Numerical simulation of new proposed tsunami scenarios for Iquique, Chile

Rafael Aranguiz, Luisa Urra, Juan Gonzalez, Teun Jager, Franse Wester, Anna Smoor, Bernardien Tiehatten

Friday 3 july 2015

13:45 - 14:00h at Europe 2 (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Flood resilient cities and infrastructures

Parallel session: 16I. Extreme events - Resilient

Iquique is an important city in northern Chile, not only due to its tourism and historical buildings, but also for its commercial activities. The last major earthquake and tsunami in northern Chile took place in 1877 with an estimated magnitude of 8.8. The generated tsunami reached an inundation height of 5-6 m. Since then, the accumulated energy was estimated to be enough to generate another Mw 8.8 earthquake. However, on April 2014, a Mw 8.1 earthquake took place, which released only about 20% of the total accumulated energy. Therefore, a similar or even larger earthquake could occur in the near future. The present paper analyzes the propagation and inundation of possible future tsunamis for the Iquique area in order that proper mitigation measures can be proposed. Tsunami numerical simulations were performed with 5 nested grids by means of the NEOWAVE model with a highest grid resolution of 10m. Firstly, the April 2014 tsunami was simulated in order to validate the numerical model. Then, several possible tsunami sources were proposed and simulated, which included a major earthquake and tsunami along the whole seismic gap and three smaller events at the northern, center and southern parts. The results showed that the smaller tsunamis would not generate a significant inundation area; however, the flow velocities could affect the fishing activity in a significant manner. The major tsunami could inundate an area up to the 5m ground elevation, which is large enough to affect most of the important commercial areas of Iquique, thus the economic activity could be seriously damaged. Furthermore, it can be observed that the inundation can also occur on both sides of the Cavancha peninsula, thus transforming the peninsula into an island. Subsequently, evacuations routes would not be safe and thus the use of Tsunami Evacuation Buildings should be studied