Magnitude Scale Research Articles

A Proposal for a High-Frequency Earthquake Magnitude (m3Hz) for Seismic Hazard and Rapid Damage Assessment

Abstract Obtaining a size estimate of an earthquake that well represents its potential impact is of primary importance in seismology and earthquake engineering. The magnitude scales currently used in earthquake catalogs, mainly Ms and Mw, are not designed to represent the variability of shaking due to variations in high-frequency radiation. Conversely, ML, which best describes the seismic-wave energy released by an earthquake, is unable to provide an accurate representation of events with magnitudes exceeding approximately 6.5. Therefore, building on and extending the concept of high-frequency magnitude (Atkinson and Hanks, 1995), we propose in this article a new high-frequency magnitude scale m3Hz. This magnitude is estimated by also considering correction factors for the crustal model and site effects. We apply the new magnitude scale m3Hz to two data sets (Central Italy and Japan) and validate its ability to capture high-frequency radiation effects through comparison with available source parameters. Finally, a procedure for estimating m3Hz is also proposed for preinstrumental earthquakes. This procedure addresses a limitation of previous magnitude estimation techniques, such as Me, and is validated for four events for which both macroseismic and instrumental intensity data are available.

Generative Adversarial Networks-Based Ground-Motion Model for Crustal Earthquakes in Japan Considering Detailed Site Conditions

ABSTRACT We develop a ground-motion model (GMM) for crustal earthquakes in Japan that can directly model the probability distribution of ground-motion acceleration time histories based on generative adversarial networks (GANs). The proposed model can generate ground motions conditioned on moment magnitude, rupture distance, and detailed site conditions defined by the average shear-wave velocity in the top 5, 10, and 20 m (VS5, VS10, and VS20) and the depth to shear-wave velocities of 1.0 km/s and 1.4 km/s (Z1.0 and Z1.4). We construct the neural networks based on styleGAN2 and introduce a novel neural network architecture to generate ground motions considering the effect of source, path, and such detailed site conditions. The resulting 5% damped spectral acceleration from the proposed GMM is consistent with empirical GMMs in terms of magnitude and distance scaling. The proposed GMM can also generate ground motions accounting for the shear-wave velocity profiles of surface soil with different magnitudes and distances and represent characteristics that are not explained solely byVS30.

A Coda-Duration Magnitude Scale for the Mesopotamian Seismological Network in Iraq

One of the routine tasks of local, regional, and global seismic networks is to calculate the earthquake magnitude using one or more scales. This study aims to derive a duration magnitude equation using the earthquake data recorded by the local Mesopotamian Seismological Network (MPSN) in Iraq. The seismic waveform data were collected from 13 broadband seismic stations of the local MPSN for the period June 2014 to October 2023 years. The source parameters of these earthquakes were extracted from the International Seismological Centre (ISC). To establish a coda duration magnitude scale, 476 events were used and 100 events were employed to test the derived equation. Coda-duration magnitude equations were derived using linear regression analysis. To ensure the applicability of the magnitude equation for the network, the station correction coefficient (Sc) was estimated. The established coda duration magnitude scales are as follows: (4 ≤ ML ≤ 6) (4 ≤ ML ≤ 5) There is a good agreement between the MD values calculated using the above equation with those estimated for the same events using coda-duration magnitude equation derived in previous study from data of the Iraqi Meteorological Organization and Seismology (IMOS). The significant strong scaling relationships derived between MD–ML, MD–mb, MD–Ms, and MD–MW can be used quickly and reliably in MD calculation for earthquakes recorded by the MPNS stations and vice versa.

