Emmy-Noether-Projekt "Brückenschlag zwischen Geodäsie und Seismologie"

Broadband frequency-dependent amplification of seismic waves across Bucharest, Romania

Sudhaus, H. and J. R. R. Ritter (2009)

 Journal of Seismology, 13(4), 479 – 497.   DOI: 10.1007/s10950-008-9140-0


Springer Link

Abstract

The determination of seismic amplitude amplification is a fundamental contribution to seismic hazard assessment.

While often only high-frequency amplitude variations (>1 Hz) are taken into account, we analyse broadband waveforms from 0.14 to 8.6 Hz using a temporary network of 32 stations in and around the earthquake-prone city of Bucharest.

Spectral amplitudes are calculated with an adaptive multiple-taper approach. Across our network (aperture 25 km × 25 km), we find a systematic northwest/southeast-oriented structural influence on teleseismic P-wave amplitudes from 0.14 to 0.86 Hz that can be explained by constructive interference in the dipping Cenozoic sedimentary layers.

For higher frequencies (1.4–8.75 Hz), more local site effects prevail and can be correlated partly among neighbouring stations. The transition between systematic and localised amplitude variations occurs at about 1 Hz.




 

Geofon

SRCMOD - Database

    • Inversion modelling of geodetic (InSAR) and seismological data
    • earthquake slip complexity and co-seismic rupture history
    • Connecting earthquake models to observations
    • Kinematic earthquake source inversion

     

    In my research i am interested in how earthquakes ruptures behave and how and why earthquakes develop complex ruptures in space and time. Complex means that the earthquake ruptures e.g. across multiple fault planes with different geometries or slows down/accelerates in different areas. We know that earthquakes rupture with different degrees of complexity and we believe that larger earthquake rupture in more complex ways. This would however violate the common assumption of self-similarity of earthquakes across magnitudes. Often the choice of the modeled degree of complexity is however dependent on expert knowledge. Therefore i am looking for data driven ways to help us evaluate possibly rupture segmentation. Also I focus on small to medium sized earthquakes to investigate if we can resolve any complex ruptures from them or if they do not exhibit such behavior. I am using InSAR, GPS and seismological data.

    To asses the evolution of an earthquake rupture in time i have developed a multi-array backprojection code, which is available on github: Palantiri