THE POTENTIAL OF TSUNAMI GENERATION ALONG THE MAKRAN SUBDUCTION ZONE IN THE NORTHERN ARABIAN SEA. CASE STUDY: THE EARTHQUAKE AND TSUNAMI OF NOVEMBER 28, 1945

Although large earthquakes along the Makran Subduction Zone are infrequent, the potential for the generation of destructive tsunamis in the Northern Arabian Sea cannot be overlooked. It is quite possible that historical tsunamis in this region have not been properly reported or documented. Such past tsunamis must have affected Southern Pakistan, India, Iran, Oman, the Maldives and other countries bordering the Indian Ocean.The best known of the historical tsunamis in the region is the one generated by the great earthquake of November 28, 1945 off Pakistan's Makran Coast (Balochistan) in the Northern Arabian Sea. The destructive tsunami killed more than 4,000 people in Southern Pakistan but also caused great loss of life and devastation along the coasts of Western India, Iran, Oman and possibly elsewhere.The seismotectonics of the Makran subduction zone, historical earthquakes in the region, the recent earthquake of October 8, 2005 in Northern Pakistan, and the great tsunamigenic earthquakes of December 26, 2004 and March 28, 2005, are indicative of the active tectonic collision process that is taking place along the entire southern and southeastern boundary of the Eurasian plate as it collides with the Indian plate and adjacent microplates. Tectonic stress transference to other, stress loaded tectonic regions could trigger tsunamigenic earthquakes in the Northern Arabian Sea in the future.The northward movement and subduction of the Oman oceanic lithosphere beneath the Iranian micro-plate at a very shallow angle and at the high rate is responsible for active orogenesis and uplift that has created a belt of highly folded and densely faulted coastal mountain ridges along the coastal region of Makran, in both the Balochistan and Sindh provinces. The same tectonic collision process has created offshore thrust faults. As in the past, large destructive tsunamigenic earthquakes can occur along major faults in the east Makran region, near Karachi, as well as along the western end of the subduction zone. In fact, recent seismic activity indicates that a large earthquake is possible in the region west of the 1945 event. Such an earthquake can be expected to generate a destructive tsunami.Additionally, the on-going subduction of the two micro-plates has dragged tertiary marine sediments into an accretionary prism - thus forming the Makran coastal region, Thick sediments, that have accumulated along the deltaic coastlines from the erosion of the Himalayas, particularly along the eastern Sindh region near the Indus River delta, have the potential to fail and cause large underwater tsunamigenic slides. Even smaller magnitude earthquakes could trigger such underwater landslides. Finally, an earthquake similar to that of 1945 in the Makran zone of subduction, has the potential of generating a bookshelf type of failure within the compacted sediments – as that associated with the “silent” and slow 1992 Nicaragua earthquake – thus contributing to a more destructive tsunami. In conclusion, the Makran subduction zone has a relatively high potential for large tsunamigenic earthquakes

BRIEF HISTORY OF EARLY PIONEERING TSUNAMI RESEARCH – Part A

ABSTRACT The year 2015 marked the 50th anniversary of operations of the International Tsunami Warning System in the Pacific Ocean - which officially begun in 1965. Our previous report in this journal described briefly the establishment of early tsunami warning systems by the USA and other countries and the progressive improvements and international cooperative efforts which were expanded to include other regions in establishing the International Tsunami Warning System under the auspices of the Intergovernmental Oceanographic Commission (IOC) of UNESCO, with the purpose of mitigating the disaster’s impact. The present paper (Part A) provides a brief historical review of the early, pioneering research efforts undertaken mainly in the U.S.A. and in Canada, initially by scientists at the Hawaii Institute of Geophysics of the University of Hawaii, at the U. S. Coast and Geodetic Survey, at the Honolulu Observatory - later renamed Pacific Tsunami Warning Center (PTWC) - at the International Tsunami Information Center (ITIC), at the Joint Tsunami Research Effort (JTRE) and at the later-established Joint Institute of Marine and Atmospheric Research (JIMAR) at the University of Hawaii, in close cooperation with scientists at the Pacific Division of the National Weather Service (NWS) of and the Pacific Marine Environmenal Laboratory (PMEL) of NOAA in Seattle. Also, reviewed briefly - but to a lesser extent - are some of the additional early research projects undertaken by scientists of the U.S. Coast of Geodetic Survey (USC&GS), of the U.S. Geological Survey (USGS), of the U.S. National Geophysical Data Center (NGDC) in Boulder, Colorado, of the U.S. Army, Coastal Engineering Research Center (CERC) and the Waterways Experiment Station (WES) in Vicksburg, Mississippi, and of researchers at different U.S. Universities and by members of the Tsunami Society, as well as at by many other national and international governmental and non-governmental institutions and Civil Defense Agencies. Part B will expand on international contributions