EQGraphNet: Advancing single-station earthquake magnitude estimation via deep graph networks with residual connections

Magnitude estimation is a critical task in seismology, and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution. In this context, we propose the Earthquake Graph Network (EQGraphNet) to enhance the performance of single-station magnitude estimation. The backbone of the proposed model consists of eleven convolutional neural network layers and ten RCGL modules, where a RCGL combines a Residual Connection and a Graph convolutional Layer capable of mitigating the over-smoothing problem and simultaneously extracting temporal features of seismic signals. Our work uses the STanford EArthquake Dataset for model training and performance testing. Compared with three existing deep learning models, EQGraphNet demonstrates improved accuracy for both local magnitude and duration magnitude scales. To evaluate the robustness, we add natural background noise to the model input and find that EQGraphNet achieves the best results, particularly for signals with lower signal-to-noise ratios. Additionally, by replacing various network components and comparing their estimation performances, we illustrate the contribution of each part of EQGraphNet, validating the rationality of our approach. We also demonstrate the generalization capability of our model across different earthquakes occurring environments, achieving mean errors of ±0.1 units. Furthermore, by demonstrating the effectiveness of deeper architectures, this work encourages further exploration of deeper GNN models for both multi-station and single-station magnitude estimation.

The use of sugar kelp (Saccharina latissima) as a seasoning for popcorn: An investigation of consumer acceptance, sensory perception and emotional response

Increasing consumer demand for health-promoting sustainable food products has led to interest in seaweed. Sugar kelp, Saccharina latissimi, is a rich source of vitamins, minerals, fibre, antioxidants, and protein, but it is underutilized as a food ingredient. Seaweed has been identified as a possible seasoning and could be used in snack foods. As such, the purpose of this study was to evaluate how consumers would use sugar kelp as a seasoning on popcorn. The consumers (n = 95) evaluated popcorn and then were asked to add sugar kelp seasoning and to reevaluate the popcorn. The amount of popcorn consumed, and the amount of seasoning used were recorded. Furthermore, the consumers evaluated the popcorn with and without sugar kelp using hedonic scales, free comment, generalized Labelled Magnitude Scales, as well as emotional response (using the EsSense25 profile). The consumers, on average, used 2.5 g of seasoning and consumed the same amount of both samples (with and without sugar kelp). The addition of sugar kelp decreased the liking scores, increased the intensity of umami and bitterness in the samples, and led to fishy, seaweed, and pepper flavours being perceived. It also led to the reduction of positive emotions and an increased selection of negative emotions. The consumers identified that they are interested in foods containing seaweed, but based on the results of the study, the addition of sugar kelp seasoning needs to be further explored.

Development of earthquake early warning algorithm magnitude scale for the 2023 Kahramanmaraş earthquake region

On 6 February 2023, Türkiye suffered two major earthquakes with magnitudes of Mw = 7.7 and Mw = 7.6 at 04:17 and 13:24 local time in Pazarcık and Elbistan districts of Kahramanmaraş, which were called as the disaster of the century. On 20 February 2023 at 20:04 local time, another major earthquake with Mw = 6.4 occurred in Yayladağı, Hatay. This disaster caused great loss of life and heavy destruction. The burden of the earthquake on the Turkish economy is extremely heavy. The purpose of earthquake early warning systems (EEWS) is to protect people and property, save time for precautions to be taken and prepare emergency response teams. An effective EEWS has a major role in reducing life, structural and economic losses. This study is an implementation of the original California optimized EPIC, an early warning algorithm, in the region of the 2023 Kahramanmaraş earthquakes. A total of 212 earthquakes in the region are replayed to derive magnitude scaling equations based on peak displacement amplitude (Pd) and predominant period (Tpmax). The performance of the modified equations is tested for three large earthquakes. By comparing the magnitudes estimated by Pd and Tpmax, it is observed that Pd gives more suitable results. The 2023 Kahramanmaras earthquakes real-time tests suggested a warning time of 32 s for the first earthquake in Antakya (Hatay), where the heaviest destruction and loss of life was observed. In the other earthquakes, the warning times were interpreted as quite useful to minimize the loss of life. The geography of the 2023 Kahramanmaraş earthquakes is a seismically active region and will be subject to earthquakes in the future. As a result of this study, a region-specific scaling of the magnitude, which is the most important parameter if an early warning system is established in the region, is presented. It is also a good example of how an effective earthquake early warning system can reduce potential hazards.

