Once More about Deep Caucasus Earthquakes

The upper crustal location of the foci of the Spitak earthquake of December 7, 1988, and its aftershocks is proved. It is demonstrated that the seismological network in Armenia and Georgia allowed unequivocal focal depth identification based on the kinematic data. The waveforms of all the Spitak earthquakes are typical of sources in the upper crust. It is noted that up to now, mantle earthquakes in the Caucasus have only been revealed in the Terek–Sunzha depression.     

Wavelet analysis of paleomagnetic data: 3. Wavelet analysis of the basic series of archaeomagnetic data on the geomagnetic field intensity for the past 7500 years

We performed wavelet analysis of series of the magnetic field intensity obtained through archaeomagnetic studies in Bulgaria, Georgia, Central Asia, China, and Japan. The duration of the studied intervals is 2000, 4000, and more than 7000 yrs. It has been shown that periodic oscillations as well as those with varying characteristic times are present in this series. The distribution of oscillations with characteristic times up to 800–1000 yrs by periods, characteristic times, time, and place of their manifestation is random.     

Hybrid-Empirical Ground Motion Estimations for Georgia

Ground motion prediction equations are essential for several purposes ranging from seismic design and analysis to probabilistic seismic hazard assessment. In seismically active regions without sufficiently strong ground motion data to build empirical models, hybrid models become vital. Georgia does not have sufficiently strong ground motion data to build empirical models. In this study, we have applied the host-totarget method in two regions in Georgia with different source mechanisms. According to the tectonic regime of the target areas, two different regions are chosen as host regions. One of them is in Turkey with the dominant strike-slip source mechanism, while the other is in Iran with the prevalence of reverse-mechanism events. We performed stochastic finite-fault simulations in both host and target areas and employed the hybrid-empirical method as introduced in Campbell (2003). An initial set of hybrid empirical ground motion estimates is obtained for PGA and SA at selected periods for Georgia.     

Soil moisture–temperature relationships: results from two field experiments

This paper analyses data from two field experiments in Chickasha, Oklahoma, and Tifton, Georgia, carried out in July 1999 and June 2000 respectively. The observations on soil moisture at two depths, viz. 0–2·5 and 0–5·0 cm, surface temperature, and temperatures at 1, 5 and 10 cm depths are analysed. The relationship between the soil moisture and the temperature variability in time is examined as a function of vegetation type and location. Results from these experiments show that, during drydown, surface temperature shows an increase that corresponds to a decrease in the soil moisture. Linear models for prediction of soil moisture (at both depths) using surface temperature observations are examined. Copyright © 2003 John Wiley & Sons, Ltd.     

The territory of Georgia and surrounding countries in the Upper Cretaceous: paleomagnetic data

Paleomagnetic researches of the Upper Cretaceous rocks, collected from 24 cross-sections (530 samples) of Georgia have shown that only nine samples are suitable for the paleotectonic problem to be solved. The method of thermomagnetic cleaning was used for the paleomagnetic directions of these rocks to be determined. Magnetic-mineralogical data and the tests of paleomagnetic accuracy have proved the ancient age of the stable part of the natural remnant magnetization (NRM) that is close to the initial one. The study results have demonstrated that the position of the areas studied in the Upper Cretaceous time was located 11°–18° southward from their modern latitudinal position; the distance between structures of the Great Caucasus and Trans-Caucasus was 10°–14°. The wide variations of the paleoinclinations are connected with the local turns of tectonic blocks     

Fission track ages of North American tektites

Fission track ages of North American tektites from Texas, Georgia and Martha's vineyard range widely between 0.8 my and 34.2 my with the tektites from Georgia giving the lowest ages. Size studies of the fission track etch pits reveal the thermal history of each individual tektite resulting in the partial loss of tracks. Therefore, the measured fission track ages can be understood as thermally lowered.

Based on annealing experiments, correction factors for the thermally lowered fission track ages are found. The weighted mean of the corrected fission track ages is 34.9 my for the bediasites and the Martha's Vineyard tektite. On the other hand, the corrected fission track ages of the Georgia tektites are much lower resulting from a more complex thermal history.

It may now be stated that North American tektites and Libyan Desert glasses cannot have had a simultaneous origin.     

Seismic hazard map of the Middle East

The collaborative project Earthquake Model of the Middle East (EMME, 2010–2015) brought together scientists and engineers from the leading research institutions in the region and delivered state-of-the-art seismic hazard assessment covering Afghanistan, Armenia, Azerbaijan, Cyprus, Georgia, Iran, Iraq, Jordan, Lebanon, Palestine, Pakistan, Syria and Turkey. Their efforts have been materialized in the first homogenized seismic hazard model comprising earthquake catalogues, mapped active faults, strong motions databank, ground motion models and the estimated ground motion values for various intensity measure types and relevant return periods (e.g. 475–5000 years). The reference seismic hazard map of the Middle East, depicts the mean values of peak ground acceleration with a 10% chance of exceedance in 50 years, corresponding to a mean return period of 475 years. A full resolution poster is provided with this contribution.     

GROUND-WATER MANAGEMENT IN GEORGIA

Abstract. Although Georgia receives approximately 50 inches of precipitation annually, concern over water quantity is increasing in this State. Historically, ground-water problems were associated with major urban-industrial withdrawals but recent irrigation development in the southwestern portion of the State has attracted attention. Irrigation withdrawals were exempted from the permit requirements of the 1972 Ground Water Use Act. This has led to an inability to manage the resource and questions regarding legal rights to the use of water. Current activities in the State indicate that measures may be taken during the 1980 session of the Georgia General Assembly to enable better management of the State's water resources.     

Rainfall–runoff trends in the south‐eastern USA: 1938–2005

An extensive dataset (230 precipitation gauges and 79 stream gauges) was used to analyse rainfall–runoff relationships in 10 subregions of a 482000 km² area in the south‐eastern USA (Maryland, Virginia, North Carolina, South Carolina and Georgia). The average annual rainfall and runoff for this study area between 1938 and 2005 were 1201 and 439 mm, respectively. Average runoff/rainfall ratios during this period varied between 0·24 in the southernmost Coastal Plain subregion to 0·64 in the Blue Ridge Province. Watershed elevation and relief are the principal determinants governing the conversion of rainfall to runoff. Temporal rainfall variation throughout the south‐eastern USA ranges from ～40% above and below normal while the variation for runoff is higher, from ? 75% to + 100%. In any given year there can exist a ± 25–50% error in predicted runoff deviation using the annual rainfall–runoff regression. Fast Fourier Transform and autoregressive spectral analysis revealed dominant cyclicities for rainfall and runoff between 14 and 17 years. Secondary periodicities were typically between 6–7 and 10–12 years. The inferred cyclicity may be related to ENSO and/or Central North Pacific atmospheric phenomena. Mann–Kendall analyses indicate that there were no consistent statistically significant temporal trends with respect to south‐eastern US rainfall and runoff during the study period. The results of U‐tests similarly indicated that rainfall between 1996 and 2005 was not statistically higher or lower than during earlier in the study period. Copyright © 2008 John Wiley & Sons, Ltd.     

Pelagic tar off Georgia and Florida in relation to physical processes

Following the Ixtoc I oil rig blowout in Campeche Bay we hypothesized that resulting tarballs should eventually appear in the Gulf Stream off Gerogia and that because of dynamic barriers in the innershelf little would reach nearshore areas. To test these hypotheses, surface tows to collect floating tar were taken off the coasts of Georgia and Florida in October and December, 1979.No tar was found within 40 km of the shore. All samples more than 40 km offshore contained some tar. The mean concentration was 0.82 mg m^?2 with a range of 0.01–5.6 mg m^?2. Closely spaced sampling showed extreme variation but trends were consistent. Perylene was the most abundant compound in the tarballs.     

Geomagnetic field paleointensity in the cretaceous from Upper Cretaceous rocks of Georgia

A representative collection of Upper Cretaceous rocks of Georgia (530 samples from 24 sites) is used for the study of magnetic properties of the rocks and the determination of the paleodirection and paleointensity (H _an) of the geomagnetic field. Titanomagnetites with Curie points of 200–350°C are shown to be carriers of natural remanent magnetization (NRM) preserving primary paleomagnetic information during heatings to 300–350°C. The characteristic NRM component of the samples is identified in the interval 120–350°C. The Thellier and Thellier-Coe methods are used for the determination of H _an meeting modern requirements on the reliability of such results. New paleointensity determinations are obtained and virtual dipole magnetic moment (VDM) values are calculated for four sites whose stratigraphic age is the Upper Cretaceous (Cenomanian-Campanian). It is shown that, in the interval 99.6–70.6 Ma, the VDM value was two or more times smaller than the present value, which agrees with the majority of H _an data available for this time period. According to our results, the H _an value did not change at the boundary of the Cretaceous normal superchron.     

The Peculiarities of Hydrological Processes in Mountain Reservoirs

The results of studying hydrological processes in mountain reservoirs in Georgia are discussed. It is shown that in mountainous regions, water budgets of reservoirs, level regime, water exchange, currents and waves have specific features governed by a variety of factors.     

Tritium in ground water of the georgia piedmont: Implications for recharge and flow paths

Environmental tritium was measured in 33 natural water samples representative of precipitation, stream runoff, and groundwater (derived principally from production wells) within the Georgia Piedmont Province. Major ion analyses were used to assist in the interpretation of the tritium results. Tritium concentrations were significantly greater within shallow groundwater derived from the regolith (28–34 TU) and stream runoff (25–30 TU) than within recent rainfall (4–17 TU). Based upon the decay-corrected tritium input function, this probably indicates that at least some of the shallow water is stored within the regolith for a period of approximately 25 years. A ‘post-bomb’ component of recharge was present in all groundwater derived from production wells in the study area. Groundwater sampled from the bedrock aquifers was commonly less tritiated than either stream runoff or shallow water stored in the regolith. the lower tritium concentrations May, have resulted from the mixing of ‘pre-bomb’ water stored within the fractures or the transitional zone directly above the bedrock and modern water stored in the shallow regolith. the preponderance of modern water provides evidence that groundwater flow paths are areally restricted within this setting, probably confined to local surface water drainage basins. the residence time of groundwater in the Piedmont is limited by the lack of deep, gravity-driven regional flow and the localized vertical flow induced by pumping. the results of this study indicate that relatively small tritium concentration variations (10-20 TU) May, have regional hydrological significance in the southeastern Piedmont Province and similar settings.     

A statistical methodology for assessing the long‐term effects of antecedent drought conditions on stream runoff: applications to the Piedmont Province,southeastern United States

A method was developed to investigate the long‐term (months‐to‐years) effects (both magnitude and duration) of antecedent rainfall upon subsequent runoff coefficients (RCs) or runoff/rainfall ratios. The method was applied to a four‐state region (Georgia, South Carolina, North Carolina, and Virginia) within the southeastern Piedmont Province of the United States and incorporated a 59‐year data set of 19 United States Geological Survey stream gages and 57 National Climatic Data Center rain gages. The method was designed to facilitate statistical comparisons [Mann–Whitney rank sum tests] between various groups of normalized runoff coefficients (NRCs) representing 6–36 month periods which differed in terms of antecedent rainfall conditions. The results of this study show that under all subsequent rainfall conditions, with the exception of excess rainfall, a 1‐year period of antecedent drought lowered NRCs for at least 1 year following the drought. The principal finding of this study is that a year‐long drought period within the southeastern Piedmont Province lowers NRCs by ～25% during the following year when rainfall returns to normal. In most cases, RCs are significantly lower during the second year following a drought than they would be when anteceded by normal rainfall; however, the effects of drought wane during this period. This is a statistical and regional method that can be modified to other study areas; however, it cannot be used to predict storm‐event rainfall–runoff relationships for any specific basin. Copyright © 2010 John Wiley & Sons, Ltd.     

Temperature trends and interannual variability in the Strait of Georgia,British Columbia

A continuous 36 year long record of semi-monthly temperature profiles from the central Strait of Georgia, British Columbia is used to examine low frequency variability and trends through the water column. Decomposition of temperature anomalies into empirical orthogonal functions shows that the dominant mode accounts for 78% of the variance, while the principal component associated with this mode (PC1) is dominated by fluctuations on interannual time scales. To relate the variability within the Strait to that occurring over the northeast Pacific, PC1 is compared with anomalies in local air temperature, sea surface temperatures off the west coast of Vancouver Island, and upper ocean temperatures along Line-P. These comparisons suggest that much of the interannual variability observed in the Strait of Georgia occurs in response to large-scale atmospheric forcing over the northeast Pacific. However, following tropical El Niño events there are significant anomalies associated with processes occurring along the coastal oceanic wave guide. The strongest event in the entire record, the remarkable negative temperature anomaly of winter 1978/1979, appears to be associated with a deep water intrusion that was forced locally.     

Evidence for ∼80–75 Ma subduction jump during Anatolide–Tauride–Armenian block accretion and ∼48 Ma Arabia–Eurasia collision in Lesser Caucasus–East Anatolia

Orogens formed by a combination of subduction and accretion are featured by a short-lived collisional history. They preserve crustal geometries acquired prior to the collisional event. These geometries comprise obducted oceanic crust sequences that may propagate somewhat far away from the suture zone, preserved accretionary prism and subduction channel at the interplate boundary. The cessation of deformation is ascribed to rapid jump of the subduction zone at the passive margin rim of the opposite side of the accreted block. Geological investigation and ⁴⁰Ar/³⁹Ar dating on the main tectonic boundaries of the Anatolide–Tauride–Armenian (ATA) block in Eastern Turkey, Armenia and Georgia provide temporal constraints of subduction and accretion on both sides of this small continental block, and final collisional history of Eurasian and Arabian plates. On the northern side, ⁴⁰Ar/³⁹Ar ages give insights for the subduction and collage from the Middle to Upper Cretaceous (95–80 Ma). To the south, younger magmatic and metamorphic ages exhibit subduction of Neotethys and accretion of the Bitlis–Pütürge block during the Upper Cretaceous (74–71 Ma). These data are interpreted as a subduction jump from the northern to the southern boundary of the ATA continental block at 80–75 Ma. Similar back-arc type geochemistry of obducted ophiolites in the two subduction–accretion domains point to a similar intra-oceanic evolution prior to accretion, featured by slab steepening and roll-back as for the current Mediterranean domain. Final closure of Neotethys and initiation of collision with Arabian Plate occurred in the Middle-Upper Eocene as featured by the development of a Himalayan-type thrust sheet exhuming amphibolite facies rocks in its hanging-wall at c. 48 Ma.     

<Emphasis Type="Italic">M</Emphasis>9 Tohoku Earthquake Hydro- and Seismic Response in the Caucasus and North Turkey

Presently, there are a lot of observations on the significant impact of strong remote earthquakes on underground water and local seismicity. Teleseismic wave trains of strong earthquakes give rise to several hydraulic effects in boreholes, namely permanent water level changes and water level oscillations, which closely mimic the seismograms (hydro-seismograms). Clear identical anomalies in the deep borehole water levels have been observed on a large part of the territory of Georgia during passing of the S and Love–Rayleigh teleseismic waves (including also multiple surface Rayleigh waves) of the 2011 Tohoku M9 earthquake. The analysis carried out in order to find dynamically triggered events (non-volcanic tremors) of the Tohoku earthquake by the accepted methodology has not revealed a clear tremor signature in the test area: the Caucasus and North Turkey. The possible mechanisms of some seismic signals of unknown origin observed during passage of teleseismic waves of Tohoku earthquake are discussed.     

Assessment of the macrobenthos in an Antarctic environment following recent pollution abatement

Quantative population data for shallow Antarctic soft-bottom communities in King Edward Cove, South Georgia indicate that although once grossly polluted by organic effluent and fuel oil from a whaling station, the fauna recovered within some eight years after contamination ceased. The results are discussed in relation to comparable studies in other polar and temperate areas.     

Scaling features of ambient noise at different levels of local seismic activity: A case study for the Oni seismic station

Investigation of dynamical features of ambient seismic noise is one of the important scientific and practical research challenges. We investigated scaling features of the ambient noises at the Oni seismic station, Georgia, using detrended fluctuation analysis method. Data from this seismic station, located in the epicentral zone of Oni M6.0, 2009, earthquake, were selected to include time periods with different levels of local seismic activity.