Dienstag, 17. November 2015, 12:15 - 13:15 iCal

Meteorologisch-Geophysikalisches Kolloquium

Body-Wave Imaging Using the Ambient Seismic Field

Hörsaal 1, 2A120
Althanstr. 14, UZA 2,, 1090 Wien


Correlation-based analyses of ambient seismic wavefields is a powerful tool for retrieving subsurface information such as stiffness, anisotropy, and heterogeneity at a variety of scales. Studies of ambient-field tomography have focused on the surface waves, especially fundamental-mode Rayleigh waves. Although the surface-wave tomography is useful to model 3D velocity variations, spatial resolution is limited due to the diffuse depth sensitivity of the surface wave measurements. Moreover, to represent elastic media, we need at least two stiffness parameters (e.g., shear and bulk moduli). I develop a technique to retrieve diving P waves from the ambient field and apply it to the data observed by the dense geophone network (~2500 receivers with 100-m spacing) at Long Beach, California. With two-step filtering, I improve the signal-to-noise ratio of body waves sufficiently to extract P waves that I use for 3D tomography of P-wave velocity structure. The small scale-length heterogeneity of the velocity model follows a power law with ellipsoidal anisotropy of heterogeneity. These small-scale heterogeneities are important for high-frequency motion prediction for earthquakes.


Institut für Meteorologie und Geophysik


Leo Haimberger
Institut für Meteorologie und Geophysik