Version classiqueVersion mobile
OpenEdition Books

Atlas of Lebanon

Part 5 - Major Environmental Issues

A Country Facing a High Seismic Risk

ANR Libris

Texte intégral

1Lebanon is a country characterized by a low to moderate seismicity and the presence of major faults which have generated devastating historic earthquakes. Several factors have turned Lebanon into one of the most exposed Mediterranean countries when it comes to seismic risks: extremely marked urbanization on the coastal strip, including in Beirut where more than 40% of the Lebanese population lives and where most of the economic, political and administrative activities are concentrated, and an embryonic building code when one considers anti-earthquake measures.

Figure V-12: Recent and historical seismicity in Lebanon

Figure V-12: Recent and historical seismicity in Lebanon

Major faults, moderate seismicity but destructive historic earthquakes

2Lebanon is located over the massive “Levant fault”, which is 1,200 km-long and stretches from the Gulf of Aqaba to Turkey. In Lebanon, this fault is divided into three major sections which have already generated numerous devastating earthquakes characterized by a magnitude above 7: among others, the 551 earthquake and tsunami which happened over the Mount Lebanon thrust (at sea) and the 1202 earthquake which happened over the Yammouneh fault. The information given by the speleothems found in the caves of Jeita and Kanaan (north of Beirut) confirms that severe earthquakes, with a peak ground acceleration of 0.2 to 0.6 g, can be observed in the region. Even though the seismicity recorded in recent years has only been moderate, paleoseismic studies have shown that the faults linked to the Yammouneh one and the Mount Lebanon Thrust could now rupture again.

A real seismic vulnerability

3Since 1990, the reconstruction of Beirut has boosted a vertical form of urbanization. During the 2008–2012 period of the real estate boom, the administration yearly granted building permits mentioning areas which approximately amounted to 80% of the city’s gross area. Nowadays saturated, Beirut is composed of a heterogeneous cluster of buildings of various heights and ages. The practice of building on stilts, the overcharge of water tanks located on roofs, the addition of floors to preexisting buildings, sometimes mediocre soil quality, and construction on unstable embankments considerably increase the risks of damage in case an earthquake occurs. The survey of nearly 8,000 buildings has allowed for a first assessment of the harm which could be caused by a seismic solicitation of 0.25 g: it reveals that half of them would be very much damaged. Socio-demographic, economic, anthropologic and psychological studies have brought to light the high vulnerability of Beirut’s residents to earthquakes and the urgency of setting up efficient protection and prevention policies, adapted to the Lebanese context.

Figure V-13: Damages estimated with the FEMA method for a seismic acceleration of 0.25 g

Figure V-13: Damages estimated with the FEMA method for a seismic acceleration of 0.25 g

Table des illustrations

Titre Figure V-12: Recent and historical seismicity in Lebanon
URL http://books.openedition.org/ifpo/docannexe/image/13274/img-1.png
Fichier image/png, 385k
Titre Figure V-13: Damages estimated with the FEMA method for a seismic acceleration of 0.25 g
URL http://books.openedition.org/ifpo/docannexe/image/13274/img-2.png
Fichier image/png, 31k

© Presses de l’Ifpo, 2019

Conditions d’utilisation : http://www.openedition.org/6540