pararas - EVALUATION OF THE THREAT OF MEGA TSUNAMI...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
POSTULATED MASSIVE SLOPE FAILURES OF ISLAND STRATOVOLCANOES ON LA PALMA, CANARY ISLANDS, AND ON THE ISLAND OF HAWAII George Pararas-Carayannis Honolulu, Hawaii ABSTRACT Massive flank failures of island stratovolcanoes are extremely rare phenomena and none have occurred within recorded history. Recent numerical modeling studies, forecasting mega tsunami generation from postulated, massive slope failures of Cumbre Vieja in La Palma, Canary Islands, and Kilauea, in Hawaii, have been based on incorrect assumptions of volcanic island slope instability, source dimensions, speed of failure and tsunami coupling mechanisms. Incorrect input parameters and treatment of wave energy propagation and dispersion, have led to overestimates of tsunami far field effects. Inappropriate media attention and publicity to such probabilistic results have created unnecessary anxiety that mega tsunamis may be imminent and may devastate densely populated coastlines at locations distant from the source - in both the Atlantic and Pacific Oceans. The present study examines the assumptions and input parameters used by probabilistic numerical models and evaluates the threat of mega tsunami generation from flank failures of island stratovolcanoes. Based on geologic evidence and historic events, it concludes that massive flank collapses of Cumbre Vieja or Kilauea volcanoes are extremely unlikely to occur in the near geologic future. The flanks of these island stratovolcanoes will continue to slip aseismically, as in the past. Sudden slope failures can be expected to occur along faults paralleling rift zones, but these will occur in phases, over a period of time, and not necessarily as single, sudden, large-scale, massive collapses. Most of the failures will occur in the upper flanks of the volcanoes, above and below sea level, rather than at the basal decollement region on the ocean floor. The sudden flank failures of the volcanoes of Mauna Loa and Kilauea in 1868 and 1975 and the resulting earthquakes generated only destructive local tsunamis with insignificant far field effects. Caldera collapses and large slope failures associated with volcanic explosions of Krakatau in 1883 and of Santorin in 1490 B.C., generated catastrophic local tsunamis, but no waves of significance at distant locations. Mega tsunami generation, even from the larger slope failures of island stratovolcanoes, is extremely unlikely to occur. Greater source dimensions and longer wave periods are required to generate tsunamis that can have significant, far field effects. The threat of mega tsunami generation from massive flank failures of island stratovolcanoes has been greatly overstated. Science of Tsunami Hazards, Volume 20, Number 5, page 251 - 277 (2002
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/31/2011 for the course GLY 4921 taught by Professor Snow,e during the Spring '08 term at University of South Florida - Tampa.

Page1 / 27

pararas - EVALUATION OF THE THREAT OF MEGA TSUNAMI...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online