Modelling of the ground motion of the maximum probable earthquake and its impact on buildings, Vilnius city

The Baltic region is characterised by a low seismic activity. The recent Kaliningrad earthquake of magnitude M= 5.0 in 2004 persuades that the previous estimates of the seismic hazard of the Baltic region were underrated. It urges the re-assessment of characteristics of the maximum possible earthquake that may take place elsewhere in the Baltic region. The Kaliningrad earthquake scenario was modelled for Vilnius city area. It is motivated by occurrence of several moderate historical earthquakes that took place close to the city, also the presence of some large-scale fault zones in proximity to the city. The maximum probable earthquake of magnitude M= 5.0 and hypocentral depth of 15 km was modelled to take place in Vilnius city area. The modelled seismic response spectra are dominated by low frequencies 2-5 Hz that is accounted to soft soil effect. The peak ground acceleration (PGA) was modelled to range from 1.05 m/s2 to 1.40 m/s2 depending on soil type, i.e. moraine dominated and sand/technosoil dominated, and on stress-strain relationship (linear vs. non-linear soil behaviour). Estimated PGA corresponds to macroseismic intensity Io= 7 (MSK-64) implying only minor building damages. The modelled seismic signal implies that 2-10 store buildings are subject to the highest (though modest) seismic risk

Correlation of shear-wave velocities and cone resistance of quaternary glacial sandy soils defined by Seismic Cone Penetration Test (SCPT)

The derivation of dynamic geotechnical parameters of soil are of primary importance in designing specific structures. Direct measurements are expensive and time-consuming. In this study the correlation between the seismic wave velocities and cone resistance was derived from seismic cone penetration testing (SCPT) of Quaternary glacial sandy soils in Lithuania. The close relationship was obtained for sandy soils indicating wide range of cone resistance and seismic wave velocities. The correlation is as high as R = 0.80. The derived regression equation could be reasonably used in assessing dynamic geotechnical and seismic parameters in Lithuania and other territories characterized by similar geological conditions using conventional cone penetration testing (CPT) method. It enables consistent geotechnical and seismic zoning of sandy soils

Predicting porosity through simulating quartz cementation of Middle Cambrian sandstones, West Lithuania

Quartz cementation is a major parameter controlling the reservoir properties of the Middle Cambrian quartz arenites of the central and western parts of the Baltic Basin. Marked local variations in the porosity and permeability severely complicate oil exploration and exploitation inWest Lithuania. Commonly, the porosity of the oil reservoirs is 6–8%. Therefore even minor changes in the porosity have a considerable impact on the potential of oil fields. A predictive model of the quartz cementation is proposed, based on kinetic modelling results. The precipitation rate-limiting model effectively explains sharp variations in quartz cementation controlled by grain-size changes. The model was further improved by incorporating the sorting factor. Even so, the amount of quartz cementation is overpredicted by 4–7% in some intervals, implying that the precipitation rate-limiting model is too simplified. A good correlation was obtained between stylolite spacing and quartz cementation, the overpredicted quartz amount increasing with an increase in stylolite spacing. The modelling results argue against any discernable impact of the oil on the reservoir quality of the sandstones. The successful prediction of reservoir quality mainly depends on correct reconstruction of the sedimentary environment of the Middle Cambrian deposits. The evolutionary model of the quartz cementation suggests a good reservoir quality of the Cambrian sandstones during the later part of Late Palaeozoic, when most of oil was generated in the basin

Geochemistry and 40

The Early Carboniferous magmatic event in the southern Baltic Sea is manifested by dolerite intrusions. The presumable area in which the dolerite intrusions occur ranges from 30 to 60 km in east–west direction, and is about 100 km in north–south direction. The dolerites were sampled in well D1-1 and investigated by applying chemical analysis and 40Ar/39Ar step-heating dating. Dolerites are classified as alkali and sodic, characterized by high TiO2 (3.92, 3.99 wt%) and P2O5 (1.67, 1.77 wt%) and low MgO (4.89, 4.91 wt%) concentrations, enriched in light rare earth elements, originated from an enriched mantle magma source and emplaced in a continental rift tectonic setting. The 351 ± 11 Ma 40Ar/39Ar plateau age for groundmass plagioclase indicates a considerable age gap with the 310–250 Ma magmatism in southern Scandinavia and northern Germany. The magmatic rocks in the Baltic Sedimentary Basin are coeval with alkaline intrusions of NE Poland. Both magmatic provinces lie in the northwestward prolongation of the Pripyat–Dnieper–Donetsk Rift (370–359 Ma) and may constitute a later phase of magmatic activity of this propagating rift system

