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Landslides are among the most dangerous natural processes. Debris avalanches and debris flows in particular have often caused casualties and severe damage to infrastructures in a wide range of environments. The assessment of susceptibility to these phenomena may help policy makers in mitigating the associated risk and thus it has attracted special attention in the last decades. In this experiment, we assessed susceptibility to debris-avalanche and -flow landslides by using a stochastic approach. Two different modeling techniques were employed: i) Multivariate Adaptive Regression Splines (MARS) and ii) Logistic Regression (LR). Both MARS and LR allow for calculating the probability of landslide occurrence by building statistical relationships between a set of environmental variables and the target variable, i.e. presence/absence of the landslide event. The target variable was extracted from an inventory of debris-avalanche and - flow landslides which were triggered by the tropical storm that hit the area of Mocoa (Colombia) on 1 April 2017. As predictor variables, we employed nine terrain attributes derived from a 5-m resolution DEM (i.e. elevation, slope angle, northness, eastness, upslope slope angle, convergence index, topographic position index, valley depth and topographic wetness index), in addition to lithology, distance from faults and presence/absence of soil creep processes. In our experiment, we used three different landslide datasets which contain i) the highest point of each recognized landslide crown-lines (dataset LIP), ii) the highest 10% of cells of each landslide area (dataset SOURCE), and iii) the entire landslide areas, which include initiation and accumulation zones (dataset MASS). In order to evaluate their predictive ability, LR and MARS models were submitted to k -fold spatial cross-validation strategy, which consists in extracting random training and test subsets from k spatially disjoint sub-areas. The results of model validation, expressed in terms of Area Under the ROC Curve (AUC), demonstrate better predictive performance of MARS models with respect to LR models, for all the three landslide datasets. The mean AUC values calculated for the datasets LIP, SOURCE and MASS of the MARS models are 0.776, 0.788 and 0.768, respectively, whereas AUC values of the LR models are 0.748, 0.751 and 0.703, respectively. Model validation also shows that the predictive skill of the models is better when landslide data are sampled from the highest portions of the landslides (dataset SOURCE). Maps of susceptibility to debris-avalanche and -flow landslides for the Mocoa area were produced by using both LR and MARS and the three landslide datasets. The analysis of the distribution of events versus the susceptibility classes of the maps confirm that MARS and the dataset SOURCE provide the best ability to discriminate between event and non-event cells. • A stochastic approach was used to predict debris avalanches/flows occurred in Mocoa. • MARS and logistic regression were employed as modeling techniques. • The performance of the models was assessed by using k -fold spatial cross-validation. • MARS achieved better ability to discriminate between event and non-event pixels. • Models demonstrated better accuracy in predicting landslide source areas. [ABSTRACT FROM AUTHOR]

We deployed five broadband three-components seismic stations in the Iles Eparses in the south-west Indian Ocean and on Mayotte Island, between April 2011 and January 2014. These small and remote oceanic islands suffer the effects of strong ocean swells that affect their coastal environments but most islands are not instrumented by wave gauges to characterize the swells. However, wave action on the coast causes high levels of ground vibrations in the solid earth, so-called microseismic noise. We use this link between the solid earth and ocean wave activity to quantify the swells locally. Spectral analyses of the continuous seismic data show clear peaks in the 0.05–0.10 Hz frequency band (periods between 10 and 20 s), corresponding to the ocean wave periods of the local swells. We analyze an example of austral swell occurring in August 2013 and a cyclonic event (Felleng) that developed in January 2013, and quantify the ground motion at each station induced by these events. In both cases, we find a linear polarization in the horizontal plane with microseismic amplitude directly correlated to the swell height (as predicted by the global swell model WaveWatchIII), and a direction of polarization close to the predicted swell propagation direction. Although this analysis has not been performed in real time, it demonstrates that terrestrial seismic stations can be efficiently used as wave gauges, and are particularly well suited for quantifying extreme swell events. This approach may therefore provide useful and cheaper alternatives to wave buoys for monitoring swells and the related environmental processes such as beach erosion or coral reef damages. [ABSTRACT FROM AUTHOR]

