scholarly journals Seismic Hazard and Risk Due to Induced Earthquakes at a Shale Gas Site

2021 ◽  
Author(s):  
Benjamin Edwards ◽  
Helen Crowley ◽  
Rui Pinho ◽  
Julian J. Bommer
Keyword(s):  
United Kingdom ◽  
Ground Motion ◽  
Shale Gas ◽  
Structural Damage ◽  
Nonlinear Dynamic Analysis ◽  
Peak Ground Velocity ◽  
Seismic Risk Analysis ◽  
British Geological Survey ◽  
Waveform Data ◽  
Macroseismic Intensities

ABSTRACT Hydraulic fracturing of the first shale gas well at Preston New Road (PNR), Blackpool, United Kingdom, in late 2018, marked the end of a 7 yr United Kingdom-wide moratorium on fracking. Despite a strict traffic-light system being in place, seismic events up to ML 2.9 were induced. The ML 2.9 event was accompanied by reports of damage and was assigned European Macroseismic Scale 1998 (EMS-98) intensity VI by the British Geological Survey. The moratorium was subsequently reinstated in late 2019. The study here presents a pseudo-probabilistic seismic risk analysis and is applied to the larger of the induced events at PNR, in addition to hypothetical larger events. Initially, site characterization analysis is undertaken using direct and indirect methods. These analyses show low-velocity deposits dominate the region (VS30‾=227  m/s). We test existing ground-motion prediction equations using spatially dependent VS30 to determine applicability to the recorded waveform data and produce a referenced empirical model. Predicting median and 84th percentile peak ground velocity fields, we subsequently determine macroseismic intensities. Epicentral intensities of IV, IV–V, and VI–VII are predicted for the observed ML 2.9, and hypothetical ML 3.5 and 4.5 scenarios, respectively. A probabilistic analysis of damage is performed for 3500 ground-motion realizations (2.1≤ML≤4.5) using the OpenQuake-engine, with nonlinear dynamic analysis undertaken to define building fragility. Based on these analyses, the onset of cosmetic damage (DS1) in terms of median risk is observed for the ML 2.9 event. Mean modeled occurrences of DS1 and DS2 (minor structural damage), 75 and 10 instances, respectively, are consistent with reported damage (DS1:97, DS2:50). Significant occurrences (median≥30 buildings) of DS2, DS3, and DS4 (minor to major structural damage) are likely for ML 3.5, 4.0, and 4.5 events, respectively. However, by comparing reported damage with modeled damage due to the ML 2.9 event and considering the fact that low macroseismic intensities (EMS-98 <4) are often not reported by the public, we conclude that the previously assigned intensity of VI is too high, with V being more appropriate.

scholarly journals Raspberry Shake Instruments Provide Initial Ground-Motion Assessment of the Induced Seismicity at the United Downs Deep Geothermal Power Project in Cornwall, United Kingdom

2021 ◽  
Vol 1 (1) ◽  
pp. 27-34
Author(s):  
Joanna M. Holmgren ◽  
Maximilian J. Werner
Keyword(s):  
United Kingdom ◽  
Ground Motion ◽  
Induced Seismicity ◽  
Ground Motions ◽  
Peak Ground Velocity ◽  
Preliminary Evaluation ◽  
British Geological Survey ◽  
Ground Acceleration ◽  
Geothermal Power ◽  
Motion Assessment

Abstract Raspberry Shake (RS) seismographs offer the potential for affordable and citizen-led seismic monitoring in areas with few publicly available seismometers, especially in previously quiescent regions experiencing induced seismicity. However, their scientific and regulatory potential remains largely untested. We examine the ground motions recorded by 11 RS and one broadband station within 15 km of the United Downs Deep Geothermal Power (UDDGP) project in Cornwall, United Kingdom, to evaluate the RS network’s suitability to provide an initial ground-motion assessment of the region. To date, the British Geological Survey (BGS) has reported 232 induced events originating at UDDGP since flow testing began in summer 2020, with two events exceeding local magnitude (ML) 1.5. Although the RS accelerometers are too noisy for UDDGP’s microseismic events, the vertical geophones are useful. Peak ground velocity observations are consistent with relevant ground-motion models, whereas peak ground acceleration (PGA) values are greater than predicted. Regional trends in the PGA levels are likely caused by path effects. Finally, RS estimates of ML are similar to those reported by the BGS. For sparse national seismic networks, RS stations can enable a preliminary evaluation of seismic events and their ground motions.

