Hazard potential of volcanic flank collapses raised by new megatsunami evidence

Ramalho, Ricardo S.; Winckler, Gisela; Madeira, José; Helffrich, George; Hipólito, Ana; Quartau, Rui; Adena, K.; Schaefer, Joerg M.

doi:10.1126/sciadv.1500456

Cited by 102 publications

(113 citation statements)

References 52 publications

Supporting

Mentioning

108

Contrasting

Order By: Relevance

“…(). In general, tsunami deposits typically mantle the topography (even on steep slopes) and are usually preserved as patches (lenticular geometry) at different elevations (Moore & Moore, ; Moore, ; McMurtry et al ., ,b; Perez‐Torrado et al ., ; Paris et al ., , , ; Ramalho et al ., ). Additionally, tsunami conglomerates and gravel beds almost invariably exhibit chaotic textures, being either clast or matrix‐supported but generally featuring a mixing of sediments from different sources redistributed both inland and offshore (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…Additionally, tsunami conglomerates and gravel beds almost invariably exhibit chaotic textures, being either clast or matrix‐supported but generally featuring a mixing of sediments from different sources redistributed both inland and offshore (i.e. terrestrial and marine) (Perez‐Torrado et al ., ; Ramalho et al ., ; Paris et al ., , ). Grain‐size distribution is commonly highly heterogeneous, often including large boulders ‘floating’ in finer conglomeratic or sandy matrixes and frequently displaying a mixture of both well‐rounded and angular boulders/pebbles (Moore & Moore, ; Moore, ; McMurtry et al ., ,b; Perez‐Torrado et al ., ; Paris et al ., , , ).…”

Section: Methodsmentioning

confidence: 99%

“…The collapse of Fogo volcano, in Cape Verde, is yet another example of a tsunamigenic event that resulted in a devastating impact to adjacent coastlines. Effectively, fields of stranded megaclasts (up to 243 m 3 ) and chaotic marine conglomerates occur in the adjacent island of Santiago, up to 220 m of elevation, attesting to the impact of a tsunami triggered by this collapse at ca 73 ka (Paris et al ., , ; Ramalho et al ., ; Martínez‐Moreno et al ., ). These deposits imply tsunami runups exceeding 270 m along the northern shore of Santiago, once again confirming the hazard potential of volcanic flank collapses as near‐field sources of highly devastating tsunamis (Ramalho et al ., ; Paris et al ., ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A geological record of multiple Pleistocene tsunami inundations in an oceanic island: The case of Maio, Cape Verde

et al. 2019

Self Cite

View full text Add to dashboard Cite

In the Central Atlantic archipelagos – the Canaries, Cape Verde, Madeira and the Azores – tsunami hazard is often regarded as low, when compared with other extreme wave events such as hurricanes and storms. The geological record of many of these islands, however, suggests that tsunami hazard may be underestimated, notwithstanding being lower than in areas adjacent to subduction zones, such as the margins of the Pacific and Indian oceans. Moreover, tsunamis in oceanic islands are generally triggered by local large‐scale volcanic flank collapses, for which little is known about their frequency, making it difficult to estimate the probability of a new occurrence. Part of the problem lies in the fact that tsunami deposits are usually difficult to date, and few islands in the world exhibit evidence for repeated tsunami inundation on a protracted timescale. This study reports on the presence of abundant tsunami deposits (conglomerates and sandstones) on Maio Island (Cape Verde) and discusses their stratigraphy, sedimentological characteristics, probable age and tsunamigenic source. Observations indicate that four distinct inundation events of variable magnitude took place during the Pleistocene. One of the tsunami deposits yielded a high‐confidence U/Th age of 78·8 ± 0·9 ka, which overlaps within error with the 73 ± 7 ka age proposed for Fogo volcano's flank collapse, an event known to have had a significant tsunami impact on nearby Santiago Island. This shows that the Fogo tsunami also impacted Maio, resulting in runups in excess of 60 m above coeval sea‐level at ca 120 km from the source. Two older deposits, possibly linked to recurrent flank collapses of the Tope de Coroa volcano in Santo Antão Island, yielded lower‐confidence ages of 479 to 390 ka and 360 to 304 ka. A younger deposit (<78 ka) remains undated. In summary, the geological record of Maio exhibits well‐preserved evidence of repeated tsunami inundation, reinforcing the notion that tsunami hazard is not so low at volcanic archipelagos featuring prominent and highly‐active volcanoes such as in Cape Verde.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A geological record of multiple Pleistocene tsunami inundations in an oceanic island: The case of Maio, Cape Verde

