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Honolulu, HI, United States

The potential tsunami risk for Hispaniola, as well as for the other Greater Antilles Islands is assessed by reviewing the complex geotectonic processes and regimes along the Northern Caribbean margin, including the convergent, compressional and collisional tectonic activity of subduction, transition, shearing, lateral movements, accretion and crustal deformation caused by the eastward movement of the Caribbean plate in relation to the North American plate. These complex tectonic interactions have created a broad, diffuse tectonic boundary that has resulted in an extensive, internal deformational sliver slab - the Gonâve microplate - as well as further segmentation into two other microplates with similarly diffused boundary characteristics where tsunamigenic earthquakes have and will again occur. The Gonâve microplate is the most prominent along the Northern Caribbean margin and extends from the Cayman Spreading Center to Mona Pass, between Puerto Rico and the island of Hispaniola, where the 1918 destructive tsunami was generated. The northern boundary of this sliver microplate is defined by the Oriente strike-slip fault south of Cuba, which appears to be an extension of the fault system traversing the northern part of Hispaniola, while the southern boundary is defined by another major strike-slip fault zone where the Haiti earthquake of 12 January 2010 occurred. Potentially tsunamigenic regions along the Northern Caribbean margin are located not only along the boundaries of the Gonâve microplate's dominant western transform zone but particularly within the eastern tectonic regimes of the margin where subduction is dominant - particularly along the Puerto Rico trench. The Haiti earthquake of 12 January 2010 and its focal mechanism are examined, as they provide additional clues of potential tsunami generation that can occur along transform zones and, more specifically, from interplate and intraplate seismic events and subsequently induced collateral hazards, such as aerial or submarine landslides triggered by strong surface seismic waves. Source

Pararas-Carayannis G.,Tsunami Society International
Science of Tsunami Hazards | Year: 2010

The great earthquake of February 27, 2010 occurred as thrust-faulting along a highly stressed coastal segment of Chile's central seismic zone - extending from about 33°S to 37°S latitude - where active, oblique subduction of the Nazca tectonic plate below South America occurs at the high rate of up to 80 mm per year. It was the 5th most powerful earthquake in recorded history and the largest in the region since the extremely destructive May 22, 1960 magnitude Mw9.5 earthquake near Valdivia. The central segment south of Valparaiso from about 34° South to 36° South had been identified as a moderate seismic gap where no major or great, shallow earthquakes had occurred in the last 120 years, with the exception of a deeper focus, inland event in 1939. The tsunami that was generated by the 2010 earthquake was highest at Robinson Crusoe Island in the Juan Fernández archipelago as well as in Talchuano, Dichato, Pelluhue and elsewhere on the Chilean mainland, causing numerous deaths and destruction. Given the 2010 earthquake's great moment magnitude of 8.8, shallow focal depth and coastal location, it would have been expected that the resulting tsunami would have had much greater Pacific-wide, far field effects similar to those of 1960, which originated from the same active seismotectonic zone. However, comparison of the characteristics of the two events indicates substantial differences in source mechanisms, energy release, ruptures, spatial clustering and distributions of aftershocks, as well as in geometry of subduction and extent of crustal displacements on land and in the ocean. Also, the San Bautista and the Juan Fernández Islands - ridges rising from the ocean floor - as well as the O'Higgins seamount/guyot may have trapped some of the tsunami energy, thus accounting for the smaller, far field tsunami effects observed elsewhere in the Pacific. Apparently, complex, localized structural anomalies and interactions of the Nazca tectonic plate with that of South America, can account for differences in the spatial distribution and clustering of shallow event hypocenters, as well as for seismic gaps where large tsunamigenic earthquakes could strike Chile's Central Seismic zone in the future. Source

Pararas-Carayannis G.,Tsunami Society International
Pure and Applied Geophysics | Year: 2014

The great Tohoku-Oki earthquake of March 11, 2011 generated a very destructive and anomalously high tsunami. To understand its source mechanism, an examination was undertaken of the seismotectonics of the region and of the earthquake’s focal mechanism, energy release, rupture patterns and spatial and temporal sequencing and clustering of major aftershocks. It was determined that the great tsunami resulted from a combination of crustal deformations of the ocean floor due to up-thrust tectonic motions, augmented by additional uplift due to the quake’s slow and long rupturing process, as well as to large coseismic lateral movements which compressed and deformed the compacted sediments along the accretionary prism of the overriding plane. The deformation occurred randomly and non-uniformly along parallel normal faults and along oblique, en-echelon faults to the earthquake’s overall rupture direction—the latter failing in a sequential bookshelf manner with variable slip angles. As the 1992 Nicaragua and the 2004 Sumatra earthquakes demonstrated, such bookshelf failures of sedimentary layers could contribute to anomalously high tsunamis. As with the 1896 tsunami, additional ocean floor deformation and uplift of the sediments was responsible for the higher waves generated by the 2011 earthquake. The efficiency of tsunami generation was greater along the shallow eastern segment of the fault off the Miyagi Prefecture where most of the energy release of the earthquake and the deformations occurred, while the segment off the Ibaraki Prefecture—where the rupture process was rapid—released less seismic energy, resulted in less compaction and deformation of sedimentary layers and thus to a tsunami of lesser offshore height. The greater tsunamigenic efficiency of the 2011 earthquake and high degree of the tsunami’s destructiveness along Honshu’s coastlines resulted from vertical crustal displacements of more than 10 m due to up-thrust faulting and from lateral compression and folding of sedimentary layers in an east-southeast direction which contributed additional uplift estimated at about 7 m—mainly along the leading segment of the accretionary prism of the overriding tectonic plate. © 2013, Springer Basel. Source