scholarly journals The 30 October 2020 Samos (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions

2021 ◽  
Author(s):  
Aybige Akinci ◽  
Daniele Cheloni ◽  
AHMET ANIL DINDAR
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Ground Motions ◽  
Aegean Sea ◽  
Peak Ground Velocity ◽  
Ground Shaking ◽  
Local Site ◽  
Eastern Aegean ◽  
Motion Characteristics ◽  
Eastern Aegean Sea

Abstract On 30 October 2020 a MW 7.0 earthquake occurred in the eastern Aegean Sea, between the Greek island of Samos and Turkey’s Aegean coast, causing considerable seismic damage and deaths, especially in the Turkish city of Izmir, approximately 70 km from the epicenter. In this study, we provide a detailed description of the Samos earthquake, starting from the fault rupture to the ground motion characteristics. We first use Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data to constrain the source mechanisms. Then, we utilize this information to analyze the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and spectral pseudo-accelerations. Modelling of geodetic data shows that the Samos earthquake ruptured a NNE-dipping normal fault located offshore north of Samos, with up to 2.5-3 m of slip and an estimated geodetic moment of 3.3 ⨯ 1019 Nm (MW 7.0). Although low PGA were induced by the earthquake, the ground shaking was strongly amplified in Izmir throughout the alluvial sediments. Structural damage observed in Izmir reveals the potential of seismic risk due to the local site effects. To better understand the earthquake characteristics, we generated and compared stochastic strong ground motions with the observed ground motion parameters as well as the ground motion prediction equations (GMPEs), exploring also the efficacy of the region-specific parameters which may be improved to better predict the expected ground shaking from future large earthquakes in the region.

scholarly journals A Novel Approach to Assessing Nuisance Risk from Seismicity Induced by UK Shale Gas Development, with Implications for Future Policy Design

2020 ◽  
Author(s):  
Gemma Cremen ◽  
Maximilian J. Werner
Keyword(s):  
Ground Motion ◽  
Shale Gas ◽  
Induced Seismicity ◽  
Structural Damage ◽  
Policy Design ◽  
Risk Mitigation ◽  
Forecast Model ◽  
Ground Shaking ◽  
North West ◽  
Novel Approach

Abstract. We propose a novel framework for assessing the risk associated with seismicity induced from hydraulic fracturing, which has been a notable source of recent public concern. The framework combines statistical forecast models for injection-induced seismicity, ground motion prediction equations, and exposure models for affected areas, to quantitatively link the volume of fluid injected during operations with the potential for nuisance felt ground motions. Such (relatively small) motions are expected to be more aligned with the public tolerance threshold for induced seismicity than larger ground shaking that could cause structural damage. This proactive type of framework, which facilitates control of the injection volume ahead of time for risk mitigation, has significant advantages over reactive-type magnitude and ground motion-based systems typically used for induced seismicity management. The framework is applied to the region surrounding the Preston New Road shale gas site in North West England. A notable finding is that the calculations are particularly sensitive to assumptions of the seismicity forecast model used, i.e. whether it limits the cumulative seismic moment released for a given volume or assumes seismicity is consistent with the Gutenberg–Richter distribution for tectonic events. Finally, we discuss how the framework can be used to inform relevant policy.

scholarly journals The 2020 national seismic hazard model for the United Kingdom

2022 ◽  
Author(s):  
I. Mosca ◽  
S. Sargeant ◽  
B. Baptie ◽  
R. M. W. Musson ◽  
T. C. Pharaoh
Keyword(s):  
United Kingdom ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Model ◽  
Border Region ◽  
Eurocode 8 ◽  
Hazard Maps ◽  
British Geological Survey ◽  
The United Kingdom ◽  
The Uk

