Recalibration of the Distance Correction Term for Local Magnitude (ML) Computations in Italy

2015 ◽  
Vol 86 (5) ◽  
pp. 1383-1392 ◽  
Author(s):  
Barbara Lolli ◽  
Paolo Gasperini ◽  
Francesco Mariano Mele ◽  
Gianfranco Vannucci
Keyword(s):  
Correction Term ◽  
Local Magnitude ◽  
Distance Correction

Determination of Local Magnitude for Earthquakes Recorded from the Texas Seismological Network (TexNet)

2020 ◽  
Vol 91 (6) ◽  
pp. 3223-3235
Author(s):  
Florentia Kavoura ◽  
Alexandros Savvaidis ◽  
Ellen Rathje
Keyword(s):  
Correction Term ◽  
Local Magnitude ◽  
Hypocentral Distance ◽  
Original Definition ◽  
Definition Of ◽  
Refracted Waves ◽  
Attenuation Characteristics ◽  
Seismological Network ◽  
Distance Correction

Abstract In this study, we present a local magnitude (ML) relation for the earthquakes recorded from the Texas Seismological Network (TexNet) between the dates of 1 January 2017 and 31 July 2019. Using a comprehensive seismic dataset from earthquakes in Texas, we propose a distance correction term −logA0, which is consistent with the original definition of the Richter magnitude. The proposed distance correction calculation for the TexNet events accounts for the attenuation characteristics of the direct and refracted waves over different distance ranges. Regression analysis of Wood–Anderson amplitudes results in the following trilinear function, which represents the attenuation attributes of the events under investigation: −logA0={2.07×log(Rhyp)+0.0002×(Rhyp−100)−0.72Rhyp≤16  km1.54×log(Rhyp)+0.0002×(Rhyp−100)−0.0816  km<Rhyp≤105  km,0.29×log(Rhyp)+0.0002×(Rhyp−100)+2.45Rhyp>105  km in which Rhyp is the hypocentral distance (km). The derived distance correction relationship results in an accurate ML relationship for Texas that is unbiased over a 200 km distance range. Compared with other ML relations, the proposed relation in this study gives lower ML values over all distances than those calculated by Richter (1958), Hutton and Boore (1987), Babaie Mahani and Kao (2019), and Quinones et al. (2019) by an average of 0.01, 0.12, 0.16, and 0.15 units, respectively; this study’s proposed relation gives higher ML values over all distances than those calculated by Scales et al. (2017), Yenier (2017), and Greig et al. (2018) by an average of 0.28, 0.01, and 0.08 units, respectively.

Calibration of Local Magnitude Scale for Colombia

2020 ◽  
Vol 110 (4) ◽  
pp. 1971-1981
Author(s):  
Camilo Muñoz Lopez ◽  
Laura Velasquez ◽  
Viviana Dionicio
Keyword(s):  
Volcanic Activity ◽  
Seismic Data ◽  
Correction Function ◽  
Local Magnitude ◽  
Linear Inversion ◽  
Hypocentral Distance ◽  
International Networks ◽  
Base Level ◽  
Attenuation Values ◽  
Distance Correction

ABSTRACT New calibration for local magnitude (ML) was performed for Colombia. The territory was divided into five zones using reported attenuation values for different areas of the country and correlating this information with the mapped lithologies, the absence or presence of volcanic activity, and patterns in the hypocentral locations of seismicity. Seismic data from the Colombian National Seismic Network—Colombian Geological Survey (RSNC-SGC) were used to obtain a total of 81,232 peak amplitudes from 22,816 earthquakes recorded between January 2015 and August 2017. This set of data was incorporated into a linear inversion to calculate the distance-correction functions for each zone. A new methodology is proposed for calculating the base level of the distance-correction function or parameter c, using the amplitude values for earthquakes with moment magnitudes (Mw) close to 3 measured at stations at distances close to 100 km. The distance-correction logA0 functions obtained in this study for the five zones are: Zone  1:−logA0=1.245×log(r)+0.0024×r−2.051,Zone  2:−logA0=1.056×log(r)+0.0021×r−1.76,Zone  3:−logA0=1.07×log(r)+0.0013×r−1.531,Zone  4:−logA0=1.241×log(r)+0.0015×r−2.178,Zone  5:−logA0=0.711×log(r)+0.0009×r−0.69, in which r is the hypocentral distance in kilometers. The results of this study are in use in the RSNC-SGC since September 2018. Before using the equations presented here, the values of local magnitude were previously underestimated for the entire Colombian territory. This work allows the calculation of the local magnitude using the largest attenuation changes in addition to decreasing discrepancies with other magnitude types such as Mw and those calculated by international networks.

