The ML scale in eastern North America

1998 ◽  
Vol 88 (4) ◽  
pp. 935-951 ◽  
Author(s):  
Won-Young Kim
Keyword(s):  
Vertical Component ◽  
Horizontal Component ◽  
Peak Amplitude ◽  
Eastern North America ◽  
Attenuation Curve ◽  
Local Magnitude ◽  
Magnitude Range ◽  
The Mean ◽  
Large Earthquakes ◽  
Comparable Quality

Abstract An attenuation curve for the local magnitude scale, ML, of eastern North American (ENA) earthquakes was empirically determined using synthetic Wood-Anderson seismograms derived from newly available broadband recordings from the U.S. National Seismographic Network (USNSN) and from additional stations of comparable quality. Wood-Anderson peak amplitudes measured on approximately 210 three-component, broadband digital records from 38 earthquakes in the distance range of 50 to 800 km were inverted for the attenuation curve and magnitude of each event. The earthquakes ranged from ML = 2.2 to 4.6 and were recorded at about 20 stations in the region. Separate attenuation curves were determined for the N-S, E-W, and vertical components, as well as for the mean of the two horizontal components. All curves had similar slopes indicating that ML can be determined from any one of the three components available. The Wood-Anderson peak amplitude phases were predominantly Lg waves arriving with a mean group velocity of 3.40 ± 0.23 km/sec and a mean period of 0.50 ± 0.26 sec. ML for earthquakes in ENA can be obtained from the horizontal-component Wood-Anderson peak amplitude in millimeters, A(Δ), using the formula ML = log10A(Δ) (in mm) + 1.55 log10 Δ (in km) − 0.22 + C, for distances 100 to 800 km and 2.2 ≦ ML ≦ 4.6 and where C = station magnitude correction. The ML is tied to Richter's (1935) ML scale for southern California. A similar formula is given to determine ML from the vertical-component synthetic Wood-Anderson seismograms. ML is related to Nuttli's mb(Lg) by ML = 0.976 mb(Lg) − 0.05 for earthquakes with 2.2 ≦ ML ≦ 4.6 in ENA. Analysis of six additional large earthquakes with ML ≧ 5 indicates that ML ≈ mb(Lg) − 0.15 in a wide magnitude range of 2 ≦ ML ≦ 6.5 in ENA.

scholarly journals Station correction analysis for surface-wave magnitudes of New Zealand earthquakes

1999 ◽  
Vol 32 (1) ◽  
pp. 21-29 ◽  
Author(s):  
D. A. Rhoades ◽  
D. J. Dowrick
Keyword(s):  
New Zealand ◽  
Surface Wave ◽  
Linear Model ◽  
World Wide ◽  
Vertical Component ◽  
Horizontal Component ◽  
Standard Errors ◽  
Station Correction ◽  
The Mean

Station terms and standard errors are presented for 345 world-wide stations used in the determination of surface-wave magnitudes of 190 selected New Zealand earthquakes over the period 1901-1993 [1]. These will facilitate the estimation of surface-wave magnitudes of other earthquakes in the New Zealand region. The station terms and the residuals from the linear model used to estimate them are both found to be weakly related to the mean distance from the earthquakes recorded by each station. The horizontal and vertical components at a given site are treated as separate stations. The station term for the horizontal component tends to exceed that for the vertical component at mean distances in the 20°-40° range.

scholarly journals Remarks on the mean-square values of the geomagnetic field and its components

1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A. De Santis ◽  
C. Falcone ◽  
F. J. Lowes
Keyword(s):  
Geomagnetic Field ◽  
Spherical Surface ◽  
Vertical Component ◽  
Relative Magnitude ◽  
Field Vector ◽  
Horizontal Component ◽  
Mean Square ◽  
The Mean ◽  
Harmonic Components ◽  
Spatial Power Spectrum

When considering functions on the Earth's (spherical) surface, mean-square values are often used to indicate their (relative) magnitude. If a function is separated into it, (essentially) spherical harmonic components then, provided these individual harmonic components are orthogonal over the surface, the concept of spatial power spectrum can be introduced, with each harmonic contributing separately to the total mean square value; this is true for the geomagnetic field vector B, its horizontal component vector H, and its vertical component z. However, because of the lack of orthogonality this concept is not applicable to the horizontal X and y components individually; problems which arise from this are discussed.

