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

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

COMPARATIVE NUMERICAL SIMULATION OF THE TOHOKU 2011 TSUNAMI

The comparative numerical simulation of generation and propagation of tsunami waves generated by the source of the catastrophic 2011 Tohoku earthquake in Japan was performed based on the Okada model and the dynamic keyboard block model. The initial model is connected with the choice of orientation of longitudinal and transverse ruptures within the source region and the values of displacements along the main fault. A subsequent model is based on the premise that the initial stress distribution along the fault zone affects essentially the character of movements around the earthquake source and takes into account the stress-strain state of keyboard blocks. In the first case of the present study, the earthquake source was designated and constructed based on the parameters of the ten largest aftershocks within a finite time interval, while in the second case the source used included all aftershocks on the first day following the main event. Based on such comparative source simulations and far-field tsunami wave measurements, the results with both models were determined to have close similarities. However, in the near-field zone, the agreement with observable data was not as good. That can be attributed to inaccuracies in the placement of virtual tide gauges relative to real ones, as well as to features of bottom relief near the coast

Manifestation of the 1963 URUP Tsunami on Sakhalin: Observations and modeling

In the history of instrumental observations, the tsunami of 1963 generated in the vicinity of Urup in the Kuril Islands had the highest runup heights on the coasts of Sakhalin Island. It was generated by a strong earthquake which had a moment magnitude Mw 8.1. The present study summarizes the known observations of this event along the coasts of Sakhalin, in the Hawaiian Islands and elsewhere in the Pacific Ocean. Additionally, the prestent study includes the numerical simulation of this 1963 tsunami event in the framework of nonlinear shallow water theory. The results of the numerical calculations are in good agreement with the observational data. © 2017-TSUNAMI SOCIETY INTERNATIONAL

A NEW TSUNAMI RISK SCALE FOR WARNING SYSTEMS - APPLICATION TO THE BAY OF ALGIERS IN ALGERIA, WEST MEDITERRANEAN SEA

The city of Algiers and the surrounding coastal areas in northern Algeria are vulnerable to earthquakes which range from moderate to severe. In 2006, using several possible earthquake scenarios for the Western Mediterranean, the Japan International Cooperation Agency and the Algerian National Seismic Engineering Research Center predicted that heavy damage could occur in the Algiers region. Algerian Civil Defense authorities are particularly concerned by the threat of near-field earthquakes, associated slides and rock falls, as well as for tsunamis that can be generated. The present study proposes a new tsunami risk scale that provides information about the exposed communities and infrastructure, which can be used for regional tsunami alerts and warnings. Furthermore, it evaluates the vulnerability along the Bay of Algiers from tsunamigenic earthquakes. The JMA seismic intensity scale (Shindo scale) and the corresponding seismic peak ground accelerations are used in the evaluation. The results of tsunami modeling studies and of earthquake vulnerability assessment described by the present study, emphasize the significance of public education and preparedness in efforts to mitigate loss of life and damage to property