scholarly journals The ML scale in Southern California

1987 ◽  
Vol 77 (6) ◽  
pp. 2074-2094
Author(s):  
L. K. Hutton ◽  
David M. Boore
Keyword(s):  
Southern California ◽  
Strong Motion ◽  
Body Waves ◽  
Local Magnitude ◽  
Hypocentral Distance ◽  
Station Corrections ◽  
Original Definition ◽  
Definition Of ◽  
Large Earthquakes ◽  
Distance Correction

Abstract Measurements (9,941) of peak amplitudes on Wood-Anderson instruments (or simulated Wood-Anderson instruments) in the Southern California Seismographic Network for 972 earthquakes, primarily located in southern California, were studied with the aim of determining a new distance correction curve for use in determining the local magnitude, ML. Events in the Mammoth Lakes area were found to give an unusual attenuation pattern and were excluded from the analysis, as were readings from any one earthquake at distances beyond the first occurrence of amplitudes less than 0.3 mm. The remaining 7,355 amplitudes from 814 earthquakes yielded the following equation for ML distance correction, log A0 − log A 0 = 1.110 log ( r / 100 ) + 0.00189 ( r − 100 ) + 3.0 where r is hypocentral distance in kilometers. A new set of station corrections was also determined from the analysis. The standard deviation of the ML residuals obtained by using this curve and the station corrections was 0.21. The data used to derive the equation came from earthquakes with hypocentral distances ranging from about 10 to 700 km and focal depths down to 20 km (with most depths less than 10 km). The log A0 values from this equation are similar to the standard values listed in Richter (1958) for 50 < r < 200 km (in accordance with the definition of ML, the log A0 value for r = 100 km was constrained to equal his value). The Wood-Anderson amplitudes decay less rapidly, however, than implied by Richter's correction. Because of this, the routinely determined magnitudes have been too low for nearby stations (r < 50 km) and too high for distant stations (r > 200 km). The effect at close distances is consistent with that found in several other studies, and is simply due to a difference in the observed ≈ 1/r geometrical spreading for body waves and the 1/r2 spreading assumed by Gutenberg and Richter in the construction of the log A0 table. ML's computed from our curve and those reported in the Caltech catalog show a systematic dependence on magnitude: small earthquakes have larger magnitudes than in the catalog and large earthquakes have smaller magnitudes (by as much as 0.6 units). To a large extent, these systematic differences are due to the nonuniform distribution of data in magnitude-distance space (small earthquakes are preferentially recorded at close distances relative to large earthquakes). For large earthquakes, however, the difference in the two magnitudes is not solely due to the new correction for attenuation; magnitudes computed using Richter's log A0 curve are also low relative to the catalog values. The differences in that case may be due to subjective judgment on the part of those determining the catalog magnitudes, the use of data other than the Caltech Wood-Anderson seismographs, the use of different station corrections, or the use of teleseismic magnitude determinations. Whatever their cause, the departures at large magnitude may explain a 1.0:0.7 proportionality found by Luco (1982) between ML's determined from real Wood-Anderson records and those from records synthesized from strong-motion instruments. If it were not for the biases in reported magnitudes, Luco's finding would imply a magnitude-dependent shape in the attenuation curves. We studied residuals in three magnitude classes (2.0 < ML ≦ 3.5, 3.5 < ML ≦ 5.5, and 5.5 < ML ≦ 7.0) and found no support for such a magnitude dependence. Based on our results, we propose that local magnitude scales be defined such that ML = 3 correspond to 10 mm of motion on a Wood-Anderson instrument at 17 km hypocentral distance, rather than 1 mm of motion at 100 km. This is consistent with the original definition of magnitude in southern California and will allow more meaningful comparison of earthquakes in regions having very different attenuation of waves within the first 100 km.

A local-magnitude scale for the western Great Basin-eastern Sierra Nevada from synthetic Wood-Anderson seismograms

1995 ◽  
Vol 85 (4) ◽  
pp. 1236-1243
Author(s):  
Martha Kane Savage ◽  
John G. Anderson
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Magnitude Scale ◽  
Local Magnitude ◽  
Digital Network ◽  
Original Definition ◽  
Correction Curve ◽  
Fitting Parameters ◽  
Distance Correction ◽  
Eastern Sierra Nevada

Abstract We have computed synthetic Wood-Anderson seismograms for over 1100 arrivals at 10 three-component, broadband digital stations in the UNR western Great Basin-eastern Sierra Nevada network. These represent all the available records from local earthquakes over magnitude 3.5 between 1990 and June of 1993, plus selected events of smaller magnitude. There were 77 events ranging in magnitude from 2.2 to 5.9, including four events over magnitude 5. The distances considered ranged from 15 to 600 km, with the best-represented range being from 30 to 450 km. We invert these measurements to determine distance and station corrections appropriate for a local-magnitude scale, constrained by Richter's original definition that an earthquake of ML = 3 will cause a 1-mm zero to peak deflection of the Wood-Anderson seismogram at 100 km from the epicenter. The results between 30 and 450 km were essentially independent of choice of curve-fitting parameters. In the 30- to 500-km distance region, the smooth distance-correction curves were very similar to that determined by Richter (1958), which is still used for southern California earthquakes. We propose to use Richter's distance-correction curve in reporting amplitude magnitudes from our digital network.