Morphotectonic implication of the Paleoproterozoic Mid-Lithuanian Suture Zone

The Paleoproterozoic Mid-Lithuanian Suture Zone represents one of the major structures of the crystalline basement of Lithuania, separati ng the West Lithuanian and the East Lithuanian domains. This zone has shown persistently low tectonic activity during the Phanerozoic. The Mid-Lithuanian Suture Zone is marked by a distinct Middle Lithuanian topographic low underlain by a trough in the sub-Quaternary surface that suggests the morphotectonic nature of this depression. This is supported by high-precision geodetic level l ing data that has unravelled the subsidence trend of the Middle Lithuanian trough. The zone is also distinct in its pattern of topographic lineaments. The persistence of the tectonic activity of the Mid-Lithuanian Suture Zone suggests that it represents a large-scale mechanical boundary of the Earth's crust, resulting in increased accumulation of tectonic strain

Lithology and diagenesis of the poorly consolidated Cambrian siliciclastic sediments in the northern Baltic Sedimentary Basin

The present study discusses lithology and diagenetic characteristics of the siliciclastic Cambrian and the enclosing Ediacaran and Ordovician deposits in the northern Baltic Sedimentary Basin (BSB). The Neoproterozoic and Lower Palaeozoic sediments are despite their age unconsolidated with primary porosity of 20-25% for both shales and sandstones. The sparse Fe-dolomite cementation of arenitic and subarenitic sandstones and siltstones occurs mainly at lithological contacts with the massive Ediacaran and Lower Cambrian claystones and is probably related to ions released during llitization. In contrast to weak mechanical and chemical compaction of sandstone, the clay mineral diagenesis of Cambrian deposits is well advanced. The highly illitic (80-90%) nature of illite-smectite (I-S) suggests evolved diagenetic grade of sediments which conflicts with shallow maximum burial and low compaction. Smectite-to-illite transformation has resulted in formation of diagenetic Fe-rich chlorite in claystones. Some porosity reduction of sandstones is due to formation of authigenic kaolinite at the expense of detrital mica or K-feldspar

CO2 storage potential of sedimentary basins of Slovakia, the Czech Republic, Poland and the Baltic States

It has been increasingly realised that geological storage of CO2 is a prospective option for reduction of CO2 emissions. The CO2 geological storage potential of sedimentary basins with the territory of Slovakia, the Czech Republic, Poland, and the Baltic States is here assessed, and different storage options have been considered. The most prospective technology is hydrodynamic trapping in the deep saline aquifers. The utilisation of hydrocarbon (HC) fields is considered as a mature technology; however storage capacities are limited in the region and are mainly related to enhanced oil (gas) recovery. Prospective reservoirs and traps have been identified in the Danube, Vienna and East Slovakian Neogene basins, the Neogene Carpathian Foredeep, the Bohemian and Fore-Sudetic Upper Paleozoic basins, the Mesozoic Mid-Polish Basin and the pericratonic Paleozoic Baltic Basin. The total storage capacity of the sedimentary basins is estimated to be as much as 10170 Mt of CO2 in deep saline aquifer structures, and 938 Mt CO2 in the depleted HC fields. The utilisation of coal seams for CO2 storage is related to the Upper Silesian Basin where CO2 storage could be combined with enhanced recovery of coal-bed methane

Processing and interpretation of vintage 2D marine seismic data from the outer Hanö Bay area, Baltic Sea

A grid of previously unpublished, vintage 2D marine seismic lines has been processed and interpreted to the east of Hanö Bay, SW Baltic Sea. The 3200km2 study area lies on the transition between the Hanö Bay Basin to the West and Baltic Synelcise to the East, NE of the Tornquist intra shield tectonic zone.Data from the NA79, NA80 and RW84 surveys were selected for this study from the extensive Oljeprospektering AB (OPAB) Baltic Sea dataset. New processing workflows have been developed for the data which focus on suppressing two significant forms of noise, namely multiple and side scattered noise. Deconvolution in the tau-p domain, parabolic radon demultiple and post stack deconvolution are shown to be effective at attenuating multiple noise, while FK filtering in shot and receiver gathers is effective at removing side scattered noise.The newly processed data were interpreted and a series of maps detailing the structure of the basement, Cambrian and Silurian/Paleozoic horizons were constructed. These maps differ significantly to previously published interpretations of the area. Within the study area, a region of significant Late Carboniferous/Early Permian transtensional faulting and Late Cretaceous inversion is mapped in detail. This structure would have exhibited normal offsets of up to 600. m before inversion with later inverted displacements of up to approximately 200. m in places. This feature appears to extend some 20. km to the SW of the study area to the major fault bounding the Christiansø High. Based on the seismic interpretation, the area appears to have had a similar overall geological history as the adjacent Tornquist Zone to the SW. © 2013 The Authors