Seismic T-Wave Observations at Dense Seismic Networks

2020 ◽  
Vol 91 (6) ◽  
pp. 3444-3453
Author(s):  
Catherine D. de Groot-Hedlin
Keyword(s):  
Wave Propagation ◽  
West Coast ◽  
East Coast ◽  
Seismic Energy ◽  
Polarization Analysis ◽  
The West ◽  
P Waves ◽  
Transverse Waves ◽  
T Wave ◽  
T Waves

Abstract Seismic T waves, which result from transformation of hydroacoustic to seismic energy at coastlines, were investigated for two strong earthquakes. A 2014 Caribbean event generated seismic T waves that were detected at over 250 seismometers along the east coast of the U.S., primarily at seismic stations operated by the USArray Transportable Array. A 2006 Hawaiian event generated seismic T waves observed at over 100 seismometers along the west coast. Seismic T-wave propagation was treated as locally 2D where the incoming hydroacoustic wavefronts were nearly parallel to the coastlines. Along the east coast, seismic T-wave propagation velocities were consistent with surface waves and a polarization analysis indicated that they were transverse waves, supporting their interpretation as Love waves. They were observed at inland distances up to 1134 km from the east coast. Along the west coast, the propagation velocity was over 5  km/s and a polarization analysis confirmed that the seismic T waves propagated as seismic P waves. Differences between the modes of propagation along the east and west coasts are attributed to differences in the slope and thickness of the sediment coverage at the continental slopes where hydroacoustic to seismic conversion takes place.

scholarly journals ENSO and Wintertime Extreme Precipitation Events over the Contiguous United States

2008 ◽  
Vol 21 (1) ◽  
pp. 22-39 ◽  
Author(s):  
Siegfried D. Schubert ◽  
Yehui Chang ◽  
Max J. Suarez ◽  
Philip J. Pegion
Keyword(s):  
United States ◽  
West Coast ◽  
Extreme Precipitation ◽  
East Coast ◽  
Daily Precipitation ◽  
Precipitation Variability ◽  
The West ◽  
Extreme Precipitation Events ◽  
The Impact ◽  
Precipitation Events

Abstract In this study the authors examine the impact of El Niño–Southern Oscillation (ENSO) on precipitation events over the continental United States using 49 winters (1949/50–1997/98) of daily precipitation observations and NCEP–NCAR reanalyses. The results are compared with those from an ensemble of nine atmospheric general circulation model (AGCM) simulations forced with observed SST for the same time period. Empirical orthogonal functions (EOFs) of the daily precipitation fields together with compositing techniques are used to identify and characterize the weather systems that dominate the winter precipitation variability. The time series of the principal components (PCs) associated with the leading EOFs are analyzed using generalized extreme value (GEV) distributions to quantify the impact of ENSO on the intensity of extreme precipitation events. The six leading EOFs of the observations are associated with major winter storm systems and account for more than 50% of the daily precipitation variability along the West Coast and over much of the eastern part of the country. Two of the leading EOFs (designated GC for Gulf Coast and EC for East Coast) together represent cyclones that develop in the Gulf of Mexico and occasionally move and/or redevelop along the East Coast producing large amounts of precipitation over much of the southern and eastern United States. Three of the leading EOFs represent storms that hit different sections of the West Coast (designated SW for Southwest coast, WC for the central West Coast, and NW for northwest coast), while another represents storms that affect the Midwest (designated by MW). The winter maxima of several of the leading PCs are significantly impacted by ENSO such that extreme GC, EC, and SW storms that occur on average only once every 20 years (20-yr storms) would occur on average in half that time under sustained El Niño conditions. In contrast, under La Niña conditions, 20-yr GC and EC storms would occur on average about once in 30 years, while there is little impact of La Niña on the intensity of the SW storms. The leading EOFs from the model simulations and their connections to ENSO are for the most part quite realistic. The model, in particular, does very well in simulating the impact of ENSO on the intensity of EC and GC storms. The main model discrepancies are the lack of SW storms and an overall underestimate of the daily precipitation variance.

scholarly journals Physiological ECG Value for Polish Half-Bred Anglo-Arab Horses

2012 ◽  
Vol 56 (4) ◽  
pp. 631-635 ◽  
Keyword(s):  
Heart Rate ◽  
P Wave ◽  
P Waves ◽  
T Wave ◽  
Duration Time ◽  
Qt Intervals ◽  
Electrocardiographic Examination ◽  
Electrocardiographic Findings ◽  
Almost All ◽  
T Waves

