Mining Induced Seismic Event on an Inactive Fault

On 19 March 2013, a tremor shook the surface of Polkowice town where the Rudna Mine is located. This event, of ML = 4.2, was the third most powerful seismic event recorded in the Legnica G?ogów Copper District (LGCD). Inhabitants of the area reported that the felt tremor was bigger and lasted longer than any other ones felt in the last couple of years. Analysis of spectral parameters of the records from in-mine seismic system and surface LUMINEOS network along with broadband station KSP record were carried out. The location of the event was close to the Rudna G?ówna Fault zone; the nodal planes orientations determined with two different approaches were almost parallel to the strike of the fault. The mechanism solutions were also obtained as Full Moment Tensor from P-wave amplitude pulses of underground records and waveform inversion of surface network seismograms. The results from the seismic analysis along with macroseismic survey and observed effects from the destroyed part of the mining panel indicate that the mechanism of the event was complex rupture initiated as thrust faulting on an inactive tectonic normal fault zone. The results confirm that the fault zones are the areas of higher risk, even in case of carefully taken mining operations.     

Sublimation-driven evolution of the local radius and the moment of inertia of a long-period comet

In this paper we intend to analyze how the sublimation of ice from cometary nuclei affects changes of the moments of inertia. Our aim is to show general trends for different orientations of cometary nucleus’ rotation axis. Thus we apply numerical model of a hypothetical homogeneous and initially spherical nucleus composed of water ice and dust. As an example we present simulations for a model comet of the orbital elements and the nucleus size the same as determined for C/1995 O1 Hale-Bopp, a widely analyzed long-period comet. We calculated water production from the nucleus and changes of the shape (initially spherical) and of the moment of inertia versus time. Simulations are performed for the full range (0–90°) of inclinations I of the rotation axis. The second paramater related to the orientation of the rotation axis is the argument Φ (0–360°). The heat conductivity of the nucleus spans over the vast range, 0.04–4 W m⁻¹ K⁻1.     

Role of the Lakes in Groundwater Recharge and Discharge in the Young Glacial Area,Northern Poland

The aim of this research was to delineate characteristic hydrogeological lake types in the Young Glacial Area (YGA). The YGA is in the central and east part of the Kashubian Lake District (KLD) in Northern Poland, an area covered by deposits of Quaternary glaciation. All the bigger lakes were investigated in the area of about 1500 km² (39 lakes). The role of lakes in groundwater recharge and discharge was determined from total dissolved solids (TDS) in lake waters and also from groundwater flow simulation. The general trend was that gaining lakes, as determined by flow modeling, had higher values of TDS than losing lakes. In addition to typical gaining lakes (with TDS > 250 mg/l), there were losing lakes perched on glacial till deposits with very low TDS (<100 mg/l). Two groups of losing lakes were delineated: ones with very low TDS and another group with slightly higher TDS (due to local contact with groundwater). Flow‐through lakes with TDS of 170–200 mg/l were also delineated.     

Allometric relations between fluvial impulse and morphometric parameters of floodplain lakes

The general role of river water input in shaping the basic morphometric parameters of floodplain lakes has been previously investigated. However, the process has not been quantitatively described in detail. This study is the first attempt in the literature to determine the allometric relation between fluvial impulse, expressed as Fluvial Connectivity Quotient, and morphometric parameters of six floodplain lakes of Bug River valley in the period 1952–2014. This relationship is given by Y = aX^b, from which the value of b exponent was analysed to determine the strength of the allometric relation. Extreme values of allometric compounds during the time period under study ranged from 5.99 to ?4.91. Volume was the morphometric parameter showing the highest variability in all the lakes. General similarity in allometric relations was observed in the lakes under study. During analysis, no long‐term trends were observed in the relationship between the Fluvial Connectivity Quotient and morphometric parameters. The results obtained show that fluvial impulse was the factor determining the variability of morphometric parameters of the lakes. Direct catchments topography of lake has periodically (during limnophase periods) played a significant role in shaping the morphometry of floodplain lakes. The most stable allometric relations occurred in a confluent lake, with a low limnological effective rise value and consequently, relatively long potamophase periods.Copyright © 2015 John Wiley & Sons, Ltd.     

