What is the Smallest Earthquake Magnitude that Needs to be Considered in Assessing Liquefaction Hazard
TL;DR: Probabilistic assessments of the potential impact of earthquakes on infrastructure entail the consideration of smaller magnitude events than those generally considered in deterministic hazard and risk assessment as mentioned in this paper, which is not the case here.
Abstract: Probabilistic assessments of the potential impact of earthquakes on infrastructure entails the consideration of smaller magnitude events than those generally considered in deterministic hazard and ...
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TL;DR: In this article, the authors present a framework for evaluating the liquefaction potential of the region for moment magnitudes ranging from 3.5 to 7.0 in the Groningen field.
Abstract: The Groningen gas field is one of the largest in the world and has produced over 2000 billion m3 of natural gas since the start of production in 1963. The first earthquakes linked to gas production in the Groningen field occurred in 1991, with the largest event to date being a local magnitude (ML) 3.6. As a result, the field operator is leading an effort to quantify the seismic hazard and risk resulting from the gas production operations, including the assessment of liquefaction hazard. However, due to the unique characteristics of both the seismic hazard and the geological subsurface, particularly the unconsolidated sediments, direct application of existing liquefaction evaluation procedures is deemed inappropriate in Groningen. Specifically, the depth-stress reduction factor (rd) and the magnitude scaling factor relationships inherent to existing variants of the simplified liquefaction evaluation procedure are considered unsuitable for use. Accordingly, efforts have first focused on developing a framework for evaluating the liquefaction potential of the region for moment magnitudes (M) ranging from 3.5 to 7.0. The limitations of existing liquefaction procedures for use in Groningen and the path being followed to overcome these shortcomings are presented in detail herein.
50 citations
TL;DR: In this article, a global database of earthquakes with moment magnitudes in the range from 4.0 to 5.5 for which damage and/or casualties have been reported has been compiled and is made publicly available.
Abstract: Interest in small-to-medium magnitude earthquakes and their potential consequences has increased significantly in recent years, mostly due to the occurrence of some unusually damaging small events, the development of seismic risk assessment methodologies for existing building stock, and the recognition of the potential risk of induced seismicity. As part of a clear ongoing effort of the earthquake engineering community to develop knowledge on the risk posed by smaller events, a global database of earthquakes with moment magnitudes in the range from 4.0 to 5.5 for which damage and/or casualties have been reported has been compiled and is made publicly available. The two main purposes were to facilitate studies on the potential for earthquakes in this magnitude range to cause material damage and to carry out a statistical study to characterise the frequency with which earthquakes of this size cause damage and/or casualties (published separately). The present paper describes the data sources and process followed for the compilation of the database, while providing critical discussions on the challenges encountered and decisions made, which are of relevance for its interpretation and use. The geographic, temporal, and magnitude distributions of the 1958 earthquakes that make up the database are presented alongside the general statistics on damage and casualties, noting that these stem from a variety of sources of differing reliability. Despite its inherent limitations, we believe it is an important contribution to the understanding of the extent of the consequences that may arise from earthquakes in the magnitude range of study.
22 citations
TL;DR: The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and risk of the region due to induced earthquakes, including overseeing one of the most comprehen...
Abstract: The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and risk of the region due to induced earthquakes, including overseeing one of the most comprehen...
20 citations
Cites methods from "What is the Smallest Earthquake Mag..."
...This actually required an additional step backward to develop a revised liquefaction triggering model for tectonic earthquakes due to potential biases in the rd and MSF relationships inherent to existing variants of the simplified model (Lasley et al. 2016, 2017; Green et al. 2019)....
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...10 shows a comparison of the Groningen-specific MSF relationship for Zone 602, as an example, and the worldwide relationships proposed by Idriss and Boulanger (2008) (MSFIB08) and Green et al. (2019) (MSFWUS)....
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...In the next section, the Groningen-specific relationships, rd-Gron and MSFGron, in conjunction with the revised CRR curve (Green et al. 2019), are used to assess the liquefaction hazard across the Groningen liquefaction study area shown in Fig....
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...For each event scenario considered, the Green et al. (2019) triggering model is used in conjunction with Groningen-specific rd and MSF relationships to compute the factor of safety against liquefaction triggering (FSliq) as a function of depth for 95 profiles across the study area....
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...Green et al. (2019) did this using the rd relationship proposed by Lasley et al. (2016) and an MSF that they developed using the number of equivalent cycles (neq) correlation proposed by Lasley et al. (2017)....
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References
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TL;DR: In this paper, the authors studied the characteristics, geologic environments, and hazards of landslides caused by seismic events and found that the maximum area likely to be affected by landslides in a seismic event increases from approximately 0 at M ≅ 4.0 to 500,000 km2 at M = 9.2.
Abstract: Data from 40 historical world-wide earthquakes were studied to determine the characteristics, geologic environments, and hazards of landslides caused by seismic events. This sample of 40 events was supplemented with intensity data from several hundred United States earthquakes to study relations between landslide distribution and seismic parameters. Fourteen types of landslides were identified in the earthquakes studied. The most abundant of these were rock falls, disrupted soil slides, and rock slides. The greatest losses of human life were due to rock avalanches, rapid soil flows, and rock falls. Correlations between magnitude (M) and landslide distribution show that the maximum area likely to be affected by landslides in a seismic event increases from approximately 0 at M ≅ 4.0 to 500,000 km2 at M = 9.2.
