Comparative analysis of Rayleigh and Love waves detected propagating in the Nobi and Kanto basins during the 2004-, 2007- Chuetsu and 2011 Tohoku earthquakes

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 143; p. 106606
• Main Authors: Meza-Fajardo, Kristel C., Aochi, Hideo, Papageorgiou, Apostolos S.
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.04.2021; Elsevier BV; Elsevier
• Subjects: Basins; Comparative analysis; Earth Sciences; Earthquakes; Electromagnetic wave filters; Frequency ranges; Ground motion; Information processing; Long-period ground motion; Love; Love waves; Lowlands; Orthogonality; Phasors; Polarization; Polarization characteristics; Prograde; Propagation; Rayleigh; Rayleigh waves; Retrograde; Sciences of the Universe; Sediment deposits; Sedimentary basins; Seismic activity; Seismic energy; Seismic waves; Signal processing; Surface waves; Wave energy; Wave identification; Wave power; Polarization; Surface waves; Wave identification; Prograde; Love; Retrograde; Rayleigh
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2021.106606

Propagation of long-period ground motion in sedimentary basins has been a subject of great interest among seismologists and engineers. Intense long-period ground motions consist primarily of surface waves that get trapped or generated locally as seismic energy travels through sedimentary deposits. In the present work, we investigate the propagation of surface waves in the basins of Kanto and Nobi in Japan, during three relatively recent events: The Mw 6.6 2004 Niigata Chuetsu, the Mw 6.6 2007 Chuetsu-Oki and the Mw 9.0 2011 Tohoku earthquakes. We identify the surface waves using a signal processing technique that detects their polarization characteristics, in the time-frequency space, using orthogonality relations among phase vectors. Then, by applying the “Normalized Inner Product” (NIP), regions of a particular type of polarization are delineated and filters are applied to isolate the associated surface waves, along with their direction of propagation. With our investigation, we attempt to follow the ‘flow’ of seismic energy as it approaches just outside the basins, and then how it evolves once inside the basin. Our analysis shows that the long period (<0.1 Hz) surface wave energy approaching the Kanto basin during the 2011 Tohoku earthquake consists of Rayleigh waves, and that part of the seismic energy is converted to Love waves. In a higher frequency range (0.1–0.5 Hz), prograde Rayleigh and Love waves were detected in selected areas such as the Chiba sub-basin and the Tokyo lowlands. Regarding the Nobi basin, we find that whereas the Rayleigh waves in the frequency range (0.1–0.5 Hz) radiated during the 2011 Tohoku earthquake strongly interact with the basin, the Rayleigh waves radiated by the Chuetsu events appear to propagate through the basin unaffected. This difference in basin response is attributed to the different azimuthal direction of incidence of the surface wave energy. •Rayleigh and Love waves are for the first time extracted from recorded seismograms during well known major events in Japan.•We apply a procedure that permits to follow the flow of the propagation of the different wave types through the basins.•We present the spatial distribution of the amplification coefficients of the different types of surface waves.•The analysis illustrates the different response of the Kanto and Nobi basins when radiated by the same events.