Application of Refraction Microtremor (ReMi) technique for determination of 1-D shear wave velocity in a landslide area

Coccia, Stella; Gaudio, Vincenzo Del; Venisti, N.; Wąsowski, J.

doi:10.1016/j.jappgeo.2010.05.001

Cited by 34 publications

(11 citation statements)

References 15 publications

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“…Lately, slope and coastal instabilities have also been investigated by recording ambient noise, Active coastal spreading and ambient noise 1167 and the use of techniques such as H/V (horizontal-to-vertical spectral ratio) analysis, f-k analysis, site spectral ratios, polarization analysis, etc. (Del Gaudio et al 2008;Burjánek et al 2010Burjánek et al , 2012Coccia et al 2010;Panzera et al 2012). In particular, single station methods prove to be a very cost effective and rapid way of surveying an area, bypassing the problem of bringing bulky instrumentation into mostly inaccessible areas.…”

Section: Introductionmentioning

confidence: 99%

Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

Galea

D’Amico

Farrugia

2014

Geophysical Journal International

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S U M M A R YAnchor Bay and surrounding regions are located on the northwest coast of the island of Malta, Central Mediterranean. The area is characterized by a coastal cliff environment having an outcropping layer of hard coralline limestone (UCL) resting on a thick (up to 50 m) layer of clays and marls (Blue Clay, BC). This configuration gives rise to coastal instability effects, in particular lateral spreading phenomena and rock falls. Previous and ongoing studies have identified both lateral spreading rates and vertical motions of several millimetres per year. The area is an interesting natural laboratory as coastal detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of this study area by recording ambient noise time-series at more than 30 points, over an area of 0.07 km 2 , using a portable three-component seismograph. The timeseries are processed to give both horizontal-to-vertical spectral ratio graphs (H/V) as well as frequency-dependent polarisation analysis. The H/V graphs illustrate and quantify aspects of site resonance effects due both to underlying geology as well as to mechanical resonance of partly or wholly detached blocks. The polarization diagrams indicate the degree of linearity and predominant directions of vibrational effects. H/V curves closer to the cliff edge show complex responses at higher frequencies, characteristic of the dynamic behaviour of individual detached blocks. Particle motion associated with the higher frequencies shows strongly directional polarization and a high degree of linearity at well-defined frequencies, indicative of normalmode vibration. The stable plateau areas, on the other hand, show simple, single-peak H/V curves representative of the underlying stratification and no predominant polarization direction. These results, which will be compared with those from other experiments in the area, have important implications for the understanding of ongoing processes in geologically active and unstable coastal environments.

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Section: Introductionmentioning

confidence: 99%

Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

Galea

D’Amico

Farrugia

2014

Geophysical Journal International

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“…The Conditional NA has found many applications in site characterization (e.g. Coccia et al 2010;Kühn et al 2011;Souriau et al 2011;Di Giulio et al 2012Hobiger et al 2013;Michel et al 2014;Mundepi et al 2015;Gouveia et al 2016).…”

Section: Inversionmentioning

confidence: 99%

Rayleigh Wave Ellipticity Modeling and Inversion for Shallow Structure at the Proposed InSight Landing Site in Elysium Planitia, Mars

2016

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The SEIS (Seismic Experiment for Interior Structure) instrument onboard the InSight mission will be the first seismometer directly deployed on the surface of Mars. From studies on the Earth and the Moon, it is well known that site amplification in low-velocity sediments on top of more competent rocks has a strong influence on seismic signals, but can also be used to constrain the subsurface structure. Here we simulate ambient vibration wavefields in a model of the shallow sub-surface at the InSight landing site in Elysium Planitia and demonstrate how the high-frequency Rayleigh wave ellipticity can be extracted from these data and inverted for shallow structure. We find that, depending on model parameters, higher mode ellipticity information can be extracted from single-station data, which significantly reduces uncertainties in inversion. Though the data are most sensitive to properties of the uppermost layer and show a strong trade-off between layer depth and velocity, it is possible to estimate the velocity and thickness of the sub-regolith layer by using reasonable constraints on regolith properties. Model parameters are best constrained if either higher mode data can be used or additional constraints on regolith properties from seismic analysis of the hammer strokes of InSight's heat flow probe HP 3 are available. In addition, the Rayleigh wave ellipticity can distinguish between models with a constant regolith velocity and models with a velocity increase in the regolith, information which is difficult to obtain otherwise.

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“…This appears to be a major resonance frequency, possibly related to the effects of the 40 m-thick colluvium. Seismic investigations conducted at this site using the ReMi technique provided for shear wave velocity Vs an average estimate of about 400 m s −1 (Coccia et al, 2010). Following the simplified relation connecting surface layer V s velocity and thickness H to resonance frequency F o (i.e.…”

Section: Measurements At Accelerometer Sites On Landslide-prone Slopesmentioning

confidence: 99%

New developments in ambient noise analysis to characterise the seismic response of landslide-prone slopes

Gaudio

Wąsowski

Muscillo

2013

Nat. Hazards Earth Syst. Sci.

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We report on new developments in the application of ambient noise analysis applied to investigate the dynamic response of landslide-prone slopes to seismic shaking, with special attention to the directional resonance phenomena recognised in previous studies. These phenomena can be relevant for seismic slope susceptibility, especially when maximum resonance orientation is close to potential sliding directions. Therefore, the implementation of an effective technique for site response directivity detection is of general interest. In this regard methods based on the calculation of horizontal-to-vertical noise spectral ratio (HVNR) are promising. The applicability of such methods is investigated in the area of Caramanico Terme (central Italy), where ongoing accelerometer monitoring of slopes with different characteristics offers the possibility of validation of HVNR analysis. The noise measurements, carried out in different times to test the result repeatability, revealed that sites affected by response directivity persistently show major peaks with a common orientation, consistent with the resonance direction inferred from accelerometer data. In some cases such a directivity turned out parallel to maximum slope direction, but this cannot be considered a systematic feature of slope dynamic response. At sites where directivity is absent, the HVNR peaks do not generally show a preferential orientation, with rare exceptions that could be linked to the presence of temporarily active sources of polarised noise. The observed variations of spectral ratio amplitude can be related to temporal changes in site conditions (e.g. groundwater level/soil water content variations affecting P wave velocity and Poisson's ratio of surficial layer), which can hinder the recognition of main resonance frequencies. Therefore, we recommend conducting simultaneous measurements at nearby sites within the same study area and repeating measurements at different times in order to distinguish significant systematic polarisation caused by site-specific response directivity from polarisation controlled by properties of noise sources. Furthermore, an analysis of persistence in noise recordings of signals with systematic directivity showed that only a portion of recordings contains wave trains having a clear polarisation representative of site directional resonance. Thus a careful selection of signals for HVNR analysis is needed for a correct characterisation of site directional properties

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Application of Refraction Microtremor (ReMi) technique for determination of 1-D shear wave velocity in a landslide area

Cited by 34 publications

References 15 publications

Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

Rayleigh Wave Ellipticity Modeling and Inversion for Shallow Structure at the Proposed InSight Landing Site in Elysium Planitia, Mars

New developments in ambient noise analysis to characterise the seismic response of landslide-prone slopes

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