ALBERT

Description: The Erzincan strike-slip earthquake of March 13, 1992 ruptured a section of the North Anatolian fault (NAF) at the northern margin of the Erzincan basin. The focal depth of about 10 km was less than given by ISC and NEIC. Erzincan and the surrounding villages were considerably damaged. In the Erzincan basin and in the neighbouring mountains a seismic network of ten stations was installed. It was operating continuously from March 21 through June 16, 1992. More than 3,000 aftershocks were recorded of which 505 could be located. The spectral parameters of 394 and the fault-plane solutions of 53 aftershocks were determined. For the given region the frequency dependent coda Q was derived as Qc = 122*f^0.68. The aftershock area increased with time, reflecting the process of stress redistribution. Some events clustered in the immediate vicinity of the town of Erzincan close to the epicentre of the main event and seem to trace the NAF. Their source mechanism is similar to that of the main event (strike slip). About 150 aftershocks clustered in the southeastern part of the Erzincan basin where a concentration of the events in a small volume of 5 x 5 x 3 km^3 was observed. The majority of fault-plane solutions available for these aftershocks showed a normal faulting mechanism with an east-west directed extension. Most of the aftershocks southeast of the basin clustered between two lineaments that were mapped by satellite images. The P-wave velocity below the Erzincan basin, derived from travel-time residual analysis, is lower compared to areas NE and SW of the basin. Three-dimensional stress modelling of the Erzincan region qualitatively explains the occurrence of the aftershocks southeast of the basin. The calculated displacement distribution which exhibits the north-westward motion of the basin and tension at its southeastern margin, caused by the Erzincan earthquake, is in agreement with derived fault-plane solutions.

Description: The Mecklenburg Lake District in Germany was used to verify MIDORI AVNIR"s potential for water quality assessment. By means of remote sensing, water quality can be assessed by estimating chlorophyll content. Chlorophyll shows spectral characteristics with relatively high reflectance in the green and near-infrared spectral region. Chlorophyll concentration is one parameter to estimate the trophic state of a lake and it can be related to the amount of algae in the water. Complementary data sets (CASI, AVNIR, IRS-1C PAN and LISS) and a spectral database acquired by a field spectrometer are available for the test site. In this study, AVNIR data are being evaluated regarding water quality. Relative chlorophyll concentration of the lakes is differentiated by techniques of linear spectral unmixing on atmospherically corrected data. Results are in accordance to field measurements. Even though it is not feasible to estimate absolute chorophyll concentration using only 4 wavebands, groups of lakes with different states of bioproduction can be differentiated.

Description: In this study DAIS 7915 reflective imaging spectrometer (IS) data was analyzed for its potential for evaporite mineral mapping in the area of Mt. Sedom, Israel. The data was analyzed with a new processing strategy, due to the high noise content found in the SWIR-II spectral region, which is of high relevance for a mineralogical interpretation of IS data. The implemented approach avoids analysis on the noisy picture element (pixel) scale through delineation of spectrally homogeneous areas in the data cube based on a supervised neural network approach. Class endmembers are chosen through a manual selection process that is based on ideas taken from multi-spectral image interpretation. The underlying assumption is that color differences found in special false color composites created from the IS data can be directly related to an abundant surface lithology. Results show that based on this procedure, even given a high noise content in the data, lithologically important surface units can be classified, which agree well with an existing geological map. Further spectral analysis of the mean class spectra shows that a lithological interpretation in terms of the class bulk mineralogy is possible. Lithological information extracted from class endmember spectra is in good qualitative agreement with results from XRD/XRF measurements for collected field samples.