Island arc debris avalanches and tsunami generation

Abstract

On the early morning of 13 March 1888, roughly five cubic kilometers of the Ritter Island volcano fell violently into the sea northeast of Papua New Guinea (Figure 1). This event, the largest lateral collapse of a volcanic island in historical time, flung devastating tsunamis tens of meters high onto adjacent shores [Cooke, 1981]. Calamitous as they might be, natural disasters like these must be viewed in perspective. One should ask, “Were the events of that March day unique, or are they common geological occurrences?” Partly to address this question, a seafloor imaging and sampling program was conducted around Ritter Island and elsewhere along the Bismarck volcanic arc during November–December 2004 on the research vessel Kilo Moana.

Offshore evidence of large-scale lateral collapses on the eastern flank of Stromboli, Italy, due to structurally-controlled, bilateral flank instability

“…The availability of high-resolution geophysical data on the submarine portion of the volcano uncovers a new scenario. Indeed, on land, geological evidence of flank instability may be easily erased or buried beneath younger volcanic products, often causing major disparities between subaerial and subaqueous remnants of collapses (see, for instance: Oshima-Oshima volcano, Satake and Kato, 2001;Ritter volcano, Johnson, 1987;Silver et al, 2005).…”

Late Pleistocene stratigraphy of IODP Site U1396 and compiled chronology offshore of south and south west Montserrat, Lesser Antilles

“…Volcanic islands can be the source of hazardous eruptions and undergo flank collapses that generate offshore debris avalanche deposits and associated tsunamis [ Masson et al ., ]. Deposits derived from a variety of mass‐wasting processes, including large landslides, have been identified from a number of volcanic islands, including the Aleutian Islands [ Waythomas et al ., ], Hawaii [ Moore et al ., ], Ritter Island, Papua New Guinea [ Silver et al ., ], the Canary Islands [ Hunt et al ., ], and Ischia [ Chiocci and De Alteriis , ], demonstrating that the interaction of volcanic processes with the marine environment is widespread. It is, therefore, important to understand the chronology of past events at a volcanic island to assess the most likely future hazards, their frequency, and temporal variation in activity.…”

Support for the Giant Wave Hypothesis: evidence from submerged terraces off Lanai, Hawaii

“…Recent observational and modelling investigations of the flanks of Tahiti-Nui (Hildenbrand et al 2006), La Palma (Canary Islands) (Ward and Day 2001), Reunion (Labazuy 1996) and Ritter Islands (Papua New Guinea) (Ward and Day 2003;Silver et al 2005) indicate that massive landslides are common features of tropical, volcanic islands. Given the large run ups possible (> 170-400 m) in the Hawaiian Islands (this study and Moore and Moore 1988;Moore et al 1994;McMurtry et al 2004a), it is entirely plausible that subaerial coral conglomerate and boulder deposits observed on other tropical islands such as Papua New Guinea (Morgan et al 2005) and Mauritius (Camoin et al 2004) were emplaced by tsunami waves.…”