Overview of local site effects and seismic microzonation mapping in Metropolitan Vancouver, British Columbia, Canada

Molnar, Sheri; Assaf, Jamal; Sirohey, Aamna; Adhikari, Sujan Raj

doi:10.1016/j.enggeo.2020.105568

Cited by 29 publications

(11 citation statements)

References 31 publications

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“…Documentation of metadata becomes cumbersome as the quantity of microtremor measurements increases into hundreds and thousands of sites. Large quantity microtremor campaigns performed for seismic microzonation mapping, site characterization of a seismic network’s stations, or post-earthquake reconnaissance purposes (e.g., Puglia et al 2011 ; Albarello 2011 ; Molnar et al 2020 ; Ladak et al 2021 ) may include multiple equipment, practitioners, and/or span multiple years. In such cases, the importance of minimal standardized yet robust metadata of the microtremor measurements and their processing and interpretation increases.…”

Section: Microtremor Recordingmentioning

confidence: 99%

A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method

et al. 2022

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The single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method was initially proposed to retrieve the site amplification function and its resonance frequencies produced by unconsolidated sediments overlying high-velocity bedrock. Presently, MHVSR measurements are predominantly conducted to obtain an estimate of the fundamental site frequency at sites where a strong subsurface impedance contrast exists. Of the earthquake site characterization methods presented in this special issue, the MHVSR method is the furthest behind in terms of consensus towards standardized guidelines and commercial use. The greatest challenges to an international standardization of MHVSR acquisition and analysis are (1) the what — the underlying composition of the microtremor wavefield is site-dependent, and thus, the appropriate theoretical (forward) model for inversion is still debated; and (2) the how — many factors and options are involved in the data acquisition, processing, and interpretation stages. This paper reviews briefly a historical development of the MHVSR technique and the physical basis of an MHVSR (the what). We then summarize recommendations for MHVSR acquisition and analysis (the how). Specific sections address MHVSR interpretation and uncertainty assessment.

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Section: Microtremor Recordingmentioning

confidence: 99%

A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method

et al. 2022

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“…A comprehensive geodatabase with adequate spatial coverage to achieve mapping of ground shaking, mass movements and soil liquefaction hazards at a 1:25,000 scale is under development [9]. The geodatabase is assembled from a compilation of available and private geological, geophysical and geotechnical data sources, and supplemented with non-invasive seismic testing.…”

Section: The Metro Vancouver Seismic Microzonation Projectmentioning

confidence: 99%

“…This information, in the form of map products, will be provided to a diverse group of stakeholders/decision-makers in Metro Vancouver for engineering, seismic design and retrofitting, building code amendment, land-use planning, and disaster preparation. The MVSMP is tasked with the assessment and mapping of earthquake shaking, liquefaction susceptibility and landslide/slope instability hazards [9], all of which utilize technical metrics to describe ground motion. This case study focuses primarily on effective communication of earthquake shaking hazard for intermediate users without fundamental understanding of technical metrics; however, mapping format recommendations will be applied to all earthquake hazard mappings of the MVSMP.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Use and Communication of Seismic Hazard Maps: A Case Study of Metro Vancouver, British Columbia, Canada

Fyfe

Molnar

2020

Risk Analysis XII

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The Metro Vancouver region of southwestern British Columbia, Canada, is exposed to significant earthquake risk. Earthquake hazard has yet to be mapped to an effective scale in Metro Vancouver and so it is critical to generate comprehensive seismic hazard maps for the region. The Metro Vancouver Seismic Microzonation Project is tasked with the assessment and mapping of earthquake shaking hazard and liquefaction and landslide susceptibility hazards at a 1:25,000 scale. The detailed hazard information and data collected as part of this project, like most traditional hazard studies, is highly technical and unsuitable for the needs of intermediate users (e.g. regional planners and emergency managers). In this study we evaluate metrics and delivery format used to communicate seismic hazard information to intermediate users so it may be applied effectively in regional planning and emergency management strategies. Our methodology to evaluate effective communication of the seismic hazard products (GIS shapefiles and maps) involves a stakeholder workshop and online questionnaire survey. Existing microzonation maps for other regions in Canada are referenced throughout this consultation process and feedback is used as a benchmark to develop upon. A sequence of iterative discussion and consultation is necessary to determine the comprehensible metrics, desired interaction level and stylistic preferences to be used in final mapped products. Responses reiterate that the use of technical metrics is not effective in communicating hazard to intermediate users; separate map products are required for primary and intermediate users. Additionally, participants express importance of visual simplicity, open access to background data and interactive capabilities (e.g. GIS shapefiles). Feedback indicates that a lack of standardization leads to misinterpretation when comparing seismic microzonation maps of different regions; thus, results of this consultation process are integrated into a set of preliminary recommendations for producing seismic microzonation maps in a move towards standardization.

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“…Due to its lower cost, environmental friendliness and relative ease of computing with respect to other geotechnical and geophysical methods, the H/V technique has been used extensively for geologic and engineering studies (e.g., Leyton et al, 2013;Molnar et al, 2018;Famiani et al, 2020;Molnar et al, 2020;Rohmer et al, 2020). Motivated by the increasing use of the H/V method, standard criteria for data acquisition, processing and interpretation were provided in the frame of the European project SESAME (Site EffectS assessment using AMbient Excitations) (SESAME, 2004;Bard, 2008).…”

Section: Introductionmentioning

confidence: 99%

A new autoregressive moving average modeling of H/V spectral ratios to estimate the ground resonance frequency

Ugalde

Egozcue

Ranero

2021

Engineering Geology

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We propose a new method to estimate the horizontal-to-vertical (H/V) spectral ratio using microtremor measurements. The technique is based on modeling the H/V transfer function by means of an AutoRegressive Moving Average (ARMA) filter. As compared with the conventional, Fourier-based spectra processing routines, this method is efficient in extracting the fundamental resonant frequency with a higher spectral resolution. We demonstrate its usefulness by an application to several sites in northeastern Iberian Peninsula. For the data sets examined, our approach shows improvement over the Fourier transform-based method under adverse experimental conditions. We conclude that the new technique provides robust estimates of the fundamental resonance frequency and can be effective to characterize empirically the unconsolidated sediment thickness and bedrock geometry.

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Overview of local site effects and seismic microzonation mapping in Metropolitan Vancouver, British Columbia, Canada

Cited by 29 publications

References 31 publications

A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method

A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method

Evaluating the Use and Communication of Seismic Hazard Maps: A Case Study of Metro Vancouver, British Columbia, Canada

A new autoregressive moving average modeling of H/V spectral ratios to estimate the ground resonance frequency

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