Abstract The electrocardiographic examination was performed in 33 training horses (2-16 years of age, 11 males and 22 females). Einthoven and precordial leads (I, II, III, aVR, aVL, aVF, CV1, CV2, CV4) were used. The ECG was performed in resting horses and immediately after exercise (10 min walk, 15 min trot, 10 min canter) using a portable Schiller AT-1 3-channel electrocardiograph, with a paper speed of 25 mm sec-1 and a sensitivity of 10 mm.mV-1. The heart rate, wave amplitudes, and duration time were estimated manually. All horses presented a significant increase in heart rate after exercise (rest 43.83 ±10.33 vs. exercise 73.2 ±14.8). QT intervals were significantly shortened in most of the leads. In resting horses, all P waves in the lead I were positive and almost all II, III and CV4 leads were positive. Simple negative P wave dominated in aVR and only simple negative T wave was found in the leads I. The biphasic shape was observed. After exercise, the amplitude of P and T waves rose, however, clear changes were not observed in wave polarisation and form. In the absence of specific racial characteristics of the electrocardiogram in the Polish Anglo- Arabians, electrocardiographic findings can be interpreted according to ECG standards adopted for horses.

RESEARCH ON PREMATURE INFANTS—SOME PERSPECTIVES

PEDIATRICS ◽  
1963 ◽  
Vol 32 (3) ◽  
pp. 319-325
Author(s):  
S. Z. LEVINE
Keyword(s):  
Clinical Research ◽  
Premature Infants ◽  
West Coast ◽  
East Coast ◽  
Good Friend ◽  
The West ◽  
Clinical Research Center ◽  
Principle Investigator ◽  
Long Time ◽  
The Many

THERE ARE A number of reasons why I appreciate deeply your invitation to join in these dedication exercises of the Clinical Research Center for Premature Infants. This Center for the care and study of premature infants extends to the West Coast a field of study in which I, on the East Coast, have been interested for many years. Equally gratifying is the circumstance that it will have Dr. Norman Kretchmer, my long-time colleague and good friend, as its Principle Investigator; and Dr. Sumner Yaffe, his distinguished associate, as its first Program Director. Under their direction and with a team of competent workers, with splendid facilities and an adequate budget, we are assured of imaginative exploration and new approaches to the many unknowns still awaiting solution.

Quantitative seismicity maps of India

1972 ◽  
Vol 62 (5) ◽  
pp. 1119-1132 ◽  
Author(s):  
K. L. Kaila ◽  
V. K. Gaur ◽  
Hari Narain
Keyword(s):  
Return Period ◽  
West Coast ◽  
Active Zone ◽  
East Coast ◽  
Indian Subcontinent ◽  
B Value ◽  
Tibet Plateau ◽  
The West ◽  
Period Map ◽  
A Value

Abstract Using the Kaila and Narain (1971) method, three quantitative seismicity maps have been prepared for the Indian subcontinent which are compared with regional tectonics. These are the A-value map, the b-value map and the return-period map for earthquakes with magnitude 6 and above where A and b are the constants in the cumulative regression curve represented by log N = A - bM. The A-value seismicity map shows that India can be divided into two broad seismic zones, the northern seismically highly active zone and the southern moderately active zone. In the northern active zone, a number of seismic highs have been delineated such as the Pamir high, the northwest-southeast trending Srinagar-Almora high, the Shillong massif high, the Arakan Yoma high and the West Pakistan highs. These seismic highs are consistent with the Himalayan tectonic trends. Contrary to this, two seismic highs fall in the Tibet plateau region which align transversely to the main Himalayan trend. In the southern moderately active zone, two seismic highs are clearly discernible, the east and the west coast high, the latter being seismically more active than the former. The least active zone encompasses the Vindhyan syncline and the areas of Delhi and Aravalli folding. Between this zone and the east coast high lies another moderately active zone which encloses the Godavari graben, western part of the Mahanadi graben and the Chattisgarh depression. The b-value seismicity map also demarcates the same active zones as are brought out on the A-value map. The return-period map of India for earthquakes with magnitude 6 and above shows a minimum return period of 100 years in the Pamirs, about 130 years in the various seismic highs in the northern active zone, 180 years on the west coast high, 200 years on the east coast high and about 230 years in the least active Vindhyan-Aravalli zone and the Hyderabad-Kurnool area. These quantitative seismicity maps are also compared with the seismic zoning map of Indian Standards Institution and seismicity maps of India prepared by other workers.