Predictive capabilities, robustness and limitations of two event-based approaches for lag time estimation in heterogeneous watersheds

Several studies have demonstrated that response times in natural catchments decrease with increasing rainfall intensity. Consequently, event-based estimations of catchment response times are of paramount importance in applied hydrology. Specifically, they have the potential to address a major inconsistency in the use of empirical formulas. These formulas often assume response times as constant parameters, regardless of whether extreme or frequent flood events are considered, thus neglecting the role of flow velocities.In this paper, built upon previous approaches developed and/or analyzed by the authors, two different recent methods for event-based estimations of catchment response times are critically reviewed, and their predictive performances are compared. First, four “physically-based” formulas, calibrated using synthetic rainfalls in three small Italian watersheds to reproduce the results of a two-dimensional hydrodynamic-based rainfall/runoff model and, consequently, the simulated wave celerities, are considered. Then, the detrending moving-average cross-correlation analysis (DMCA) has been applied to assess the average time elapsed between the centroids of precipitation and discharge time series.The soundness of these two approaches is initially assessed based on their ability to reproduce estimated lag times from observations. Their robustness is further evaluated by analyzing the magnitude and basin scale dependence of the inferred velocities compared to observed values, following a recent approach proposed in the literature. These issues are discussed with reference to 60 rainfall-runoff events occurring across 27 watersheds in Hungary and Italy, which possess substantially different geomorphic and climatic features, highlighting both the potential and the need for further improvements. Both approaches give error rates of around 37% for the proposed dataset.

T1R2/T1R3 polymorphism affects sweet and fat perception: Correlation between SNP and BMI in the context of obesity development.

Genetic variations in taste receptors are associated with gustatory perceptionand obesity, which in turn affects dietary preferences. Given the increasing tendency of people with obesity choosing sweet, high-fat meals, the current study assessed the cross-regulation of two polymorphisms of the sweet taste receptor (T1R2/T1R3), rs35874116 and rs307355, on fat sensitivity in Indian adults. We investigated the association between taste sensitivity and BMI in the T1R2, T1R3, and CD36 polymorphic and non-polymorphic groups. The general labelled magnitude scale (gLMS) was used to assess the taste sensitivity of 249 participants in addition to anthropometric data. TaqMan Probe-based RT-PCR was employedto determine the polymorphisms. Additionally, the colorimetric method utilizing 3, 5-dinitro salicylic acid was used to evaluate the participants' salivary amylase activity. The mean detection thresholds for linoleic acid (LA) and sucrose were greater in individuals with obesity (i.e., 0.97±0.08mM and 0.22±0.02M, respectively) than in healthy adults (p < 0.0001), indicating lower sensitivity. Moreover, it was found that a greater proportion of persons with obesity fall into the polymorphic groups (i.e., 52% with genotype CD36 AA, 44% with genotype T1R2 CC, and 40% with genotype T1R3 TT). All three single nucleotide polymorphisms support the Hardy-Weinberg equilibrium (p = 0.78). The Pearson correlation analysis between LA and the sucrose detection threshold revealed a significant (p < 0.0001) positive relationship with an rvalue of 0.5299. Moreover, salivary amylase activity was significantly (p < 0.05) higher in the polymorphic sub-groups. The results of our study imply that genetic variations in T1R2/T1R3 receptors affect perception of both sweetness and fat, which may have an effect on obesity.

Special needs school community preparedness facing earthquake (Case study: Special needs school in a very high earthquake’s seismicity region in DIY)

Background: DIY is a province in Indonesia that is very susceptible to earthquakes. In 2006, a seismic event measuring 6.2 on the moment magnitude scale struck DIY, causing injuries and extensive damage to both the structural and non-structural elements of several buildings, including one in the education sector. The problem of structural damage to educational facilities is a significant worry, especially in school communities that cater to vulnerable children, such as those in special needs schools (SLB), who are more susceptible to harm during disasters. This study aims to assess the level of preparedness and accessibility of the special needs school community located in a very high seismic region of earthquakes in the DIY, in the event of an earthquake. Methods: The structural assessment took the form of a binary question, requiring a simple yes or no response. Findings: To reduce the risk of earthquakes in the special needs education sector, a review of the preparedness of the special needs school building and community was carried out by implementing “Satuan Pendidikan Aman Bencana (SPAB)” or Disaster Safe Education Unit guidelines. The findings suggest that SLB Sekar Melati Muh. Imogiri (78,26) was classed as having moderate earthquake risk, whereas SLB Dharma Bhakti Piyungan (88,55), SLB Insan Mandiri Dlingo (90,29), and SLB Purworaharjo (88,41) featured infrastructure that was rated as very vulnerable. With respect to SLB Dharma Bhakti Piyungan (64,52), SLB Insan Mandiri Dlingo (60,11), and SLB Purworaharjo (76,94), their average community readiness index scores put them in the intermediate capability category for earthquake preparedness. SLB Sekar Melati Muhmmadiyah Imogiri, however, was categorized as having a low capacity for earthquake readiness with an average index score of 56,92 for community preparedness. Conclusion: special needs school communities should raise their level of preparedness by undertaking seismic socialization and regular simulations to boost the community's understanding of earthquakes and reduce the likelihood of harm following an earthquake. Novelty/Originality of this Study: The study breaks new ground by assessing earthquake preparedness and accessibility in special needs schools within a high-seismicity region, addressing a critical gap in disaster risk reduction for vulnerable populations.