VOLCANIC TSUNAMI GENERATING SOURCE MECHANISMS IN THE EASTERN CARIBBEAN REGION

Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pelée on Martinique, of Soufriere on St. Vincent and of the Kick’em Jenny underwater volcano near Grenada and provides an overall risk assessment of tsunami generation from volcanic sources in the Caribbean region

EVALUATION OF EARTHQUAKE RECURRENCE ON THE NORTHERN ANATOLIAN FAULT OF ASIA MINOR AND OF TSUNAMI GENERATION IN THE SEA OF MARMARA – Review of the 17 August 1999 Earthquake and Tsunami.

The North Anatolian Fault Zone (NAFZ) is the most prominent active fault system in Northwestern Turkey. It is a major fracture that traverses the Northern part of Asia Minor and marks the boundary between the Anatolian tectonic plate and the larger Eurasian continental block, and has been the source of numerous large earthquakes throughout history. The NAFZ splits into three strands at the eastern part of the Marmara Sea. The northern strand passes through Izmit Bay, traverses the Marmara Sea and reaches to the Saros Gulf. The central fault zone passes through Izmit Bay, traverses the Sea of Marmara and reaches the Saros Gulf to the southeast. Earthquakes on this zone involve primarily horizontal ground motions (strike-slip type of faulting). Because of this unstable tectonic system, the area is considered to be as one of the most seismically active zones of the world. In the last hundred years, numerous large earthquakes have also occurred along the NAFZ, in the western part of Turkey. Beginning with an earthquake in 1939, several more quakes - with Richter magnitudes greater than 6.7 - struck in progression along adjacent segments of the great fault. The August 17, 1999 Izmit earthquake was the eleventh of such a series that have broken segments of the NAFZ, in both eastward and westward direction. The epicenter of the 1999 earthquake was near Izmit, as well as the location of previous events. The sequence of historic events indicates that the next destructive tsunamigenic earthquake could occur west of the 1999 event in the Sea of Marmara. The present study incorporates the results of a subsequent 2001 study which uses standardized remote sensing techniques and GIS-methods – based on Digital Elevation Model (DEM) data, and on geo- morph metric parameters that influenced local site conditions in the Sea of Marmara, as determined with Digital elevation data of the Shuttle Radar Topography Mission (SRTM), and with high resolution ASTER-data. With such remote sensing methods, areas that are potentially vulnerable areas in the Sea of Marmara were detected, so that disaster mitigation strategies can be implemented more effectively in the future. Based on such technology, local site conditions, which exacerbated earthquake intensities and collateral disaster destruction in the Marmara Sea region, were identified. Also reviewed by the present study are the similarities of NAFZ with the San Andreas fault in California in the USA, for the formation of an active transform boundary of the strike-slip type, with the two sides moving horizontally and continuously past each other. Finally examined is the tectonic and continuing geodynamic evolution and collision between the Arabian Plate and Eurasia, which places in danger many cities in southeastern Turkey and NorthWest Syria - which is are located on the boundary with the Arabian tectonic plate, as evidenced by the recent disastrous earthquake of 8 February 2023 along the Eastern Anatolian Fault Zone (EAFZ)

EARTHQUAKE AND TSUNAMI SAFETY OF NUCLEAR POWER PLANTS – Case Study: The San Onofre Nuclear Plant in California, USA

The present study addresses briefly the safety and design requirements of nuclear power plants from earthquakes and tsunamis that may affect the structure or cooling systems of their reactors, and which may result in additionally and longer term destructive impacts on nearby communities and marine life due to the additional release of radioctivity - as was the case with the 11 March 2011 Fukushima Daichi nuclear plant in Japan, as well as with the release of radioactivity by other nuclear power plants by tsunamigenic earthquakes in other parts of the world. The vulnerability of nuclear power plants to earthquakes and tsunamis was specifically examined by the author in conducting a comprehensive study of historic earthquakes and tsunamis, as well as by an extensive air and land field survey of Southern California, undertaken under contract with the U.S. Nuclear Regulatory Agency (NRC), and the U. S. Army Coastal Engineering Research Center (CERC), in connection with the licencing of the San Onofre Nuclear Power Plant near San Clemente in California, and of subsequent attempts to licence the additional Units 2 and 3 of the same facility of the Southern California Edison Company (the licensee). The present evaluation is also based on historical records extended back in time for determining earthquake and tsunami events when California was still under Spanish control under Gaspar de Portolá, the Spanish military officer from Catalonia in Spain, the first governor of Upper California, and founder of Monterey and San Diego, before California was annexed by the United States as a State of its Union. Also researched were archives in Seville, Spain