• Conduct field measurements on a 600-m-tall building equipped with an active tuned mass damper (ATMD) system during seven tropical storms. • Assess the ability of the ATMD system for mitigating wind-induced vibrations. • Evaluate control performance of the ATMD system by investigating its effects on structural dynamic properties. On the basis of field measurements on a super high-rise building equipped with an active tuned mass damper (ATMD) system during seven tropical storms, this paper presents a systematic investigation of the vibration mitigation performance of the active control system under extreme wind conditions. The field-measured building acceleration responses indicate that the ATMD system can be precisely triggered to operate following its operating principle and significantly suppress the acceleration responses of fundamental sway modes of the monitored skyscraper but has marginal effects on those of higher modes. Moreover, the effects of the ATMD system on structural dynamic properties of the super high-rise building are investigated. The results show that the damping ratios of the fundamental sway modes can be remarkably boosted from about 0.6 % to 2 % ∼ 7 % by the active damper system, and the increment of damping ratios decreases as building vibration amplitude. The outputs of this paper aim to offer advantageous guidance for the design of vibration control devices and thereby provide helpful information for the wind-resistant design of super high-rise buildings. [ABSTRACT FROM AUTHOR]

Abstract: Based on moored observations and remote sensing data in July and August 2005, energy sources for enhancing turbulent mixing and possible mechanisms of phytoplankton bloom in the continental shelf southeast of Hainan Island under the influence of Washi, a fast-moving and weak tropical storm, are analyzed in this paper. Observations show that strong near-inertial internal waves were generated by the rapidly changing wind stress and the near-inertial energy was dissipated quickly across the thermocline. The strong turbulent mixing associated with the near-inertial baroclinic shear instability occurred with maximum eddy diffusivity above 3.2×10−4 m2 s−1, and the surface chlorophyll-a (Chl-a) concentration after the storm increased by 22.2%. The Chl-a concentration augment was inferred to be an upper ocean biophysical response to the enhanced near-inertial turbulent mixing which could increase the upward nutrient flux into the surface low eutrophic zone during the passage of Washi. [Copyright &y& Elsevier]

Abstract: The coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system was used to investigate atmosphere–ocean–wave interactions in November 2009 during Hurricane Ida and its subsequent evolution to Nor’Ida, which was one of the most costly storm systems of the past two decades. One interesting aspect of this event is that it included two unique atmospheric extreme conditions, a hurricane and a nor’easter storm, which developed in regions with different oceanographic characteristics. Our modeled results were compared with several data sources, including GOES satellite infrared data, JASON-1 and JASON-2 altimeter data, CODAR measurements, and wave and tidal information from the National Data Buoy Center (NDBC) and the National Tidal Database. By performing a series of numerical runs, we were able to isolate the effect of the interaction terms between the atmosphere (modeled with Weather Research and Forecasting, the WRF model), the ocean (modeled with Regional Ocean Modeling System (ROMS)), and the wave propagation and generation model (modeled with Simulating Waves Nearshore (SWAN)). Special attention was given to the role of the ocean surface roughness. Three different ocean roughness closure models were analyzed: (which is based on wave age), (which is based on wave steepness), and (which considers both the effects of wave age and steepness). Including the ocean roughness in the atmospheric module improved the wind intensity estimation and therefore also the wind waves, surface currents, and storm surge amplitude. For example, during the passage of Hurricane Ida through the Gulf of Mexico, the wind speeds were reduced due to wave-induced ocean roughness, resulting in better agreement with the measured winds. During Nor’Ida, including the wave-induced surface roughness changed the form and dimension of the main low pressure cell, affecting the intensity and direction of the winds. The combined wave age- and wave steepness-based parameterization () provided the best results for wind and wave growth prediction. However, the best agreement between the measured (CODAR) and computed surface currents and storm surge values was obtained with the wave steepness-based roughness parameterization (), although the differences obtained with respect to were not significant. The influence of sea surface temperature (SST) fields on the atmospheric boundary layer dynamics was examined; in particular, we evaluated how the SST affects wind wave generation, surface currents and storm surges. The integrated hydrograph and integrated wave height, parameters that are highly correlated with the storm damage potential, were found to be highly sensitive to the ocean surface roughness parameterization. [Copyright &y& Elsevier]

