How hazardous are tsunamis triggered by small-scale mass-wasting events on volcanic islands? New insights from Madeira – NE Atlantic

Omira, Rachid; Baptista, Maria Ana; Quartau, Rui; Ramalho, Ricardo S.; Kim, Jihwan; Ramalho, Inês; Rodrigues, Armanda

doi:10.1016/j.epsl.2021.117333

Cited by 12 publications

(7 citation statements)

References 53 publications

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“…The short travel time of the waves to the threatened coasts and the absence of real-time monitoring systems make the implementation of forecasting capabilities for such tsunami events quite challenging (Omira et al, 2022a). Nevertheless, it should also be noted that in cases where the maximum inundation takes place much later than the initial tsunami arrival, the time window of the tsunami early warning increases due to the dispersive nature of the wave propagation along the coast (Bellotti et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Landslide Induced Tsunami Hazard at Volcanoes: the Case of Santorini

Necmioğlu

Heidarzadeh

Vougioukalakis

et al. 2023

Pure Appl. Geophys.

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The destructive tsunami on 22 December 2018 due to the flank collapse of the Anak Krakatau volcano was a bitter reminder of large tsunami risks and of the shortcomings of the existing tsunami warning systems for atypical sources (tsunamis generated by non-seismic and complex sources). In the Mediterranean, several tsunamis were generated by landslides associated with volcanic systems in the past.The volcanic unrest experienced in 2011–2012 on the Santorini volcanic island in the Southern Aegean Sea pointed out the need to identify and quantify tsunami hazard and risk due to possible flank instability which may be triggered as a result of volcanic unrest or nearby seismotectonic activities. Inspired from this need, in this study we examined three possible landslide scenarios in Santorini Island with tsunamigenic potential. The results show that the scenarios considered in our study are able to generate significant local tsunamis impacting Santorini and the nearby islands, as well as producing significant impact along the coasts of the Southern Aegean Sea. While maximum tsunami amplitudes/arrival time ranges are 1.2 m/30-90 min for locations in the Greek-Turkish coasts in the far field, they are in the order of ≈60 m/1-2 min for some locations at the Santorini Island. The extreme tsunami amplitudes and short arrival times for locations inside the Santorini Island is a major challenge in terms of tsunami hazard warning and mitigation. As an effort to address this challenge, a discussion on the requirements for local tsunami warning system addressing atypical sources in the context of multi-hazard disaster risk reduction is also provided.

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Section: Discussionmentioning

confidence: 99%

Landslide Induced Tsunami Hazard at Volcanoes: the Case of Santorini

Necmioğlu

Heidarzadeh

Vougioukalakis

et al. 2023

Pure Appl. Geophys.

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“…Apparent evacuated volume (Ve void ) the void space in the source area. Ve void is calculated following the approach of Völker (2010) where the volume of evacuated landslide material is calculated by comparing the present-day with the reconstructed pre-failure sea oors (e.g, Omira et al, 2022;Sun et al, 2018;Webster et al, 2016). The prefailure sea oor of the source area of Ana Slide is reconstructed by manually interpolating the course of local and regional contour lines from outside the landslide scar into the inside of it using the contour-line approach (Fig.…”

Section: Datasetsmentioning

confidence: 99%

Assessment of Submarine Landslide Volume

Sager

Urlaub

Berndt

2023

Preprint

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Submarine landslides pose major geohazards as they can destroy seafloor infrastructure such as communication cables and cause tsunamis. The volume of material displaced with the landslide is one factor that determines its hazard and is typically estimated using bathymetric and/or seismic datasets. Here, we review methods to determine the initial failed volume based on a well-constrained case study, the Ana Slide, a small slope failure in the Eivissa Channel off the eastern Iberian Peninsula. We find that not only the availability and quality of datasets but also the emplacement mechanism determines the quality of the volume estimation. In general, the volume estimation based on comparison of modern and reconstructed pre-failure seafloor topographies yields conservative, yet robust volumes for the amount of material that was mobilized. In contrast, volume estimated from seismic data may be prone to overestimation if no detailed constraints on the nature of the chaotic, transparent, or disrupted seismic facies commonly used to identify landslide material are available.

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“…With no more quantitative constraint of the seafloor deformation, we tentatively assume 𝐻 as 10-15 m, then the possible dimension of seafloor crustal deformation responsible for the small-scale tsunami could be in the scale of 0.8-1.8 km (Figure 9a). The estimated size is very likely from partial caldera collapse that usually has limited scale in volcanic site (Ramalho et al, 2015;Omira et al, 2022). If it is the case, the partial flank collapse could be located between Hunga Tonga and Hunga Ha'apai Islands.…”

Section: Tsunami From Caldera Collapse and Its Long-distance Travelin...mentioning

confidence: 99%

The characteristics of the 2022 Tonga volcanic tsunami in the Pacific Ocean

Gui

Ren

et al. 2022

Preprint

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Abstract. On 15th January 2022, an exceptional eruption of Hunga Tonga–Hunga Ha’apai volcano generated atmospheric and tsunami waves that were widely observed at oceans globally, gaining a remarkable attention to scientists in related fields. The tsunamigenic mechanism of this rare event remains an enigmatic due to its complexity and lacking of direct underwater observations. Here, to explore the tsunamigenic mechanisms of this volcanic tsunami event and its hydrodynamic processes in the Pacific Ocean, we conduct tsunami waveform and spectral analyses of the waveform recordings at 116 coastal gauges and 38 deep-ocean buoys across the Pacific Ocean. Combined with the constraints of some representative barometers, we obtain the plausible tsunamigenic origins during the volcano activity. We identify four distinct tsunami wave components generated by air-sea coupling and seafloor crustal deformation. Those tsunami components are differentiated by their different propagating speeds or period bands. The first-arriving tsunami component with ~80–100 min period was from shock waves spreading at a velocity of ~1000 m/s in the vicinity of the eruption. The second component with extraordinary tsunami amplitude in deep sea was from Lamb waves. The Lamb wave with ~30–40 min period radically propagated outward from the eruption site with spatially decreasing propagation velocities from ~340 m/s to ~315m/s. The third component with ~10–30 min period was probably from some atmospheric gravity wave modes propagating faster than 200 m/s but slower than Lamb waves. The last component with ~3–5 min period originated from partial caldera collapse with dimension of ~0.8–1.8 km. Surprisingly, the 2022 Tonga volcanic tsunami produced long oscillation in the Pacific Ocean which is comparable with those of the 2011 Tohoku tsunami. We point out that the long oscillation is not only associated with the resonance effect with the atmospheric acoustic-gravity waves, but more importantly the interactions with local bathymetry. This rare event also calls for more attention to the tsunami hazards produced by atypical tsunamigenic source, e.g., volcanic eruption.

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How hazardous are tsunamis triggered by small-scale mass-wasting events on volcanic islands? New insights from Madeira – NE Atlantic

Cited by 12 publications

References 53 publications

Landslide Induced Tsunami Hazard at Volcanoes: the Case of Santorini

Landslide Induced Tsunami Hazard at Volcanoes: the Case of Santorini

Assessment of Submarine Landslide Volume

The characteristics of the 2022 Tonga volcanic tsunami in the Pacific Ocean

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