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Sea Hazards” Atmospheric Atmospheric Measurement Measurement E EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Nat. Hazards Earth Syst. Sci., 13, 1063–1067, 2013 Natural Hazards Natural Hazards www.nat-hazards-earth-syst-sci.net/13/1063/2013/ doi:10.5194/nhess-13-1063-2013 and Earth System and Earth System © Author(s) 2013. CC Attribution 3.0 License. Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry and Physics and Physics Preface Discussions Open Access Open Access “Sea hazards” Atmospheric Atmospheric Measurement Measurement E. Pelinovsky1, I. Didenkulova2,3, F. Mendez4, D. Rybski5, and S. Tinti6 Techniques Techniques 1 Department of Nonlinear Geophysical Processes, Institute of Applied Physics, Nizhny Novgorod, Russia Discussions 2 Open Access Laboratory of Wave Engineering, Institute of Cybernetics, Tallinn University of Technology, Tallinn, Estonia Open Access 3Nizhny Novgorod State Technical University, Nizhny Novgorod, Russia 4 Environmental Hydraulics Institute “IH Cantabria”, Universidad de Cantabria, Santander,Biogeosciences Spain Biogeosciences 5Potsdam Institute for Climate Impact Research, Potsdam, Germany Discussions 6Dipartimento di Fisica e Astronomia, Universita` di Bologna, Bologna, Italy Open Access Correspondence to: I. Didenkulova ([email protected]) Open Access Climate Climate 1 Tsunamis finding on tsunami coastal distributionof the Past by Van Dorn (1965) of the Past and by Kajiura (1983) who studied tsunami events in Hawaii Discussions and in Japan, respectively. What is new in Choi et al.’s (2012) Tsunamis are the most known and most disastrous sea haz- Open Access analysis is that the log-normal distribution was proven to be Open Access ards and can occur in all world oceans as well as in closed fitted by the experimental data only when they are statisti- Earth System or almost closed seas like the Mediterranean. Interest in cally independent. This issueEarth was notSystem evident while handling tsunamis has substantially increased in the last few years, es- data of the historical tsunamisDynamics (1896 and 1933) since those Dynamics pecially after the case of the 2004 Indian Ocean tsunami that data were too few and referring to coastal places usually Discussions devastated the coasts of several near-field and far-field coun- several kilometers apart (which ensures their independence). tries and that claimed a death toll of about 220 thousands Instead, it came to light with the 2011 tsunami where the Open Access Open Access human lives mostly in Indonesia, India, Sri Lanka and Thai- space density of data is quiteGeoscientific larger (many observations were Geoscientific land. Since then and even more after the big Japan tsunami taken in locations very closeInstrumentation to each other). It was found that Instrumentation of 11 March 2011, the issues of what we can learn from to get statistical independence and log-normal distribution, past experiences and of how coastal communities can be pro- Methods and Methods and data should be averaged overData a scale Systems not smaller than 7.5 km, tected from the attack of catastrophic tsunamis have become which therefore can be taken as a sort of data correlation dis- Data Systems of paramount importance. tance. How this distance is related to basic geomorphologi- Discussions Open Access This SI collects a number of papers on the Tohoku tsunami Open Access cal features of the bathymetry and topography of the coastal Geoscientific that address different aspects of this event. Choi et al. (2012) zone is an issue still unresolved.Geoscientific study the run-up heights of the 2011 tsunami and compare The Tohoku tsunami hit the Japan coasts catastrophically, Model Development them with the data from the largest tsunamis that attacked Model Development but also reached significant wave heights in very distant Discussions the east Japanese coast in the last 150 yr, namely the Meiji coasts after travelling across the Pacific. Numerical codes Sanriku tsunami of 1896 and the Showa Sanriku tsunami Open Access for tsunami generation and propagation are indispensableOpen Access of 1933. The main interest of the authors was the study of tools to compute tsunamiHydrology radiation from and the source areas Hydrology and the space distribution of the run-up heights along the coast. and to provide adequate estimates of tsunami amplitude and Data are very abundant for the 2011 tsunami (more than travel times. In operationalEarth tsunami System warning systems, one Earth System 5000 data points) since the post-event surveys carried out by of the main constraints is time,Sciences since obviously predictions Sciences local experts and by international teams investigated the af- should be made and transmitted to the threatened