AbstractWe present updated seismic hazard maps for the United Kingdom (UK) intended for use with the National Annex for the revised edition of Eurocode 8. The last national maps for the UK were produced by Musson and Sargeant (Eurocode 8 seismic hazard zoning maps for the UK. British Geological Survey Report CR/07/125, United Kingdom, 2007). The updated model uses an up-to-date earthquake catalogue for the British Isles, for which the completeness periods have been reassessed, and a modified source model. The hazard model also incorporates some advances in ground motion modelling since 2007, including host-to-target adjustments for the ground motion models selected in the logic tree. For the first time, the new maps are provided for not only peak ground acceleration (PGA) but also spectral acceleration at 0.2 s (SA0.2s) and 1.0 s for 5% damping on rock (time-averaged shear wave velocity for the top 30 m Vs30 ≥ 800 m/s) and four return periods, including 475 and 2475 years. The hazard in most of the UK is generally low and increases slightly in North Wales, the England–Wales border region, and western Scotland. A similar spatial variation is observed for PGA and SA0.2s but the effects are more pronounced for SA0.2s. Hazard curves, uniform hazard spectra, and disaggregation analysis are calculated for selected sites. The new hazard maps are compared with the previous 2007 national maps and the 2013 European hazard maps (Woessner et al. in Bull Earthq Eng 13:3553–3596, 2015). There is a slight increase in PGA from the 2007 maps to this work; whereas the hazard in the updated maps is lower than indicated by the European maps.

scholarly journals Observations about the seismic response of RC buildings in Mexico City

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 154-174
Author(s):  
Sergio Alcocer ◽  
Anahid Behrouzi ◽  
Sergio Brena ◽  
Kenneth J Elwood ◽  
Ayhan Irfanoglu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Mexico City ◽  
Peak Ground Acceleration ◽  
Structural Damage ◽  
Peak Ground Velocity ◽  
Rc Buildings ◽  
Ground Acceleration ◽  
Better Than

Over 2000 buildings were surveyed by members of the Colegio de Ingenieros (CICM) and Sociedad Mexicana de Ingenieria Estructural (SMIE) in Mexico City following the Puebla-Morelos Earthquake of 2017. This inventory of surveyed buildings included nearly 40 collapses and over 600 buildings deemed to have structural damage. Correlation of damage with peak ground acceleration (PGA), peak ground velocity (PGV), predominant spectral period, building location, and building properties including height, estimated stiffness, and presence of walls or retrofits was investigated for the surveyed buildings. The evidence available suggests that (1) ground motion intensity (PGV) drove the occurrence of damage and (2) buildings with more infill and stiff retrofit systems did better than other buildings.

Empirical Correlations of Spectral Input Energy with Peak Amplitude, Cumulative, and Duration Intensity Measures

2021 ◽  
Author(s):  
Yin Cheng ◽  
Tongtong Liu ◽  
Jianfeng Wang ◽  
Chao-Lie Ning
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Peak Amplitude ◽  
Peak Ground Velocity ◽  
Input Energy ◽  
Empirical Correlations ◽  
Seismic Risk Analysis ◽  
Intensity Measures ◽  
Single Measure

ABSTRACT In earthquake engineering, it is acknowledged that a vector of intensity measures (IMs) can better predict seismic structural responses than a single measure. Hence, a vector of IMs is widely applied in a number of applications, such as probabilistic seismic hazard analysis, probabilistic seismic risk analysis, and ground-motion selections. Spectral input energy (EI) has been demonstrated as a promising IM in earthquake engineering, especially in the energy-based seismic design of structures. However, this important measure has not been included in the vector of IMs. Therefore, it is worthwhile to incorporate EI with other important IMs by examining correlations. This study analyzes the empirical correlations of spectral EI with peak amplitude-based IMs, cumulative-based IMs, and duration-related IMs. It is found that spectral absolute EI has strong correlations with peak ground velocity at all investigated periods. However, spectral EI is negatively correlated with duration-based IMs. To demonstrate the applicability of the examined correlations, a simple example is finally presented by employing EI for the ground-motion selections and seismic hazard assessment based on the generalized conditional intensity measure approach.