A local magnitude scale (ML) for Northern Algeria

This study presents a local magnitude scale (ML) based on the original Richter definition and designed for use within the Algerian Digital Seismic Network (ADSN). The magnitude scale is derived from the analysis of 17,377 zero-peak maximum amplitude traces extracted from the vertical component, simulated as Wood-Anderson seismograms. These traces are taken from a dataset of 1901 earthquakes recorded between January 1, 2010, and June 1, 2022, at a minimum of five stations in the ADSN network. To better account for the attenuation of direct and refracted waves in northern Algeria, amplitude decay analysis reveals the presence of two transition distances at 90 and 190 km, resulting in three segments. A distance correction term, −log10(A0), is introduced and described by the following trilinear function:−logA0=0.6747∗log10R+0.0002∗R+1.6306R≤901.7736∗log10R+0.0002∗R−0.516990<R≤1902.4580∗log10R+0.0002∗R−2.0765R>190R represents the hypocentral distance in kilometers. The derived distance correction formula provides a well-constrained ML relationship for northern Algeria that is valid over a distance range of 5 to 600 km. Compared to other local magnitude relationships, the methodology proposed in this study consistently gives ML values slightly higher than those calculated by the Southern California relationship over all distances, with an average difference of 0.2 units. We computed corrections for 72 stations by minimizing the ML residuals. These corrections range from −0.50 to 0.54, highlighting the influence of local site effects on the amplitude of the seismic signal. The magnitude residuals using our magnitude relationship and incorporating the station corrections, show that the standard deviation has improved significantly, from 0.34 to 0.24. An ML relationship specific to the northern Algerian region provides a valuable tool for seismic monitoring, hazard assessment, and earthquake research in the region.

A Pn magnitude scale mb(Pn) for earthquakes along the equatorial Mid-Atlantic Ridge

SUMMARY We developed a short-period Pn magnitude scale mb(Pn) for earthquakes along the equatorial Mid-Atlantic Ridge. Due to low signal-to-noise ratios, teleseismic body wave magnitude and long-period surface wave magnitude cannot be confidently determined for small earthquakes of mb &amp;lt; 4. Local magnitude scales are also not useful for these events because the oceanic environment does not allow the propagation of crustal phases. However, regional high-frequency Pn waves from these small- to moderate-size (mb 3–6) earthquakes are well recorded in the equatorial Atlantic region and can be used to assign magnitudes. We measured over 2041 Pn peak amplitudes on vertical records from about 21 stations in northeastern Brazil and 11 stations in western Africa in the distance range of 700–3700 km. We analysed data from 189 events from the global centroid moment tensor catalogue to tie our mb(Pn) scale to Mw so that seismic moments can be readily estimated. Pn arrivals show apparent group velocity between 7.9 km s−1 at short ranges (∼1000 km) and up to 9.1 km s−1 at 3500 km. The measured peak amplitudes have a frequency between 0.8 and 3 Hz at 1000–1800 km, but at greater distances, 1800–3700 km, they show a remarkably consistent frequency of about 0.8 Hz. The peak amplitude attenuates at a higher rate at short distances (∼0.65 magnitude units between 700 and 2000 km) but attenuates at a lower rate at long distances (∼0.35 magnitude units between 2000 and 3700 km). The low rate of amplitude decay with distance and nearly constant frequency content of the peak amplitudes suggest that Pn waves propagate efficiently in the lower part of the upper mantle in the equatorial Atlantic Ocean basins. These are important attributes of oceanic Pn waves that can be used to assign magnitude for small- to moderate-size earthquakes in the equatorial mid-Atlantic region. The estimated station corrections correlate well with upper mantle low-velocity anomalies, especially in Brazil.

