A Comparative Earthquakes Risk Assessment Approach Applied to the United Arab Emirates
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CORE Metadata, citation and similar papers at core.ac.uk Provided by International Institute for Science, Technology and Education (IISTE): E-Journals Jordan Journal of Civil Engineering, Volume 2, No. 2, 2008 A Comparative Earthquakes Risk Assessment Approach Applied to the United Arab Emirates 1) 1) 2) Samer A. Barakat , Abdallah Shanableh and Abdallah I. Husein Malkawi 1) Department of Civil Engineering, University of Sharjah, P.O.Box 27272, Sharjah, United Arab Emirates, [email protected], [email protected] 2) Department of Civil Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan, [email protected] ABSTRACT This paper presents the preliminary results of a long research project on the assessment and mitigation of seismic risk in major cities in the UAE. UAE’s earthquake activity has long been recognized as one of the lowest in the world. All cities have experienced moderate earthquakes in the past, and will again do in the future. Recent earthquakes in Iran (e.g., Bam in 2003, --- in 2005) have killed thousands of people. Because of the different design and construction practices, different population density concentrations and economic activities in the UAE, different damages and losses are likely to be experienced. The impact of an earthquake is not limited to direct losses, such as the loss of life, loss of structures and business interruptions. Earthquakes also cause indirect losses by producing supply shortages and demand reductions in various economic sectors. In a country such as the UAE, which is undergoing an unprecedented construction- based development with high-rise buildings being the main feature, a large earthquake in a major city can actually cause a considerable economic loss. In this study, a framework for assessing and comparing the risk associated with the adverse consequences of earthquakes in the UAE is presented. The framework is based on a simple risk-characterization model that is used to assess the health risks associated with toxic chemicals. The model: Risk = D × RF × Pop × ER, adopted to fit our purpose of estimating the risk associated with the consequences of earthquakes, the various parameters in the above mentioned model are translated as follows: Dose (D)= seismic “force” at a specific location or weighted for an area; Response Factor (RF) = degree of damage or losses per unit “force”; Population (Pop) = a factor representing exposed population. Equivalent populations may also include exposed environment or exposed infrastructure. Emergency Response (ER) = effectiveness of available emergency response programs to reduce risk immediately as the adverse effects take place. It should be noted that emergency response in this case is different than deliberate risk management. First, the earthquake hazard and risk in the UAE, including the estimation of the amplitudes of the ground motion parameters, is stochastically assessed. Then the comparative risk framework to assess the relative impacts on people and buildings in the seven emirates and the major cities of the UAE is applied. The result is a ranking system for risk that is being integrated within a geographic information system (GIS). The database is intended for detailed development to maximize benefits to the various stake holders in the community. KEYWORDS: Seismic hazards, Adverse consequences of earthquakes, Risk to people, Risk to buildings, United Arab Emirates, Comparative risk assessment. Accepted for Publication on 1/4/2008. - 139 - © 2008 JUST. All Rights Reserved. A Comparative… Samer A. Barakat, Abdallah Shanableh and Abdallah I. Husein Malkawi INTRODUCTION strong motions which were recorded on 10 Dec. 2002 and on 25 April 2003, and the several small earthquakes Earthquakes have claimed hundreds of thousands of which have been recorded since that time, represent a lives in the past 100 years and improvements in sufficient evidence of the existence of considerable technology have only slightly reduced the death toll. seismic activity in the UAE (Abdalla, 2003). Most of the biggest urban disasters are due to Seismic risk is the probability of losses due to an earthquakes. Past earthquakes have shown that the socio- earthquake. Earthquake damage can be devastating and economic impact of a large, urban earthquake can be wide spread, affecting human lives and health, huge and widespread. After a huge Asian Tsunami and environmental health, buildings and infrastructure, in earthquake on 26 December 2004, 280000 people lost addition to business and economic activity. Although each their lives and more than one million people were earthquake has a unique magnitude (of a specific type), its displaced. The economic damage