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

We used in situ measurements and remote-sensing data sets to evaluate the mass budgets of the Lambert, Mellor and Fisher Glaciers and the basal melting and freezing rates beneath their flowbands on the Amery Ice Shelf. Our findings show the Lambert and Mellor Glaciers upstream of the ANARE Lambert Glacier Basin (LGB) traverse may have positive imbalances of 3.9±2.1 Gt a-1 and 2.1±2.4 Gt a-1, respectively, while the Fisher Glacier is approximately in balance. The upstream region as a whole has a positive imbalance of 5.9±4.9 Gt a-1. The three same glaciers downstream of the ANARE LGB traverse line are in negative imbalance, where the whole downstream region has a negative imbalance of -8.5±5.8 Gt a-1. Overall the mass budgets of the Lambert, Mellor, and Fisher Glaciers are close to bal-ance, and the collective three-glacier system is also nearly in balance with a mass budget of -2.6±6.5 Gt a-1. The significant positive imbalances for the interior basin upstream of the ice-movement stations established in the early 1970s (GL line) reported previously are possibly due to an overestimate of the total accumulation and an underestimate of the ice flux through the GL line. The mean melting rate is -23.0±3.5 m ice a-1 near the southern grounding line, which decreases rapidly downstream, and transitions to refreezing at around 300 km from the southern extremity of the Amery Ice Shelf. Freezing rates along the flowbands are around 0.5±0.1 to 1.5±0.2 m ice a-1. The per-centage of ice lost from the interior by basal melting beneath the flowbands is about 80%±5%. The total basal melting and refreezing beneath the three flowbands is 50.3±7.5 Gt ice a-1 and 7.0±1.1 Gt ice a-1, respectively. We find a much larger total basal melting and net melting than the results for the whole Amery Ice Shelf derived from previous modeling and oceanographic measurements.     

Seismic event near Jarocin (Poland)

The earthquake of magnitude M _L = 3:8 (EMSC) took place on Friday, 6 January 2012, north-east of the town of Jarocin in Wielkopolska Region, Poland. The only historical information about past earthquakes in the region was found in the diary from 1824; apart of it, there was a seismic event noticed in the vicinity of Wielkopolska in 1606 (Pagaczewski 1982). The scope of this paper is to describe the 6 January 2012 event in view of instrumental seismology, macroseismic data analysis and known tectonics of the region, which should be useful in future seismic hazard analysis of Poland.     

Variable stars in the globular cluster NGC 6362

We report the results of a CCD search for short-period variables in the field of a southern globular cluster NGC 6362. We identified 19 new candidate variables, five of which are cluster RR Lyraes, four are probable SX Phe-type stars and eight are eclipsing binaries. Of the discovered binaries, three are EA-type systems, two of which are located on the cluster CMD in the turn-off region and the third 1 mag above the turn-off point, in the yellow straggler region. Five other systems are of W UMa type, three of which are foreground objects and two are likely cluster members. The remaining two candidates exhibit a modulation of the brightness level with an amplitude of 0.1–0.2 mag; further observations are needed to reveal the nature of their variability. Phased VI light curves for 20 variables (18 RR Lyrae stars and two blue stragglers) located in the central region of the cluster are presented.     

Climatic versus tectonic factors in the formation of the glaciolacustrine succession (Be chatów outcrop, central Poland)

Pleistocene glaciolacustrine sediments of the Kleszczów Graben (the Be chatów outcrop, central Poland) record the origin, development, and decay of a glacial lake formed in the area of a subsiding basin during the advance of the Elsterian ice sheet. The sediments represent a transition from glaciofluvial to glaciolacustrine facies at the bottom part, and from glaciolacustrine to glacial facies at the top. The glaciolacustrine facies represent a few environments inside the lake basin, from the marginal sub-aqueous slope through the bottom part to the sub-aqueous fan. The contact of the glaciolacustrine facies and the overlying glacial till is erosional, and implies that a considerable part of the shallow-water lake facies was eroded.The lake existed for not longer than 600 years, but its development proceeded under the conditions of the Kleszczów Graben subsidence and the approach of the Elsterian ice sheet. Both factors influenced the sedimentation processes. The tectonic and climatic factors were recognised on the basis of facies analysis of lithofacies associations, and of their vertical and lateral changes.     

Local Seismic Events in the Area of Poland Based on Data from the PASSEQ 2006–2008 Experiment

PASSEQ 2006–2008 (Passive Seismic Experiment in TESZ; Wilde-Piórko et al. 2008) was the biggest passive seismic experiment carried out so far in the area of Central Europe (Poland, Germany, the Czech Republic and Lithuania). 196 seismic stations (including 49 broadband seismometers) worked simultaneously for over two years. During the experiment, multiple types of data recorders and seismometers were used, making the analysis more complex and time consuming. The dataset was unified and repaired to start the detection of local seismic events. Two different approaches for detection were applied for stations located in Poland. The first one used standard STA/LTA triggers (Carl Johnson’s STA/LTA algorithm) and grid search to classify and locate the events. The result was manually verified. The second approach used Real Time Recurrent Network (RTRN) detection (Wiszniowski et al. 2014). Both methods gave similar results, showing four previously unknown seismic events located in the Gulf of Gdańsk area, situated in the southern Baltic Sea. In this paper we discuss both detection methods with their pros and cons (accuracy, efficiency, manual work required, scalability). We also show details of all detected and previously unknown events in the discussed area.