Strain-Estimated Ground Motions Associated with Recent Earthquakes in California

2020 ◽  
Vol 110 (6) ◽  
pp. 2766-2776
Author(s):  
Noha Farghal ◽  
Annemarie Baltay ◽  
John Langbein
Keyword(s):  
Shear Wave ◽  
Ground Motion ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Structural Damage ◽  
The United States ◽  
Peak Ground Velocity ◽  
Earthquake Ground Motion ◽  
Plate Boundaries ◽  
Horizontal Shear

ABSTRACT Peak ground velocity (PGV) is a commonly used parameter in earthquake ground-motion models (GMMs) and hazard analyses, because it is closely related to structural damage and felt ground shaking, and is typically measured on broadband seismometers. Here, we demonstrate that strainmeters, which directly measure in situ strain in the bulk rock, can easily be related to ground velocity by a factor of bulk shear-wave velocity and, thus, can be used to measure strain-estimated PGV. We demonstrate the parity of velocity to strain utilizing data from borehole strainmeters deployed along the plate boundaries of the west coast of the United States for nine recent M 4.4–7.1 earthquakes in California, including the largest two events of the July 2019 Ridgecrest earthquake sequence. PGVs derived from maximum horizontal shear strains fall within the range of seismic-estimated values recorded at the same distances. We compare the strain-estimated data with GMMs based on seismic PGVs and find consistency in residual polarity (positive vs. negative; the sign of the difference between observed and modeled data) for certain earthquake–station paths, where some paths indicate an overestimation and others indicate an underestimation of strain-derived PGVs, as compared with the GMMs. We surmise that this may be indicative of over or underestimation of shear-wave velocity along those paths, as compared with the average velocity used to derive PGV from strain measurements, or indicative of repeatable site and path effects that are not accounted for in our analyses. This direct comparison of strain with velocity can highlight physical path effects, as well as improve the density and capability of ground-motion recordings.

scholarly journals Vector-Valued Fragility Analysis Using PGA and PGV Simultaneously as Ground-Motion Intensity Measures

2010 ◽  
Vol 5 (4) ◽  
pp. 407-416
Author(s):  
Sei’ichiro Fukushima ◽  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Fragility Curves ◽  
Fragility Analysis ◽  
Peak Ground Velocity ◽  
Seismic Risk Analysis ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Vector Valued

Seismic risk analysis usually expresses ground-motion intensity using a single index such as peak ground acceleration (PGA), spectral acceleration for a specified period, or peak ground velocity (PGV). Limiting the number of indices, however, adds greater uncertainty when estimating annual failure probability given by convolving seismic hazard and fragility curves. This is because information other than ground-motion intensity is missing. Author proposed seismic hazard analysis using PGA and PGV simultaneously as groundmotion input measures. After analyzing the correlation coefficient between PGA and PGV using K-NET and KiK-net databases, probabilistic seismic hazard for seven sites in Kanto district in Japan was evaluated. In this study, seismic fragility analysis using PGA and PGV is conducted followed by advantage of vector-valued fragility analysis.

scholarly journals A novel approach to assessing nuisance risk from seismicity induced by UK shale gas development, with implications for future policy design

2020 ◽  
Vol 20 (10) ◽  
pp. 2701-2719
Author(s):  
Gemma Cremen ◽  
Maximilian J. Werner
Keyword(s):  
Ground Motion ◽  
Shale Gas ◽  
Induced Seismicity ◽  
Structural Damage ◽  
Policy Design ◽  
Risk Mitigation ◽  
Forecast Model ◽  
Ground Shaking ◽  
North West ◽  
Novel Approach

Abstract. We propose a novel framework for assessing the risk associated with seismicity induced by hydraulic fracturing, which has been a notable source of recent public concern. The framework combines statistical forecast models for injection-induced seismicity, ground motion prediction equations, and exposure models for affected areas, to quantitatively link the volume of fluid injected during operations with the potential for nuisance felt ground motions. Such (relatively small) motions are expected to be more aligned with the public tolerance threshold for induced seismicity than larger ground shaking that could cause structural damage. This proactive type of framework, which facilitates control of the injection volume ahead of time for risk mitigation, has significant advantages over reactive-type magnitude and ground-motion-based systems typically used for induced seismicity management. The framework is applied to the region surrounding the Preston New Road shale gas site in North West England. A notable finding is that the calculations are particularly sensitive to assumptions of the seismicity forecast model used, i.e. whether it limits the cumulative seismic moment released for a given volume or assumes seismicity is consistent with the Gutenberg–Richter distribution for tectonic events. Finally, we discuss how the framework can be used to inform relevant policy.

scholarly journals Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Gansu Province ◽  
Mitigation Measures ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Acceleration Time Histories

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.

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