TY  - JOUR
A1  - Mohr, Christian Heinrich
A1  - Manga, Michael
A1  - Wald, David
T1  - Stronger peak ground motion, beyond the threshold to initiate a response, does not lead to larger stream discharge responses to earthquakes
JF  - Geophysical research letters
N2  - The impressive number of stream gauges in Chile, combined with a suite of past and recent large earthquakes, makes Chile a unique natural laboratory to study several streams that recorded responses to multiple seismic events. We document changes in discharge in eight streams in Chile following two or more large earthquakes. In all cases, discharge increases. Changes in discharge occur for peak ground velocities greater than about 7-11cm/s. Above that threshold, the magnitude of both the increase in discharge and the total excess water do not increase with increasing peak ground velocities. While these observations are consistent with previous work in California, they conflict with lab experiments that show that the magnitude of permeability changes increases with increasing amplitude of ground motion. Instead, our study suggests that streamflow responses are binary. Plain Language Summary Earthquakes deform and shake the surface and the ground below. These changes may affect groundwater flows by increasing the permeability along newly formed cracks and/or clearing clogged pores. As a result, groundwater flow may substantially increase after earthquakes and remain elevated for several months. Here we document streamflow anomalies following multiple high magnitude earthquakes in multiple streams in one of the most earthquake prone regions worldwide, Chile. We take advantage of the dense monitoring network in Chile that recorded streamflow since the 1940s. We show that once a critical ground motion is exceeded, streamflow responses to earthquakes can be expected.
KW  - earthquake
KW  - streamflow
KW  - shaking
KW  - Chile
KW  - modeling
Y1  - 2018
U6  - https://doi.org/10.1029/2018GL078621
SN  - 0094-8276
SN  - 1944-8007
VL  - 45
IS  - 13
SP  - 6523
EP  - 6531
PB  - American Geophysical Union
CY  - Washington
ER  -