Nonlinear site response evidence of K-NET and KiK-net records from the 2011 off the Pacific coast of Tohoku Earthquake
BONILLA ; TSUDA ; PULIDO ; REGNIER ; LAURENDEAU
Type de document
ARTICLE A COMITE DE LECTURE REPERTORIE DANS BDI (ACL)
Langue
anglais
Auteur
BONILLA ; TSUDA ; PULIDO ; REGNIER ; LAURENDEAU
Résumé / Abstract
We analyzed the acceleration time histories recorded by the K-NET and KiK-net stations of the Mw 9 Tohoku Earthquake in order to investigate site response issues related to near-source effects. Time-frequency analysis of K-NET stations in the Miyagi prefecture, closest to the rupture area, show that sites having a Vs30 < 400 m/s present a combination of deamplification at frequencies higher than 5 to 10 Hz and cyclic mobility (high acceleration peaks riding over a low frequency carrier). This suggests strong nonlinear site response at these stations. Furthermore, using KiK-net data we are able to compute borehole transfer functions from the mainshock and events having small PGA values from the local dataset. The ratio between weak-motion and strong-motion borehole transfer functions constitutes an indicator of nonlinear site response. This ratio reveals strong dependence on Vs30 and shows that widespread nonlinear behavior took place during this large earthquake.
Source
Earth Planets and Space, num. 7, pp.785-789 p.
Editeur
Springer/Terra Scientific Publishing Company