Galilean Relativity

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Inertial Frame ◽  
Vertical Component ◽  
Horizontal Component ◽  
The Other ◽  
One Dimension ◽  
Everyday Experience ◽  
Low Speed ◽  
Principle Of Relativity ◽  
Galilean Relativity ◽  
Laws Of Motion

Galilean relativity is a useful description of nature at low speed. Galileo found that the vertical component of a projectile’s velocity evolves independently of its horizontal component. In a frame that moves horizontally along with the projectile, for example, the projectile appears to go straight up and down exactly as if it had been launched vertically. The laws of motion in one dimension are independent of any motion in the other dimensions. This leads to the idea that the laws of motion (and all other laws of physics) are equally valid in any inertial frame: the principle of relativity. This principle implies that no inertial frame can be considered “really stationary” or “really moving.” There is no absolute standard of velocity (contrast this with acceleration where Newton’s first law provides an absolute standard). We discuss some apparent counterexamples in everyday experience, and show how everyday experience can be misleading.

Peripheral representation of antennal orientation by the scapal hair plate of the cockroach Periplaneta americana

2001 ◽  
Vol 204 (24) ◽  
pp. 4301-4309 ◽  
Author(s):  
J. Okada ◽  
Y. Toh
Keyword(s):  
Single Unit ◽  
Periplaneta Americana ◽  
Vertical Component ◽  
Horizontal Component ◽  
Vertical Position ◽  
Horizontal Position ◽  
Joint Movement ◽  
Basal Segment ◽  
Dynamic Phase ◽  
Hair Sensilla

SUMMARY Arthropods have hair plates that are clusters of mechanosensitive hairs, usually positioned close to joints, which function as proprioceptors for joint movement. We investigated how angular movements of the antenna of the cockroach (Periplaneta americana) are coded by antennal hair plates. A particular hair plate on the basal segment of the antenna, the scapal hair plate, can be divided into three subgroups: dorsal, lateral and medial. The dorsal group is adapted to encode the vertical component of antennal direction, while the lateral and medial groups are specialized for encoding the horizontal component. Of the three subgroups of hair sensilla, those of the lateral scapal hair plate may provide the most reliable information about the horizontal position of the antenna, irrespective of its vertical position. Extracellular recordings from representative sensilla of each scapal hair plate subgroup revealed the form of the single-unit impulses in response to hair deflection. The mechanoreceptors were characterized as typically phasic-tonic. The tonic discharge was sustained indefinitely (>20 min) as long as the hair was kept deflected. The spike frequency in the transient (dynamic) phase was both velocity- and displacement-dependent, while that in the sustained (steady) phase was displacement-dependent.

Modeling some empirical vertical component Lg relations

1983 ◽  
Vol 73 (1) ◽  
pp. 157-171
Author(s):  
Robert B. Herrmann ◽  
Andrzej Kijko
Keyword(s):  
Time Domain ◽  
Scaling Laws ◽  
Vertical Component ◽  
Wave Theory ◽  
Eastern North America ◽  
Peak Time ◽  
Coda Q ◽  
Crustal Model ◽  
Lg Wave ◽  
Spatial Attenuation

abstract Higher mode surface wave theory is used to model the vertical component Lg wave observed in eastern North America at regional distances. Tests of the model are made to determine whether it is capable of describing empirical spectral scaling laws, spatial attenuation, and peak time domain Lg amplitudes. It is found that a simple crustal model and a rough estimate of crustal Qβ are all that are required to accomplish this. Good results are obtained if the average crustal Qβ is equated to the coda Q of the same frequency.

scholarly journals A Comparison of Equatorial Electrojet in Peru and East Brazil

2013 ◽  
Vol 7 (1) ◽  
pp. 29-36 ◽  
Author(s):  
R.G. Rastogi ◽  
H. Chandra ◽  
Rahul Shah ◽  
N.B. Trivedi ◽  
S.L. Fontes
Keyword(s):  
South America ◽  
Geomagnetic Field ◽  
Daily Variation ◽  
Equatorial Electrojet ◽  
Horizontal Component ◽  
Low Latitude ◽  
Vertical Field ◽  
The Mean ◽  
Western Side ◽  
The Magnetic Field

