arabian Sea basin (ASB). This highly atypical trajectory, directed by easterly steering winds, caused Shaheen to move into the narrow Gulf of Oman and subsequently make landfall on the northern Oman coastline as a category-1 intensity cyclone on 3 October. According to established records, the last cyclone to achieve such a distinctive geographical landfall was in June 1890, well over a century ago (NOAA, 2021a). The unique track and landfall of Cyclone Shaheen have therefore made history this century. The high waves, storm surge and heavy rainfall were sufficient to cause coastal inundation and flash flooding in many wadis (dry river beds), resulting in much damage over northern Oman (AlRuheili, 2022). Aims

Lake Tagimaucia, a montane volcanic lake on Taveuni Island, is Fiji's only high-elevation lake. This study examined a lacustrine sediment core to explore the lake's potential as a palaeoenvironmental archive through the Late Holocene. Dating reveals no simple age-depth relationship due to sediment agereversals. However, phases of fire activity are evidenced by two distinct charcoal bands. Catchment burns were probably related to significant ENSO-driven drought, although fire ignition by volcanic eruptions on Taveuni cannot be ruled out. Above the dominant charcoal band, the sediment profile exhibits notable positive shifts in organic matter, bulk density, d13C, and C:N ratio. These peaks suggest a phase of accelerated catchment erosion, possibly triggered by post-burn instability. We introduce a conceptual model to explain the influence of sedge peat swamps on lake sedimentation processes. Surrounding sedge-dominated peatlands have extensively encroached Lake Tagimaucia. Floating peat mats, gradually accumulating through time, act as a repository of organic material that is stored directly on the lake surface. Episodes of drought and fire release old organics directly into the lake itself, probably contributing to the complex chronological sequence in the Late Holocene stratigraphy.

<p>Ludao Island in south eastern Taiwan regularly experiences strong Pacific typhoons.  Fieldwork was undertaken to investigate the characteristics of a boulder field comprising massive limestone and volcanic clasts (10<sup>3</sup>–10<sup>4</sup> kg) on the exposed SE coast.  Old large clasts on the Holocene emerged platform provide evidence for multiple high-energy palaeowave events.  Of particular interest were clasts stacked and imbricated together to form distinct boulder trains.  Inferred minimum flow velocities of 4.3–13.8 m/s were needed for their deposition.  What can imbricated boulder trains tell us about the wave processes and geomorphic influences responsible?  One hypothesis here is that localized funnelling of water flow through narrow relict channels is able to concentrate onshore flow energy into powerful jets.  These channels represent inherited (fossil) spur-and-groove morphology, oriented perpendicular to the modern reef edge, now overdeepened by subaerial karstic solution.  Support for this idea is the location and train-of-direction of the main imbricated boulder cluster at the landward head of one such feature.  Geomorphic controls amplifying wave-breaking flow velocities across Ludao's coastal platform mean that a palaeotyphoon origin is sufficient to account for large rock clast stacking and imbrication, without recourse to a tsunami hypothesis.</p>

W e a t h e r – O c t o b e Daily wind frequencies recorded by John Gadbury in London display a significant bias towards the west–northwest according to Brooks and Hunt (1933) who expected dominant southwest winds. Bias is confirmed by comparisons with contemporary daily records in Rothamstead and London. It is attributed to an over-recorded frequency of west winds, but not inconsistent with the common use of cardinal terms such as ‘westerlies’, as in John Goad’s diary. Over 16 years, Gadbury’s daily westerly winds display consistent and strong periodic patterns, and a mean value just south of west. Significant correlations are discovered with Wittewronge’s record from Rothamstead using monthly and bimonthly wind vectors for 1684–1688. Despite a bias to west winds, the wind structures as a whole are a reliable basis for regional comparisons.

January 2022 witnessed the violent eruption of Hunga Tonga–Hunga Haʻapai submarine volcano in the South Pacific. With a volcanic explosivity index possibly equivalent to VEI 5, this represents the largest seaborne eruption for nearly one and a half centuries since Indonesia’s cataclysmic explosion of Krakatau in AD 1883. The Tongan eruption remarkably produced ocean-wide tsunamis, never documented before in the Pacific instrumental record. Volcanically generated tsunamis have been referred to as a ‘blind spot’ in our understanding of tsunami hazards, particularly in the Pacific Ocean. This event therefore presents a unique opportunity for investigating the multiple processes contributing to volcanic tsunamigenesis. It is argued that, although challenges exist, integrating theoretical, observational, field and modelling techniques offers the best approach to improving volcanic tsunami hazard assessment across Oceania.

Ludao Island in south eastern Taiwan regularly experiences strong Pacific typhoons. Fieldwork was undertaken to investigate the characteristics of a boulder field comprising massive limestone and volcanic clasts (103–104 kg) on the exposed SE coast. Old large clasts on the Holocene emerged platform provide evidence for multiple high-energy palaeowave events. Of particular interest were clasts stacked and imbricated together to form distinct boulder trains. Inferred minimum flow velocities of 4.3–13.8 m/s were needed for their deposition. What can imbricated boulder trains tell us about the wave processes and geomorphic influences responsible? One hypothesis here is that localized funnelling of water flow through narrow relict channels is able to concentrate onshore flow energy into powerful jets. These channels represent inherited (fossil) spur-and-groove morphology, oriented perpendicular to the modern reef edge, now overdeepened by subaerial karstic solution. Support for this idea is the location and train-of-direction of the main imbricated boulder cluster at the landward head of one such feature. Geomorphic controls amplifying wave-breaking flow velocities across Ludao's coastal platform mean that a palaeotyphoon origin is sufficient to account for large rock clast stacking and imbrication, without recourse to a tsunami hypothesis.

For tsunami science within Oceania, the vast Central and Western Pacific (CEWEP) is an anomalous region because of the scarcity of historical tsunami observations and the complete absence of dated palaeotsunami evidence. This paper therefore records the first dated high‐magnitude palaeotsunami event within the CEWEP region. A combination of both geological data and oral history is provided for a palaeotsunami that struck remote Makin island, northernmost of the Gilbert Islands in Kiribati, toward the end of the 16th century. A previously undocumented oral tradition of giant waves is well known to the people of Makin. Narration of this legend by the Wiin te Maneaba, traditional storyteller on Makin, provided important details supporting a tsunami hypothesis. The legend preserves credible information surrounding the giant‐wave origin of Rebua and Tokia, two prominent subaerial megaclasts of blade and block geometry that were transported 80–130 m shorewards from the reef‐edge source and deposited in sideways and inverted orientations. From available hydrodynamic flow transport equations, minimum flow velocities of 7.3–16.3 m s−1 were generated, depending on whether the reefblocks were rotated or lifted onto the reef platform. The youngest U‐Th age‐dates for fossil corals retrieved from the reefblocks give a maximum age for the palaeotsunami of circa AD 1576. Several far‐field Pacific Rim and regional possibilities exist for tsunamigenesis. These include subduction‐zone seismicity and catastrophic volcanic eruption, both of which have been linked to earlier (late 15th century) palaeotsunami events recorded elsewhere in the Pacific Islands. However, the available evidence here suggests that the ~AD 1576 Makin palaeotsunami was more likely to have been locally generated by tsunamigenic offshore submarine slope failure close to Makin's western reef, associated with the giant arcuate bight structure that characterizes the northern rim of Butaritari atoll.