Consumers' sensory perception and emotional response towards animal and plant‐based soups (familiar food items) with the addition of shio‐koji (an unfamiliar ingredient)

SummaryGlobally, consumers continue to seek out novel foods and ingredients from different cultures and regions. Shio‐koji is a fermented seasoning that is usually made by fermenting rice with koji (Aspergillus oryzae). It has been proposed that shio‐koji can be used as a flavour enhancer of foods. This study investigated consumers' (n = 96; generally unfamiliar with koji) liking (hedonic scales), emotional response (using the EsSense25 profile in check‐all‐that‐apply format), as well as their sensory perception (generalised Labelled Magnitude Scales and free comment) of shio‐koji additions to food items. Participants evaluated three different soups (chicken, vegetable and tomato), a familiar food product, with and without the addition of shio‐koji. The shio‐koji increased the consumers' liking of the vegetable soup and increased their perception of saltiness in the vegetable and tomato soups. The bitterness and sourness intensity of the chicken soup decreased with the addition of shio‐koji, while the sweetness increased. However, the umami taste of all soups was not impacted. The soups with shio‐koji were also associated with positive emotions. During the free comment task, shio‐koji led to an increased mention of meaty attributes to describe the vegetable soup, but the inverse occurred when the participants evaluated the chicken soup. The results indicate that shio‐koji impacted consumer perceptions of both animal‐ and plant‐based soups. Future studies should continue to investigate the use of shio‐koji to enhance the flavour of different food products.

Investigating Taste Perception of Maltodextrins Using Lactisole and Acarbose.

Previous research has demonstrated that complex carbohydrates (maltodextrins) can be perceived in the oral cavity. However, little research has been conducted to thoroughly investigate complex carbohydrate taste perception and contributing factors. This study explored the effects of the degree of polymerization and the concentration of complex carbohydrates on taste perception. Additionally, the impact of lactisole and acarbose on carbohydrate taste perception was investigated. Using a blinded, Latin Square design, participants (n = 40) received samples (control) or samples with acarbose (5 mM) or lactisole (1.4 mM). Per visit, participants received solutions: (1) short chain maltodextrin (average DP 6) (SCM), (2) long chain maltodextrin (average DP 24) (LCM), (3) maltose, and (4) glucose. Samples were evaluated in duplicate, both at low concentration and high concentration. Participants tasted the samples and rated sweetness, starchiness, and viscosity (mouthfeel) perceived on a 10 cm continuous line scale and perceived intensity on a Labelled Magnitude Scale. There was a significant effect of degree of polymerisation on sweetness (p = 0.001) and intensity (p = 0.001). For low concentration samples, no significant differences were found between LCM and acarbose LCM or SCM and acarbose SCM for sweetness, starchiness, or mouthfeel (all p > 0.05). Significant differences were observed between LCM and lactisole LCM for sweetness (1.1 ± 0.1 vs. 2.5 ± 0.3, p = 0.001), starchiness (1.4 ± 0.2 vs. 2.3 ± 0.3, p = 0.005), and mouthfeel (1.4 ± 0.2 vs. 2.3 ± 0.3, p = 0.013). In conclusion, the taste perception of maltodextrins is influenced by the degree of polymerisation. Furthermore, for this study, the sweet taste receptor was not involved in maltodextrin taste perception. While salivary α-amylase did not appear to influence taste perception with low concentration maltodextrins, further investigation is necessary.

Fat, protein, and temperature each contribute to reductions in capsaicin oral burn.

