SKP and related phases*

1956 ◽  
Vol 46 (3) ◽  
pp. 185-201 ◽  
Author(s):  
R. D. Forester
Keyword(s):  
Inner Core ◽  
Energy Content ◽  
Focal Point ◽  
Vertical Component ◽  
Continuous Increase ◽  
Long Period ◽  
Amplitude Data ◽  
Short Period ◽  
Additional Support ◽  
Period Instruments

Abstract For shallow shocks, multiple SKP phases are observed after the initial SKP motion as long as 54 seconds on short-period instruments and as long as 87 seconds on long-period instruments. Amplitude data indicate that each multiple phase has a focal point similar to that of the initial SKP phase. The focal point for waves having periods of 1 to 5 seconds occurs at 131½°, and that for waves having periods of 5 to 10 seconds is broadly defined between 130° and 131°. Short-period SKP waves extend from 129° to at least 140°; long-period SKP waves, from 125° to 145°. The long-period waves are believed to be diffracted from the caustic in accordance with Airy's hypothesis. For all types of SKP phases the energy content of the short-period waves is several times less than that of the long-period waves. For the vertical component the agreement between theoretical and observed values of energy of long-period waves is good. For the horizontal component the observation of too little energy is not satisfactorily explained. SKP″, the SKP phase associated with the inner core, is observed between 114° and 125°. It records with very short periods. The observations of SKP″ present additional support for the hypothesis of large but continuous increase of velocity at the transitional boundary of the inner core.

scholarly journals Inversion of the body waves from the Borrego Mountain earthquake to the source mechanism

1976 ◽  
Vol 66 (5) ◽  
pp. 1485-1499 ◽  
Author(s):  
L. J. Burdick ◽  
George R. Mellman
Keyword(s):  
Body Wave ◽  
High Stress ◽  
Time Function ◽  
The Body ◽  
Body Waves ◽  
Polarization Angle ◽  
Long Period ◽  
Amplitude Data ◽  
Short Period ◽  
Wide Range

abstract The generalized linear inverse technique has been adapted to the problem of determining an earthquake source model from body-wave data. The technique has been successfully applied to the Borrego Mountain earthquake of April 9, 1968. Synthetic seismograms computed from the resulting model match in close detail the first 25 sec of long-period seismograms from a wide range of azimuths. The main shock source-time function has been determined by a new simultaneous short period-long period deconvolution technique as well as by the inversion technique. The duration and shape of this time function indicate that most of the body-wave energy was radiated from a surface with effective radius of only 8 km. This is much smaller than the total surface rupture length or the length of the aftershock zone. Along with the moment determination of Mo = 11.2 ×1025 dyne-cm, this radius implies a high stress drop of about 96 bars. Evidence in the amplitude data indicates that the polarization angle of shear waves is very sensitive to lateral structure.

Surface-wave magnitudes of Eurasian earthquakes and explosions

1975 ◽  
Vol 65 (3) ◽  
pp. 693-709 ◽  
Author(s):  
Otto W. Nuttli ◽  
So Gu Kim
Keyword(s):  
Surface Wave ◽  
Focal Mechanism ◽  
Rayleigh Waves ◽  
Body Wave ◽  
Focal Depth ◽  
Vertical Component ◽  
P Waves ◽  
Long Period ◽  
Short Period ◽  
Continental Interior

abstract Body-wave magnitudes, mb, and surface-wave magnitudes, MS, were determined for approximately 100 Eurasian events which occurred during the interval August through December 1971. Body-wave magnitudes were determined from 1-sec P waves recorded by WWSSN short-period, vertical-component seismographs at epicentral distances greater than 25°. Surface-wave magnitudes were determined from 20-sec Rayleigh waves recorded by long-period, vertical-component WWSSN and VLPE seismographs. The earthquakes had mb values ranging from 3.6 to 5.7. Of 96 presumed earthquakes studied, 6 lie in or near the explosion portion of an mb:MS plot. The explosion mb:MS curve was obtained from seven Eurasian events which had mb values ranging from 5.0 to 6.2 and MS values from 3.2 to 5.1. All six anomalous earthquakes were located in the interior of Asia, in Tibet, and in Szechwan and Sinkiang provinces of China. In general, oceanmargin earthquakes were found to have more earthquake-like mb:MS values than those occurring in the continental interior. Neither focal depth nor focal mechanism can explain the anomalous events.