The paper describes the characteristics of the equatorial electrojet at Huancayo (HUA, 12.1oS, 75.3oW, inclination 1.5oN, declination 1.0oE) in western side of South America, where the geomagnetic field is aligned almost along the geographic meridian, and at Itinga (ITI, 4.3oS, 47.oW, inclination 1.4oN, declination 19.3oW) in eastern part of South America, where the geomagnetic field is aligned about 19o west of the geographic meridian; although the mean intensity of the magnetic field in the two regions are almost of the same order. Further comparisons are made of the current at Itinga and at Tatuoca (TTB, 1.2oS, 48.5oW, inclination 7.8o N, declination 18.7oW), a low latitude station in the same longitude sector. The daily range of horizontal component of the geomagnetic field, H, is shown to be almost 16% higher at HUA compared to that at ITI. The daily variation of the eastward field, Y, showed a strong minimum of -40 nT around 13-14 hr LT at ITI whereas very low values were observed at HUA with a positive peak of about 4 nT around 11- 12 hr LT. The vertical field, Z, showed abnormally large negative values of -70 nT at TTB around 13 hr LT. The day-today fluctuations of midday and midnight values of X field were positively correlated between HUA and ITI with a high correlation coefficient of 0.78 and 0.88 respectively. Values of Y field were also significantly positively correlated between HUA and ITI for midnight hours (0.72), while no correlation was observed for the midday hours. The midnight values of X field at HUA, ITI and TTB showed significant (0.90 or greater) correlation with Dst index. Correlation values of about 0.7 were observed between Dst and midday values of X at ITI and TTB and to a lesser degree (0.4) at HUA.

scholarly journals Comparison between sprinkler irrigation and natural rainfall based on droplet diameter

2016 ◽  
Vol 14 (1) ◽  
pp. e1201 ◽  
Author(s):  
MaoSheng Ge ◽  
Pute Wu ◽  
Delan Zhu ◽  
Daniel P. Ames
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Droplet Diameter ◽  
Vertical Component ◽  
Radial Distance ◽  
Sprinkler Irrigation ◽  
Application Rate ◽  
Horizontal Component ◽  
Natural Rainfall ◽  
Actual Field

<p>An indoor experiment was conducted to analyze the movement characteristics of different sized droplets and their influence on water application rate distribution and kinetic energy distribution. Radial droplets emitted from a Nelson D3000 sprinkler nozzle under 66.3, 84.8, and 103.3 kPa were measured in terms of droplet velocity, landing angle, and droplet kinetic energy and results were compared to natural rainfall characteristics. Results indicate that sprinkler irrigation droplet landing velocity for all sizes of droplets is not related to nozzle pressure and the values of landing velocity are very close to that of natural rainfall. The velocity horizontal component increases with radial distance while the velocity vertical component decreases with radial distance. Additionally, landing angle of all droplet sizes decreases with radial distance. The kinetic energy is decomposed into vertical component and horizontal component due to the oblique angles of droplet impact on the surface soil, and this may aggravate soil erosion. Therefore the actual oblique angle of impact should be considered in actual field conditions and measures should be taken for remediation of soil erosion if necessary.</p>

Single-station SVD-based polarization filtering of ground roll: Perfection and investigation of limitations and pitfalls

Geophysics ◽  
2012 ◽  
Vol 77 (2) ◽  
pp. V41-V59 ◽  
Author(s):  
Olena Tiapkina ◽  
Martin Landrø ◽  
Yuriy Tyapkin ◽  
Brian Link
Keyword(s):  
Time Window ◽  
Synthetic Data ◽  
Vertical Component ◽  
Horizontal Component ◽  
Frequency Bandwidth ◽  
Polarization Filter ◽  
Data Set ◽  
Single Station ◽  
Ground Roll ◽  
Polarization Filtering

The advent of single receiver point, multi-component geophones has necessitated that ground roll be removed in the processing flow rather than through acquisition design. A wide class of processing methods for ground-roll elimination is polarization filtering. A number of these methods use singular value decomposition (SVD) or some related transformations. We focus on a single-station SVD-based polarization filter that we consider to be one of the best in the industry. The method is comprised of two stages: (1) ground-roll detection and (2) ground-roll estimation and filtering. To detect the ground roll, a special attribute dependent on the singular values of a three-column matrix formed by a sliding time window is used. The ground roll is approximated and subtracted using the first two eigenimages of this matrix. To limit the possible damage to the signal, the filter operates within the record intervals where the ground roll is detected and within the ground-roll frequency bandwidth only. We improve the ground-roll detector to make it theoretically insensitive to ambient noise and more sensitive to the presence of ground roll. The advantage of the new detector is demonstrated on synthetic and field data sets. We estimate theoretically and with synthetic data the attenuation of the underlying reflections that can be caused by the polarization filter. We show that the underlying signal always loses almost all the energy on the vertical component and on the horizontal component in the ground-roll propagation plane and within the ground-roll frequency bandwidth. The only signal component, if it exists, that can retain a significant part of its energy is the horizontal component orthogonal to the above plane. When 2D 3C field operations are conducted, the signal particle motion can deviate from the ground-roll propagation plane and can therefore retain some of its energy due to a set of offline reflections. In the case of 3D 3C seismic surveys, the reflected signal always deviates from the ground-roll propagation plane on the receiver lines that do not contain the source. This is confirmed with a 2.5D 3C synthetic data set. We discuss when the ability of the filter to effectively subtract the ground roll may, or may not, allow us to ignore the inevitable harm that is done to the underlying reflected waves.

