TY  - JOUR
A1  - von Specht, Sebastian
A1  - Öztürk, Ugur
A1  - Veh, Georg
A1  - Cotton, Fabrice Pierre
A1  - Korup, Oliver
T1  - Effects of finite source rupture on landslide triggering
BT  - the 2016 M-w 7.1 Kumamoto earthquake
JF  - Solid earth
N2  - The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wave field surrounding the fault. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (M-w 7.1) in central Kyushu (Japan). Although the distribution of some 1500 earthquake-triggered landslides as a function of rupture distance is consistent with the observed Arias intensity, the landslides were more concentrated to the northeast of the southwest-northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, the median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors sufficiently explains the landslide distribution or orientation (aspect), although the landslide head scarps have an elevated hillslope inclination and MAF. We propose a new physics-based ground-motion model (GMM) that accounts for the seismic rupture effects, and we demonstrate that the low-frequency seismic radiation pattern is consistent with the overall landslide distribution. Its spatial pattern is influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies < 2 Hz. This azimuth dependence implies that comparable landslide concentrations can occur at different distances from the rupture. This quantitative link between the prevalent landslide aspect and the low-frequency seismic radiation pattern can improve coseismic landslide hazard assessment.
Y1  - 2019
U6  - https://doi.org/10.5194/se-10-463-2019
SN  - 1869-9510
SN  - 1869-9529
VL  - 10
IS  - 2
SP  - 463
EP  - 486
PB  - Copernicus
CY  - Göttingen
ER  -