Seismic damage scenarios in the municipa lities of Elche and Alicante (Spain ). A first step to the emergency planning

Abstract

South and SouthEast of Spain are the regions with a higher seismic hazard in Spain. Therefore, a regional normative, focused on the importance of developing seismic emergency planning in many of the municipalities of the Valencian community, was established in 2011. consequently, all the municipalities in Alicante province have to develop a seismic emergency planning. however, only Elche and Alicante have completed the seismic risk analysis and they have started to prepare their emergency plans which will be finished before the end of 2019. This paper shows the main results of the seismic risk analysis carried out in both municipalities. The seismic hazard update in the region has shown that the main earthquake scenarios, which may hit both cities, correspond to the crevillente and the Bajo Segura faults (also responsible for damaging historical earthquakes). In both cases, the urban areas are on a sedimentary deposit, which can reach hundreds of meters so site effects and possible site-building resonance can be important. Additionally, most of the building stock belongs to periods without seismic normative, increasing, therefore, their vulnerability and the obtained damage. The mean damage ratio for a magnitude of 5.5 increases from a 0.8% to a 10.3% at Alicante and Elche, respectively. Besides, if the magnitude increases to a 6.5 then the mean damage ratio increases from a 16.6% to a 60.3%. In conclusion, we recommend that the emergency planning developed for both municipalities has to take into consideration that even the occurrence of a probable earthquake (475 yrs return period) corresponding to a mw 5.5 will affect both cities so the procedures and protocols should be written in close cooperation.

Seismic Emergency Planning in the Municipalities of Elche and Alicante, Spain: First Step for Disaster Management

“…From the previous results, it was observed that even the Mw 5.5 which cause important damages in the municipality of Elche affect also the municipality of Alicante and the oldest districts of both cities with buildings constructed without any seismic regulations are the most affected [3]. Additionally, soil effects also have an important effect on damage distribution.…”

“…On the other hand, the maximum PGA ranges from 0.11 g to 0.24 g in Alicante. As a summary, they found that 13% of the building stock in Elche and 0.7% in Alicante would be inhabitable after a Mw 5.5 earthquake (74% in Elche and 18% in Alicante for a Mw 6.5) [3]. The homeless will range from 0.4% in Alicante to 17% in Elche for a Mw 5.5 and 8 to 82% for a Mw 6.5.…”

“…A detailed seismic risk analysis has been carried out for the municipalities of Elche and Alicante using several scenarios that can hit both cities [3]. The Crevillente Fault will be the responsible of the two main earthquakes (Mw 5.5 and 6.5) that can affect severely the municipalities in terms of damage and losses.…”

“…At the top, we can compare the impact for the magnitude 5.5 (left) and 6.5 (right) so we can see that some districts of the urban area are widely affected in both cases although the impact is obviously higher in the magnitude 6.5 (MDR of 68 to 88%) and lower in the magnitude 5.5 (MDR of 15 to 22%). [3]).…”

“…Ground motion scenarios of a magnitude 5.5 (top) and 6.5 (bottom) at the Crevillente Fault for Elche (left) and Alicante (right). (Source: Molina et al[3]. )…”