commu- fected coastal areas (about 300 km long) with great accuracy. Discussions Open Access nities before the tsunami attacks. To meet thisOpen Access requirement, In contrast, the available observations for the 1896 and 1933 the most common strategy is to pre-compute a database of tsunamis are quite less (132 and 205, respectively). It was tsunami scenarios and, in case of tsunami occurrence, to ex- Ocean Science found that the space distribution of the observed run-ups is Ocean Science tract the case or cases that are most suited to (i.e. best fit) Discussions basically log-normal, which is a confirmation of the original Open Access Published by Copernicus Publications on behalf of the European Geosciences Union. Open Access Solid Earth Solid Earth Discussions Open Access Open Access The Cryosphere The Cryosphere Discussions 1064 E. Pelinovsky et al.: Preface “Sea hazards” the data from the monitoring networks. This strategy is moti- and Tinti noted that, though the highest values were mea- vated by the fact that tsunami simulations are usually very sured in the Japanese stations (close to the source; notice time-consuming and there would be no time to run simu- however that the tide gauges were destroyed and their data lations under an impending tsunami. Popinet (2012) argues went lost), there is no clear decrease of the tsunami height that adaptive codes can be used instead of fixed-grid numeri- with distance and very large heights (in excess of 2 m) were cal codes to cut down the computation time significantly even measured in some of the Hawaiian and of Chilean stations. for propagation over large oceanic areas, which can possibly Regional tsunami warning systems worldwide are today allow also real-time computations. Indeed Popinet uses an based on first reaction to large earthquakes. Though in gen- adaptive quadtree-based discretization algorithm to densify eral warning operations are quite complex and though dif- cells where it is dynamically needed, i.e. depending on the ferent procedures are established and followed by different characteristics of the tsunami waves, which reduces the total warning systems, the starting point of the operational proto- number of grid cells and hence of the required mathematical col is quite standard for most of them: i.e. the first decision operations. Whereas the computational cost of typical non- on tsunami occurrence is based on seismic data, more specif- flexible tsunami codes increases by a factor of 4 when the ically on the earthquake magnitude and hypocentral location, grid resolution doubles, adaptive methods tend to confine the since these determinations can be made in a few minutes cost increase to a factor of 2.60–2.65 (Popinet, 2011), which (less than 2–3 min) with the present level of technology by is a remarkable advantage. The application of this code to using seismic networks and seismic processing procedure of the Tohoku tsunami propagation in the near-field (with 250 m standard quality. Practically, a decision matrix is defined in resolution during flooding) and over long oceanic distances a way that, on entering earthquake magnitude, hypocentral (where cells size can be as big as 250 km) also provides re- depth and epicentral distance from the coast, it provides the sults in satisfactory agreement with the observations as re- alert level for the countries in the area covered by the warn- gards inundation on the Japan coasts and DART buoy records ing center. This first raw-decision bulletin can be later up- in the far-field. dated as a consequence of more sophisticated analyses made As already noted above, data for the 2011 Japan tsunami possible by the availability of more data. This strategy has are very abundant and indeed this is the tsunami event with also been defined and approved in the European region, i.e. the largest base of data recorded in the whole tsunami his- the last region in the world where tsunami warning centers tory, including coastal tide gauge and offshore buoy records. have been established and have started to be operational. Bressan and Tinti (2012) analyzed as many as 123 records of Here, the coordination body of the tsunami warning sys- tide gauges from most of the countries of the Pacific ocean to tems, called ICG/NEAMTWS (Intergovernmental Coordina- study tsunami changes in coastal waters and to test the per- tion Group for the North-East Atlantic and Mediterranean formance of the tsunami detection algorithm called TEDA: Tsunami Warning System), operating in the frame of the this is devised for real-time detection and is the combination IOC (Intergovernmental Oceanographic Commission) within of two threshold algorithms one based on time gradient and UNESCO, has adopted a specific decision
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