The I-4 Corridor

2019 ◽  
pp. 76-108
Author(s):  
Susan A. MacManus ◽  
David J. Bonanza ◽  
Anthony A. Cilluffo
Keyword(s):  
West Coast ◽  
Political Geography ◽  
East Coast ◽  
The West ◽  
Rural Counties

This chapter examines the critical political geography of Florida—the 130-mile expanse from Tampa on the west coast to Daytona Beach on the east coast known as the I-4 corridor.This mix of urban, suburban, and rural counties usually decides elections in Florida.

scholarly journals A Recent History of 14C, 137Cs, 210Pb, and 241Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 517-525 ◽  
Author(s):  
D Gallagher ◽  
E J McGee ◽  
P I Mitchell
Keyword(s):  
West Coast ◽  
East Coast ◽  
Similar Sequence ◽  
The West ◽  
Nuclear Weapons Testing ◽  
History Of ◽  
The Difference ◽  
The Uk ◽  
Ombrotrophic Peat ◽  
Coast Site

Data on radiocarbon (14C), 137Cs, 210Pb, and 241Am levels in an ombrotrophic peat sequence from a montane site on the east coast of Ireland are compared with data from a similar sequence at an Atlantic peatland site on the west coast. The 14C profiles from the west and east coasts show a broadly similar pattern. Levels increase from 100 pMC or less in the deepest horizons examined, to peak values at the west and east coast sites of 117 ± 0.6 pMC and 132 ± 0.7 pMC, respectively (corresponding to maximal fallout from nuclear weapons testing around 1964), thereafter diminishing to levels of 110–113 pMC near the surface. Significantly, peak levels at the east coast site are considerably higher than corresponding levels at the west coast site, though both are lower than reported peak values for continental regions. The possibility of significant 14C enrichment at the east coast site due to past discharges from nuclear installations in the UK seems unlikely. The 210Pbex inventory at the east coast site (6500 Bq m−2) is significantly higher than at the west coast (5300 Bq m−2) and is consistent with the difference in rainfall at the two sites. Finally, 137Cs and 241Am inventories at the east coast site also exceed those at the west coast site by similar proportions (east:west ratio of approximately 1:1.2).

Mitochondrial DNA restriction site variation in Tasmanian populations of Orange Roughy (Hoplostethus atlanticus), a deep-water marine teleost

1989 ◽  
Vol 40 (1) ◽  
pp. 1 ◽  
Author(s):  
JR Ovenden ◽  
AJ Smolenski ◽  
RWG White
Keyword(s):  
Mitochondrial Dna ◽  
West Coast ◽  
East Coast ◽  
Restriction Site ◽  
The West ◽  
Orange Roughy ◽  
Site Change ◽  
Restriction Site Variation ◽  
Site Variation ◽  
Hoplostethus Atlanticus

The orange roughy, Hoplostethus atlanticus, forms the basis of an important trawl fishery in Australia and New Zealand which is currently being over-exploited. To gain information about the stock structure of an Australian orange roughy population, ten restriction enzymes were used to survey the restriction- site variation in the mitochondrial genome of 23 individuals collected from the east coast and 26 individuals collected from the west coast of Tasmania. The mean diversity between all 49 genomes was a low 0.19%. Of the eleven haplotypes identified, only one was present in both the east and west coast samples. Four haplotypes were found only in the east coast sample and six were found only in the west coast sample. Eight haplotypes were related to the haplotype found on both coasts by the gain or loss of one restriction site. One haplotype collected in the east coast sample was related to one other east coast haplotype by one site change. One haplotype collected from the west coast was related to a west coast haplotype by one site change. If this pattern is confirmed by further mitochondrial DNA studies, it could be inferred that gene flow between the orange roughy populations on the east and west coasts of Tasmania is low.

scholarly journals Harmonisation of Chalk and Cheese

2010 ◽  
Vol 10 (3) ◽  
pp. 36-50 ◽  
Author(s):  
Philip Davenport
Keyword(s):  
Construction Industry ◽  
West Coast ◽  
East Coast ◽  
Dual Process ◽  
The West ◽  
East And West ◽  
False Premise

This is a response to Towards Harmonisation of the Construction Industry Security of Payment Legislation: A consideration of the success afforded by the East and West Coast Models in Australia by Jeremy Coggins, Robert Fenwick Elliott and Matthew Bell. Towards Harmonisation is based upon the false premise that the objectives of the East Coast and West Coast models are the same. They are chalk and cheese. Each serves a valuable purpose. Each jurisdiction needs both models.  A model for a dual process incorporating both the East Coast and the West Coast models will be found in Davenport (2007).

scholarly journals Changes in glacier dynamics in the northern Antarctic Peninsula since 1985

2018 ◽  
Vol 12 (2) ◽  
pp. 577-594 ◽  
Author(s):  
Thorsten Seehaus ◽  
Alison J. Cook ◽  
Aline B. Silva ◽  
Matthias Braun
Keyword(s):  
Antarctic Peninsula ◽  
West Coast ◽  
East Coast ◽  
Hierarchical Cluster ◽  
Flow Speed ◽  
Climatic Conditions ◽  
Surface Velocity ◽  
Ice Shelf ◽  
The West ◽  
Ice Dynamics

Abstract. The climatic conditions along the northern Antarctic Peninsula have shown significant changes within the last 50 years. Here we present a comprehensive analysis of temporally and spatially detailed observations of the changes in ice dynamics along both the east and west coastlines of the northern Antarctic Peninsula. Temporal evolutions of glacier area (1985–2015) and ice surface velocity (1992–2014) are derived from a broad multi-mission remote sensing database for 74 glacier basins on the northern Antarctic Peninsula ( <  65° S along the west coast and north of the Seal Nunataks on the east coast). A recession of the glaciers by 238.81 km2 is found for the period 1985–2015, of which the glaciers affected by ice shelf disintegration showed the largest retreat by 208.59 km2. Glaciers on the east coast north of the former Prince Gustav Ice Shelf extent in 1986 receded by only 21.07 km2 (1985–2015) and decelerated by about 58 % on average (1992–2014). A dramatic acceleration after ice shelf disintegration with a subsequent deceleration is observed at most former ice shelf tributaries on the east coast, combined with a significant frontal retreat. In 2014, the flow speed of the former ice shelf tributaries was 26 % higher than before 1996. Along the west coast the average flow speeds of the glaciers increased by 41 %. However, the glaciers on the western Antarctic Peninsula revealed a strong spatial variability of the changes in ice dynamics. By applying a hierarchical cluster analysis, we show that this is associated with the geometric parameters of the individual glacier basins (hypsometric indexes, maximum surface elevation of the basin, flux gate to catchment size ratio). The heterogeneous spatial pattern of ice dynamic evolutions at the northern Antarctic Peninsula shows that temporally and spatially detailed observations as well as further monitoring are necessary to fully understand glacier change in regions with such strong topographic and climatic variances.

Influence of regional environment in guiding the spatial distribution of marine bivalves along the Indian coast

2017 ◽  
Vol 99 (1) ◽  
pp. 163-177 ◽  
Author(s):  
Deepjay Sarkar ◽  
Madhura Bhattacherjee ◽  
Devapriya Chattopadhyay
Keyword(s):  
Species Richness ◽  
West Coast ◽  
Arabian Sea ◽  
East Coast ◽  
Environmental Parameters ◽  
Shelf Area ◽  
The West ◽  
Regional Environment ◽  
High Productivity ◽  
Marine Bivalves

Tropical coastal areas are amongst the most diverse ecosystems in the world. However, there are quite a few coasts that have rarely been studied for their macro-benthic diversity. The Indian coastline presents one such gap area. Two sub-parallel coastlines of India have a wide latitudinal span (8–23°N) and strikingly different physiographic environments. While the east coast receives a high siliciclastic input from large river systems flowing to the Bay of Bengal with fluctuating salinity, the west coast has a large shelf area and high productivity of the Arabian Sea. Such difference enables us to evaluate the effect of regional environmental parameters on marine molluscan diversity and distribution in an intra-tropical setting. Because of the wide latitudinal range, it is also possible to assess if spatial difference in species richness in such a regional scale follows the large-scale biodiversity pattern such as Latitudinal Biodiversity Gradient (LBG) despite inherent environmental variation. We used species distribution of marine bivalves, compiled using bioSearch and the Ocean Productivity database, to address this question. Our results show that intra-tropical species richness of marine bivalves is guided primarily by regional environmental parameters. Even with identical latitudinal extent, higher nutrient availability and larger shelf area, the west coast has significantly lower richness than the east coast; among environmental variables, productivity, salinity and coastline length emerged as significant predictors of species diversity. Moreover, a positive influence of a South Asian biodiversity hotspot on east coast fauna and a negative impact of the oxygen-depleted condition of Arabian Sea on west coast fauna, may have a significant contribution in developing such coastal variation in species richness. The latitudinal variation in species richness did not follow LBG. In contrast to the coast-specific diversity difference, species composition is not found to be dictated by coastal affiliation. The composition corresponds primarily to physiographic conditions. We identified three distinct eco-regions (north-western, southern, north-eastern) with characteristic species composition corresponding to unique physiography and productivity mechanism. The NW region has low siliciclastic input and high productivity associated with upwelling during winter cooling. The NE region has a distinctly high riverine input and salinity fluctuation. The southern region, in contrast, has well developed reefal system with moderate variation in salinity. Such correspondence underscores the importance of the regional environment in dictating the species diversity and distribution in the shallow marine realm.

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