Seismic Risk Analysis of Regular Girder Bridge Subjected to Mainshock-Aftershock Sequences

When a structure is subjected to an earthquake sequence, the high rate of aftershocks after the mainshock and cumulative damage caused by the earthquake sequence make the structure very dangerous. Considering the uncertainty in seismic occurrences, structural damage is often predicted using a seismic risk analysis. This approach has become a main measure for seismic disaster assessment, and provides a reasonable reference for post-earthquake emergency response decision-making and pre-earthquake seismic design. Therefore, it is of great significance to study a seismic risk analysis considering the effect(s) of aftershocks. In this study, the aftershock hazard is estimated for a post-mainshock environment based on an aftershock probabilistic seismic hazard analysis. Considering the uncertainty regarding the mainshock and aftershock occurrences, in addition to the functional relationship between the mainshock and aftershock parameters, the aftershock seismic hazard is estimated for the pre-mainshock environment. The mainshock fragility and aftershock fragility of regular girder bridges are evaluated based on the Kunnath damage model. Finally, considering the damage accumulation in bridge structures, the seismic hazard and seismic fragility are combined to establish a post-mainshock aftershock seismic risk framework and pre-mainshock mainshock-aftershock seismic risk analysis framework. Based on these, the mainshock risk and mainshock-aftershock risk are compared to verify the importance of considering the aftershock effects in seismic disaster assessments. The aftershock risks for the bridges of different post-mainshock damage states are compared, and the influence of the initial damage after the mainshock on the damage to the structure in the post-mainshock environment is studied.

Crisis Communication after Earthquakes in Greece and Japan: Effects on Seismic Disaster Management

The communication of emergency information shortly before or after the manifestation of seismic hazards is a crucial part of disaster management. Crisis communication aims to protect, support and guide the public and emergency services throughout the response and recovery phase. In the case of seismic events, a fundamental query refers to how the information to be released to the public immediately after/before the seismic event affects disaster impacts and management. This paper addresses the uncertainty involved in emergency seismic information, identifies the sources, means, content and mode of emergency communication and points to the effects of different models of crisis communication on public perceptions, on emergency responses and, hence, on disaster management. A review of past experiences of seismic crisis communication strategies in earthquake-prone countries, namely Greece and Japan, reveals successes and failures in managing uncertainty, and in building public trust and improving response capacities. The findings include the importance of crisis communication in seismic disaster management, the levels/layers of uncertainty involved in emergency seismic information and how they impact risk perceptions, the public trust/mistrust effect on scientific and management institutions as well as some recommendations for seismic crisis communication strategies to minimize uncertainty and improve emergency responses.

State of the art of seismic risk and loss assessment in structures

Earthquakes are known as one of the disasters that have fatal consequences for human safety. However, inevitably, the earthquake itself is not the leading cause of the losses suffered by humans, both material and soul. The most powerful thing in human safety is infrastructure such as buildings, bridges, and houses. Therefore, an in-depth analysis of the risk factors that the infrastructure will experience in a natural disaster is needed. There is a variable seismic hazard in the Southeast Asia region, ranging from high seismic hazard allied with the underneath of the Indonesian and Philippine archipelagos to moderate and low seismic tremors associated with a sizeable stable region on the Sunda Shelf. This paper describes the history of seismic risk and loss assessment of infrastructures. The method used is by doing literature reviews of the most recent research relating to seismic risk and assessment around the world. More than fifteen research results are studied and discussed to get a deep knowledge about seismic risk and the assessment of loss due to seismic disaster.

Liquefaction Potential Map based on Coordinates in Padang City with Google Maps Integration

Abstract— Padang City is prone to liquefaction phenomena due to earthquakes. These phenomena can cause various damages to structures, infrastructures, and even can also cause deaths. Therefore, as one of the urban populated cities, the information about liquefaction potential is needed. One of them is by providing a liquefaction potential map, which is useful for mitigation and seismic disaster risks strategies. This article aims to provide a digital map of liquefaction potential in Padang City that integrates with Google Maps. The map is based on 40 coordinates in 7 subdistricts in the city with 3 colored markers that represent the levels of potential liquefaction i.e. no liquefaction level, moderate liquefaction level, and severe liquefaction level. The levels are classified based on the analysis of the secondary Cone Penetration Test data by using the calculation of the Factor of Safety and Liquefaction Potential Index with an earthquake assumption of 8 SR. The result shows that the map has ben able to display information about liquefaction potential, where 32.05% coordinates are classified as no liquefaction level with the highest percentage are in Kuranji, 22.5% are classified as moderate liquefaction level with the highest percentage are in Padang Utara, and 45.0% are classified as severe liquefaction level with the highest percentage are in Koto Tangah.

EXPRESSION AND ANALYSIS OF SEISMIC DISASTER INFORMATION BASED ON KML

The display and recognition of geographical features based on KML and Google Earth/Google Maps provide possibilities for the visualization and analysis of earthquake disasters. In this paper, compile and generate the corresponding point and face KML files of the disaster information of Guangxi Zhuang Autonomous Region in January through the Visual Basic custom script. The KML files realize information display, query and analysis in Google Earth,and combine with Arcgis's topography, elevation and image information of feature points to carry out multi-information source analysis and realize the interpretation and analysis of the current situation of earthquakes, which can provide some reference information for the monitoring and evaluation of earthquakes.

Four years after the catastrophe, are educational institutions in the Region of Murcia in Spain prepared for the next seismic disaster?

Un terremoto de magnitud 6.0 o más está esperado en la falla Alhama de Murcia, la más activa de la región de Murcia, localizada en el sureste de España. El 11 de Mayo de 2011, en un intervalo de una hora y 42 minutos, dos terremotos de magnitud 4.5 y 5.1 sacuden las ciudades deLorca y Totana, resultando en nueve fatalidades y 330 heridos. Sin embargo, cuatro años después de la catástrofe, estas ciudades no parecen estar preparadas a hacer frente a un terremoto de magnitud moderada. Todos los factores están combinados para terminar en una catástrofe es decir, una superficie geomorfológica que favorece los efectos de sitio, construcciones que no cumplen con las normas parasísmicas y la falta de conocimiento sobre el riesgo sísmico por parte de la población. Este estudio propone unanálisis del nivel de vulnerabilidad de los centros educacionales contra el riesgo sísmico en Lorca y Totana basado en la creación de un índice de vulnerabilidad considerando los factores de riesgo sociales y estructurales. Además propone una serie de medidas de mitigación para hacer frenteal próximo desastre sísmico mayor. A magnitude 6.0 or more earthquake is expected on the Alhama de Murcia fault, the most active in the area of Murcia, located in the south-eastern Spain. On May 11th 2011, within one hour and 42 minutes period, a magnitude 4.5 and a magnitude 5.1 earthquakes shake the towns of Lorca and Totana, killing nine people and injuring 330. However, four years after the catastrophe, these towns do not seem to be prepared to face a moderate earthquake. All elements are gathered to result in a disaster, i.e. a surface geomorphology conducive for site effects, constructions which do not comply the earthquake-resistant requirements and a lack of knowledge from the population about the seismic risk. This report proposes an analysis of the level of vulnerability of educational institutions against the seismic risk in Lorca and Totana based on creating a vulnerability index which considers social and structural risk factors. As well as a series of mitigation measures proposals to face the next major seismic disaster.