scholarly journals Broadband time domain modeling of earthquakes from Friuli, Italy

1981 ◽  
Vol 71 (4) ◽  
pp. 1215-1231
Author(s):  
John Cipar
Keyword(s):  
Time Domain ◽  
Main Shock ◽  
Waveform Inversion ◽  
High Stress ◽  
Point Sources ◽  
Domain Modeling ◽  
Long Period ◽  
Short Period ◽  
Stress Drops ◽  
Period Instruments

abstract Short-period (SP) and long-period (LP) seismograms written by the main shock and two principal aftershocks of the 1976 Friuli, Italy, earthquake sequence are modeled in the time domain using synthetic seismograms. The main shock occurred on 6 May 1976 (20h 00m, Ms = 6.5) and both aftershocks on 15 September 1976 (03h 15m, Ms = 6.0 and 09h 21m, Ms = 5.9). Source models were determined initially by trial and error and then refined using a waveform inversion program. Two point sources of radiation are required to adequately model the aftershock short-period records. For the 09h 21m aftershock, the model derived from short-period records also produces good fits to the long-period data. The seismic moment of this earthquake is found to be 0.8 to 1.0 × 1025 dyne-cm. The SP model for the 03h 15m aftershock, on the other hand, predicts long-period synthetics which do not agree with the observations. In particular, the SP moment (0.37 × 1025 dyne-cm) is about 212 times smaller than the LP moment (1 × 1025 dyne-cm). Adding a long-period component to the SP model considerably improves LP waveform and moment agreement. In the case of the main shock, a reasonable fit to the observed SP data is obtained using three point sources of radiation. However, LP synthetics computed using this model do not agree with the observations, and the SP moment (0.65 × 1025 dyne-cm) is a small fraction of the LP moment (3 to 5 × 1025 dyne-cm). Time function durations indicate that the individual events inferred from the SP records are radiated from patches of the fault having radii of 2 to 4 km and stress drops in the range 35 to 276 bars. In comparison, stress drops estimated from LP data are found to be 12 bars (main shock) and 24 bars (09h 21m aftershock). These observations suggest that the short-period instruments are sensitive to the high-frequency radiation emitted from small, high-stress drop areas on the fault plane whereas the long-period instruments record the overall motion during the earthquake.

Diffraction from the PKP caustic B

1974 ◽  
Vol 64 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Goetz G. R. Buchbinder
Keyword(s):  
Transition Zone ◽  
Inner Core ◽  
Focal Depth ◽  
Travel Times ◽  
Depth Data ◽  
Long Period ◽  
Short Period ◽  
Amplitude Decrease

abstract Long-period energy preceding the PKPDF branch on long-period seismograms was identified as resulting from diffraction from the PKP caustic B. This conclusion is based on the measurements of the travel times, and, therefore, the slope of the travel times, on the amplitude decrease, and the very rapid dispersion of the periods of one earthquake of intermediate focal depth. Data from three deepfocus earthquakes support this interpretation. Thus, the long-period precursors are not due to the same cause as short-period precursors and are not produced by discontinuities in the transition zone between the inner and outer cores nor by structure in the inner core.

scholarly journals Body-wave amplitude and travel-time correlations across North America

1983 ◽  
Vol 73 (4) ◽  
pp. 1063-1076
Author(s):  
Thorne Lay ◽  
Donald V. Helmberger
Keyword(s):  
North America ◽  
Travel Time ◽  
Body Wave ◽  
Rocky Mountain ◽  
S Wave ◽  
Arrival Times ◽  
S Waves ◽  
Long Period ◽  
Amplitude Data ◽  
Short Period

abstract Relationships between travel-time and amplitude station anomalies are examined for short- and long-period SH waves and short-period P waves recorded at North American WWSSN and Canadian Seismic Network stations. Data for two azimuths of approach to North America are analyzed. To facilitate intercomparison of the data, the S-wave travel times and amplitudes are measured from the same records, and the amplitude data processing is similar for both P and S waves. Short-period P- and S-wave amplitudes have similar regional variations, being relatively low in the western tectonic region and enhanced in the shield and mid-continental regions. The east coast has intermediate amplitude anomalies and systematic, large azimuthal travel-time variations. There is a general correlation between diminished short-period amplitudes and late S-wave arrival times, and enhanced amplitudes and early arrivals. However, this correlation is not obvious within the eastern and western provinces separately, and the data are consistent with a step-like shift in amplitude level across the Rocky Mountain front. Long-period S waves show no overall correlation between amplitude and travel-time anomalies.

