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Tsunami Intensity: A Valuable Parameter of Multiple Usefulness Papadopoulos G.A., Daskalaki E., Fokaefs A. Institute of Geodynamics National Observatory of Athens, Greece email@example.com
Intensity of natural phenomena Size of a natural event is traditionally measured by the intensity that is the impact of the event Examples • Beaufort 12-point scale for wind • Saffir-Simpson 5-point scale for typhoons • Mercalli-Sieberg 12-point scale for earthquakes • EMS-98 new 12-point scale for earthquakes
Modern measure of the size of a natural event is magnitude which expresses the energy of the event Examples Richter and moment-magnitude scales for earthquakes Newhall-Self 8-point scale for volcanic eruptions Iida scale for tsunamis Magnitude of natural phenomena
Size of a tsunami based on the macroscopic observation of tsunami’s effect on humans, objects, including various size of marine vessels and buildings What factors control the disastrous effects of the tsunami? - humans, - effects on objects (e.g. vessels of variable size), - nature (e.g. ground erosion), - damage to buildings. Tsunami intensity
12-point tsunami intensity scale • Incorporates twelve divisions • Is consistent with several 12-grade seismic intensity scales. (Papadopoulos & Imamura, 2001) • Independent from physical parameters • Sensitive to the small difference in tsunami effects • Detailed description of each division by taking into account all possible tsunami impacts on human and natural environment
Empirical correlation between the intensity K, introduced by Papadopoulos & Imamura (2001) and the quantities H and i introduced in formula by Shuto (1993) K H(m) i I-V <1.0 0VI 2.0 1VII-VIII 4.0 2IX-X 8.0 3XI 16.0 4XII 32.0 5
The 12-point scale has been used in: • Indian Ocean after the tsunami of 2004 (Narayan J.P. et al., Pure & Applied Geophysics, 163, 1279p., 2006; Rossetto T. et al., Natural Hazards, 2006; Maheshwari et al., Earthquake Spectra, 23/III, S475p.; Chang et al., Earthquake Spectra, 23/III, S863p.) • Black Sea (Yalciner A. et al., J. Geophys. Res., 109, C12023p., 2004) • Mediterranean Sea (Tinti, S. et al., Marine Geology, 225, 311p., 2006) • Azores Islands (Andrade C, J. Volcanol. & Geoth. Res., 156, 172p., 2006) • Australia (Dominey-Howes, D., Marine Geology, 239, 99p., 2007) • Indonesia (Lavinge et al., Nat. Hazards Earth Syst. Sci., 177p., 7, 2007) • Portugal (Baptista et al., NHESS, 2009)
Further Presentation of the 12-scale can be found in the following books: • Β. Levin & Μ. Nosov: Physics of Tsunamis & Kindred Phenomena in Ocean, Moscow, Janus-K, 2005; Physics of Tsunamis, Springer, 2009. • Tsunami Glossary from the Intergovernmental Oceanographic Commission of UNESCO and the International Tsunami Information Centre, USA, 20p, 2006. • M. Woods & Μ.B. Woods: Tsunamis, Lerner Publ. Comp., Minneapolis, 2007. • E. Guidoboni & J.E. Ebel: Earthquakes & Tsunamis in the Past: A guide to techniques in historical seismology, 2009.
Possible applications of the new 12-point tsunami intensity scale • Revision of tsunami catalogues • Mapping the geographical distribution of the impact of past tsunamis • Description of the tsunami impact by intensity isolines • Construction of empirical attenuation laws of the tsunami impact • Tsunami statistics
Indian Ocean 2004 Intensities Observation points: 206
Indian Ocean 2004 Intensities Observation points: 53
Indian Ocean 2004 Intensities Observation points: 149
Tsunamicity of Greece: the highest in the Euro-Mediterranean region Papadopoulos & Fokaefs, 2005
VI-VIII IV V III
Wave attenuation of 9th July 1956 3 largest intensities K per 50km / epicentral distances Attenuation law /epicentral distances
Earthquake Statistics • Magnitude-frequency or G-R relation (Gutenberg and Richter, 1944) extensively used in seismology to describe the exponential decrease of the event frequency, Nc, with the increase of the event magnitude, M:
Application of the tsunami statistics: West Hellenic Arc • Intensity-frequency → equivalent to the magnitude-frequency or G-R relation (Gutenberg & Richter, 1944) used in seismology: • Describes the exponential degree of the event frequency with the decrease of the event size • Excluding frequencies of events with K ≥ 3:
From it comes out that the mean repeat time, TK, of events of intensity equal to or larger than K is: or the mean yearly rate of occurrence is maximum intensity, Kmax, which is the most probable to be observed within time interval t is given by the expression
Poissonian Statistics • From the mean yearly rate of tsunami occurrence we calculated the probability, , to observe at least one tsunami of intensity K equal to or larger than a given value within particular time interval, t. • The probability to observe x events in t years is while the probability to observe at least one tsunami event in t years is
Seismic damage: e.g. Bucharest, 4 March, 1997, M= 7.4 intensity map shake map SAFER Project, EU-FP6, 2009, Partner NIEP, Romania
Possible future application for tsunamis • Construction of expected tsunami damage maps in terms of tsunami intensity in analogy to expected seismic damage • This requires: - inundation zone from numerical simulation - Vulnerability analysis - Damage scenario