Threshold magnitudes, minimum shaking intensities, and relations between M and distance from epicenter or fault rupture were used to define relative levels of shaking that trigger landslides in susceptible materials. Four types of internally disrupted landslides—rock falls, rock slides, soil falls, and disrupted soil slides—are initiated by the weakest shaking. More coherent, deeper-seated slides require stronger shaking; lateral spreads and flows require shaking that is stronger still; and the strongest shaking is probably required for very highly disrupted rock avalanches and soil avalanches.
Each type of earthquake-induced landslide occurs in a particular suite of geologic environments. These range from overhanging slopes of well-indurated rock to slopes of less than 1° underlain by soft, unconsolidated sediments. Materials most susceptible to earthquake-induced landslides include weakly cemented rocks, more-indurated rocks with prominent or pervasive discontinuities, residual and colluvial sand, volcanic soils containing sensitive clay, loess, cemented soils, granular alluvium, granular deltaic deposits, and granular man-made fill. Few earthquake-induced landslides reactivate older landslides; most are in materials that have not previously failed.
1,724 citations
"What is the Smallest Earthquake Mag..." refers background in this paper
...Similarly, all cases of lateral spreading reported by Keefer (1984) and Rodriguez et al. (1999) are larger than magnitude 5....
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TL;DR: A simplified procedure using shear-wave velocity measurements for evaluating the liquefaction resistance of soils is presented in this paper, which follows the general format of the Seed-Idriss simplified procedure based on standard penetration test blow count.
Abstract: A simplified procedure using shear-wave velocity measurements for evaluating the liquefaction resistance of soils is presented. The procedure was developed in cooperation with industry, researchers, and practitioners and evolved from workshops in 1996 and 1998. It follows the general format of the Seed-Idriss simplified procedure based on standard penetration test blow count and was developed using case history data from 26 earthquakes and >70 measurement sites in soils ranging from fine sand to sandy gravel with cobbles to profiles including silty clay layers. Liquefaction resistance curves were established by applying a modified relationship between the shear-wave velocity and cyclic stress ratio for the constant average cyclic shear strain suggested by R. Dobry. These curves correctly predicted moderate to high liquefaction potential for >95% of the liquefaction case histories and are shown to be consistent with the standard penetration test based curves in sandy soils. A case study is provided to illustrate application of the procedure. Additional data are needed, particularly from denser soil deposits shaken by stronger ground motions, to further validate the simplified procedure.
665 citations
"What is the Smallest Earthquake Mag..." refers methods in this paper
...This apparent disparity with the conclusion drawn herein is likely due to the stress reduction factor (rd) relationship that Goda et al. (2011) used in conjunction with the small-strain shear-wave velocity (VS)–based liquefaction evaluation procedure proposed by Andrus and Stokoe (2000)....
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TL;DR: In this paper, the authors present new correlations for assessment of the likelihood of initiation (or triggering) of soil liquefaction, which eliminate several sources of bias intrinsic to previous, similar correlations, and provide greatly reduced overall uncertainty and variance.
Abstract: This paper presents new correlations for assessment of the likelihood of initiation (or “triggering”) of soil liquefaction. These new correlations eliminate several sources of bias intrinsic to previous, similar correlations, and provide greatly reduced overall uncertainty and variance. Key elements in the development of these new correlations are (1) accumulation of a significantly expanded database of field performance case histories; (2) use of improved knowledge and understanding of factors affecting interpretation of standard penetration test data; (3) incorporation of improved understanding of factors affecting site-specific earthquake ground motions (including directivity effects, site-specific response, etc.); (4) use of improved methods for assessment of in situ cyclic shear stress ratio; (5) screening of field data case histories on a quality/uncertainty basis; and (6) use of high-order probabilistic tools (Bayesian updating). The resulting relationships not only provide greatly reduced uncertai...
554 citations
"What is the Smallest Earthquake Mag..." refers background in this paper
...Subsequent rd relationships proposed by Idriss (1999), Cetin et al. (2004), and Lasley et al. (2016), among others, show that rd tends to decrease as magnitude decreases (i.e., the soil column responds less rigidly as magnitude decreases)....
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01 Jan 1982
Abstract: A cyclic strain approach for evaluating the buildup of excess pore water pressures and the potential for liquefaction of level sandy sites during earthquakes Is proposed In this report. This strain approach Is based on the premise that, for undralned loading of sand, there Is a predictable correlation between cyclic shear strain and excess pore water pressure; also, that there Is a threshold shear strain below which there Is no sliding at the contacts between sand particles and no pore water pressure buildup can occur. As the result, a sand deposit will not develop excess pore pressures If the Induced seismic shear strain Is less than the threshold strain. Both theoretical evidence and experimental verification supporting the cyclic strain approach and the existence of the threshold, are presented In the report. Based on all these findings, a specific design method is proposed for predicting if excess pore pressures will develop at a specific site during a design earthquake.
419 citations
"What is the Smallest Earthquake Mag..." refers background in this paper
...…being incapable of inducing sufficient strain to generate excess pore water pressure in the soil, which is requisite for liquefaction triggering (Dobry et al. 1982, Rodriguez-Arriaga and Green 2018), but to use such an approach for screening of liquefaction hazard would require estimation of…...
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TL;DR: A database of earthquake-induced landslides has been compiled which extends the work of Keefer (Keefer DK), who covered the period 1811-1980 to 1997 as mentioned in this paper.
414 citations
"What is the Smallest Earthquake Mag..." refers background in this paper
...Similarly, all cases of lateral spreading reported by Keefer (1984) and Rodriguez et al. (1999) are larger than magnitude 5....
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