Interstitial vs. Substitutional Metal Insertion in V2O5 as Post-Lithium Ion Battery Cathode: A Comparative GGA/GGA+U Study with Localized Bases

2020 ◽  
Author(s):  
Daniel Koch ◽  
Sergei Manzhos
Keyword(s):  
Electronic Structure ◽  
Plane Wave ◽  
Transition Metal Oxides ◽  
Reasonable Agreement ◽  
Correction Term ◽  
Lithium Ion ◽  
Generalized Gradient ◽  
Main Group Metals ◽  
Generalized Gradient Approximation ◽  
Metal Insertion

<p></p><p>The generalized gradient approximation (GGA) often fails to correctly describe the electronic structure and thermochemistry of transition metal oxides and is commonly improved using an inexpensive correction term with a scaling parameter <i>U</i>. We tune <i>U</i> to reproduce experimental vanadium oxide redox energetics with a localized basis and a GGA functional. We find the value for <i>U</i> to be significantly lower than what is generally reported with plane-wave bases, with the uncorrected GGA results being in reasonable agreement with experiments. We use this computational setup to calculate interstitial and substitutional <a>insertion energies of main group metals in vanadium pentoxide</a> and find <a>interstitial doping to be thermodynamically favored</a>.</p><p></p>

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

scholarly journals Design and Development of a Low Cost, Non-Contact Infrared Thermometer with Range Compensation

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3817
Author(s):  
Nicholas Wei-Jie Goh ◽  
Jun-Jie Poh ◽  
Joshua Yi Yeo ◽  
Benjamin Jun-Jie Aw ◽  
Szu Cheng Lai ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Low Cost ◽  
Common Symptom ◽  
Ultrasonic Sensors ◽  
Design And Development ◽  
Infrared Thermometer ◽  
Compensation Methods ◽  
Monitoring Devices ◽  
Distance Correction

Fever is a common symptom of many infections, e.g., in the ongoing COVID-19 pandemic, keeping monitoring devices such as thermometers in constant demand. Recent technological advancements have made infrared (IR) thermometers the choice for contactless screening of multiple individuals. Yet, even so, the measurement accuracy of such thermometers is affected by many factors including the distance from the volunteers’ forehead, impurities (such as sweat), and the location measured on the volunteers’ forehead. To overcome these factors, we describe the assembly of an Arduino-based digital IR thermometer with distance correction using the MLX90614 IR thermometer and HC-SR04 ultrasonic sensors. Coupled with some analysis of these factors, we also found ways to programme compensation methods for the final assembled digital IR thermometer to provide more accurate readings and measurements.

scholarly journals Predicting Rates of Inbreeding in Populations Undergoing Selection

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1851-1864 ◽  
Author(s):  
John A Woolliams ◽  
Piter Bijma
Keyword(s):  
Overlapping Generations ◽  
Linear Models ◽  
Selection Process ◽  
Correction Term ◽  
Random Mating ◽  
Nonrandom Mating ◽  
Selection Processes ◽  
Genetic Contributions ◽  
The Relationship

AbstractTractable forms of predicting rates of inbreeding (ΔF) in selected populations with general indices, nonrandom mating, and overlapping generations were developed, with the principal results assuming a period of equilibrium in the selection process. An existing theorem concerning the relationship between squared long-term genetic contributions and rates of inbreeding was extended to nonrandom mating and to overlapping generations. ΔF was shown to be ~¼(1 − ω) times the expected sum of squared lifetime contributions, where ω is the deviation from Hardy-Weinberg proportions. This relationship cannot be used for prediction since it is based upon observed quantities. Therefore, the relationship was further developed to express ΔF in terms of expected long-term contributions that are conditional on a set of selective advantages that relate the selection processes in two consecutive generations and are predictable quantities. With random mating, if selected family sizes are assumed to be independent Poisson variables then the expected long-term contribution could be substituted for the observed, providing ¼ (since ω = 0) was increased to ½. Established theory was used to provide a correction term to account for deviations from the Poisson assumptions. The equations were successfully applied, using simple linear models, to the problem of predicting ΔF with sib indices in discrete generations since previously published solutions had proved complex.

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