Journal of Earthquake and Tsunami

Assessing the hazard and damage of a potential tsunami is an ongoing challenge in tsunami research. This study begins by simulating tsunami hazards using historical events. A tsunami propagation model is used to obtain the estimated maximum tsunami height along the west coast of Thailand for a rough return period, and rupture locations that have the potential to generate catastrophic tsunamis in Thailand for a specific return period are proposed. A tsunami inundation model is then performed to quantify each building's maximum inundation depth, using high-resolution satellite images to extract each building's location for the areas of interest located in southern Thailand. Nam Khem village and Patong beach are selected as study areas to represent village communities and tourist attractions, respectively. The model results are then used to obtain the numbers of exposed inhabitants and buildings for each earthquake return period. The developed tsunami fragility curves are applied to these figures to determine the number of potentially damaged buildings. The analysis suggests that the propagation model can be used to obtain rough estimations because it provided results similar to those of the inundation model. However, material type must be considered when fragility curves are used in a different country (i.e. reinforced concrete buildings in Thailand from the 2004 tsunami and wooden houses in Japan from the 2011 East Japan tsunami).

Vegetation along a coastline could offer significant protection of the adjoining land area against natural hazards such as storm surge and tsunami. In this context, the flexibility of the individual that stems within the green belt is understood to play an important role in the attenuation of momentum of the incoming waves. The physics of which, is yet to be understood completely. Difficulty in modeling the rigidity of the plantations, both numerically and experimentally, is the main cause for this lack of understanding. In the present work, a detailed laboratory study is taken up to examine the resistance characteristics of a group of model slender flexible cylinders. The individual cylinders of the group were fixed to the bed in a staggered configuration. The size, vegetation density and the elastic modulus of the individual stems were chosen such that the tests covered the practical ranges of vegetation in coastal forestry. The Manning's n for different flow conditions as well as for vegetative parameters was obtained from the physical tests in uniform steady current. The results clearly bring out the variation of flow resistance in terms of flow velocity, density of plantation, individual stem diameter and its elastic property. A new empirical relationship is proposed for estimation of Manning's n for staggered flexible emerging plantations which is valid for depths of flow greater than 0.8 times the undeflected plant height.

A centrifuge shaking table test was implemented for the first time to simulate the dynamic failure process of arch dam–abutment systems. The test procedure and results are presented in this paper. The test model was composed of an arch dam, left and right abutments, foundation, and reservoir. Three planes of weakness in the right abutment were artificially mounted to simulate potential sliding blocks in the abutment rock. The model was shaken inside a centrifuge using harmonic excitation with five different amplitudes. At the end of each harmonic excitation action, white noise excitation with lower amplitude was conducted to identify possible damage to the model. The dynamic response of the arch dam–water–abutment system was measured by accelerometers, strain gauges, and joint meters. The complete damage process was also observed. The test results demonstrate that the centrifuge shaking table test cannot only assess directly the failure mechanism of arch dam–abutment systems, but it could also provide a database to verify the nonlinear numerical procedure for stability analysis of arch dam–abutment systems.

The MS 8.0 Wenchuan earthquake of May 12, 2008, in the Longmen Shan mountain range area in China, led to two roughly parallel NE-trending thrust and strike-slip surface ruptures of the Beichuan, Pengguan, and the Xiaoyudong faults. Coseismic deformation changed the topographical gradient and produced massive landslides and debris flows, causing a corresponding response of the fluvial landforms. In this paper, based on data regarding the surface ruptures and changes to the topography and drainage resulting from the earthquake, the influence of the thrusting and strike-slipping on fluvial landforms and drainage are integrated and analyzed. The results are shown for the following five main aspects: (1) the strike-slipping driven by the earthquake caused the formation of new tectonic diversion points of river channels; (2) the thrusting driven by the earthquake caused the formation of new tectonic slope-break points in the river channel; (3) the strikes of the faults activated by the earthquake controlled the river channel direction; (4) the uplifting driven by the earthquake led to changes of riverbed gradient profiles and their base levels; and (5) exceptionally heavy rainfall after the earthquake initiated landslides, debris flows and floods, and will continue to be a hazard for several decades to come.

Although the 2004 Indian Ocean tsunami occurred several years ago and all the building repair and infrastructure reconstruction needed in Thailand to repair the damage caused by the tsunami are complete, there is still a need for damage assessment methods that can be used in future tsunami damage assessments in Thailand and that can possibly be applied to other countries. This study summarizes three methods for assessing tsunami damage, "tsunami damage criteria," "tsunami damage ratios" and "tsunami fragility curves," based on damage data from the 2004 Indian Ocean tsunami in Thailand, and these methods are compared using other tsunami events. Using the data from a field survey of damaged buildings, tsunami damage criteria were summarized for each degree of damage as a function of inundation depth for different building types. Tsunami damage ratios were summarized using building damage data obtained from surveys in the field and reconstruction cost estimates provided by the Thai government. The fragility curves developed were validated based on building performance data obtained from full-scale experiments on buildings and columns. Despite differences in the tsunami characteristics (inundation depth, current velocity and hydrodynamic force), the damage probabilities were nearly the same. The summarized methods might be useful for future tsunami damage assessments and loss estimation in Thailand and serve as guidelines for tsunami damage assessment in other countries.

To strengthen reinforced concrete (RC) structures against possible future earthquakes, several techniques are used in practice such as adding new RC shear walls, column jacketing using steel or RC or carbon fibers, adding steel bracing, and using seismic isolation and dampers. To apply these techniques, the whole building or part of it should be evacuated for several months and if this building is a school or a factory it means that the building will lose its function for several months during the strengthening construction. In this paper, parallel braced steel frame strengthening technique is proposed to strengthen the low or middle raise RC structures in which all the construction works are applied from outside of the building and do not affect the building function. The main features of this technique are ensuring the view, ventilation, and sunlight from windows after the retrofitting work is done. Furthermore, using the construction steel members lead to shortening the construction term, improve in quality, and reduce costs. The idea of this technique is to reduce the earthquake displacement demand on the nonductile existing RC structures by attaching steel frames to the building floors. These frames are parallel to the structural system of the building and their foundations are connected to the existing building's foundation. In doing so, it is expected that during an earthquake the building's interstory drifts will reduce in half and prevent building collapse. The parallel steel frames can be designed to the desired limit states using performance-based design method in FEMA or Turkish earthquake code. A study case of a factory building in Turkey is presented. The seismic performance of the building before and after the strengthening was evaluated according to the Turkish earthquake code TERDC-2007. Analysis results indicate the effectiveness of the proposed technique.

In this study, the b-values of frequency-magnitude earthquake distributions were mapped spatially along the sagaing fault zone (SFZ), central Myanmar. Three sub-datasets of the complete earthquake catalogue were tested in order to ensure the applied assumption. Using the present-day dataset (1980–2010), two areas of low b-values, which are prospective potential earthquake sources, were identified at the Naypyidaw-Mandalay and southwestern part of Myitkyina in the central and northern part of the SFZ, respectively. To assess the possible earthquake magnitudes, the b-values were mapped in the cross-section dimension along the SFZ. The obtained areas of low b-values, referred to as the fault asperity regions, conformed to those illustrated in the surface map. The asperity's sizes, examined from specific low b-values of ≤ 0.65 and ≤ 0.060 were quantitatively estimated and empirically converted to the potential earthquake magnitudes. This analysis revealed three prospective areas surrounding the Myitkyina regions capable of generating earthquakes in the future with a possible magnitude of 8.6 Richter. The contribution of effective mitigation plans are, therefore, urgently needed for Myanmar and the adjacent area.