Abstract: Wave data collected off Goa along the west coast of India during February 1996–May 1997 has been subjected to spectral analysis, and swell and wind sea parameters have been estimated by separation frequency method. Dominance of swells and wind seas on monthly and seasonal basis has been estimated, and the analysis shows that swells dominate Goa coastal region not only during southwest monsoon (93%), but also during the post-monsoon (67%) season. Wind seas are dominant during the pre-monsoon season (51%). The mean wave periods (T m ) during southwest monsoon are generally above 5s, whereas T m is below 5s during other seasons. Co-existence of multiple peaks (from NW and NE) was observed in the locally generated part of the wave spectrum, especially during the post-monsoon season. NCEP reanalysis winds have been used to analyse active fetch available in the Indian Ocean, from where the predominant swells propagate to the west coast of India. A numerical model was set up to simulate waves in the Indian Ocean using flexible mesh bathymetry. The correlation coefficients between measured and modelled significant wave heights and mean wave periods are 0.96 and 0.85, respectively. Numerical simulations reproduced the swell characteristics in the Indian Ocean, and from the model results potential swell generation areas are identified. The characteristics of swells associated with tropical storms that prevail off Goa during 1996 have also been analysed. [Copyright &y& Elsevier]

Abstract: We examined the relationships between water motion and the distribution, abundance, and sizes (heights) of Amphimedon compressa, an abundant sponge in reefs of La Parguera, Puerto Rico. Amphimedon populations were surveyed at different depths (3, 5, 8 and 12 m) in 3 inner-shelf and 3 mid-shelf reefs, which are protected and fully exposed to wave action respectively. More detailed studies on sponge survival and growth were performed at Las Pelotas (LP), a low wave energy site, and Media Luna West (MLW), a fully exposed reef. The effects of Tropical Storm Dean on sponge survivorship were also evaluated at these reefs. With the exception of an inner-shelf site, Amphimedon was absent in the 3 m depth zone in all reefs. Otherwise, no consistent depth-related patterns in abundances were detected among reefs. Sponges'' heights generally increased with depth with the tallest sponges occurring in the 12 m zone. Survivorships at LP before Dean were not size-specific with semiannual rates averaging 86.3%. Survivorships at MLW before Dean were size-specific with the lowest semiannual rates (69.4%) for large sponges (>20 cm) and the highest (94.5%) for small sponges (<10 cm). Tropical Storm Dean reduced survivorships to 41% and 30% at LP and MLW, respectively. At both sites, small and large sponges suffered significantly more losses compared to the mid-size sponges. Sponge growth rates were significantly higher at LP (4.5 cm yr−1) compared to MLW (1.5 cm yr−1). Growth rates were not size dependent at MLW while larger sponges grew faster at LP. The results of this study suggest that water motion may be an important factor controlling and structuring populations of A. compressa. [Copyright &y& Elsevier]

Tropical weather events can contribute large wet depositional fluxes of biogeochemically important rainwater constituents over relatively short time periods. One composite sample during these events does not capture the dynamic nature of rainwater composition and can lead to misinterpretation of the impact of tropical events on local aquatic systems. Eight sequential samples were collected at 2–3h intervals in Wilmington, NC during the duration of tropical storm Ernesto to examine a suite of rainwater constituents influenced by gas phase, aerosol, or mixed sources in the atmosphere. Real time wind speed and air mass back trajectories were used to examine the progression of the storm. Hydrogen peroxide and nitrate displayed washout trends during the storm. Dissolved organic carbon (DOC), hydrogen ion (H+), and total mercury (HgT) displayed washout at the beginning of the storm but toward the end of the storm concentrations increased, which corresponded to a shift in air masses from marine to terrestrial, increased ground air mass influence, and increased wind speeds. Integrated fluorescence, a measure of the chromophoric properties of the DOC, was highest at the beginning of the storm and than decreased but unlike DOC, the fluorescence did not increase at the end of the storm, indicating a change in the DOC source and composition during the storm. Chloride and sulfate, which are strongly influenced by seasalt aerosols, increased with increasing wind speeds. Factors such as wind speed, storm trajectory, and rainwater volume influenced rainwater constituent concentrations; the relative importance of these factors was a function of the sources of these rainwater constituents in rainwater. [Copyright &y& Elsevier]