It is widely accepted that milk provides the greatest relief from capsaicin burn, an effect typically attributed to its fat content and temperature. Previously, Lawless etal. reported partitioning lipophilic capsaicin in fat reduces burn, whereas Green showed lower temperature reduces burn. Recent research shows that dairy and nondairy proteins also reduce capsaicin burn, suggesting that multiple factors reduce oral burn from chilies. Here, we investigated the effectiveness of palate cleansers with varied viscosities, temperatures, and sugar, fat, and protein content. Specifically, we tested ice cream, Italian ice, yogurt, lassi, cold water (4°C), and warm water (37°C). Participants rinsed with a 5ppm capsaicin solution, followed by a palate cleanser, before rating burn intensity continuously for 2min on a general Labeled Magnitude Scale. Inspection of the time-intensity (TI) curves revealed all palate cleansers performed better than warm water. Italian ice performed on par with cold water, which did better than yogurt. Pairwise comparisons showed that ice cream and lassi had significantly lower burn ratings at some time points relative to warm or cold water. We extracted scaffolding parameters for each TI curve, finding that ice cream and lassi had the lowest areas-under-the-curve and the greatest percent decrease from their maxima, with ice cream performing slightly better in both parameters. These data support the view that it is not just one characteristic of a product, but rather a combination of product factors that reduce oral burn, including fat content, protein content, and temperature. More research is required to determine the relative weight of these factors in combination, given the multiple mechanisms underlying burn reduction.

Potency–Magnitude Scaling Relations and a Unified Earthquake Catalog for the Western United States

Abstract Quantifying the size of earthquakes is a foundational task in seismology, and over the years several magnitude scales have been developed. Of these, only scales based on seismic moment or potency can properly characterize changes in event size without saturation. Here, we develop empirical potency–magnitude scaling relations for earthquakes in the western United States, allowing us to translate instrumental magnitude estimates into uniform measures of earthquake size. We use synthetic waveforms to validate the observed scaling relations and to provide additional insight into the differences between instrumental and physics-based magnitude scales. Each earthquake in our catalog is assigned a clustering designation distinguishing mainshocks from triggered seismicity, along with a potency-based magnitude estimate that is comparable to moment magnitude and that can be easily converted into other magnitude scales as needed. The developed catalog and associated scaling relations have broad applications for fundamental and applied studies of earthquake processes and hazards.

Are maximum magnitudes of induced earthquakes controlled by pressure diffusion?

There is an ongoing discussion about how to forecast the maximum magnitudes of induced earthquakes based on operational parameters, subsurface conditions and physical process understanding. Although the occurrence of damage caused by induced earthquakes is rare, some cases have caused significant economic loss, injuries and even loss of life. We analysed a global compilation of earthquakes induced by hydraulic fracturing, geothermal reservoir stimulation, water disposal, gas storage and reservoir impoundment. Our analysis showed that maximum magnitudes scale with the characteristic length of pressure diffusion in the brittle Earth's crust. We observed an increase in the nucleation potential of larger-magnitude earthquakes with time and explained it by diffusion-controlled growth of the pressure-perturbed part of faults. Numerical and analytical fault size modelling supported our findings. Finally, we derived magnitude scaling laws to manage induced seismic hazard of upcoming energy projects prior to operation. This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'.

EFFECTS OF CHEWING TIME OF HIGH PROTEIN MEAL ON SATIETY AND GLP-1 HORMONE

Background: Chewing or mastication process affects satiety as well as satiety regulating hormone Glucagon-like Peptide-1 (GLP-1). Proteins have the highest satiating effects among the macronutrients. This study explored the association of chewing with satiety and GLP-1 in participants consuming high-protein meal. Methods: Fifteen healthy volunteers, aged 25-35 years were enrolled through random sampling. Effects of chewing on postprandial satiety and plasma GLP-1 was examined through quasi-experimental study conducted in Khyber Medical University, Peshawar, from Jan to Mar 2023. Three visits were designed with one week wash-out period. Satiety and GLP-1 were compared among normal, fast, and slow chewing conditions, while providing high protein meal. Subjective satiety was assessed via visual analogue scale (VAS) and labelled magnitude scale (LMS), while serum GLP-1 levels were analysed through ELISA at baseline, 30, 120 and 240 min in each visit. Results: The participants had a mean chewing time of 793.66±311 second at normal rate. Mean chewing time was decreased to 496.60±135.82 second during fast chewing, while significantly increased to 1459.66±400.83 second during slow chewing. A comparison of satiety at different chewing rates revealed that slow chewing significantly reduced hunger and enhanced fullness (p&lt;0.05), relative to normal and fast chewing, at 240 minutes (p&lt;0.05). However, no significant difference was observed in plasma GLP-1 levels at any time intervals (p&gt;0.05). Conclusion: Satiety is significantly influenced by chewing and number of chews per bite of a high protein meal, whereas postprandial plasma GLP-1 levels show no significant differences across different chewing rates. Pak J Physiol 2024;20(2):31-35