EARTHQUAKE AND TSUNAMI SAFETY OF NUCLEAR POWER PLANTS – Case Study: The San Onofre Nuclear Plant in California, USA

Tsunami Society International The present study addresses briefly the safety and design requirements of nuclear power plants from earthquakes and tsunamis that may affect the structure or cooling systems of their reactors, and which may result in additionally and longer term destructive impacts on nearby communities and marine life due to the additional release of radioctivity - as was the case with the 11 March 2011 Fukushima Daichi nuclear plant in Japan, as well as with the release of radioactivity by other nuclear power plants by tsunamigenic earthquakes in other parts of the world. The vulnerability of nuclear power plants to earthquakes and tsunamis was specifically examined by the author in conducting a comprehensive study of historic earthquakes and tsunamis, as well as by an extensive air and land field survey of Southern California, undertaken under contract with the U.S. Nuclear Regulatory Agency (NRC), and the U. S. Army Coastal Engineering Research Center (CERC), in connection with the licencing of the San Onofre Nuclear Power Plant near San Clemente in California, and of subsequent attempts to licence the additional Units 2 and 3 of the same facility of the Southern California Edison Company (the licensee). The present evaluation is also based on historical records extended back in time for determining earthquake and tsunami events when California was still under Spanish control under Gaspar de Portolá before California was annexed by the United States as a State of its Union. Also researched were archives in Seville, Spain

ASSESSMENT OF POTENTIAL TSUNAMI GENERATION IN CHINA'S BOHAI SEA FROM DIRECT GEOTECTONIC AND COLLATERAL SOURCE MECHANISMS

The Bohai Sea borders northeastern China's most populous and highest economic valuecoastal areas where several megacities are located. Critical infrastructure facilities exist or areunder construction, including a nuclear power plant and super port facilities. Large reserves of oilhave been discovered and a number of offshore oil platforms have been built. The extent ofdevelopment along coastal areas requires a better assessment of potential tsunami risks. Althoughtsunamis do not pose as much of a threat as earthquakes in this region, locally destructive tsunamishave been generated in the past and future events could have significant impacts on coastalpopulations and China's economy, particularly because most of the development has taken place inlow-lying regions, including river deltas. The present study examines the geotectonics of the Bohaibasin region, the impact of past historical events, and the potential for local tsunami generationfrom a variety of direct and collateral source mechanisms triggered by intra plate earthquakes.More specifically, the present study examines: a)major active faults bounding the Bohai Basin; b)the resulting crustal deformation patterns of tectonic structures that have resulted in catastrophicearthquakes in recent years; c) the basin-wide extension - with local inversion - extending into theBohai Sea that generated tsunamigenic earthquakes in 1888 and 1969; and d) deformational futureseismic events with the potential to generate local tsunamis directly or by collateral mechanisms offolding, en-echelon bookshelf failures, or from destabilization/dissociation of structuralaccumulations of gas hydrate deposits within the basin's thick sedimentary stratigraphic layers

INCIPIENT EVALUATION OF TEMPORAL EL NINO AND OTHER CLIMATIC ANOMALIES IN TRIGGERING EARTHQUAKES AND TSUNAMIS – Case Study: The Earthquake and Tsunami of 16th April 2016 in Ecuador.

