Basement tectonic structure and sediment thickness of a valley defined using HVSR geophysical investigation, Azuela valley, Ecuador

Alonso-Pandavenes, Olegario; Torres, Gabriela; Echarri, Francisco Javier Torrijo; Garzón-Roca, Julio

doi:10.1007/s10064-022-02679-y

Cited by 10 publications

(14 citation statements)

References 21 publications

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“…In contrast, the b factor is related to sediment thickness and the geometrical shape of the basement. The obtained factors here are close to those obtained in [20], an investigation also made in Ecuador, where geological conditions are more similar to the present one.…”

Section: Data Correlation and Reliability Discussionsupporting

confidence: 91%

“…Of course, the more that can be used could reach better accuracy. Nevertheless, the most important thing is to get a variety of thicknesses to adjust the empirical curve (Equations 1 and 3), as can be seen in other investigations (related in [20][21]). That accuracy and reliability in the final results are related to the precision of geophysical models that were employed [21,47].…”

Section: Data Correlation and Reliability Discussionmentioning

confidence: 99%

“…At every point where VES tests have been carried out, an HVSR test has been applied. These combinations of HVSR and VES results were used to establish the empirical correlation between sedimentary thickness with the fundamental frequency of the ground, and they are used as control points [18][19][20][21].…”

Section: Applied Methodologymentioning

confidence: 99%

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Early Investigation of a Landslide Sliding Surface by HVSR and VES Geophysical Techniques Combined. A Case Study in Guarumales (Ecuador)

Alonso-Pandavenes¹,

Echarri²,

Garzón-Roca³

et al. 2023

Preprint

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The access road to the powerhouse's hydraulic system's facilities in Guarumales (Azuay, Ecuador) presents a medium-sized landslide. Geophysical tests were conducted in the initial research stage, combining electrical and seismic methods. A SEV and HVSR surveys campaign have been taken as a reference for the analysis of the landslide area. The distribution of these test points has been at three different levels along the landslide where the access road crosses it and trying to cover the area's most extensive possible length and width. In the area, we find the geology dominated by the presence of schists, altered to different degrees and presenting blocks of material with a lower degree of alteration within colluvium formed by a clayey matrix and coarse material of the exact nature. There is also evidence of surface and groundwater in the area. The results obtained through SEV tests have allowed for defining the separation zone of the mobilized or sliding materials compared to the fixed or immobile ones (potentially, the sliding surface was marked). Using the HVSR technique, the natural vibration frequencies of the ground associated with the sliding mass (separation of seismic impedances between a two-layer model: mobile and fixed) have been determined. Previous authors proposed an empirical relationship establishing the exponential relationship, already proposed by previous authors, between sediment thickness and natural frequencies. It has been possible to determine the depth of the position of the loosely compacted sediment zone (and probably moving or mobilized) compared to that of compact materials (immobile) and thereby define the potential rupture surface.

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Section: Data Correlation and Reliability Discussionsupporting

confidence: 91%

Section: Data Correlation and Reliability Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Early Investigation of a Landslide Sliding Surface by HVSR and VES Geophysical Techniques Combined. A Case Study in Guarumales (Ecuador)

Alonso-Pandavenes¹,

Echarri²,

Garzón-Roca³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…It was used, along with the f o values obtained at every HVSR test point, to compute the thickness of the upper sedimentary layer over a compact layer based on Equation (1). The f o fundamental frequency used to define the depth of a basement is described in the works of various authors [10,[79][80][81], including in Ecuador [19]. as a reliable tool for defining sediment thicknesses.…”

Section: Discussionmentioning

confidence: 99%

“…The geological materials must exhibit a high-level elastic parameter contrast to establish f o in a two-layer model (sediment-rock or a soft-soil layer over a compact or cemented half-space), meaning a marked difference in seismic impedance must characterize them. Currently, the HVSR technique is recognized for setting f o and fundamental periods of the ground [41][42][43][44][45], defining sediment thickness [18,19,46], and studying soil-structure interactions [15,47].…”

Section: Geophysical Methodsmentioning

confidence: 99%

A Comparative Analysis for Defining the Sliding Surface and Internal Structure in an Active Landslide Using the HVSR Passive Geophysical Technique in Pujilí (Cotopaxi), Ecuador

Alonso-Pandavenes

Bernal

Echarri

et al. 2023

Land

Self Cite

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Geophysical techniques were employed to analyze one of the landslides that affected the main access road to Pujilí (Ecuador). A passive seismic technique was utilized to test a total of 70 horizontal to vertical spectral ratio (HVSR) points, complemented by an active seismic-refraction profile and a multichannel analysis of surface waves (MASW) survey. The results from the active geophysical surveys facilitated the determination of the shear-wave-velocity value for the surface materials that were in motion. However, the HVSR provided the fundamental frequency fo and amplification Ao values of the ground. The Nakamura (1989) relationship was applied to obtain the thickness of the sediments over a compact material from the fundamental frequency of the terrain in a two-layer model. Additionally, constrained models of the shear-wave velocity (Vs) distribution in the landslide area, obtained from the active seismic surveys, were used to invert the ellipticity curves. The results from this inversion were compared with those obtained by applying the Nakamura equation. The landslide-rupture surface was delineated for each type of analysis, which verified the correlation and minimal differences between the results of the three proposed studies, thus validating the procedure. The directivity of the microtremor HVSR signals was also analyzed, demonstrating a relationship with the internal structure of the sliding material. Furthermore, the ability to slide concerning the Kg parameter (vulnerability index, Nakamura, 1989) was studied. The usefulness of the directivity analysis in defining the internal structures in landslide materials and in determining the areas with the most significant instability was demonstrated. Overall, the HVSR is considered valuable when conducting early landslide studies and is helpful in determining the rupture plane while remaining a simple, fast, and economical technique.

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Geophysical investigation on the subsoil characteristics of the Dendam Tak Sudah Lake site in Bengkulu City, Indonesia

Mase,

Amri,

Ueda

et al. 2023

Acta Geophys.

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Basement tectonic structure and sediment thickness of a valley defined using HVSR geophysical investigation, Azuela valley, Ecuador

Cited by 10 publications

References 21 publications

Early Investigation of a Landslide Sliding Surface by HVSR and VES Geophysical Techniques Combined. A Case Study in Guarumales (Ecuador)

Early Investigation of a Landslide Sliding Surface by HVSR and VES Geophysical Techniques Combined. A Case Study in Guarumales (Ecuador)

A Comparative Analysis for Defining the Sliding Surface and Internal Structure in an Active Landslide Using the HVSR Passive Geophysical Technique in Pujilí (Cotopaxi), Ecuador

Geophysical investigation on the subsoil characteristics of the Dendam Tak Sudah Lake site in Bengkulu City, Indonesia

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