Implementation of Tsunami Evacuation Maps at Setubal Municipality, Portugal

Abstract

Abstract:The Setubal municipality, Portugal, has diversified land use along its coastline (mostly located in a low-lying area): on the west there are beaches; the centre is dominated by a densely populated downtown; and the east has an important industrial area. Although the seismic activity in mainland Portugal is moderate, considering the variety of exposed elements, the objectives of this study are to present and discuss the implementation of tsunami evacuation maps at Setubal municipality. Thus, tsunami numerical modelling was carried out by considering the 1969 tsunami and the 1755 tsunami scenarios. The model results show that the first tsunami wave arrived within 30-40 min of the earthquake. The inundation depth was up to 9 m at the beaches, 4.9 m downtown, and 4.0 m in the industrial area. These velocities are too dangerous if beach users are caught by the tsunami waves, even in a moderate scenario. Therefore, coastal communities must evacuate the inundated zones to high ground before the arrival of the first tsunami wave. For this reason, tsunami evacuation maps were created, indicating the quickest and safest routes to the meeting points, located on high ground and outside of the inundation zones.

The historical reconstruction of the 1755 earthquake and tsunami in downtown Lisbon, Portugal

“…The authors were able to validate the tsunami initial response, which was the subsidence at Cadiz, Spain and Morocco, as reported by the witnesses. The authors also validated most of the travel times reported by the witnesses, and tsunami water level waveforms in the UK; f) numerical modeling of the 1755 tsunami carried out at the local scale on several Portuguese coastal areas allowed researchers to calculate the tsunami inundation, reproducing tsunami travel times and local tsunami features such as the number of waves, inundation extension, and run-up [17,[26][27][28]. As a consequence, in this study, the tsunami source area will be considered at the Gorringe Bank, with the source parameters used by [11,17,[25][26][27][28].…”

“…It is the origin of the M s = 8.0 earthquake occurred in 28 February, 1969 ( Figure 4). This was the highest instrumental earthquake event in the Iberia-Morocco-Atlantic domain [11,17].…”

“…These images are available on a permanent exhibition at the Museum of Lisbon and allow a more comprehensive analysis of the disaster. The tsunami source model considered the earthquake fault parameters proposed by [11,17,[25][26][27][28], with dimensions of 200 km by 80 km, located on the Gorringe Bank. The co-seismic displacement of the seafloor is transferred to the sea surface displacement because the rupture process of an earthquake is usually much shorter than the tsunami wave period.…”

“…The fact that many present-day earthquakes are situated on this section shows that the tectonic activity is still continuing, with the potential to generate large earthquakes that trigger tsunamis [20,21]. [4,17]).…”

“…Other Portuguese cities have similar urban fabric characteristics, such as an old town with narrow streets located on low ground areas. Therefore, in order to mitigate tsunamis and other urban disasters, it is fundamental to implement emergency plans, which include installation of emergency equipment, disaster awareness activities for residents and the regular practice of evacuation exercises and drills [17]. A previous study showed that in Lisbon municipality the disaster killed more than 10,000 people due to the earthquake, fire, and tsunami [1].…”