The present study provides an incipient, cursory evaluation of the unusually strong 2015-2016 El Niño Southern Oscillation (ENSO) and of the quasi-periodic fluctuation and anomalies of sea surface temperature (SST) across the equatorial Pacific during that period, as being the cause for the prolonged rainfall and flooding of coastal valleys near Guayaquil and Esmeraldas in Ecuador in December 2015, as well as in late January and February 2016 – which proceeded the 16 April, 2016 tsunamigenic earthquake in Ecuador. Also examined is the seasonality of recent tsunamigenic and non-tsunamigenic earthquakes in Ecuador and elsewhere in South America, in relation to strong ENSO and documented SST Anomalies - as well as to the differently proposed mechanisms that may cause them in Ecuador and elsewhere, with climatic changes induced by the global impact of volcanic explosions and by other terrestrial and extraterrestrial influences, as to impacts they may have on the geostrophic circulation and surface water temperatures of oceanic currents, which perhaps are also associated with the cycles of Atlantic Multidecadal Oscillations (AMO’s) of small water temperature differences which may result in clusters of hurricanes generated near the earth’s oceanic equatorial zones. Regarding the 7.8 Mw earthquake and tsunami of 16 April 2016 in Ecuador and based on the above stated partial data, the present study postulates that the excessive volume and weight of flood-waters retained in the coastal crustal layers following the cataclysmic rains of late 2015 and early 2016, triggered an earlier rupture of the already strained offshore fault near the city of Muisne. As an additional contributing mechanism of earthquake and tsunami generation, the evaluation proposes that the extreme volume and weight of floodwaters may have also altered temporarily the crustal buoyancy characteristics of the intersecting Carnegie Ridge with the South America continent along the central part of the country. Additionally examined and evaluated are the unusual clusters of the 16 April 2016 event(s) and the three-dimensional and temporal anomalous distribution of aftershocks - which did not follow a typical pattern as would have been expected. Similarly atypical was the distribution of observed Modified Mercalli high intensities of this earthquake over a rather large and separated geographical area that stretched more than 200 km along the Ecuadorian coastline

SEISMICITY ANOMALIES OF M 5.0+ EARTHQUAKES IN CHILE DURING 1964-2015

The study of magnitude-frequency distribution of earthquake hazards in a region remains a crucial analysis in seismology. Its significance has varied from seismicity quantification to earthquake prediction. The analysis of seismicity anomalies of magnitude M => 5.0 earthquakes in Chile from 1964 to 2015 was undertaken by the present study with a view of reporting the trend of earthquake occurrences in the region. Chile has an area of about 756, 950 km2 with an extensive coastline of approximately 6,435 kms. It is situated in a highly seismically and volcanically active zone with a long, narrow strip of land between the Andes Mountains to the east and the Pacific Ocean to the west.It borders Peru to the north, Bolivia to the northeast, Argentina to the east and the Drake Passage in the far south. Of a total of 3,893 earthquakes that have been documented historically, magnitudes Richter 5.0 to 5.9 represent 92.6%, magnitudes 6.0 to 6.9 represent 6.8%, magnitudes 7.0 to 7.9 represent 0.6%, and magnitudes 8.0 to 8.9 about 0.1%. The quantity of earthquakes (a-value) revealed an estimate of 8.4. The b-value was estimated using Gutenberg-Richter (GR) and the Maximum Likelihood Estimation (MLE) methods. The estimated b-value using GR and MLE methods are 0.97 and 1.1 respectively, with an estimated average b-value ≈ 1. The present studies supprort the conclusion that Chile is seismically very active and prone to the recurrence of moderateto- great earthquakes in the future

SEISMICITY ANOMALIES OF M 5.0+ EARTHQUAKES IN CHILE DURING 1964-2015

The study of magnitude-frequency distribution of earthquake hazards in a region remains a crucial analysis in seismology. Its significance has varied from seismicity quantification to earthquake prediction. The analysis of seismicity anomalies of magnitude M => 5.0 earthquakes in Chile from 1964 to 2015 was undertaken by the present study with a view of reporting the trend of earthquake occurrences in the region. Chile has an area of about 756, 950 km2 with an extensive coastline of approximately 6,435 kms. It is situated in a highly seismically and volcanically active zone with a long, narrow strip of land between the Andes Mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east and the Drake Passage in the far south. Of a total of 3,893 earthquakes that have been documented historically, magnitudes Richter 5.0 to 5.9 represent 92.6%, magnitudes 6.0 to 6.9 represent 6.8%, magnitudes 7.0 to 7.9 represent 0.6%, and magnitudes 8.0 to 8.9 about 0.1%. The quantity of earthquakes (a-value) revealed an estimate of 8.4. The b-value was estimated using Gutenberg-Richter (GR) and the Maximum Likelihood Estimation (MLE) methods. The estimated b-value using GR and MLE methods are 0.97 and 1.1 respectively, with an estimated average b-value ≈ 1. The present studies supprort the conclusion that Chile is seismically very active and prone to the recurrence of moderate- to-great earthquakes in the future