24 research outputs found
Slope instability and sediment redistribution in the Rockall Trough: constraints from GLORIA
No full textObservation of PS reflections from the Moho
No full textFuchs (1975) has described the theory and computation of synthetic seismograms for PS reflections from first order discontinuities and transition zones with various properties. A number of record sections were shown in which PS reflections were not discernable. In the course of a programme of explosion work which has been carried out around Scotland (SOSP, outlined by Jacob, 1974) a line of shots fired in the North Minch was observed by a station, WR, situated at Cape Wrath (Fig. 1). Though sub-critical PmP Moho reflections were seen, which indicated that PS reflections from the Moho might be expected, a section of vertical component seismograms (Fig. 2) gave only a weak indication of the phase. However, further processing of the data has shown a clear PS Moho reflection to be present.
ARK: https://n2t.net/ark:/88439/y012585
Permalink: https://geophysicsjournal.com/article/273
 
Dispersed shots at optimum depth - an efficient seismic source for lithospheric studies
No full textThe case for dispersing charges fired at sea into a number of packages fired simultaneously at optimum depth is outlined and an experiment, carried out to check that linear addition of the signals from separate sources does occur, is described. The advantages of this system for lithospheric studies are demonstrated.
ARK: https://n2t.net/ark:/88439/y018705
Permalink: https://geophysicsjournal.com/article/97
 
Een automatische procedure ter verkrijging van corresponderende punten in Caesar-beelden
No full textThis report describes an automatic procedure in finding corresponding points in CAESAR-images. CAESAR is a multispectral scanner jointly developed by the Nationaal Lucht- en Ruimtevaartlaboratorium (National Aerospace Laboratory) and Technisch-Physische Dienst. First, the ' CAESAR-images are geometrically corrected by the software-package OPTIPARES, using inertial system data and a geometrical analysis is performed. These images are then used in an automatic procedure to calculate the geometrical transformation-model between these images. This is done in order to use the spectral information as good as possible. Correlation-techniques are used within this procedure. By using two images, in the first image interesting points are found by using the Moravec-operator. The corresponding points in the second image are determined by a ~2D-cross-correlation. From the -two point-lists the geometrical transformation-model can be calculated. In the opinion of the NLR, a shift is sufficient in this model. The results show that this assumption can not hold. Higher-order polynomals give better results. When the geometrical transformation-model is known, a resampling takes place to match the imagesCivil Engineering and GeosciencesFotogrammetrie en remote sensin
Magnitude determination on LOWNET
No full textRoutine processing of seismic signals observed on LOWNET involves
making measuremen"ts of (1) time and (2) amplitude and period. The time
measure~ents contribute to a determination of the source position and
origin time while the amplitude/period measurements allow a determination
of its magnitude. The determination of source position and origin time
15 relatively straightforward relying on accuracy of onset t1ming and
phase identification and a clear statement of which earth model is used.
The position with magnitudes had al~ays been rather more confused
and there are a number of magnitude scales in general. usc. This" reportdescrib~
s the methods of magnitude determination used on LOWNET, compares
LOInmT results with those from the world network, and finally makes some
attempt to link some of the S~21f!S using data from LOWNET plus some
neighbouring stations. The results should be relevant to other networks
set up vithin Britain. Finally some "magnitude/charge si~e"
plots for quarries and underwater explosions are shown and brieflY discussed
Crustal structure on the northeastern flank of the Kenya Rift
No full textGeologi, geofysik, seismik, tektoni
Seismic structure of the upper mantle beneath the southern Kenya Rift from wide-angle data
No full text