measured by the aid effects vary greatly according to distance, ground commitments to Tsunami affected countries, as of 21- conditions, construction standards and other factors. February 2005 was about $6317.5 million. The United Arab Emirates (UAE) is undergoing high levels of development that represent high level of financial investments and high densities of populations. Designing, constructing and maintaining high rise buildings are the major challenges, especially in the presence of ground motions due to earthquakes that might subject the structures to complex force distribution. These forces should be carefully calculated and accounted for in the design process. The hazard assessment of Dubai for close and distant earthquakes reported by Sigbjornsson and Elnashai (2006) explored the implications of the hazard from near and far earthquakes. UAE is located at the eastern coast of the Arabian Peninsula (Figure 1). The UAE is geographically, geologically and geophysically situated in a unique location. Figure (1): Location of the United Arab Emirates within its Facing the subduction boundary just across the waters of the region, (Source: Google Earth, Downloaded September, 2005). Arabian Gulf, the tip of the country lies opposite to the The significance of the present research program lies Hurmuz Straits, north of which one of the most notorious in presenting a systematic approach for risk assessment seismically active zones in the world is situated. This and in its comparative results and parametric products situation necessarily implies that the U.A.E is not only (e.g., maps, sections, plots, spectra, relative risk exposed but is ultimately vulnerable to excessively large assessment,… etc.) that can directly and effectively be strong earthquake ground motions originating not too far a used by national and local governments, decision makers, distance on the southern shores of Iran. geoscientists, engineers, planners, designers, emergency Till recently, the general conception about UAE is response specialists, building contractors and universities that there is little or no earthquake activity. However, the in order to improve and upgrade methods and procedures Mb5 (March 2002) earthquake, which shocked the Masafi for land-use, building design and construction, area, north east of the UAE, with its epicenter at emergency disaster preparedness plans as well as socio- (25.24°N 56.15°E) and at 16 km depth is alarming. The economic planning and forecasting. - 140 - Jordan Journal of Civil Engineering, Volume 2, No. 2, 2008 Figure (2): Tectonic and geologic structure of the Arabian plate with Zagros folded belt (Reported by Wassel, 2005 based on James E. Fox and Thomas S. Ahlbrandt, U.S. Geological Survey Bulletin, 2002). Figure (3): Seismogenic zone taken as the whole area for seismicity results from the subduction zone activity (Sources I and II). - 141 - A Comparative… Samer A. Barakat, Abdallah Shanableh and Abdallah I. Husein Malkawi BACKGROUND In order to take steps to reduce risks posed by natural The seismic activity in the UAE may be attributed to hazards, individual property owners, developers, insurers, the regional geologic settings and local geology of the emergency management personnel as well as local UAE, as follows (Abdalla, 2003; UNESCO, 1983): governments need to know the location of hazard-prone • Major faults of unknown activity level have been areas. Maps of earthquake hazard areas should be mapped as transecting the UAE. available. Wassel (Malkawi et al., 2007) used a • The horn formed by the territory of the UAE penetrates probabilistic approach to assess seismic hazard and risk into the plate- boundary of collision between the Arabian within the UAE to account for the uncertainties in Peninsula and Asia; thus accumulating stresses. earthquake magnitude, which is reflected in amplitude, • The Zagros Mountain is a folded belt that extends for location and return period. Methods developed by about 1500 km in northwest-southeast direction along researchers (Kijko and Graham, 1998; Kijko and the western part of Iran and the northeastern part of Sellevoll, 1989; Kijko and Sellevoll, 1992; Kijko and Iraq from Oman in the southeast to the Turkish borders Graham, 1999) were used for determining the parameters in the northwest, as shown in Figure 2. The occurrences of seismogenic zone, including the mean rate of seismic of earthquake events in the Zagros province define a activity, return periods and the maximum regional zone, about 200 km wide, which runs parallel to the earthquake. Using of a suitable attenuation equation and folded belt. The majority of the earthquakes occur in ground motion parameter seismic activity and seismic the crustal part of the Arabian plate that underlies the zoning was introduced. Seismic sources vary; due to both