Recent investigations of surficial and deeper crustal structures of the Eastern and Southern Alps

Abstract

ZusammenfassungNach einem l~berblick tiber die Oberfl~ichenstrukturen der Ost-und Siidalpen werden einige wichtige Theorien fiber die alpidische Gebirgsbildung besproehen. Es folgt eine Beschreibung geologischer Profile, die nach dem derzeitigen Kenntnisstand entworfen wurden.Im geophysikalischen Tell werden die wichtigsten Ergebnisse seismiseher, gravimetrischer und magnetischer Untersuchungen zusammengefaBt. In zwei Vertikalschnitten durch die Erdkruste werden die Linien gleicher Geschwindigkeit der Longitudinalwellen dargestellt. AbstractAfter a review of the surficial structures of the Eastern and Southern Alps a discussion of some important theories of the Alpidic Orogeny is presented. Geological cross sections, based as far as possible on the latest data, are then presented in detail.In the geophysical part the most important results of seismic, gravimetrie and magnetic work have been compiled. Two vertical profiles through the earth's crust are preseDted showing lines of equal velocity of longitudinal waves.

Changes in failure stress and stress transfer during the 1976-77 Friuli earthquake sequence

“…Focal depths were estimated by matching the variation of SPn-Pn arrival times between synthetic and observed seismograms recorded at the Grafenberg (Germany) seismic array. Then the epicentres were located with the crustal velocity model of Angenheister et al (1972), using stations within a radius of 500 km from the epicentral area. The estimated errors were less than ±1 km.…”

“…The estimated errors were less than ±1 km. The location coordinates of event 6, that is missing from the data set of Barbano et al (1985), are taken from Slejko et al (1999), which also used the velocity model of Angenheister et al (1972). From the available focal plane solutions, we chose those of Pondrelli et al (2001).…”

On the distribution of the electrical conductivity below the Eastern Alps

“…Before we started our measurements an indication for an increased temperature below the central eastern Alps was probably found by seismic refraction measurements and gravity measurements, The velocity of seismic p-waves and the density of the rocks is diminished there at the depth range between about 10 km and 20 km (ANGENHEISTER et al, 1972;ANGENHEISTER et al,, 1975). Below the central eastern Alps, however, the distribution of the electrical conductivity should give us information about the distribution of the temperature, as the electrical conductivity of rocks at greater depths is a function of temperature.…”

The deep structure of the central Alps inferred from both geophysical and geological data

“…The disharmony between the upper and the lower parts of the crust is not only one of information, it is also structural: a low-velocity channel (e.g. compare Angenheister et al, 1972;Mueller, 1989) separates the brittle upper crust, that remains in an essentially horizontal position, from the downbulge of the lower crust. This divergent behaviour implies the opening of a potential empty space.…”