2015 | Dec
The exposure of Athens to Natural Hazards
Attica has always been one of the country’s regions that is most exposed to natural hazards, particularly earthquakes, floods, heat waves and forest fires. The high exposure of Attica and the basin of the Capital in particular is due to its high concentration of population, activities, infrastructure and high-value stock in a confined area that is designated as a high-risk zone.
Attica is one of the Greek regions with the highest macroseismic intensities over the last 50 years (Papanastasiou et al. 2008). Attica’s exposure to seismic hazards was reassessed after the Parnitha earthquake in 1999 (size 5.9 R and epicentre 18 km northwest of Athens) that caused more than 140 fatalities and 3 billion EUR in losses (Map 1). It was the deadliest earthquake of the last 50 years in Greece (Photo 1) and led to the revision of the country’s seismic hazard map. The new map, which forms the basis of the 2000 Hellenic Earthquake-Resistant Buildings Regulations, registered a significant part of Attica and the northernmost municipalities of the capital in Zone II i.e medium seismicity. State policy for the prevention of earthquake risk is based almost exclusively on the construction of earthquake-resistant structures. Thus, buildings in Attica that have been built without permit remain exposed. After the earthquake of 1999, the limited public financial support for restoration and reconstruction only covered owners (not tenants) and mainly residences (not premises related to economic activities). Thus, the post-earthquake reconstruction did not lead to a substantive reduction in exposure and vulnerability of the affected areas against seismic hazards. Quite the opposite.
Map 1: The epicentre of the 1999 Parnitha earthquake
Photo 1: Damage caused by the1999 earthquake in the Municipality of Acharnes, Attica
Source: PM Delladetsimas, 1999
Athens also often suffers from flooding, although the eastern part of Greece has a low annual rainfall (~ 300mm). Thunderstorms in Athens are nearly as frequent as in the rest of Greece. Apart from climatic and geomorphological factors, flood susceptibility is mainly due to human interventions (Κουτσογιάννης 2002). Due to rapid urbanisation and frequent development without permit, the city was gradually stripped of its natural flood protection, as a considerable proportion of its stream network was covered or built over (Map 2) and few open planted areas were left unbuilt. Moreover, repeated forest fires in the mountains surrounding the basin increased exposure to floods, especially in peripheral municipalities. The historic city centre has a mixed sewage system that offers increased protection as compared to the municipalities developed later, especially those along the Saronic coast.
Map 2: Covered and uncovered stream networks in the Basin of Athens
Source: Authors’ own processing
Attica is one of the country’s regions that is most affected by heat waves. Despite its mild Mediterranean climate, there are significant temperature differences among seasons. Heatwave temperatures (38oC or more) are not rare during the summer and the 49oC recorded in Athens in 1977 is the highest temperature ever to be recorded in Europe (WMO, 2011). At the same time, Athens suffers the consequences of the urban heat island effect that contributes to and enhances heat wave temperatures. The highest surface temperatures in Attica during the summer are recorded in Elefsina-Aspropyrgos, Megara, Athens city centre (due to the urban heat island effect) and Mesogeia (Map 3). The public management of heat waves is limited to preparedness/emergency response.
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