Tsunami Warning

This paper discusses various Information and Communication Tools  in the form of  Internet, GIS, Remote Sensing, Satellite communication for Disaster preparedness, warning and forecasting, Mitigation and Management

Keywords: Internet, GIS, Remote Sensing, Satellite-Based Communication, Warning and Forecasting, Financial and Administrative Arrangements.

"The Great East Japan moment magnitude (Mw) 9.0 earthquake occurred at 14:46 (Japanese Standard Time) on March 11th 2011. Significant seabed displacement generated thesubsequent tsunami, which caused significant damage in Iwate, Miyagi, Fukushima and Ibaraki Prefectures. As a result of this event over 19,000 people are dead or missing, with over 295,000 collapsed buildings along 600 km of affected coastline.

Reconnaissance-level analysis of evacuation preparedness and actions related to thetsunami has been carried out using semi-structured interviews with local disaster prevention officials and emergency services officials. Interviews were carried out in Tarō Town, Kamaishi City, Ōfunato City (Iwate Prefecture) and Kesennuma City, Minami-Sanriku Town, Ishinomaki City and Natori City (Miyagi Prefecture). The interviews covered tsunami
awareness, observations and response to natural and informal warnings; style and derivation of evacuation maps; official warning timing and dynamics; evacuation timing, mechanisms and issues; and vertical evacuation buildings – availability, designation, public awareness, utilisation, relationship to maps, and post-event review. The report also presents examples of
hazard and evacuation maps and signs employed in the Tōhoku region.

Experiences in Tōhoku during this event are relevant to tsunami mitigation activities in the State of Washington and in New Zealand, which co-funded this research. These areas have
local earthquake and tsunami risk posed by the Cascadia Subduction Zone and the offshore Hikurangi subduction margin, respectively. This report provides recommendations for further
development of tsunami mitigation activities in these areas, based on findings from the interviews.

Overall there was a 96% survival rate of those living in the inundated area of the municipalities visited. This can be attributed to mostly effective education and evacuation procedures. Schools education, hazard maps and exercises appear to be the most common forms of education. Community involvement in planning of evacuation maps, routes and buildings is common, with many places conducting regular community-level exercises. Hazard and evacuation maps lacked consistency and both maps and safe locations were generally designed for a tsunami height that under-represented the worst case scenario.

The natural warning of long ground shaking (reported as more than two minutes, and often more than three) was widely agreed as enough by itself to have triggered evacuation. Sea walls reduced effective observation of the natural warning of unusual ocean behaviour in many places, and fostered a false sense of security in some locations.

Although an early warning system is often seen publicly as key infrastructure in enhancing tsunami resilience, the expectation of official warnings (and their content) may have slowed the time taken for people to initiate evacuation in Tōhoku, compared to if there had been total reliance on natural warnings. Exposure to previous false ‘major tsunami’ warnings apparently led to complacency in this event, despite this earthquake feeling much larger than anything previously experienced. The philosophy of tsunami tendenko was shown to be a positive education tool which promoted immediate self-evacuation and save many lives.

Peoples’ movements during and after evacuation reveal that many people died unnecessarily due to delayed evacuation or non-evacuation as a result of social or parental responsibility, lack of education or scepticism of warnings. Widespread use of motor vehicles caused traffic congestion in some areas, when walking, running or cycling would have been much more effective and saved lives.

Many people returned to the evacuation zone too early in some places because they had not seen the wave arrive at the expected time given in official warnings, or because they
expected no more waves to arrive. It is critical that people have the awareness that the first wave may come later than estimated by rapid scientific analysis, and the largest wave may
not be the first.

The evacuation strategy in place at March 11th 2011 was appropriate in that it sent people to safe locations, used maps and community involvement and was regularly exercised in many
places. Some evacuation centres were not located far enough inland or on high enough ground because they were not designated using the worst-case tsunami inundation.

There was extensive effective use of both designated and informal vertical evacuation buildings. The most important considerations for effective use are sufficient height (in relation to expected inundation depth), reinforced concrete construction, community engagement, owner agreement, signage, 24-hour access and evacuee welfare. More than one building owner considered use of their building in evacuation as corporate social responsibility. To enhance evacuee safety it is prudent to minimise the opportunities for spilled accelerants such as oil, and debris such as logs in tsunami-prone locations."

SEE ALSO: Tsunami Vertical Evacuation Buildings - Lessons for International Preparedness Following the 2011 Great East Japan Tsunami, Journal of Disaster Research; http://www.fujipress.jp/finder/xslt.php?mode=present&inputfile=DSSTR000700070005.xml (requires free registration to access paper)

El presente documento describe brevemente los esfuerzos por coordinar acciones entre instituciones de los diferentes niveles del estado, hacia la conformación de un sistema de alerta temprana en caso de tsunamis, en lo relativo a la organización de la respuesta institucional y comunitaria ante alertas de tsunami. Se muestran los avances y las dificultades experimentadas por el equipo coordinador nacional, en su primer intento para articular niveles nacionales, regionales y locales de organización que permitan ofrecer una respuesta institucional adecuada y articulada con entes públicos, privados, y comunidades que hacen vida en las zonas costeras de Venezuela, en el marco de los preparativos para el ejercicio internacional Caribe Wave 2011, en los municipios costeros Guanta, Sotillo, Lic. Urbaneja y Bolívar, del Edo. Anzoátegui, y para la reducción del riesgo de desastres en las zonas costeras de Venezuela.