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The summit is truncated at ~1700 m a.s.l. by the Cha Caldera (Figure 1c), a 9 km wide depression open to East (E) by a flank collapse scar [35] formed ~73 ka [36]. The upper part of this depression has a flat bottom, confined to the North (N), W and South (S) by the 1000 m high vertical cliff known as Bordeira (Figure 1c).…”

Section: Geologic Backgroundmentioning

confidence: 99%

Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014–2015 Effusive Eruption at Fogo Volcano (Cape Verde)

et al. 2018

View full text Add to dashboard Cite

Fogo volcano erupted in 2014-2015 producing an extensive lava flow field in the summit caldera that destroyed two villages, Portela and Bangaeira. The eruption started with powerful explosive activity, lava fountains, and a substantial ash column accompanying the opening of an eruptive fissure. Lava flows spreading from the base of the eruptive fissure produced three arterial lava flows. By a week after the start of the eruption, a master lava tube had already developed within the eruptive fissure and along the arterial flow. In this paper, we analyze the emplacement processes based on observations carried out directly on the lava flow field, remote sensing measurements carried out with a thermal camera, SO 2 fluxes, and satellite images, to unravel the key factors leading to the development of lava tubes. These were responsible for the rapid expansion of lava for thẽ 7.9 km length of the flow field, as well as the destruction of the Portela and Bangaeira villages. The key factors leading to the development of tubes were the low topography and the steady magma supply rate along the arterial lava flow. Comparing time-averaged discharge rates (TADR) obtained from satellite and Supply Rate (SR) derived from SO 2 flux data, we estimate the amount and timing of the lava flow field endogenous growth, with the aim of developing a tool that could be used for hazard assessment and risk mitigation at this and other volcanoes.

show abstract

“…With a volume of 5 km 3 the collapse of Ritter Island (Papua New Guinea) in 1888 was the largest historical volcano flank failure and the tsunami devastated all the coasts of the Bismarck Sea at distances up to 500 km from the volcano (Ward & Day, ). (3) Tsunami conglomerates found at unusually high elevations in Hawaii, the Cape Verde, and Canary Islands represent geological evidence of megatsunamis generated by massive (tens to hundreds of cubic kilometers) flank failures of oceanic shield volcanoes (Moore & Moore, ; McMurtry et al, ; Pérez Torrado et al, ; Paris et al, ; Ramalho et al, ). Recent studies suggest that these failures are often retrogressive (Hunt et al, ; Giachetti et al, ) and sometimes coupled with major explosive eruptions (Paris et al, ).…”

Section: Tsunami Generation and Propagation: Causes Mechanisms And mentioning

confidence: 99%

Probabilistic Tsunami Hazard Analysis: Multiple Sources and Global Applications

Grezio

Babeyko²,

Baptista

et al. 2017

Reviews of Geophysics

210

165

View full text Add to dashboard Cite

Applying probabilistic methods to infrequent but devastating natural events is intrinsically challenging. For tsunami analyses, a suite of geophysical assessments should be in principle evaluated because of the different causes generating tsunamis (earthquakes, landslides, volcanic activity, meteorological events, and asteroid impacts) with varying mean recurrence rates. Probabilistic Tsunami Hazard Analyses (PTHAs) are conducted in different areas of the world at global, regional, and local scales with the aim of understanding tsunami hazard to inform tsunami risk reduction activities. PTHAs enhance knowledge of the potential tsunamigenic threat by estimating the probability of exceeding specific levels of tsunami intensity metrics (e.g., run‐up or maximum inundation heights) within a certain period of time (exposure time) at given locations (target sites); these estimates can be summarized in hazard maps or hazard curves. This discussion presents a broad overview of PTHA, including (i) sources and mechanisms of tsunami generation, emphasizing the variety and complexity of the tsunami sources and their generation mechanisms, (ii) developments in modeling the propagation and impact of tsunami waves, and (iii) statistical procedures for tsunami hazard estimates that include the associated epistemic and aleatoric uncertainties. Key elements in understanding the potential tsunami hazard are discussed, in light of the rapid development of PTHA methods during the last decade and the globally distributed applications, including the importance of considering multiple sources, their relative intensities, probabilities of occurrence, and uncertainties in an integrated and consistent probabilistic framework.

show abstract

Hazard potential of volcanic flank collapses raised by new megatsunami evidence

Abstract: Giant tsunami triggered by catastrophic flank collapse of Fogo volcano.

Cited by 102 publications

References 52 publications

A geological record of multiple Pleistocene tsunami inundations in an oceanic island: The case of Maio, Cape Verde

A geological record of multiple Pleistocene tsunami inundations in an oceanic island: The case of Maio, Cape Verde

Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014–2015 Effusive Eruption at Fogo Volcano (Cape Verde)

Probabilistic Tsunami Hazard Analysis: Multiple Sources and Global Applications

Contact Info

Product

Resources

About