Directional Amplification at Rock Sites in Fault Damage Zones

Pischiutta, Marta; Rovelli, A.; Salvini, Francesco; Fletcher, J. B.; Savage, Martha K.

doi:10.3390/app13106060

Cited by 3 publications

(1 citation statement)

References 86 publications

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“…3, p. 224, Figure 3.113". To get an image of possible effects which can stand in the background of seismic phenomena, see [39,40] "Figure 4".…”

Section: Elementary Fluctuation-formal and Real Meaningmentioning

confidence: 99%

Seismogram Rearrangement as a Perspective Basis for Defining New Attributes

Babić,

Babić

2023

Applied Sciences

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Proper regulative in earthquake risk reduction, hazard assessment, earthquake resistant design and construction of structures, should be under perpetual improvement. They are mainly the result of earthquake study and analysis of post-seismic effects. In this context, a new frame for seismogram analysis is proposed, based on its decomposition into elementary and single (positive and negative) fluctuations (EF/SF). Decomposition enables rearrangement, both providing the frame for defining new attributes, where several main ones are proposed and elaborated in the paper: fan diagram of EFs structural axes; R- or RQ-envelope, formed over positive and over negative peaks of ordered SFs; two forms of difference functions of positive and negative R/RQ-envelopes, as a measure of seismogram’s (a)symmetry, in respect to t-axis; distributions of SFs durations. Several others are in perspective. Analogy between R-envelope and seismogram’s spectrum is considered from the aspects of arranged elements, and asymptotic behavior of these two functional attributes. More objective definition of seismogram duration is proposed, determined by linear regression across the scatter plot of SFs peaks. R-envelope showed itself as an invariant in the seismogram population, and the distribution of SFs durations as well. Results are presented through extensive graphics, backed with mathematical description. Thorough discussion of the concept and results is given.

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“…3, p. 224, Figure 3.113". To get an image of possible effects which can stand in the background of seismic phenomena, see [39,40] "Figure 4".…”

Section: Elementary Fluctuation-formal and Real Meaningmentioning

confidence: 99%

Seismogram Rearrangement as a Perspective Basis for Defining New Attributes

Babić,

Babić

2023

Applied Sciences

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Directional HVSR at the Chalco lakebed zone of the Valley of Mexico: Analysis and interpretation

Baena-Rivera,

Arciniega-Ceballos,

Sánchez-Sesma

et al. 2024

Journal of Applied Geophysics

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Directional amplification across the San Jacinto fault zone, CA

Pischiutta,

Baker,

Fletcher

et al. 2024

Geophysical Journal International

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SUMMARY The amplitude, frequency and polarization of ground motion at the surface can be affected by the local geology. While low-velocity sediments and fill can amplify ground motions in certain frequency ranges, the low velocities found in fault zones can also produce prominent wavelets. In this paper, we provide further evidence that polarization of ground motion can be affected by the geological fabric in fault zones that have sustained significant brittle deformation. Aside from the well-known effect of fault-trapped waves in the low-velocity zone with polarization azimuths parallel to the fault strike, the effect of stiffness anisotropy was recently recognized with polarization azimuths at high-angle to the fault strike and orthogonal to the locally predominant fracture field in the fault damage zone. To clarify further such features, we investigate directional amplification effects across the San Jacinto fault zone in Southern California using seismic data recorded by permanent seismic stations and dense across-fault arrays. We observe three main polarization trends. The first trend parallel to the fault strike is ascribed to fault-trapped waves along the low-velocity zone, in agreement with several studies in the last decade in the same region. The second and third trends are orthogonal to the orientation of R and T Riedel planes, respectively. They are related to the stiffness anisotropy in densely fractured rocks in the damage zone, which are more compliant orthogonal to their fractures. At some locations the two effects are superimposed, occurring in different and distinct frequency ranges. Directional amplification at rock sites can be important for expected ground motion and seismic hazard. However, in seismic engineering the current prescriptions of seismic codes do not account for amplification effects at rock sites at frequencies of engineering interest.

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Directional Amplification at Rock Sites in Fault Damage Zones

Cited by 3 publications

References 86 publications

Seismogram Rearrangement as a Perspective Basis for Defining New Attributes

Seismogram Rearrangement as a Perspective Basis for Defining New Attributes

Directional HVSR at the Chalco lakebed zone of the Valley of Mexico: Analysis and interpretation

Directional amplification across the San Jacinto fault zone, CA

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