Abstract: On 28 and 29 November 2005, the tropical storm Delta struck the Canary Islands (Spain) and the western shores of Morocco. Gravimetric and radiometric measurements carried out in atmospheric aerosol and water samples, collected after the storm, showed increased levels of total suspended particles (TSP) in the atmosphere and gross alpha, gross beta as well as 90Sr activities in both the atmosphere and drinking water. These variations were most likely produced by local re-suspension of soil material. However, 210Pb and 7Be activities, measured in atmospheric aerosols, did not increase until a week after the storm had passed. 40K and 137Cs activities, also measured in atmospheric aerosols, did not vary significantly with respect to previous weeks indicating that the slightly higher levels of TSP, measured during the week when the storm occurred, were not produced by the long-range transport of re-suspended aerosols from the African continent, as it has been observed in other occasions at this site. Gross alpha, gross beta, 40K and 90Sr levels in drinking water samples increased after the storm over their average values by approximately 245%, 245%, 130% and 440%, respectively. These results indicate how important the local re-suspension and later deposition/scavenging of aerosols may be on the water supply in Tenerife. [Copyright &y& Elsevier]

Rapid urban development in hilly terrain, coupled with tropical storms with heavy rainfall, has led to the frequent occurrence of disastrous landslides in Hong Kong. This paper outlines several case histories of such disastrous landslides in Hong Kong and the major efforts that have been made to mitigate landslide hazards in Hong Kong since the mid-1970s. Factors that contributed to such landslides and their causative mechanisms are analyzed. Methods of predicting the runout distance and lateral extent of rainfall-induced slope failures are summarized. Slope maintenance requirements and stabilization measures are delineated, including the stabilization of loose fill slopes. [Copyright &y& Elsevier]

• Spatio-temporal maximum wave heights occur to the north-east of the cyclone's eye, where sea states are more energetic. • Individual waves with normalized extreme heights are met to the south/south-west of the moving cyclone. • Directional spread and bound nonlinear interactions play a significant role in producing extreme waves. • Different physical mechanisms can trigger high waves in the sea regions under cyclone winds. Principles of the spatio-temporal statistics are used to investigate the characteristics of short-term/range extreme sea waves and related sea-state parameters under cyclone winds (northern hemisphere). We base our analysis upon consistent stereo-imaging observations of the 3D (2D space + time) sea surface elevation field, and spectral wave model results in the Northwestern Pacific during tropical storm Kong-rey (2018). The focus is on the extreme value analysis of individual maximum sea surface elevations (crest heights) and maximum crest-to-trough wave heights. Results highlight the sea areas around the storm centre where the spatio-temporal highest waves are more likely, and, via scale analysis, the principal mechanisms responsible for the occurrence of extreme conditions in bimodal (composed of wind-sea and swell) and short-crested storm seas. We find that individual waves are the highest to the north-east of the translating cyclone, where sea states are more energetic. However, in the south/south-west of the centre, where opposing wind-sea/swell sea states dominate, directional spread and bound nonlinear interactions are enhanced. In this area, more extreme waves may occur, having the maximum crest and wave heights mean values in excess of 1.3 and 2.1 times the significant wave height, respectively. This set of results provides insights into the role of the dispersive and directional focusing enhanced by nonlinearities up to the second order as an effective mechanism for the formation of extreme waves under cyclone winds. To examine what physical mechanism is behind the generation of extreme waves in different regions around the cyclone, we also explore for comparison areas where nonlinear four-wave interactions are more likely to occur. [ABSTRACT FROM AUTHOR]

Quantitative analysis on the shape of 959 tropical storm (TS) tracks in the North West Pacific (NWP) basin was carried out over the period from 1977 to 2016 by using International Best Track Archive for Climate Stewardship (IBTrACS) provided by National Oceanic and Atmospheric Administration (NOAA) based on an established track sinuosity metric. Track sinuosity is a measure of deviation of a storm track from its straight–line path between the cyclogenesis and cyclolysis locations. More sinuosity in the storms' tracks makes it rather challenging for the atmospheric models to accurately assess the storms' respective locations on the map and potentially causes higher damages due to lack of precise information about their movement. Statistical analysis was carried out on spatial and temporal trends (monthly to decadal) of the TS track shape and the obtained results were mapped based on sinuosity categories within a GIS environment. The sinuosity distribution results are normalized using a cube–root transformation function to reduce skewness and obtain sinuosity index (SI). Distinct enhancement of TS sinuosity was noticed from the months July to October (JASO). It is also detected that early months of TS season like June–August have dominance of more predictable straighter storm tracks over sinuous kind of tracks, and vice-versa in the case of late months of season like September–October. It is also evident that there is a one- to three-year cyclic pattern of changing sinuosity over the NWP basin. The 1987–1996 decade had the maximum dominance of sinuous tracks in comparison to the other three decades. Significant longitudinal eastward shift (from 110°–140° E to 130°–160° E) in majority of cyclogenesis locations is observed as sinuosity in storm track increases from straight to sinuous patterns. Similar shift for latitudinal track was not found. Finally, we investigate the sinuosity based on the warm/cold phase of the ENSO. Warm phase of ENSO is found to be associated with a greater number of TS with higher SI values in the NWP basin. These TS during warm phase mostly originate in the eastern part of the basin where a vast open area of warm sea surface temperature encourages their formation and intensification. Lastly, the study found a moderate positive relationship between SI and TS' longevity and distance coverage, which are crucial information for disaster risk assessment, mitigation and preparedness. • From July to October the TS tracks gradually increase their sinuosity in the NWP. • Eastward shift in most of TS genesis positions is seen with increase in track sinuosity. • Warm phase of ENSO is associated with a greater number of TS with higher SI values. • Early cyclone season months dominance of sinuous TS tracks vice-versa in late months. [ABSTRACT FROM AUTHOR]

The holes that woodpeckers excavate and use for nesting are important for many other cavity-nesting birds. The availability of appropriate substrate for cavity excavation in an urban environment is an important factor governing the abundance of woodpecker nest cavities. To understand the impacts of hurricane disturbance on characteristics of trees used by cavity-nesting birds, we surveyed woodpecker cavities in urban southeast Florida before and after Hurricane Irma in 2017. We used these data to understand which cavities were most likely to persist after the hurricane, and compare cavity tree characteristics before and after the storm. Woodpecker cavities in dead slash pine (Pinus elliottii var. densa) trees (snags) fared poorly compared to cavities in palm (Arecaceae) snags, hardwoods (live and dead), and wood utility poles. In the year after Hurricane Irma, the proportion of new cavities in palm snags increased relative to other substrates, while the proportion of cavities excavated in pines, hardwoods, and utility poles decreased. Trees excavated in the year after Hurricane Irma were 23 % shorter than trees with cavities found before the hurricane, suggesting that available trees were smaller. The decay class of trees and the number of woodpecker holes did not significantly affect the persistence rates of woodpecker cavity trees. We speculate that because palms generally have softer wood, their physical structure could make them more attractive to woodpeckers in the first year after a storm. The results of this study are relevant to the management of dead trees in urban areas in hurricane-prone regions, which are experiencing high urban growth. Cutting urban palm snags immediately following a storm removes a critical resource for woodpeckers during the first year of recovery. [ABSTRACT FROM AUTHOR]