Over the past decades a number of small earthquakes have been recorded in Leamington - Ridgetown area along the north shore of Lake Erie (southwestern Ontario). A new seismic cluster is forming in this area, away from the already known clusters in Ontario. The new seismic area lays across the seismic area south of Lake Erie (along the Pennsylvania- Ohio border), known for some moderate induced events related to the oil production there. Another cluster related to the oil/gas production- in the region of Gobles, north of Lake Erie-has been documented and studied by Mereu et al. (1986). The induced seismicity is usually related not to the oil/gas production itself but to the water injection accompanying this production. The water injection is used in southern Ontario in Leamington - Ridgetown area to increase the oil/gas recovery from the existing reservoirs. The relationship between the new forming cluster and the ongoing oil/gas production north of Lake Erie is studied here. The parameters of the earthquakes in the area (hypocenter location, magnitudes, seismic moment, stress drop, and focal mechanism and/or seismic moment tensors for some events) are calculated using the POLARIS and Canadian National Seismic Network (CNSN) data. A temporary seismic network, consisting of four high-frequency three-component stations, has been installed in the fall of 2008 to record data from possible smaller events, not recorded by the permanent stations. The lithology, structural geology, and hydrology of the site are critical for determining if the water injection can induce seismic events. This type of data as well as data about the local tectonics (the existing faults) have been collected and analyzed. The main goal of this work was to find if any spatial or temporal correlations between the seismicity pattern and oil production/water injection exist. The preliminary results of the study suggest a correlation between the seismic activity and the oil/gas production. The study provides also additional information about the tectonic regime in southern Ontario and on throws some light on the hypothesis for induced seismicity due to the oil/gas production north of Lake Erie.
Winter-forest processes affect global and local climates. Weather-forecast, climate and hydrological modelers incorporate increasingly realistic surface schemes into their models, and algorithms describing snow accumulation and snow-interception sublimation are now finding their way into these schemes. Both point and spatially variable data for calibration and verification of wintertime dynamics are therefore needed for such modeling schemes. Snow forest atmosphere interaction studies at Luleå University of Technology (in co-operation with researchers in Sweden, Finland, UK and Japan) show that seasonal sublimation fraction of snow precipitation in confined coniferous forests range about 0.35 and single events with sublimation rates of up to 3.9 mm in 7 h were observed. The most important factors for calculating the sublimation were: the relative humidity, the aerodynamic resistance, the wind speed and the intercepted mass. The techniques used to study processes and rates were weighing cut tree and weighing througfall (in Sweden) γ-ray attenuation and tree weighing systems, combined with plastic sheet net rainfall gauges for throughfall (in UK) and snow course measurements in combination with forest density measurements (in Finland) and with sky view fraction (SVF) measurements (fish eyed camera)(in Japan). For the last study forest snow accumulation (SF) could be estimated from snowfall in open fields (SO) and from SVF according to: SF = SO (0.56 + 0.6 × SVF) for SVF < 0.72 and SF = SO for SVF > 0.72 (R2 = 0.86) as well as from leaf area index (LAI). For observation plots exceeding 1 ha the SVF was correlated to the normalized difference snow index (NDSI) using a Landsat-TM image and SF was related to SO and NDSI according to SF = SO (0.81 - 0.37 × NDSI). Plot-size limitations allowed inclusion of only one sparse forest observation so the relationship.
We report three new paleomagnetic poles from the Amazon craton for the Meso/Neoproterozoic Grenvillian interval, a period notable for the eponymous continental collision that affected the eastern margin of Laurentia. The poles were derived from study of ca.1230 Ma mafic sills (Figueira Branca -V 40Ar/39Ar biotite), the 1149 , b7 Ma sediments of the Aguapeà Gp. (U-Pb SHRIMP analysis of authigenic xenotime) and the ca.980 Ma basaltic dykes and flat-lying flows (40Ar/39Ar biotite) that intrude and overlie the Aguapeà Gp. sediments. These new data define a skeletal apparent polar wander path marked by a counterclockwise loop, similar to that observed for North America and Baltica. A pole-by-pole comparison of the Amazon and North American data demonstrates the evolving paleogeographic affinity of these two continents, marked by the large-scale strike-slip movement of Amazonia relative to Laurentia. The 3000 km of sinistral offset between these two continents is substantiated by a 200 Ma record of sinistral transpression recorded in the 1.2-1.15 Ga deformation of basement rocks of the Amazon craton, the 1.1 Ga Nova Brasil\^{a}ndia belt, and the 1.05-1.0 Ga Sunsas belt of eastern Bolivia. Our observations suggest that transpressional collision of the Amazon craton and Laurentia was responsible for the bulk of Grenvillian deformation, as opposed to the multiple continents required by other Rodinia models.