Figure 4 - uploaded by Miguel Esteban
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a) Maximum tsunami flow depth. b) Maximum tsunami flow velocity. Black thick line is the coastline, while thin lines are contour lines every 5 m.
Source publication
Chañaral is a town located at the mouth of the Salado River in northern Chile (Lat 26.3 °S). The main economic activity in its vicinity is copper mining, such as at Potrerillos and El Salvador. The river mouth is typically closed due to the coastal sediment transport. In addition, a large reclamation area was built from mine tailings and a highway...
Context in source publication
Citations
... Pisagua is located at the mouth of a large ''quebrada'' (Tiliviche), and a flash-flood landslide there is plausibly capable of modifying the coastline, allowing the entry of the sea at high tide more inland than before, and changing the sea bottom topography in the harbor through fills deposits. These two things happened in exactly this way in Chañaral, located at the mouth of the ''rio salado'', during the flash-floods of 2015 (Aránguiz et al., 2018). By all means, a flash-flood land-slide (or the tsunami itself !) are more likely to have significantly altered the coastal landscape and the harbor sea bottom topography than the co-seismic rebound is to have produced simultaneously uplift and subsidence at the same location. ...
The 1877 North Chile megathrust earthquake is commonly considered as one of the largest historical earthquakes that occurred on the Chilean subduction zone. The literature generally attributes it a magnitude close to 9, associated with a rupture of about 500 km long. Because it occurred nearly a century and a half ago, the area is often described as a mature seismic gap, that is to say, a place where a great subduction earthquake similar to that of 1877 would be imminent. A careful study of historical articles describing the earthquake and subsequent tsunami shows that the size of the rupture has most likely been greatly overestimated. First of all, it seems that the area of severe shaking, corresponding to intensity VIII on the Mercalli scale, has been artificially increased. Secondly, it appears that once errors and exaggerations are corrected, nowhere was the subsequent tsunami actually higher than 10 meters. It also appears that the initial exaggerations have been further amplified in the modern literature to reach today’s estimation of the earthquake size. In reality, all historical observations, i.e. the intensities of destruction on the continent due to the earthquake itself and the characteristics of the subsequent tsunami, concur to attribute to the earthquake a rupture of only ∼225 km long, located between 20.5°S and 22.5°S. Both this reduced length and its localization match very well the patchy coupling revealed by recent GPS measurement in the area and support the hypothesis of a rupture of the Loa segment alone. The estimation of an earthquake magnitude from the subsequent tsunami is always difficult because the amplitude of the tsunami at a given place depends on many more parameters than the seismic moment alone. The source localization which changes the azimuth and path towards a given receiving place, the source depth, the rupture velocity, all play a role. They remain largely unknown for the 1877 event. However, the comparison of the 1877 revised figures with recent tsunamis suggest the magnitude should also be lowered to around 8.5 : slightly larger than Illapel 2015, significantly smaller than Maule 2010. In all cases, the seismic hazard of the region should be revised downwards: the next expected earthquake in the region should be either significantly smaller than feared (magnitude ∼8.5 rather than ∼9), or occur much later than announced.
... They used 5 nested grids, with the highest grid resolution being ~10 m. The level 5 grid was derived from several bathymetry and topography sources, such as the nautical chart N° 2213, a post-2017 detailed bathymetry provided by the Ministry of Public Works, post-2015 Lidar Topography with a resolution of 1 m contour lines provided by the Municipality of Chañaral, and a topography survey carried out by the authors themselves during august 2017 along the beach [46]. ...
... Since the extreme river flood events in 2015 and 2017 generated significant coastal morphology changes and erosion, and the official tsunami inundation map dated from 2014, the present study included the results of tsunami numerical simulations to update the tsunami hazard map. These simulations took into account the coastal morphology changes, as presented by Aránguiz et al, (2018) [46]. The numerical simulations were run by means of the Non-hydrostatic Evolution of Ocean WAVEs model (NEOWAVE) [47,48]. ...
... They used 5 nested grids, with the highest grid resolution being~10 m. The level 5 grid was derived from several bathymetry and topography sources, such as the nautical chart N • 2213, a post-2017 detailed bathymetry provided by the Ministry of Public Works, post-2015 Lidar Topography with a resolution of 1 m contour lines provided by the Municipality of Chañaral, and a topography survey carried out by the authors themselves during august 2017 along the beach [46]. ...
In 2015 and 2017 unusual ocean and atmospheric conditions produced many years’ worth of rainfall in short periods over Northern Chile’s Atacama Desert, resulting in catastrophic flooding in the town of Chañaral. However, the town is not only at risk of fluvial flooding, it is also at risk of tsunamis. Through a community mapping exercise, the authors attempted to establish the level of community awareness about tsunamis, and contrasted it with that of other types of water-related hazards facing the town (namely that of flooding due to high intensity rain). This was then compared with the results of field surveys and tsunami hazard simulations, indicating than overall the community appears to have better awareness than authorities about the threat posed by these types of events. The authors thus concluded that in cases when the community has a high level of hazard awareness (which in the case of Chile was the result of traditional knowledge being transmitted from previous generations) it would be advantageous to include them in discussions on how to improve disaster resilience.
