Strong vertical mixing of deep water of a stratified reservoir during the Maule earthquake, central Chile (M_w 8.8)

Abstract

[1] Vertical profiles of water temperature in Rapel reservoir (central Chile, 34°2′ 23″ S, 71°35′ 23″ W, 110 m.a.s.l.), recorded the hydrodynamic response of the stratified water column of the reservoir produced by the 8.8 magnitude Maule earthquake (epicentre located in 36°15′36″S, 73°14′ 20″W), showing an intense vertical mixing of deep water. The vertical mixing was characterized by changes in the potential energy of the water column and the eddy diffusivity of the mixing, and these values were used to estimate the mixing efficiency of the event. It is hypothesized that the turbulent flow that mixed the water column was mainly induced by the oscillation of the bed, although surface gravitational waves could also have contributed to the vertical mixing. So far, this is the first time that the hydrodynamic response of a reservoir during a mega-earthquake is measured and described.

Intrusions of sediment laden rivers into density stratified water columns could be an unrecognized source of mixing in many lakes and coastal oceans

“…(2020). Earthquakes can also lead to mixing of lakes (de la Fuente et al ., 2010), and can produce large amplitude internal waves (Boegman & Statsna, 2019; Brizuela et al ., 2019).…”

Suspended solids in an end pit lake: potential mixing mechanisms

“…There are undoubtedly more, including mixing due to earthquake induced motions (de la Fuente et al 2010;Pieters and Lawrence 2014). Our list of processes can be grouped according to those driven by the wind, those driven by the FFT, those occurring during ice-cover, and others.…”

Modeling the Multi-Seasonal Link between the Hydrodynamics of a Reservoir and Its Hydropower Plant Operation

“…The performance of the model ( Figure 5C) is favorable most of the time as the skill index takes values larger than 0.9 during most part of the time. Only after the end of February 2010, the skill index value starts to decrease, due to the Mw8.8 Maule earthquake that produced an intense and instantaneous vertical mixing in Rapel reservoir [24], which is not represented in the hydrodynamic model. The skill index plotted in Figure 5C was computed based on Equation (1) with the observed and predicted water temperatures plotted in Figure 5A,B, respectively.…”

“…Water withdrawal for energy production occurs at the dam between 73 and 88 m above sea level (m.a.s.l.). Further information about the power plant and basin can be found in [20,22,24]. Since its commissioning in 1968, the reservoir has been affected by several events of massive fish death and algae blooms [23].…”