STOCHASTIC CHARACTERISTIC OF EARTHQUAKE MOTION PHASE AND AMPLITUDE DAMPING DERIVED FROM ITS SELF-SIMILARITY HYPOTHESIS

• SATO Tadanobu

  東南大学 城市工程科学技術研究院

Bibliographic Information

Other Title

• 自己相似仮説から導出される地震動位相の確率特性と地震動振幅の減衰

Abstract

 When we decompose the earthquake motion phase into a linear delay part and a fluctuation part, the latter part of phase has a self-similar characteristic because of the self-similar nature of inhomogeneous medium in which earthquake wave propagates. It means that the macro scale inhomogeneous structure in the medium has a similarity with the micro scale one. Therefore we can assume that the scattering characteristic of propagating wave in high frequency range has a similarity with that of low frequency range. This means that the phase shift due to wave scattering in high frequency range has a kind of similarity with that of low frequency range. Based on this similarity hypothesis we derived mathematically the basic stochastic characteristics of phase difference. We showed that the simplest and most practical stochastic process satisfying these results could be expressed by the fractional Brownian motion (fBm) process. Assuming a pulse like wave propagating in the inhomogeneous medium and considering the uncertainty of scattering nature which is transformed into the uncertainty of phase modeled by fBm process, we found that the uncertainty of earthquake motion phase expressed by this process was evaluated by a reduction of earthquake motion amplitude. Moreover using a simple fault rupture process expressed by a train of impulses we demonstrated the effect of phase uncertainty caused by inhomogeneity of wave propagation medium on the amplitude reduction of time history of earthquake motion.

Journal

• Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE))

  Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)) 70 (3), 463-473, 2014

  Japan Society of Civil Engineers

Keywords

• phase increment
• self-similarity
• probabilistic characteristic
• fractional Brownian Motion
• Hurst index
• simulation of earthquake motion

Details

• CRID: 1390001205351505920
• NII Article ID: 130004714254
• DOI: 10.2208/jscejseee.70.463
• ISSN: 21854653
• Text Lang: ja
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed