bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of Kansas Microearthquake Network
Authors: Sheehan Anne Frances , Steeples Don W.
Published: July 2019

This study explores the magnitude-versus-distance sensitivity of the Kansas Geological Survey (KGS) microearthquake network. The ability of each seismograph station to record earthquakes of various magnitudes as a function of epicentral distance is investigated, and a series of magnitude-versus-distance graphs results. The ability of the network to monitor seismic activity in eastern Kansas is excellent to magnitude 1.5 and is sufficient to detect events greater than magnitude 2.3 in western Kansas. Station detection radii for magnitude 1.5 events range from 145 km for the Emporia seismograph station (EMK) to 225 km at Tuttle Creek (TCK); and for a magnitude 2 event, from 245 km at EMK to 385 km at TCK. The sensitivities of the nine seismographs of the network are similar despite their widespread locations across eastern Kansas.
Earthquakes and Plutons in the Midcontinent - Evidence From the Bloomfield Pluton, New Madrid Rift Complex
Authors: Ravat D. N. , Braile L. W. , Hinze W. J.
Published: July 2019

A three-dimensional gravity and magnetic model of the Bloomfield Pluton near New Madrid, Missouri, has been generated that provides an excellent match to the observed gravity and magnetic anomaly maps. Although this modeling is inherently non-unique, the steep gradients on the flanks of the anomalies constrain the causative body to a relatively shallow depth (≈2 km) and define the outline of the steep-sided (near-vertical) pluton. Comparison of the configuration of the Bloomfield Pluton with concentrated microearthquake seismicity in part of the New Madrid Seismic Zone indicates that earthquakes in the northern part of the zone occur primarily on the southeastern side of the pluton at about 10 km from the edge of the body. Based on the location of hypocenters and earthquake focal mechanisms, there is no evidence that stress concentration associated with the mass excess of the pluton is the cause of earthquakes near the pluton. The seismicity may be along zones of weakness independent of the pluton. Among other explanations investigated to explain the constant distance of earthquakes from the pluton, we favor the possibility of a zone of rigidity contrast caused by the thermal metamorphism of the country rock associated with the pluton intrusion. We have estimated increased temperatures of the country rock using an instantaneous intrusion model. Maximum anomalous country rock temperatures of greater than 100°C dominated the region within 10 km of the pluton edge. This ‘thermally metamorphosed’ aureole may provide sufficient homogeneity in the upper crust to localize anomalous stresses away from the margin and along the most favorable zones of weakness, thus influencing the locations of earthquakes.
A Note on the December 1986 - January 1987 Richmond, Virginia, Felt Earthquake Sequence
Authors: Davison Frederick C. , Bodé Melissa J.
Published: July 2019

A series of small, felt earthquakes occurred in Richmond, Virginia, during December 1986 and January 1987. Historie records show that such a sequence is unique for Richmond. There were at least 11 felt events, of which six were instrumentally recorded and four were located. Duration magnitudes of these four ranged from 1.5 to 2.2. A focal mechanism solution was calculated and indicates reverse faulting on a plane striking north-northwest and dipping either 45° northeast or 44° southwest. Epicentral intensity reports, up to MMI V, and felt areas do not conform to usual intensity - magnitude relationships. Independent estimates of depth suggest that extremely shallow foei (<2.5 km) may be the cause for this anomaly. The shallow focal depths have important implications concerning the stability of the crust around any shallow underground facilities sited in the area, especially with respect to protection of the groundwater environment.
A Preliminary Report on the Variability in Particle Velocity Recording of the June 10, 1987 Southeastern Illinois Earthquake
Authors: Street R. , Zekulin A. , Jones D. , Min G.
Published: July 2019

Free-field particle velocities for the June 10, 1987 southeastern Illinois earthquake, demonstrate the importante of site and source effects in the prediction of ground motion values for central United States earthquakes. The 54 particle velocity recordings of the 5.0 mbLg magnitude event, ranging in epicentral distances of 56 to 443 kilometers and azimuths of 19° to 282° about the epicenter, exhibit appreciable variability that can be attributed to both site and source effects.
Seismicity in South Carolina
Authors: Shedlock Kaye M.
Published: July 2019

The largest historical earthquake in South Carolina, and in the southeastern US, occurred in the Coastal Plain province, probably northwest of Charleston, in 1886. Locations for aftershocks associated with this earthquake, estimated using intensities based on newspaper accounts, defined a northwest trending zone about 250 km long that was at least 100 km wide in the Coastal Plain but widened to a northeast trending zone in the Piedmont. The subsequent historical and instrumentally recorded seismicity in South Carolina images the 1886 aftershock zone. Except for a few scattered earthquakes and a swarm of shallow (≤ 4 km deep), small (ML ≤ 2.5), primarily reverse faulting earthquakes that occurred along the flanks of a granite pluton about 60 km northwest of Columbia, the seismicity in the Piedmont province has been associated with water level changes in reservoirs. Reservoir induced seismicity (RIS) is shallow (≤ 6 km deep), primarily strike-slip or thrust faulting corresponding to an inferred maximum horizontal compressive stress oriented approximately N 60° E. Instrumentally recorded seismicity in the Coastal Plain province occurs in 3 seismic zones or clusters: Middleton Place-Summerville (MPSSZ), Adams Run (ARC), and Bowman (BSZ). Approximately 68% of the Coastal Plain earthquakes occur in the MPSSZ, a north trending zone about 22 km long and 12 km wide, lying about 20 km northwest of Charleston. The hypocenters of MPSSZ earthquakes range in depth from near the surface to almost 12 km. Thrust, strike-slip, and some normal faulting are indicated by the fault plane solutions for Coastal Plain earthquakes. The maximum horizontal compressive stress, inferred from the P-axes of the fault plane solutions, is oriented NE-SW in the shallow crust (< 9 km deep) but appears to be diffusely E-W between 9 to 12 km deep. Although there is localized variability, the current seismicity and associated faulting in South Carolina probably represent a regional response to the NE-SW maximum horizontal compressive stress prevalent throughout eastern North America.
Earthquakes, Geology and Crustal Features in Southern New England
Authors: Kafka Alan L.
Published: July 2019

Within southern New england (SNE) and adjacent areas lies a variety of tectonic regions extending from the ancient North American craton to the Avalonian Terrane. This region, which is part of the northern Appalachians, has had a moderate level of seismic activity throughout its recorded history. Although the geology and geophysics of SNE have been studied extensively, it has been difficult to correlate the seismic activity in this region with geologic structures mapped on the earth’s surface.

The distribution of earthquakes located by regional seismic networks in SNE generally resembles that of historical earthquakes in this region. In both the network and historical records, a cluster of earthquakes occurs near Moodus, CT and more diffuse seismicity occurs in the eastern coastal regions. Both data sets show earthquake activity in the vicinity of the 1755 earthquake that occurred on the coast of Cape Ann, MA, as well as seismicity near the boundary between southwestern CT and NY State. Aside from these very general similarities, the location uncertainties of the historical earthquakes make it difficult to compare the two records of seismicity in any greater detail.

Information about the lateral variation of seismic velocities in the shallow crust beneath SNE has been obtained from studies of dispersion of short-period, fundamental-mode Rayleigh waves (Rg). Rg waves with periods between about 0.2 and 2.5 sec have been studied, and dispersive properties of Rg in that period range are sensitive to lateral variation in the upper few kilometers of the crust. Based on Rg dispersion studies, it appears that SNE can be divided into regions of distinct shallow crustal structure. The pattern of lateral variation is Rg dispersion is similar to the pattern of teleseismic residuals and gravity anomalies, suggesting that the lateral variation revealed by the Rg studies extends deeper into the crust. These results, however, do not reveal any obvious correlations between crustal features and seismicity.
New Focal Mechanisms for the New England Region: Constrains on the Regional Stress Regime
Authors: Ebel John E. , Bouck Bruce R.
Published: July 2019

Single-event focal mechanisms for fifteen earthquakes in New England and New York have been determined. Thirteen of these are new focal mechanisms, while two are redeterminations for events with previously reported solutions. The focal mechanisms display considerable scatter in P-axis orientation, as has been reported in earlier studies. Some areas within the region, such as central New Hampshire and northeastern Massachusetts, show locally consistent principal stress directions. Other areas, such as central Maine, do not. All but one or two of the new focal mechanisms have P-axis and T-axis orientations which fall within the range of values calculated by Gephart and Forsyth (1985) for a regional stress field of horizontal, E-W maximum stress and vertical minimum stress in New England.
Seismogenesis in Eastern Canada
Authors: Hasegawa H. S.
Published: July 2019

The pattern of seismicity in eastern Canada depends on the presence of weak zones from previous major tectonic orogenies and how these weak zones are reactivated by local and regional stress fields and geophysical processes. Within the Canadian Shield, away from seismotectonic trends, there is a low level of seismicity and earthquakes tend to be small, less than M5. However, along seismically active trends, earthquakes as large as M7 have occurred. The seismotectonic features fall into four main categories: positive (uplift) continental basement linears; grabens formed by old plate separation; passive rifted margins offshore; and extinct spreading ridges. Two of the positive seismotectonic trends are the Boothia Uplift-Bell Arch that transects the northeastern part of the craton and northeastern Baffin Island, where the effects of postglacial rebound on the upper crustal stress field are the most pronounced. The St. Lawrence Valley (and interconnecting grabens) is a seismically active graben system that contains the most seismically active region (the Charlevoix zone) in eastern Canada. The extinct spreading ridge along the Labrador Sea and the Mesozoic rifted margin along Baffin Bay and Labrador Sea contain clusters of moderate seismicity. There are diffuse zones of moderate seismicity over some geological provinces (e.g. Central Metasedimentary Belt in western Quebec) apart from major tectonic features, a confined seismic zone (within an intrusion) in the Miramichi region and seismicity at the intersection of faults in northern Ontario. In the Nahanni region, which is situated near the boundary between the northeast Cordillera and the Interior Platform, the commencement of a noteworthy earthquake sequence with magnitude up to Ms 6.9 indicates considerable stress-strain build-up over a large area. There is an anticline in the epicentral area that is bounded by thrust faults and mountain ranges.

In order to enhance our understanding of causative factors of current seismicity, it is necessary to determine in greater detail the tectonic forces and geophysical processes that are reactivating pre-weakened faults along the seismotectonic trends and over broad, diffuse seismogenic regions. Some of these factors are the rate of stress build-up, stress concentration at the intersection of faults and between mountain ranges, residual stress, the role of pore fluids, individual block movement, whether this movement is due to postglacial rebound or to other underlying viscoelastic phenomena and the rate of sediment deposition along the continental slope. Paleoseismicity is useful not only for the reconstruction of old large earthquakes but also for providing insight as to why surface fault offsets have not been observed in regions where large earthquakes (and associated high rate of microseisrnicity) have occurred within the past several hundred years.
Disintegration, Faulting and Seismogenesis of the North China Craton
Authors: Guoyu Ding
Published: July 2019

The North China Craton (NCC) began to disintegrate completely in the Yanshan Movement period (Jurassic-Cretaceous) forming a great number of NE, NEN, NW and WNW trending faults. Such fault systems have played an important role in the development of tectonics and seismicity in the Craton area. There has been a big change of stress field since the Pliocene, from predominantly normal faulting to predominantly strike-slip faulting. The NCC is an area with high seismicity. The recent seismicity is obviously controlled by the tectonic framework derived from Craton disintegration. Six strong earthquakes with M > 8.0 in this area have occurred in the past two thousand years. Many strong earthquakes in the NCC area are mainly caused by preexisting faults that move horizontally forming pull-apart basins.
The Intersection Model for Intraplate Earthquakes
Authors: Talwani Pradeep
Published: July 2019

The tectonic cause of intraplate earthquakes has remained enigmatic. As newer data became available, several common features were apparent for intraplate earthquakes occurring in a wide variety of geologic terranes. These have been incorporated in the intersection model. Seismicity occurs near the intersection of, and by the reactivation of, preexisting zones of weakness. The intersections are the foci of anomalous stress build up in response to the ambient stress field due to plate tectonic forces. This anomalous stress buildup is relieved by strike slip motion on a suitably oriented fault and, due to kinematic adjustment, is followed by vertical or horizontal movement on the intersecting fault. The intersection model has several elements that complement other models proposed to explain intraplate earthquakes.
Geodetic Evidence for Tectonic Deformation in the Eastern United States
Authors: Reilinger Robert
Published: July 2019

The historic geodetic data base in the eastern United States dates back over 100 years. Although instrumentation and hence measurement precision has improved since the initial observations, the basic techniques [leveling, triangulation, water level gauging] remained unchanged until the recent introduction of space geodesy [Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Positioning System (GPS)]. Because of this, it has been possible to compare repeated observations to identify apparent changes in relative positions. Such “changes” can reflect observational errors, non-tectonic movements (water level effects, monument instability, loading, etc.) or tectonic/isostatic deformation.

A number of possible deformation features in the eastern U. S. have been reported in the literature, including uplift of the southern Appalachian and Adirondack mountains, doming of the Gulf coast inland of the Mississippi delta, subsidence of Chesapeak Bay and along the coast of Maine, horizontal deformation in New York and Connecticut, and possible fault related deformation near Charleston and in the New Madrid area. Unfortunately, it is not dear to what extent any of these features represent tectonic deformations and hence what their significance may be for the earthquake problem.

An important recent development in monitoring regional deformation has been the establishment of the eastern U. S. GPS strain network by the National Geodetic Survey. The network consists of roughly 45 sites uniformly distributed east of the Rocky Mountains. The network was established in 1987 and will be reobserved in 1989. Subsequent reobservations will be made at 2 to 5 year intervals depending on analysis of the early measurements. Given the precision of the GPS measurements (few cm in 3-D relative positions), a considerable time period will be required to detect the subtle deformations expected for this intraplate region.

Perhaps more immediate information will result from recent progress in recognizing and correcting systematic errors in the historic geodetic data base. This, together with the newly automated historic data base, and improved techniques for integrating and analyzing these extensive observations, provide the necessary basis for effectively evaluating the deformational features listed above. Given the potential importance of these data for understanding tectonic processes (and the huge expense of collecting these measurements over the pst century), such studies should be an integral part of future earthquake studies in the eastern U. S.
Source Parameters of Large Australian Intracontinental Earthquakes
Authors: McCaffrey Robert , Fredrich Joanne
Published: July 2019

We have examined the largest earthquakes in the Australian continent over the past 20 years by modeling their teleseismic long-period P and SH and short-period P waveforms. Eight earthquakes beneath the continent show thrust faulting at depths shallower than 10 km. Three (1, 2, 4 below) produced surface faulting and their waveforms indicate centroid depths of 3 km or less. The P-axes in the southwestern half of the continent have easterly trends. Preliminary examination of the 3 large earthquakes near Tennant Creek on 22 January, 1988, (7–9) indicate thrusting at less than 10 km depth, but with N-trending P-axes. The largest event (9), at 12:06 GMT, had a seismic moment of roughly 1019 Nm, which makes it comparable in size to the 1968 Meckering event (1). One event (6) beneath the continental margin indicates strike-slip at 26 km depth.
Selected Strong and Weak-Motion Data From the Loma Prieta Earthquake Sequence
Authors: Jarpe S. P. , Hutchings L. J. , Hauk T. F. , Shakal A. F.
Published: July 2019

The purpose of this paper is to document the strong- and weak-motion seismic data from the Loma Prieta earthquake and its aftershocks obtained by Lawrence Livermore National Laboratory (LLNL), and to present some analysis of the spectral seismic response using both weak- and strong-motion recordings. LLNL operates six free-field, digitally recorded, triaxial, strongmotion accelerographs in the vicinity of LLNL; five of these were operating during the Loma Prieta earthquake. Two days after the main event, LLNL initiated a field deployment of 3-component weak-motion instruments to record aftershocks at three LLNL sites and four California Strong Motion Instrumentation Program (CSMIP) sites that recorded strong-motion from the main event.

Spectral ratios of strong- and weak-motion recordings are computed for two pairs of rock and soil sites. One pair of stations is in the vicinity of LLNL, and the other pair is Treasure Island TRI (fill) and Yerba Buena Island YBI (rock) in San Francisco Bay near the Bay Bridge. For the first pair, the weak-motion spectral ratios predict the strong-motion amplification, within 95% confidence limits, for frequencies from 3 to 12 Hz. For TRI and YBI, the strong-motion spectral ratio is much lower than the weak-motion 95% confidence region for frequencies from 1 to 7 Hz. The strong-motion ratio, however, still suggests that the soil underlying TRI resulted in a factor of 3 amplification of energy between 1 and 4 Hz. This is in contrast to the factor of 8 amplification of the weak-motion energy, derived from the spectral ratios of 7 Loma Prieta aftershocks. The large difference between the weak-motion and strong-motion spectral ratios reinforces the limitation that weak-motion cannot be used to directly predict strong-motion amplification at sites underlain by soils that may respond non-linearly at high strain levels.

A further examination of weak-motion recordings indicates that the source effect can be removed and the propagation path effects approximated so that the site response can be isolated. Resulting site specific spectral amplifications reveal that the spectral ratio method can lead to erroneous conclusions if the “rock” site has a complicated geology. At two sites near LLNL the apparent diminishing of spectral amplitudes below 5 Hz observed in the spectral ratios was actually due to amplification of spectral response at the rock site. It appears that the reference site spectral ratios at low frequencies may have been influenced by topography or near-surface geologic features. For the other pair of sites, the spectrum at YBI, the rock site, was flat, so that the features in the spectral ratios are due to the seismic response of the soil at TRI.
A Comparison of the 1981, 1982, 1986 and 1987–1988 Microearthquake Swarms At Moodus, Connecticut
Authors: Ebel John E.
Published: July 2019

Four extensive microearthquake swarms, in 1981, 1982, 1986 and 1987–1988, have occurred near Moodus, Connecticut since the installation of a dense local monitoring network in 1979. All of the swarms have been accompanied by at least one event of M≥2.0, have had depths of less than 2.4 km, and have originated from one small primary source volume. A few of the events from 1981 and 1982 were located about 1.5 km west to southwest of this primary source locality. The time histories and energy releases have varied from swarm to swarm, with the 1981 and 1982 swarms having some foreshocks, a main shock, and a decaying aftershock pattern. The 1986 and 1987–1988 swarms were more distributed in time and totaled fewer events than the earlier swarms. The b-value for the 1987–1988 swarm is closer to that of the foreshocks from 1981 and 1982 than that of the aftershocks from those swarms. The 1980’s have been an unusually active period at Moodus, but the geologic and seismological evidence are ambiguous as to the cause the Moodus earthquakes and how large an event can take place at this locality.
The January 4, 1989, Earthquake in Bluffton, South Carolina, and its Tectonic Implications
Authors: Talwani P. , Rajendran K.
Published: July 2019

An earthquake of magnitude 2.8 occurred on January 4, 1989, at 9:39:01.47 UTC (4:39 am EST) near Bluffton, in the lower South Carolina Coastal Plain, a region of low seismicity. More than seventy people in the Bluffton-Hilton Head area reported either hearing or feeling this early morning event. Historically, there have been three earthquakes, two of which had a MMI ≥ V, near Savannah, 25 km southwest of this earthquake. Recent discoveries of earthquake induced liquefaction features in the Bluffton area suggested that this area had been subjected to large ground motion in the past. Together, these data lead to the preliminary inference of a possible seismic source zone near Bluffton.
The Woodstock Lineament: A Possible Surface Expression of the Seismogenic Fault of the 1886 Charleston, South Carolina, Earthquake
Authors: Marple Ronald T. , Talwani Pradeep
Published: July 2019

A SPOT satellite image of the Charleston, South Carolina, area revealed a linear feature, the Woodstock lineament, that may be the surface expression of a seismogenic fault of the 1886 Charleston earthquake. An enhancement of the SPOT image reveals a linear, 5 km wide band on the east side of the lineament that extends at least 65 km in a north-northeast direction and coincides with a part of the axis of the highest intensity isoseismal contours of the Charleston earthquake. Corroborative geologic, geodetic, and geophysical data suggest that the lineament and associated band may be the result of ongoing tectonic activity on the Woodstock fault inferred from seismicity.
Overview of Research in The New Madrid Seismic Zone
Authors: Johnston Arch C. , Shedlock Kaye M.
Published: July 2019

We review the development of understanding of the seismicity and tectonic structure of the New Madrid seismic zone and the upper Mississippi embayment. The broad framework of a failed intracontinental rift with reactivated seismogenic faults was not established until the mid-1970s. By the early 1990s a much more detailed knowledge of the rift and the current seismicity has been gained but fundamental questions remain. The 25 papers of this Special Issue of Seismological Research Letters convey the location of the most recent research front in such diverse fields as seismology, paleoseismology, seismic and potential-field investigation of rift structure, neotectonic deformation, and seismic hazard estimation and response. The new information content of these papers, considered ensemble, is enormous and highlights the tremendous progress made since the 1970s. These current studies, in turn, sharpen the focus on remaining outstanding problems of seismogenesis in the New Madrid seismic zone. We close with a discussion of what we believe will be the important foci of research in the 1990s.
Liquefaction Evidence for Strong Holocene Earthquake(S) in the Wabash Valley of Indiana-Illinois
Authors: Obermeier S.F. , Munson P.J. , Munson C.A. , Martin J.R. , Frankel A.D. , Youd T.L. , Pond E.C.
Published: July 2019

We have discovered hundreds of planar, nearly vertical sand- and gravel-filled dikes that we interpret to have been caused by earthquake-induced liquefaction in the Wabash Valley of Indiana- Illinois. These dikes range in width from a few cm to as much as 2.5 m. The largest dikes are centered about the general area of Vincennes, Indiana; they decrease in size and abundance to the north and south of this area. Preliminary studies indicate the high possibility that many, if not all, of the dikes were formed by a single large earthquake that took place in the Vincennes area sometime between 2,500 and 7,500 years ago. The severity of ground shaking required to have formed the dikes far exceeds the strongest level of shaking of any earthquake in the central United States since the 1811–12 New Madrid earthquakes.
Distribution and Dating of Prehistoric Earthquake Liquefaction in the Wabash Valley of the Central U.S.
Authors: Munson Patrick J. , Munson Cheryl Ann , Bleuer Ned K. , Labitzke Michael D.
Published: July 2019

Earthquake-induced paleoliquefaction features are exposed in eroding river banks at 24 sites in the lower and central Wabash Valley. North-south distribution of features is at least 165 km. Sites with very large dikes (60–250 cm wide) suggestive of lateral spreads are found near the center of the distribution and extend over an area about 35 km in diameter. Stratigraphy, sedimentology, pedology, and archaeological associations suggest that all liquefaction resulted from a single, large, middle Holocene earthquake with an epicenter in the vicinity of Vincennes, Indiana.
On the Search for Paleoliquefaction in the New Madrid Seismic Zone
Authors: Wesnousky Steven G. , Leffler Lisa M.
Published: July 2019

The great 1811–12 New Madrid earthquakes produced extensive liquefaction in the meisoseismal zone, which is largely within the St. Francis drainage basin of Missouri and Arkansas. We examined 10’s of kilometers of ditch banks within the meisoseismal zone for evidence of prehistoric liquefaction events. Radiocarbon dates indicate that the exposures studied provide a record of the last 5,000 to 10,000 years. Our search has revealed no evidence of widespread paleoliquefaction events and, hence, provides no independent support for the relatively short 550 to 1100 year return time of 1811–12 type earthquakes implied by analyses of the statistics of historical seismicity.
Analysis of the Seismic Origin of a Landslide in the New Madrid Seismic Zone
Authors: Jibson Randall W. , Keefer David K.
Published: July 2019

The New Madrid earthquakes of 1811–12 reportedly triggered many landslides from the bluffs east of the Mississippi River. We use static and dynamic slope stability analyses to determine if landslides currently visible in this area were triggered by seismic shaking or if failure could have occurred in aseismic conditions. We apply this approach to a translational block slide representative of a group of old landslides that previous investigations showed probably were triggered in 1811–12. Slope-stability modeling of aseismic conditions shows that the slide could not have formed aseismically even in unrealistically high ground-water conditions. Dynamic stability analysis using Newmark’s method shows that the landslide would have experienced large displacements – sufficient to cause catastrophic failure – during earthquake shaking similar to that which occurred in 1811–12.
A Review of Time-Frequency Analysis Techniques for Estimation of Group Velocities
Authors: Kocaoglu Argun H. , Long Leland T.
Published: July 2019

Time-frequency analysis techniques, including the classical use of zero crossings to measure period, have been widely used in seismology for the estimation of surface wave group velocities. Group velocity estimation by the short-time Fourier transform and the multiple filter techniques are equivalent. Although these techniques are used most often, their resolution is limited. The resolution is controlled by the window length in the short time Fourier transform and the filter band width in the multiple filter technique. The moving-window autoregressive spectral estimation provides the highest resolution with the shortest possible window length by predicting the properties of the signal outside the analysis window; however, high resolution is obtained at the expense of uncertainty in the amplitude. Recently, the Wigner distribution has been introduced as a tool for mapping dispersed surface waves into the time-frequency domain. Resolution of the Wigner distribution is comparable to that of the moving-window autoregressive spectral estimation. When the spectral density at a given time contains two or more dominant frequencies, their interference causes the Wigner distribution to introduce spurious spectral peaks complicating the interpretation. The Choi-Williams distribution, in which these interference effects are minimized, can be used for such dispersed signals. However, the implementation is computationally complex and the distribution offers only a medium resolution.
Australia’s Deepest Known Earthquake
Authors: McCue Kevin , Michael-Leiba Marion
Published: July 2019

Depth phases, pP and sP, of an intraplate earthquake offshore from Arnhem Land, Northern Territory, Australia on 30 September 1992 were recorded on seismographic stations throughout southern Australia and on two stations telemetered to Australia from Antarctica. The computed focal depth is 38.8 (±2.5) km, which is near the crost-mantle boundary, deeper than any other known earthquake in Australia. The near-horizontal principal stress direction, 094°, is similar to that of shallow earthquakes in southwest Australia, but the mechanism has a small dip-slip component in contrast to the predominant thrust mechanism of all past shallow earthquakes that were large enough for mechanisms to have been computed.
Low-Frequency Seismic Surface Waves in the Upper Mississippi Embayment
Authors: Dorman James , Smalley Robert
Published: July 2019

Low-frequency seismic surface waves lasting about 6 minutes were recorded at Memphis following the magnitude 4.6 Risco, Missouri earthquake of May 4, 1991. The motion following S included a very long, sinusoidal train of Love waves with periods of 3 to 5 seconds and weaker groups of Rayleigh waves of periods between 2 and 7 seconds arriving early and late.

The unusual Risco surface waves travel a source-receiver path internal to the upper Mississippi embayment, a shallow basin containing soft, young sediments overlying rigid carbonate rocks. In contrast to the strong Risco surface waves, the magnitude 4.8 Cape Girardeau, Missouri earthquake of September 26, 1990, which occurred near the edge of the basin, produced relatively weak surface waves at Memphis.

The Risco and Cape Girardeau earthquakes are the largest regional earthquakes ever recorded on long-period and broad-band seismographs within the embayment. They show that (1) the sedimentary basin has a profound effect on low-frequency seismic surface waves; (2) the velocity dispersion of a Love wave mode and two Rayleigh wave modes between periods of 2 and 7 sec is well explained by the layering of low-velocity embayment sediments overlying the high-velocity Knox dolomite; (3) because of their strong dispersion, the characteristic basin surface waves can shake the entire embayment for several minutes following any large intra-basin earthquake; (4) excitation of this characteristic basin disturbance seems to be inefficient for strong earthquakes marginal or external to the basin.

Lacking direct measurements of shear velocity in the young embayment clastic section, we find that a simple non-linear relationship between shear velocity and logged compressional velocity makes the sediment physical properties compatible with the observed surface wave dispersion.
How Old is the New Madrid Seismic Zone?
Authors: Pratt Thomas L.
Published: July 2019

Current seismicity levels on the New Madrid seismic zone should produce about 0.11 cm/year of horizontal slip which, when compared with uplift of 42 m in the subsurface strata below the Lake County uplift and assuming a 31° reverse fault model, indicates that the present seismicity levels could not have been present for more than about 64,000 years. If seismicity in the region has persisted for a much longer period of time, then (1) the seismicity has moved spatially between several deformed zones (Crowley’s Ridge and the Crittenden County fault zone); (2) the seismicity is episodic in nature, and active periods similar to the present occur between long quiescent times; or (3) there have been far fewer large earthquakes than predicted by extrapolation of the Gutenberg-Richter relation to higher magnitudes. Any of these scenarios indicates that assessing the hazard from large earthquakes is more complicated than conventional analyses have assumed because either the seismicity locations or rates change or analysis techniques relying on the Gutenberg-Richter relation are invalid for estimating the recurrence times of large earthquakes in the New Madrid area.
Chronic right ventricular failure in a patient with diffuse toxic goiter and alcoholic cirrhosis of the liver: case description
Authors: Shirtladze M. R. , Timofeeva A. A. , Shul'pekova Y. O. , Nechaev V. M. , Baranov S. A. , Supryaga I. V.
Published: July 2019

We present a case of a patient with pronounced edematous‑ascitic syndrome. Initially, its causes were considered to be alcoholic cardiomyopathy (right ventricular failure) with heart rhythm disturbances and liver cirrhosis. Targeted treatment had a low clinical eﬀect, which served as a basis for revising the diagnostic concept. Subsequent follow‑up revealed a diﬀuse toxic goiter with the predominant right ventricular lesion. Achieving euthyroidism has led to a significant improvement in the patient's condition.
Study of risk factors associated with adverse outcome in a severe coronary artery disease (syntax score >22) with different therapeutic strategies
Authors: Karnik Vidur G. , Patil Yogesh B. , Pai N. , Bhat M. N. , Kamath R. L. , Kamath P , Bhatt Rajesh
Published: July 2019

Background: The specific question of whether PCI or surgical treatment offers any advantage over MT in patients with stable angina and multivessel disease remains unanswered. Objective of our research was to study various risk factors which interferes the outcome of various therapeutic procedures in coronary artery disease.Methods: This was prospective observational study carried out in a tertiary care center from July 2014 to July 2016. A total of 98 subjects undergoing different therapeutic strategies were followed up. Risk factors which interferes the outcome of various therapeutic procedures in coronary artery disease (CAD) were studied.Results: There was a significant difference in mean SYNTAX score (P = 0.003), urine micro albumin levels (P=0.006), and body mass index (0.046) between those who had MACE and who did not have MACE.Conclusions: The urine micro albumin >30 mg/l and highest SYNTAX score were significantly associated with MACE at 1 year in subject with severe CAD.
Effect of secondhand smoke exposure on lung function among non-smoking population
Authors: C. Aravind , B. Ragul , . Monisha
Published: July 2019

Background: Secondhand Smoke (SHS) exposure is known to be associated with various cardiovascular and respiratory problems but its effect on pulmonary function remains unexplored. This study was done to evaluate the effect of Secondhand Smoke (SHS) exposure on lung function among non-smoking population.Methods: This cross-sectional study was conducted in Bahour, Pondicherry from 2017-2018.  350 participants, age 40 year and older, with no respiratory symptoms or prior lung diseases were included in this study. Both self-reported history and measurement of urinary cotinine level were used to evaluate the smoking status. Spirometry data, including FVC and FEV1 were used to assess lung function. Diverse variables between groups were compared using T- test and Chi-square test. Analysis of covariance (ANCOVA) adjusted for age, height, alcohol consumption, and level of exercise was used to see any statistical differences in lung function parameters between non-SHS exposed and SHS-exposed groups.Results: Among 350 non-smokers, 120 were SHS-exposed. The urinary cotinine levels clearly distinguished SHS exposure, and the mean urinary cotinine levels were 7±0.3 and 11±0.4 in non-SHS exposed group vs SHS-exposed group, respectively. However, both groups had no significant difference in lung function and was found normal.Conclusions: SHS exposure urinary cotinine is a valuable marker.
Efficacy of Ketamine Hcl and Tramadol Hcl by epidural route for lower abdominal surgeries
Authors: Reddy B. Srinivasulu , Reddy G. Pratapa
Published: July 2019

Background: Pain pathway has profound implications for management of acute pain and provoked interest in the use of pre-emptive analgesia and new methods of postoperative pain management with new agents like opioid and non-opioid drugs either independently or in combination. The objective of the study was to study efficacy of Ketamine Hcl and Tramadol Hcl (preservative free) by epidural route for lower abdominal surgeries.Methods: This study has been conducted on hundred patients in the age group of 20 to 50 years. These patients have undergone various lower abdominal surgeries, gynecological and surgical procedures. Failed epidurals, catheter kinking, catheter migration and dural puncture cases are excluded from the study. The patients were divided into two groups namely Group-A and Group-B, with 50 patients in each group.Results: Both groups were similar in terms of age, sex and weight. In Group-A patients who received 30 mg of Ketamine, the mean time of onset of analgesia being 17.01+2.65 minutes compared to 12.18+2.28 minutes in Group -B patients who received 100 mg of tramadol, In Group-A the mean time of duration of analgesia is 6.75+0.46 hours compared to 9.36+0.84 hours in Group-B. Nausea and vomiting (24% vs. 2%), urinary retention (4% vs. 2%) was more in group B compared to group A patients. Backache was equal in both the group patients (6% vs. 6%). Pain on injection more in group A patients i.e. 8% compared to only 2% in patients who belonged to group B.Conclusions: Epidural tramadol is superior to epidural ketamine for postoperative pain relief.
A study of Revised National Tuberculosis Control Programme quality assurance of sputum microscopy at tuberculosis unit
Authors: Kumar Pratik , Lal Roshan
Published: July 2019

Background: Since, Revised National Tuberculosis Control Programme (RNTCP) relies on sputum microscopy for diagnosis, categorization of patients and assessment of treatment, the credibility, success and sustainability of the programme depends on the lab networks. The objectives of this study were to Quality assurance of Sputum Microscopy under RNTCP in Tuberculosis Unit.Methods: A cross-sectional analytic study was conducted at DMC ML Chest hospital, DMC LLRM Hospital and DMC ESI Hospital. On-site evaluation was conducted once a month by Senior Tuberculosis Lab. Supervisor (STLS) of the DMCs (First Controller). This visit included a comprehensive assessment of laboratory safety procedure, conditions of equipment as well as technical components of AFB smear microscopy which includes prepare, staining and reading of smears. This also included examination of five positive and five negative smears in unblinded manner, to observe the quality of smear and staining as well as condition of microscope at each DMCs. A check list prepared for collection and analysis of standard data to point out remedial action.Results: The overall slide positivity rate (SPR) was 20.17% and 23.99% for ZN-stained slides and fluorescence stained slides respectively. On-site evaluation of all DMCs revealed a good result except of DMC- LLR in maintenance of microscope and well organized and clean working areas. The overall concordance for RBRC slides result of ZN-stained slides was 98.64% and overall discordance was 1.35%. The overall agreement in the re-reading of fluorescent stained slides was 100%. The overall sensitivity, specificity, positive predictive value and negative predictive value of blinded re-checked fluorescence stained slides were 100% each respectively.Conclusions: The overall performance of all DMCs is acceptable.
Study of clinical and hematological profile of anemia in hospitalized geriatric patients
Authors: K. Thyagaraja , Benny Stephan , S. Venkatakrishna Bhat , Nair Akash G.
Published: July 2019

Background: Anemia is an important but underdiagnosed cause of morbidity in elderly. The clinical and hematological profile of anemia is different in different geographical area.Methods: It was a retrospective study. Case files of 50 geriatric patients admitted in Basaveshwara Medical College and Research Institute, Chitradurga with anemia, were selected for the above study. Male patients with Hb <13 g/dl and female patients with Hb <12 g/dl were considered in the study.Cases were analyzed to find out clinical and hematological profile of anemia.Results: The commonest clinical presentation was easy fatigability (70%), followed by dyspnea (50%). The commonest cause of anemia was iron deficiency (36%) followed by Vitamin B 12 and folate deficiency (24%), anemia of chronic disease(12%).Conclusions: Failure to evaluate anemia in elderly lead to delayed diagnosis of potentially treatable conditions. Nonspecific symptoms like fatigue and weakness should not be ignored, presuming that they are part of “normal ageing”. An effort should always be made to reach etiological diagnosis before instituting treatment. Role of NSAIDs as a risk factor in anemia should not be overlooked.
Clinical and treatment patterns in neuromyelitis optica: a retrospective study from a single centre
Authors: Jagiasi Kamlesh A. , Nagendra Shashank , Ansari Afroz , Barvalia Prachi , Aglave Vikram
Published: July 2019

Background: The aim of the study was to study the different presentations, treatment patterns and relapses on therapy in patients of neuromyelitis optica (NMO) and neuromyelitis optica spectrum disorder (NMOSD).Methods: This is a retrospective, observational study in a tertiary hospital where Demographics, clinical manifestations at onset and at follow up and relapses, serum anti Aquaporin 4 antibody status, first line immunomodulatory therapy which was initiated and Relapses on first line therapy were noted.Results: Demographics and clinical presentation was largely similar to published data. 80% patients presented with LETM/ON at onset. Ten patients relapsed on oral therapy and trend was to shift from oral therapy to RTX after relapse on oral agent. No relapses were noted on RTX.Conclusions: Unaffordability and apprehension towards injections and cost were the factors affecting IMT decision, so majority received oral agents Aza/ MMF as first line therapy while remaining patients on oral therapy remained relapse free.
Drug rash with eosinophilia and systemic symptoms, uncommon and commonly missed
Authors: Das Dona , Ragav Dinesh E. , Begum A. Nasreen
Published: July 2019

Drug Rash with eosinophilia and systemic symptoms, also called DRESS syndrome, is a rare form of drug induced hypersensitivity reaction that presents with skin eruptions, blood count abnormalities (eosinophilia) and internal organ involvement (lung, kidney, liver), making it life threatening at a rapid pace. The most commonly affected organ is liver, mimicking condition similar to acute hepatitis.
Septopremaxillary ligament traction system: a review
Authors: Elayadath Rajani R. , Palakunnu Biswas P.
Published: July 2019

Over the years, several animal studies have been conducted concerning the role of cartilaginous nasal septum, septopremaxillary ligament in midfacial growth. Most of the studies utilized non primate animal models at first and then more recently in primates such as chimpanzee. Proper choice of animal model to extrapolate from is critical for successful experimental design. Although nonhuman primates are phylogenetically closer to humans than other mammalian groups for better extrapolation to human condition, not all the craniofacial experiments require primate models. Renewed interests in understanding the influence of septopremaxillary ligament resection on midfacial growth led to many in vitro experiments on animal models. Recently systematic review of relevant animal experiment is regarded as a prerequisite for the conduct of the new clinical trials. Despite this fact, the literature addressing this topic in humans and systematic review on the effect of the septopremaxillary ligament is scarce. The more recent studies show that the maxillary labial frenum encloses the septopremaxillary ligament and forms an important constituent of septopremaxillary traction system. The biomechanical force mediating through the septopremaxillary ligament, maxillary labial frenum and nasolabial muscles results in stimulating their effects on sagital growth of the maxilla. The main purpose of this review is to update and extend the knowledge of the role of septopremaxillary traction system on the midfacial growth by synthesizing the available literature involving the septopremaxillary ligament resection in experimental models. If this review could synthesize the results of relevant research, a change in the therapeutic notions can also be expected.
Perspektywy badań nad rosyjsko-polskim dyskursem prasowym
Authors: Pstyga Alicja
Published: July 2019

Artykuł dotyczy rosyjsko-polskiego dyskursu prasowego, funkcjonującego za pośrednictwem przekładu. Podstawę materiałową stanowią przełożone na język polski rosyjskie teksty medialne zamieszczane w dwutygodniku (wcześniej tygodniku) „FORUM”. Autorkę interesują więc relacje przekładowe i przestrzeń międzytekstowa jako płaszczyzna dialogu w komunikacji międzyjęzykowej Rosjan i Polaków, prowadząca do poznania opinii mediów rosyjskich. Refleksja nad aktualnym rosyjsko-polskim dyskursem prasowym funkcjonującym za pośrednictwem przekładu winna zatem oscylować wokół udziału poszczególnych tekstów w (językowej, dyskursywnej) interpretacji rzeczywistości, z włączeniem wymiaru aksjologicznego, wartości stosowanych modyfikacji tekstowych wpływających na stopień symetrii obu tekstów, a także możliwości interpretacyjnych, uwzględniających kompetencje (między)kulturowe i komunikacyjne uczestników komunikacji.