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

scholarly journals Isolation and Analysis of Six timeless Alleles That Cause Short- or Long-Period Circadian Rhythms in Drosophila

Genetics ◽  
2000 ◽  
Vol 156 (2) ◽  
pp. 665-675
Author(s):  
Adrian Rothenfluh ◽  
Marla Abodeely ◽  
Jeffrey L Price ◽  
Michael W Young
Keyword(s):  
Nuclear Translocation ◽  
Phase Response Curve ◽  
Fixed Number ◽  
Constant Darkness ◽  
Genetic Screens ◽  
Protein Levels ◽  
Long Period ◽  
Short Period ◽  
Molecular Oscillation ◽  
New Alleles

Abstract In genetic screens for Drosophila mutations affecting circadian locomotion rhythms, we have isolated six new alleles of the timeless (tim) gene. Two of these mutations cause short-period rhythms of 21–22 hr in constant darkness, and four result in long-period cycles of 26–28 hr. All alleles are semidominant. Studies of the genetic interactions of some of the tim alleles with period-altering period (per) mutations indicate that these interactions are close to multiplicative; a given allele changes the period length of the genetic background by a fixed percentage, rather than by a fixed number of hours. The timL1 allele was studied in molecular detail. The long behavioral period of timL1 is reflected in a lengthened molecular oscillation of per and tim RNA and protein levels. The lengthened period is partly caused by delayed nuclear translocation of TIML1 protein, shown directly by immunocytochemistry and indirectly by an analysis of the phase response curve of timL1 flies.

scholarly journals Wave Force Characteristics of Large-Sized Offshore Wind Support Structures to Sea Levels and Wave Conditions

2019 ◽  
Vol 9 (9) ◽  
pp. 1855
Author(s):  
Youn-Ju Jeong ◽  
Min-Su Park ◽  
Jeongsoo Kim ◽  
Sung-Hoon Song
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Wave Force ◽  
Diffraction Effect ◽  
Support Structures ◽  
Sea Levels ◽  
Irregular Wave ◽  
Long Period ◽  
Short Period ◽  
Period Wave

This paper presents the results of wave force tests conducted on three types of offshore support structures considering eight waves and three sea levels to investigate the corresponding wave forces. As a result of this study, it is found that the occurrence of shoaling in shallow water induces a significant increase of the wave force. Most of the test models at the shallow water undergo a nonlinear increase of the wave force with higher wave height increasing. In addition, the larger the diameter of the support structure within the range of this study, the larger the diffraction effect is, and the increase in wave force due to shoaling is suppressed. Under an irregular wave at the shallow water, the wave force to the long-period wave tends to be slightly higher than that of the short period wave since the higher wave height component included in the irregular wave has an influence on the shoaling. In addition, it is found that the influence of shoaling under irregular wave becomes more apparent in the long period.

scholarly journals Epistatic and Synergistic Interactions Between Circadian Clock Mutations in Neurospora crassa

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 537-543
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Temperature Compensation ◽  
Double Mutant ◽  
Synergistic Interactions ◽  
Long Period ◽  
Double Mutant Strain ◽  
Short Period ◽  
Compensation Mechanisms

Abstract We identified a series of epistatic and synergistic interactions among the circadian clock mutations of Neurospora crassa that indicate possible physical interactions among the various clock components encoded by these genes. The period-6 (prd-6) mutation, a short-period temperature-sensitive clock mutation, is epistatic to both the prd-2 and prd-3 mutations. The prd-2 and prd-3 long-period mutations show a synergistic interaction in that the period length of the double mutant strain is considerably longer than predicted. In addition, the prd-2 prd-3 double mutant strain also exhibits overcompensation to changes in ambient temperature, suggesting a role in the temperature compensation machinery of the clock. The prd-2, prd-3, and prd-6 mutations also show significant interactions with the frq7 long-period mutation. These results suggest that the gene products of prd-2, prd-3, and prd-6 play an important role in both the timing and temperature compensation mechanisms of the circadian clock and may interact with the FRQ protein.

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