TY  - JOUR
A1  - Tolorza, Violeta
A1  - Mohr, Christian Heinrich
A1  - Carretier, Sebastien
A1  - Serey, Amador
A1  - Sepulveda, Sergio A.
A1  - Tapia, Joseline
A1  - Pinto, Luisa
T1  - Suspended sediments in chilean rivers reveal low postseismic erosion after the maule earthquake (Mw 8.8) during a severe drought
JF  - Journal of geophysical research : Earth surface
N2  - We address the question of whether all large-magnitude earthquakes produce an erosion peak in the subaerial components of fluvial catchments. We evaluate the sediment flux response to the Maule earthquake in the Chilean Andes (Mw 8.8) using daily suspended sediment records from 31 river gauges. The catchments cover drainage areas of 350 to around 10,000 km(2), including a wide range of topographic slopes and vegetation cover of the Andean western flank. We compare the 3- to 8-year postseismic record of sediment flux to each of the following preseismic periods: (1) all preseismic data, (2) a 3-year period prior to the seismic event, and (3) the driest preseismic periods, as drought conditions prevailed in the postseismic period. Following the earthquake, no increases in suspended sediment flux were observed for moderate to high percentiles of the streamflow distribution (mean, median, and >= 75th percentile). However, more than half of the examined stations showed increased sediment flux during baseflow. By using a Random Forest approach, we evaluate the contributions of seismic intensities, peak ground accelerations, co-seismic landslides, hydroclimatic conditions, topography, lithology, and land cover to explain the observed changes in suspended sediment concentration and fluxes. We find that the best predictors are hillslope gradient, low-vegetation cover, and changes in streamflow discharge. This finding suggests a combined first-order control of topography, land cover, and hydrology on the catchment-wide erosion response. We infer a reduced sediment connectivity due to the postseismic drought, which increased the residence time of sediment detached and remobilized following the Maule earthquake.
KW  - earthquake
KW  - suspended sediment
KW  - Maule megathrust
KW  - Chile
KW  - catchment
Y1  - 2019
U6  - https://doi.org/10.1029/2018JF004766
SN  - 2169-9003
SN  - 2169-9011
VL  - 124
IS  - 6
SP  - 1378
EP  - 1397
PB  - American Geophysical Union
CY  - Washington
ER  -