A High-Precision Earthquake Catalog for Nevada

Abstract The state of Nevada is home to one of the most seismically active regions in the world, with crustal deformation associated with the Walker Lane transitioning into Basin and Range tectonics as one traverses from west to east across the state. Despite hosting numerous prominent earthquake sequences over the past century and beyond, at present, there exists no unified research-quality earthquake catalog for the state and its surrounding region. Here, we present a newly compiled, high-precision catalog of more than 180,000 earthquakes occurring around Nevada from 2008 to 2023. The data processing workflow to create this catalog includes an absolute location step that accounts for topography and 3D variations in subsurface wavespeed, and a relative relocation step that refines event positions using differential times measured from waveform cross-correlation. We also provide an update to the local magnitude scale that better accounts for the observed distance attenuation of waveform amplitudes as well as local site effects. We describe some fundamental insights that can be derived from the new catalog, including regional variations in event depth distributions and sequence clustering statistics, and publish the catalog to the wider community to facilitate future research efforts.

Quantifying near-fault motion effects on soil liquefaction through effective stress site response analysis

Near-fault (NF) pulse-like ground motions have a significant impact on the performance of structures, but their effects on soil liquefaction potential have been relatively understudied. This paper uses 1D effective stress site response analysis capable of modeling porewater pressure (PWP) generation to investigate the seismic site response under NF and general ground motions. The aim is to assess the effects of NF motions on soil liquefaction by considering different soil models and PWP generation models. The results show that NF ground motions generally induce larger ground responses in terms of PWP generation, especially when the durations of the motions are short. This is due to the higher cumulative absolute velocity associated with NF ground motions compared with general ground motions due to a high-velocity pulse under the same peak ground acceleration. However, this effect diminishes as the duration of motion increases. To avoid underestimating seismic demand, especially for small to moderate earthquakes, a preliminary magnitude scale factor modified for the NF effect is suggested for use in conventional soil liquefaction triggering analysis.

Integrated study on buried pipelines, co-seismic landslides, and magnitude conversion for 2023 Türkiye earthquake

Türkiye is known for its intricate tectonic structure and high seismic activity, which makes in-depth research on earthquakes necessary. This research paper presents a multifaceted examination of earthquake impact in Türkiye, encompassing critical elements of seismic vulnerability with a special focus on the latest twin earthquake of February 6, 2023. Firstly, a three-dimensional finite element (FE) analysis has been conducted to explore the buried pipeline behavior under left-lateral strike-slip faults. Secondly, making use of the earthquake data from 1976 to 2023, a new Newmark displacement-based model has been proposed which predicts co-seismic landslide displacement. Finally, new magnitude conversion relations are developed in the generalized moment magnitude scale (Mwg) for Türkiye using three statistical regression techniques. The maximum tensile strain was found to be around 2.0% based on the findings of the 3D numerical study of an underground pipe that was subjected to left-lateral strike-slip fault movement. The proposed co-seismic landslide displacement model was developed based on moment magnitude, yield acceleration, and peak ground acceleration, which yields an R-squared value of 0.93. Outcomes of the magnitude conversion study depicted that the improved general orthogonal regression (IGOR) relationships developed in this study performed better than the other conventional methods of regression. Also, the proposed regional relations based on Mwg scale perform better than global relations as they provide closer values to the observed ones. By offering a comprehensive perspective on seismic impact, the research lays the groundwork for upgraded predictive methods and refined seismic design considerations. The proposed models and conversion relations contribute to the strengthening of critical infrastructures, providing a forward-looking approach to enhance preparedness and resilience against earthquake disasters in Türkiye.