Critical Factors for Run-up and Impact of the Tohoku Earthquake Tsunami

The earthquake of March 11 of magnitude 9 offshore Tohoku, Japan, was followed by a tsunami wave with particularly destructive impact, over a coastal area extending approx. 850km along the Pacific Coast of Honshu Island. First arrival times and measurements and maximum height were recorded by the Japanese monitoring system (wherever there was no failure of the equipment). The maximum run-up is well evident in satellite images available through USGS, Google and other institutes. Moreover, personal observations of Prof. Lekkas were made during a field survey in March 2011. The results of the study of the tsunami impact and run-up show the variety of factors affecting the run-up, creating zones with similar phenomena, but also specific locations where run-up exceeds by far the run-up zone maximum values. This differentiation, observed also in the past by other authors, is here attributed to the general orientation of the coast, the distance from the tsunami generation area, bathymetry offshore, the coastline morphology and land geomorphology. In certain cases that funnelling and reflection effects in narrow gulfs parallel to the tsunami propagation vector were combined with narrow valleys onshore, peak run-up exceeded 20m, or even 40 m (Miyagi coastline, Ogatsu, Onagawa, etc).

Inundation Studies Along the East Coast of India due to Tsunamigenic Earthquakes in North-Andaman and Car Nicobar Subduction zone

The Sumatra-Andaman arc is an active subduction zone and had generated several destructive Tsunamis in the past.In this paper we have analyzed two historical Tsunamigenic earthquakes from this region. One of the historical earthquake is the earthquake of 26th June 1941 in the North Andaman region,which was one of the strongest in the Andaman Sea and Bay of Bengal of magnitude M_w=7.7.This earthquake had triggered tsunami which affected the east coast of India.The other is the earthquake in Car Nicobar region on 31 st December 1881 of magnitude M_w=7.9. This submarine earthquake beneath the

A Mega-Tsunami in the Baltic Sea 1171 BC: Geological Records with Special Reference to the Lake Mälaren Area in Sweden

At about 3000 C14-year BP or 1200 cal. yrs BC, the Baltic Sea experienced a mega-tsunami with a wave-height of 10 m or more, and a run-up height of up to 16.5 m. This event had significant geological and archaeological effects. We explore the records from the Lake M?laren area in Sweden. The tsunami event is linked to seismic ground shaking and methane venting tectonics at several sites. The triggering factor is proposed to be the Kaali meteor impact in Estonia of the same age. The documentation of a mega-tsunami in the middle of the Bronze Age has wide implications both in geology and in archaeology. The archaeological key sites at Annelund and Apalle are reinterpreted in terms of tsunami wave actions remodelling stratigraphy. By extensive coring, we are able to trace the tsunami effects in both off-shore and on-shore environment. At the time of the event, sea level was at +15 m (due to isostatic uplift). The tsunami wave erosion is traced 13.5 m below sea level. The tsunami run-up over land is traced to +29.5 m to +31.5 m (occasionally even higher), implying a run-up of 14.5 - 16.5 m. In ?ngermanland, the tsunami event was absolutely dated at 1171 varve years BC. Archaeologically, the tsunami event coincides well with the transition between Periods II and III of the South Scandinavian Bronze Age. Period III has traditionally been difficult to identify in the cultural materials of the Lake M?laren region.

Prediction of landslide tsunami run-up on a plane beach through feature selected MLP-based model

We proposed new prediction models based on multilayer perceptron(MLP)which successfully predict the maximum run-up of landslide-generated tsunami waves and assess the role of parameters affecting it.The input is approximately 55,000 rows of data generated through an analytical solution employing slide’s cross section,initial submergence,vertical thickness,horizontal length,beach slope angle and the maximum run-up itself,along with its occurrence time.The parameters are first ranked through a feature selection algorithm and six models are constructed for a 9,000-row randomly sampled dataset.These MLP-based models led predictions with a minimum Mean Absolute Percentage Error of 1.1%and revealed that vertical slide thickness has the largest impact on the maximum tsunami run-up,whereas beach slope angle has minimal effect.Com parison with existing literature showed the reliability and applicability of the offered models.The methodology introduced here can be suggested as fast and flexible method for prediction of landslide-induced tsunami run-up.

海啸作用下漂浮物行为及对陆上建筑作用力研究

根据实际物理实验,采用ALE(任意拉格朗日欧拉)有限元方法在三维数值波浪水池中模拟了海啸的产生、海啸波的传播,与漂浮物作用以及漂浮物与陆上建筑的撞击。通过将海啸上岸后的波高、与漂浮物的作用力以及漂浮物的速度等数值计算结果与物理实验结果进行对比,验证了ALE流固耦合有限元方法在研究海啸作用下漂浮物行为方面的可行性。在此基础上进一步分析漂浮物在海啸作用下对陆上建筑的作用力。通过计算发现,漂浮物的质量、撞击速度对作用力起决定性作用,而被撞建筑的刚度对作用力的影响并不大。

Mathematical modeling of tsunami wave propagation at mid ocean and its amplification and run-up on shore

The paper deals with the study of the mathematical model of tsunami wave propagation along a coast-line of an ocean.The model is based on shallow-water assumption which is represented by a system of non-linear partial differential equations.In this study,we employ the Elzaki Adomian Decomposition Method(EADM)to successfully obtain the solution for the proposed model for different coastal slopes and ocean depths.How tsunami wave velocity and run-up height are affected by the coast slope and sea depth are demonstrated.The Adomian Decomposition Method together with Elzaki transform allows for solutions,without the need of any linearization or perturbation,in the form of rapidly converging series.The obtained numerical results for tsunami wave height and velocity are very close match to the real physical phenomenon of tsunami.

AN EXPERIMENTAL OBSERVATION OF A SOLITARY WAVE IMPINGE-MENT,RUN-UP AND OVERTOPPING ON A SEAWALL

A sequence of laboratory experiments using solitary waves was performed to model the effect of leading form of three types of tsunamis（a bore,an impinging wave and an overtopping wave）on a seawall on a sloping beach.The wave evolution process,impinging pressure along the seawall surface,total overtopping discharge behind the seawall and the maximum run-up height on the rear slope were measured and compared.Laboratory data were employed to re-examine relevant empirical formulae in the literature.The effect of the presence of the seawall in reducing maximum run-up height using the present setup was briefly discussed.The present data can be used for calibrating numerical and mathematical models.

Efficient numerical scheme based on the method of lines for the shallow water equations

In this paper,a nonlinear shallow-water model of tsunami wave propagation at different points along a coastline of an ocean has been numerically simulated using method of lines.The simulation is carried out for various coastal slopes and the ocean depths.The effects of the coast slope and sea depth on the tsunami wave run-up height and velocity are illustrated.The accuracy of the mathematical model is verified by solving a classical test problem with known analytic solution.The computed run-up height and velocity show satisfactory agreement with the tsunami wave physics.