Il Bacino del Mediterraneo ha una ricca storia di terremoti ed eruzioni vulcaniche, che si può ritenere nota a tutti: non credo ci sia qualcuno in Italia, in Grecia o in Turchia che non sia consapevole della elevata sismicità della regione dove vive. Lo stesso discorso vale probabilmente per le eruzioni vulcaniche.Chi in Italia non ha sentito parlare dell’eruzione di Pompei del 79 d.C., o di quelle che avvengono frequentemente a Stromboli o all’Etna? Il discorso è ben diverso invece pergli tsunami (detti anche maremoti). Si può ipotizzare che la maggior parte degli italiani non conosca i precedenti storici in Italia e negli altri Paesi del Mediterraneo e per questo motivo non consideri il fenomeno come un rischio concreto. Probabilmente, ciò è dovuto soprattutto al fatto che gli tsunami si verificano meno frequentemente dei terremoti. In Italia l’ultimo grande maremoto, con danni considerevoli e molte vittime, risale a oltre un secolo fa, in seguito al terremoto di Messina e Reggio Calabria del 1908. Quando non c’è la memoria diretta, è molto difficile tramandare la consapevolezza di un rischio. In casi come quello del 1908, poi, l’evento terremoto tende per la sua tragicità a oscurare l’evento tsunami. Tuttavia, basta guardare una carta che riporta il catalogo dei maremoti del Mediterraneo per capire come la sensazione di basso rischio sia fallace. Si notano infatti decine di tsunami che sono avvenuti in molte zone delMare Nostrum, da Gibilterra al Medio Oriente(Fig. 1, Maramai et al., 2014). I terremoti costituiscono la principale causa di tsunami, sia a livello globale che nel Mediterraneo, con una percentuale intorno all’80% del totale dei maremoti. Meno frequenti quelli indotti da frane ed eruzioni vulcaniche, eccezionali quelli da impatto di meteoriti. In particolare, sono i grandi terremoti di subduzione quelli che hanno il maggiore potenziale tsunamigenico. Basti pensare ai due mega-terremoti dell’Indonesia del 2004 e del Giappone del 2011, entrambi di magnitudo pari o superiore a 9, che hanno generato degli tsunami di decine di metri di altezza devastando le coste prossime all’epicentro del terremoto e propagandosi anche attraverso l’oceano Indiano e il Pacifico. A parte questi casi eclatanti, in cui sono stati stimati degli spostamenti del fondale oceanico fino a decine di metri, più spesso avvengono degli tsunami meno devastanti ma comunque dannosi. Nel Mediterraneo, le zone di subduzione dell’arco ellenico, di Cipro e probabilmente anche quella dello Ionio sono tra le aree a maggiore potenziale tsunamigenico; esistono poi altre aree sismiche marine o costiere che sono state in passato sede di terremoti tsunamigenici, come le coste nordafricane, il già citato Stretto di Messina, il basso Adriatico, il Mar Ligure (Fig. 1). Se è vero che la frequenza di questi eventi è minore di quella dei terremoti, bisogna considerare che il loro impatto può essere devastante. importante mettere in atto tutte le possibili azioni per mitigare il rischio.

Over the past few years, several attempts have been performed to find alternative “chemical proxies” in order to discriminate “tsunami backwash deposits” from “typical marine sediments”. A wide range of statistical tools has been selected in order to investigate the sediments and/or terrestrial soils transportation mechanism during the tsunami inundation period by using several types of chemical tracers. To relate the physical and chemical characteristics of Typical Marine Sediments (TMS), Tsunami Backwash Deposits (TBD), Onshore Tsunami Deposits (OTD) and Coastal Zone Soils (CZS) with their synchrotron radiation based micro-X-ray Fluorescence (μ-SXRF) spectra, the μ- SXRF spectra were built in the appropriate selected spectra range from 3,000 eV to 8,000 eV. Further challenges were considered by using the first-order derivative μ-SXRF spectra coupled with Probability Distribution Function (PDF), Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) in order to ...

Scenarios represent a very useful technique for the definition and evaluation of tsunami hazard and risk for any given region, and a basic step in the frame of tsunami mitigation and preparedness and of sustainable coastal zone development. With the exception of very few countries, like Japan and the United States, emergency plans in the rest of the world have never taken serious care of tsunamis until the occurrence of the giant Indian Ocean tsunami on December 26, 2004. That event dramatically brought the problem of tsunami hazard and risk assessment to the general attention and showed the urgent need for implementation of tsunami early warning systems (TEWSs). The problem is particularly urgent for the Mediterranean countries that are known to have been attacked by numerous tsunamis in the past, several of which had catastrophic size and impact. This paper is an attempt to develop some simple scenarios of earthquake-generated tsunamis in the Mediterranean. We identify four different seismogenic areas in the western, central and eastern sectors of the basin. For each of them, we take into account a seismic fault capable of generating an earthquake with magnitude equal or larger than the highest magnitude registered in that region in historical times. Then we simulate numerically the ensuing tsunamis, highlighting the basic features of the wave propagation and roughly identifying the coastal sectors that are expected to suffer the heaviest tsunami effects. One of the most important outcomes is that these scenario tsunamis attack the nearest coasts within at most 15 minutes, which poses serious constraints for designing appropriate TEWS for the Mediterranean.