258
8.4 Earthquakes and Tsunamis
El Yali was severely affected by the earthquake and tsunami in 2010, when about
800 ha of beach and dunes were swept (Contreras 2014; Contreras-López 2014).
The absence of these dunes has turned the wetland system more vulnerable to
ocean swells, as occurred in August 2015 (Winckler et al. 2015). The recent earthquake and tsunami in September 2015 flooded about 280 ha too (Contreras-López
et al. 2016).
The littoral zone of El Yali Natural Reserve is located 367 km far from the point
where plates converge and that is part of one of the segments of the South American
subduction area (von Huene et al. 1997; Pardo et al. 2001). In zone occurs earth
quakes with important magnitudes and whose epicenter is close to the coast or
above the deep seabed. These two conditions are sufficient to consider the area as
of high tsunamigenic danger, due to the generation of near field tsunamis. Tsunamis
are not always destructive when reaching the coasts, being able to reach from a few
centimeters to several meters above sea level. A determinant factor is whether the
arrival is under low-tide or high-tide conditions (mitigating or amplifying its
effects). Likewise, it is necessary to consider a far field tsunami (generated in distant zones), whose contemporary example is the earth quake originated in Japan on
11 March 2011.
When consulting (a) Historic database about tsunamis in the Pacific (Gusiakov
2001), HTDB/Pac (2016); (b) World historic tsunami database (HTDB/WLD 2016),
and (c) NOAA/WDC tsunami database (NOAA 2016), it is possible to infer that the
coastal zone of El Yali Natural Reserve has been affected by eleven tsunamis since
1900 to present time: (1) Valparaíso 1906 Mw 8.2; (2) Constitución 1928 Mw 7.6;
(3) Alaska 1946 Mw 8.1; (4) Rusia 1952 Mw 9.0; (5) Alaska 1957 Mw 8.6; (6)
Valdivia 1960 Mw 9.5; (7) Alaska 1964 Mw 9.2; (8) Valparaíso 1971 Mw 7.5; (9)
San Antonio 1985 Mw 8.0; (10) Cobquecura 2010 Mw 8.8; (11) Japón 2011 Mw
9.1 and (12) Illapel 2015 Mw 8.3 (Table 8.2).
As mentioned, El Yali National Reserve was very affected by the Mw = 8.8 27
February 2010 earthquake (Rubio and Basic 2011; Fariña et al. 2010). The tsunami
wave entered, on average, more than 1 km inland, reaching 2 km in some cases and
flooding about 800 ha, 200 ha corresponded to protected areas. This event affected
mostly the lagoon, due to the break of the sandbar, producing a sever loss of the
equilibrium in the ecosystem.
This event provoked changes in the wetland ecosystem, destroying the vegetation and leaving many dead birds, besides altering nesting and resting sites.
Moreover, the landscape was altered because the wave transported algae and clastic
debris of a wide granulometric spectrum, domestic garbage, fishery material and
wreckage amounting 10 tons.
Due to the destruction of the dune by the tsunami, the first notorious change that
was observed was the permanent connection of the Albufera with the sea in at least
three sites. These connections would gradually close create, 6 months later, a drastic
M. Contreras-López et al.
8.4 Earthquakes and Tsunamis
El Yali was severely affected by the earthquake and tsunami in 2010, when about
800 ha of beach and dunes were swept (Contreras 2014; Contreras-López 2014).
The absence of these dunes has turned the wetland system more vulnerable to
ocean swells, as occurred in August 2015 (Winckler et al. 2015). The recent earthquake and tsunami in September 2015 flooded about 280 ha too (Contreras-López
et al. 2016).
The littoral zone of El Yali Natural Reserve is located 367 km far from the point
where plates converge and that is part of one of the segments of the South American
subduction area (von Huene et al. 1997; Pardo et al. 2001). In zone occurs earth
quakes with important magnitudes and whose epicenter is close to the coast or
above the deep seabed. These two conditions are sufficient to consider the area as
of high tsunamigenic danger, due to the generation of near field tsunamis. Tsunamis
are not always destructive when reaching the coasts, being able to reach from a few
centimeters to several meters above sea level. A determinant factor is whether the
arrival is under low-tide or high-tide conditions (mitigating or amplifying its
effects). Likewise, it is necessary to consider a far field tsunami (generated in distant zones), whose contemporary example is the earth quake originated in Japan on
11 March 2011.
When consulting (a) Historic database about tsunamis in the Pacific (Gusiakov
2001), HTDB/Pac (2016); (b) World historic tsunami database (HTDB/WLD 2016),
and (c) NOAA/WDC tsunami database (NOAA 2016), it is possible to infer that the
coastal zone of El Yali Natural Reserve has been affected by eleven tsunamis since
1900 to present time: (1) Valparaíso 1906 Mw 8.2; (2) Constitución 1928 Mw 7.6;
(3) Alaska 1946 Mw 8.1; (4) Rusia 1952 Mw 9.0; (5) Alaska 1957 Mw 8.6; (6)
Valdivia 1960 Mw 9.5; (7) Alaska 1964 Mw 9.2; (8) Valparaíso 1971 Mw 7.5; (9)
San Antonio 1985 Mw 8.0; (10) Cobquecura 2010 Mw 8.8; (11) Japón 2011 Mw
9.1 and (12) Illapel 2015 Mw 8.3 (Table 8.2).
As mentioned, El Yali National Reserve was very affected by the Mw = 8.8 27
February 2010 earthquake (Rubio and Basic 2011; Fariña et al. 2010). The tsunami
wave entered, on average, more than 1 km inland, reaching 2 km in some cases and
flooding about 800 ha, 200 ha corresponded to protected areas. This event affected
mostly the lagoon, due to the break of the sandbar, producing a sever loss of the
equilibrium in the ecosystem.
This event provoked changes in the wetland ecosystem, destroying the vegetation and leaving many dead birds, besides altering nesting and resting sites.
Moreover, the landscape was altered because the wave transported algae and clastic
debris of a wide granulometric spectrum, domestic garbage, fishery material and
wreckage amounting 10 tons.
Due to the destruction of the dune by the tsunami, the first notorious change that
was observed was the permanent connection of the Albufera with the sea in at least
three sites. These connections would gradually close create, 6 months later, a drastic
M. Contreras-López et al.