Determination of the strain ellipsoid from measurements on any three sections

An ellipsoid is defined by, and may be re-constructed from, any three sections through it. In the field, calculation of the strain ellipsoid from general sections (two-dimensional strain ellipses determined from measured strain markers) is complicated by the fact that, due to experimental error and/or strain inhomogeneity, the three ellipses may not come from the same ellipsoid. The ellipses must first be adjusted to make them compatible. A method is suggested by which an adjustment ellipse is determined analytically for each of the three sections. Application of these adjustment ellipses makes the three sections compatible, and the strain ellipsoid may be determined. The principal axes of the ellipsoid are derived from the ellipsoid matrix by eigenvector analysis. Examples are given of practical applications of this method.     

Earthquakes in Switzerland and surrounding regions during 2009

This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2009. During this period, 450 earthquakes and 68 quarry blasts were detected and located in the region under consideration. The three strongest events occurred about 15 km NW of Basel in southern Germany (M_L 4.2), near Wildhaus in the Toggenburg (M_L 4.0) and near Bivio in Graubünden (M_L 3.5). Although felt by the population, they were not reported to have caused any damage. With a total of 24 events with M_L ≥ 2.5, the seismic activity in the year 2009 was close to the average over the previous 34 years.     

Refining Population Surface Models: Experiments with Northern Ireland Census Data

This paper compares and contrasts alternative methods for the construction of discontinuous population surface models based on the census and remotely sensed data from Northern Ireland. Two main methods of population distribution are employed: (1) a method based on redistribution from enumeration district (ED) and postcode centroids, and (2) a method based on dasymetric redistribution of ED population counts to suitable land cover zones from classified remotely sensed imagery. Refinements have been made to the centroid redistribution algorithm to accommodate an empirical measure of dispersion, and to allow redistribution in an anisotropic form. These refinements are evaluated against each other and the dasymetric method. The results suggest that all of the methods perform best in urban areas, and that while the refinements may improve the statistical performance of the models, this is at the expense of reduced spatial detail. In general, the techniques are highly sensitive to the spatial and population resolution of the input data.     

Occurrence ofSpartina macrodetritus in Bay of Fundy waters

Suspended macrodetritus (>600 μm) from extensiveSpartina alterniflora marshes is widespread in the Cumberland Basin region of the macrotidal upper Bay of Fundy. The average concentration is about 5 mg C per m³ and most is found in the lower two-thirds of the water column. The total amount in the Basin at high tide is approximately 8 metric tonnes of organic carbon which is less than 1% of the annual net aerial primary production of the fringingS. alterniflora marshes. The high visibility ofSpartina detritus in Cumberland Basin is caused by the extreme tides (average tidal range about 11 m) which export marsh vegetation and distribute it widely about the estuary, and by the pronounced turbidity which has been shown to limit phytoplankton growth.     

Morphologies of Ly-emitting galaxies

Lyman alpha emitters (LAEs) are high-redshift galaxies that are believed to be actively star-forming and low in mass. Although such a population of galaxies would not be expected to lie on the Hubble Sequence, there is much we can learn from their morphological properties, including the size and distribution of their star-forming regions, the spatial correlation between emission in different bandpasses, and the possible presence of a merger/interaction with one or more neighboring galaxies. Early morphological studies suggest that most LAEs are small in size (1 kpc) and concentrated, but some (20–45%) are seen to display clumpy/irregular morphologies extending over larger radii. Constructing a more detailed picture will require a standard set of depth-independent morphological diagnostics for high-redshift galaxies. These diagnostics can then be measured differentially with redshift, shedding light on the evolution of the galaxy formation process with time.     

An integrated approach to shallow aquifer characterization: combining geophysics and geostatistics

We present a method of aquifer characterization that is able to utilize multiple sources of conditioning data to build a more realistic model of heterogeneity. This modeling approach (InMod) uses geophysical data to delineate bounding surfaces within sedimentary deposits. The depositional volumes between bounding surfaces are identified automatically from the geophysical data by a region growing algorithm. Simple geometric rules are used to constrain the growth of the regions in 3-D. The nodes within the depositional volume are assigned to categorical lithologies using geostatistical realizations and a dynamic lookup routine that can be conditioned to field data. The realizations created with this method preserve geologically expected features and produces sharp juxtapositions of high and low hydraulic conductivity lithologies along bounding surfaces. The realizations created with InMod also have higher variance than models created only with geostatistics and honor the volumetric distribution of sediments measured from field data.