Q determined from local earthquakes in the South Carolina Coastal Plain

1984 ◽  
Vol 74 (6) ◽  
pp. 2257-2268
Author(s):  
Susan Rhea
Keyword(s):  
South Carolina ◽  
Spatial Variation ◽  
Coastal Plain ◽  
Temporal Change ◽  
High Stress ◽  
Western Boundary ◽  
Coda Q ◽  
High Q ◽  
The Mean ◽  
Stress States

Abstract Coda Q, or Qc, is determined from the rate of coda decay in the Coastal Plain near Charleston, South Carolina. The mean of Qc calculated from individual estmates is near 190 at 1 Hz and increases to over 1650 at 10 Hz. A possible temporal change in Qc is identified, high values being associated with increased seismic activity during late 1977. Temporal changes have been observed elsewhere and laboratory measurements of Q under different stress states correlate high Q with high stress. A spatial variation in Qc is identified, increasing from west (Qc at 10 Hz equal to 850) to east (Qc at 10 Hz greater than 2100) across the Coastal Plain. The demarcation of high to highest zones of Qc is coincident with the western boundary of the innermost isoseismal of the Charleston 1886 earthquake. It is hypothesized that the 1886 earthquake was mislocated originally because of this spatial variation in energy attenuation that was unrecognized at that time.

scholarly journals Wintering Golden Eagles on the coastal plain of South Carolina

2015 ◽  
Vol 86 (4) ◽  
pp. 337-344 ◽  
Author(s):  
Mark Vukovich ◽  
Kelsey L. Turner ◽  
Tracy E. Grazia ◽  
Thomas Mims ◽  
James C. Beasley ◽  
...  
Keyword(s):  
South Carolina ◽  
Coastal Plain ◽  
Golden Eagles

scholarly journals Characteristics, Energetics, and Origins of Agulhas Current Meanders and Their Limited Influence on Ring Shedding

2015 ◽  
Vol 45 (9) ◽  
pp. 2294-2314 ◽  
Author(s):  
Shane Elipot ◽  
Lisa M. Beal
Keyword(s):  
Kinetic Energy ◽  
Single Mode ◽  
Cyclonic Circulation ◽  
Recent Analysis ◽  
Altimeter Data ◽  
Western Boundary ◽  
Mean Flow ◽  
Current Time ◽  
Agulhas Current ◽  
The Mean

AbstractThe Agulhas Current intermittently undergoes dramatic offshore excursions from its mean path because of the downstream passage of mesoscale solitary meanders or Natal pulses. New observations and analyses are presented of the variability of the current and its meanders using mooring observations from the Agulhas Current Time-Series Experiment (ACT) near 34°S. Using a new rotary EOF method, mesoscale meanders and smaller-scale meanders are differentiated and each captured in a single mode of variance. During mesoscale meanders, an onshore cyclonic circulation and an offshore anticyclonic circulation act together to displace the jet offshore, leading to sudden and strong positive conversion of kinetic energy from the mean flow to the meander via nonlinear interactions. Smaller meanders are principally represented by a single cyclonic circulation spanning the entire jet that acts to displace the jet without extracting kinetic energy from the mean flow. Synthesizing in situ observations with altimeter data leads to an account of the number of mesoscale meanders at 34°S: 1.6 yr−1 on average, in agreement with a recent analysis by Rouault and Penven (2011) and significantly less than previously understood. The links between meanders and the arrival of Mozambique Channel eddies or Madagascar dipoles at the western boundary upstream are found to be robust in the 20-yr altimeter record. Yet, only a small fraction of anomalies arriving at the western boundary result in meanders, and of those, two-thirds can be related to ring shedding. Most Agulhas rings are shed independently of meanders.

Recovery-Stress States of Professional Ballet Dancers During Different Phases of a Ballet Season

2021 ◽  
Author(s):  
Jana S. De Wet ◽  
Eileen Africa ◽  
Ranel Venter
Keyword(s):  
Mixed Model ◽  
High Stress ◽  
Recovery Stress ◽  
Total Recovery ◽  
Ballet Dancers ◽  
Training Adaptations ◽  
Stress States ◽  
Classical Ballet ◽  
And Performance ◽  
Negative Training

Ballet dancers are exposed to chronic high training and performance demands that are associated with overtraining syndrome and injury. Balancing high training loads with recovery to reduce the risk of negative training adaptations is critical. Moreover, the recovery-stress states of professional ballet dancers during training phases of a season are largely unknown. Professional dancers (n = 27) from one classical ballet company in South Africa were monitored for two 8-week phases of a ballet season. A recovery-stress questionnaire for Athletes (RESTQ-76 Sport) was completed weekly during the rehearsal phase (P1) and the performance phase (P2), which took place at the start and the end of the ballet season, respectively. Comparisons were calculated between phases, sexes, and levels of performance with a mixed-model ANOVA and between demographic variables with a one-way ANOVA. The performance phase was signified by lower total recovery (TR, p < 0.01) and higher total stress (TS, p < 0.01) for the group. Female dancers had significantly lower recovery scores than male dancers during P2 (p < 0.01). No differences between levels of performance were found. Subscales previously associated with overreaching and injury were identified in certain groups during P2. In conclusion, P2 was a critical period where dancers, especially females, experienced high stress and low recovery. This could increase the risk for injury and negative training adaptations.

Wave conversions from earthquakes and a new velocity model for the South Carolina coastal plain

1987 ◽  
Vol 77 (6) ◽  
pp. 2143-2151
Author(s):  
Susan Rhea
Keyword(s):  
Surface Layer ◽  
South Carolina ◽  
Coastal Plain ◽  
Velocity Structure ◽  
Velocity Model ◽  
Seismogenic Fault ◽  
Impedance Boundary ◽  
High Impedance ◽  
Hypocentral Parameters ◽  
Converted Phases

Abstract Phase conversions from P to SV and from SV to P occur at a high impedance boundary near the surface in Charleston, South Carolina. Four arrivals (P, converted P, converted S, and S) are observed on three-component records of earthquakes in this area. Using arrival-time differences between paired arrivals of direct and converted phases, a shallow surface layer Vp/Vs ratio of 2.9 was determined. Applying the Wadati method to travel times derived at the base of the surface layer yields a Vp/Vs ratio in deeper layers of 1.73. Relocating earthquakes using this more appropriate velocity structure for direct and converted shear waves alters hypocentral parameters such that epicenters diverge and depths converge. It is inferred that these relocated earthquakes are not exclusively associated with a single seismogenic fault.

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