Variance analysis of excitatory postsynaptic potentials in cat spinal motoneurons during posttetanic potentiation

1989 ◽  
Vol 61 (2) ◽  
pp. 403-416 ◽  
Author(s):  
H. P. Clamann ◽  
J. Mathis ◽  
H. R. Luscher
Keyword(s):  
Transmitter Release ◽  
Background Noise ◽  
Peak Amplitude ◽  
Posttetanic Potentiation ◽  
Excitatory Postsynaptic Potentials ◽  
Spinal Motoneurons ◽  
Postsynaptic Potentials ◽  
Release Probability ◽  
Synaptic Boutons ◽  
The Mean

1. Fluctuations in the peak amplitudes of composite excitatory postsynaptic potentials (EPSPs) in cat spinal motoneurons were analyzed during posttetanic potentiation (PTP). Each of a series of identical tetanic stimulus trains delivered to a muscle nerve was followed by 45 test stimuli applied at 2-s intervals. The mean peak amplitude and mean peak variance were calculated for EPSPs evoked by all those stimuli following a tetanus with the same time interval. It was assumed that the variance arises primarily from the probabilistic all-or-none behavior of single synaptic boutons and background noise due to spontaneous synaptic activity and thermal noise in the recording system. The variance was corrected for the contribution from additive Gaussian background noise. 2. If it is assumed that individual synaptic boutons behave independently, corrected mean peak variance and mean peak amplitude are related by a parabolic function. The expected parabolic relationship was seen in 9 of 31 cases studied, and the parameters of the best parabolic fit to the data allowed estimation of some synaptic properties. From these parameters, the mean amplitude of the unit EPSP (v) was estimated to be 102.1 +/- 57.4 (SD) microV. An average of 3.7 boutons comprised each Ia-motoneuron contact system. 3. On average, only 27% of all synaptic boutons given off by the stimulated Ia fibers to one motoneuron were active and releasing transmitter during unpotentiated reflex transmission. The remaining 73% of the synapse population was intermittently silent. The population of boutons which took part in synaptic transmission could be divided into two subpopulations, one with a release probability P = 1 and a second with a mean release probability P = 0.13 +/- 0.086. 4. We conclude that synaptic boutons connecting Ia afferents to motoneurons exist in two populations, one having a high and one a low probability of transmitter release. Transmitter release is quantal, resulting in a unit EPSP of approximately 100 microV measured at the motoneuron soma.

Experimental investigation of the instability of a sedimenting suspension of fibres

2007 ◽  
Vol 575 ◽  
pp. 307-332 ◽  
Author(s):  
BLOEN METZGER ◽  
JASON E. BUTLER ◽  
ÉLISABETH GUAZZELLI
Keyword(s):  
Vertical Component ◽  
Orientation Distribution ◽  
Velocity Fluctuations ◽  
Image Velocimetry ◽  
Wide Range ◽  
Fluid Properties ◽  
The Mean ◽  
Using Data ◽  
Horizontal Wavelength ◽  
Short Times

Observations of the flow structures formed by rigid fibres of high aspect ratio sedimenting within a viscous fluid at a Reynolds number of approximately 10−4 confirm the existence of an instability as reported in previous theories, experiments, and numerical simulations. Using data generated from particle image velocimetry measurements, we quantify the sedimentation structures over a wide range of parameters, which include the height of fluid, cross-section of the sedimentation cell, fibre dimensions, fluid properties, and volume fractions ranging from dilute to semi-dilute. Alternating structures of streamers and backflow regions which span the height of the sedimentation cell form at short times and transition from large wavelengths to smaller wavelength as the sedimentation proceeds. No simple dependence of the horizontal wavelength on the length scales and concentration was observed in the experiments, suggesting the need for additional analysis. We also report the mean velocities and velocity fluctuations; the strength of the velocity fluctuations strongly correlates with the size of the vertical component of the sedimentation structure. Measurements of the orientation distribution, using an efficient and newly employed technique, agree with previously published results. A movie is available with the online version of the paper.

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