Pararas-Carayannis G.,Tsunami Society International
Science of Tsunami Hazards | Year: 2015

The year 2015 marks the 50th anniversary of operations of the International Tsunami Warning System in the Pacific Ocean. The present report describes briefly the establishment of the rudimentary early tsunami warning system in 1948 by the USA after the disastrous tsunami of April 1, 1946, generated by a great earthquake in the Aleutian Islands, struck without warning the Hawaiian Islands and other parts of the Pacific. Also reviewed are the progressive improvements made to the U.S. warning system, following the destructive tsunamis of 1952, 1957, 1960 and 1964, and of the early, support efforts undertaken in the U.S.A., initially by the Hawaii Institute of Geophysics of the University of Hawaii, by the U. S. Coast and Geodetic Survey and by the Honolulu Observatory - later renamed Pacific Tsunami Warning Center (PTWC). Following the 1964 Alaska tsunami, there was increased international cooperation, which resulted in a better understanding of the tsunami phenomenon and the development of a new field of Science of Tsunami Hazards in support of the early U.S. Warning System. Continuous supporting international cooperative efforts after 1965, resulted in the integration of the U.S. early warning system with other early regional tsunami warning systems of other nations to become the International Tsunami Warning System under the auspices of the Intergovernmental Oceanographic Commission (IOC) of UNESCO for the purpose of mitigating the disaster’s impact in the Pacific, but later expanded to include other regions. Briefly reviewed in this paper is the subsequent institutional support of the International Tsunami Warning System in the Pacific, by the International Tsunami Information Center (ITIC), the International Tsunami Coordination Group (ICG/ITS), the Alaska Tsunami Warning Center (ATWC), the Joint Tsunami Research Effort (JTRE), NOAA’s National Geophysical Center (NGDC), the Pacific Marine Laboratory (PMEL) of NOAA and of the later-established Joint Institute of Marine and Atmospheric Research (JIMAR) and the School of Ocean and Earth Science and Technology (SOEST) of theUniversity of Hawaii, in close cooperation with scientists at the Pacific Division of the National Weather Service (NWS) of NOAA. Additionally, the present paper reviews briefly the significant supportive roles of the U.S. Geological Survey, of U.S. Universities and of other national and international governmental and of non-governmental institutions. A historical review of the pioneering research efforts in support of the Tsunami Warning System in the Pacific will be provided in a separate paper. © 2015 Tsunami Society International- Allrights reserved. Source

Pararas-Carayannis G.,Tsunami Society International
Science of Tsunami Hazards | Year: 2014

Several mega-tsunamis in the last decade have caused unprecedented deaths and destruction in many countries bordering the Pacific and Indian Oceans. Many other areas in the Atlantic Ocean and in the Caribbean and Mediterranean Seas remain highly vulnerable to future destructive events. To this day the entire world is still feeling the effects of the great tsunamis of 2011, 2010 and 2004. The combined impacts of tsunamis and of collateral hazards have caused hundreds of thousands of deaths and billions of dollars in damages. As a result, much attention has been given to planning for future tsunamis and for the collateral impacts of landslides, fires, hazardous material spills and nuclear plant accidents. In spite of the great attention that has been given, many regions of the world still remain unprepared and are highly vulnerable if similar disasters strike again. However, mass media can play a very important role in creating continuous awareness of potential threats and in achieving effective preparedness for tsunami and other marine hazards and thus minimize future losses of lives and destruction of property. Media contributions could include frequent educational programs, as well as anniversary tributes for the thousands of victims of the recent tsunamis. Such educational and commemorative programs, if repeated with frequency, will have significant long-term benefits for all the areas devastated in the past, would help enhance to a greater extent awareness and preparedness, but would also serve as paradigms in mitigating the future impact of tsunamis and other marine disasters. A multi media approach could be used in providing products for such Tributes - perhaps to be repeated annually and to serve as constant reminders of future potential disasters and of the need for adequate preparedness. Such effort could include photojournalistic exhibitions, picture handbooks and radio documentaries on disaster management. Multi media products - when completed - should receive distribution throughout the potential vulnerable areas, but particularly in the South East Asia region. Countries that would particularly benefit from mass media efforts would include the most vulnerable countries, specifically: Japan, Philippines, Indonesia, Thailand, India, Bangladesh, Malaysia, Myanmar, Sri Lanka, Yemen, Oman, Maldives, Kenya, Tanzania, Seychelles and South Africa. In summary, this presentation provides strategies, guidelines and integrating programs that mass media can employ to help ensure that local actions are taken that would enhance marine disaster education and of factors related to preparedness, overall resiliency and post-disaster recovery. Source

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