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Insights on the upper mantle beneath the Eastern Alps.

Bianchi I, Miller MS, Bokelmann G - Earth Planet. Sci. Lett. (2014)

Bottom Line: Analyses of Ps and Sp receiver functions from datasets collected by permanent and temporary seismic stations, image a seismic discontinuity, due to a negative velocity contrast across the entire Eastern Alps.The receiver functions show the presence of the discontinuity within the upper mantle with a resolution of tens of kilometers laterally.Comparison with previous studies renders it likely that the observed discontinuity coincides with the lithosphere-asthenosphere boundary (LAB) east of 15°E longitude, while it could be associated with a low velocity zone west of 15°E.

View Article: PubMed Central - PubMed

Affiliation: Institut für Meteorologie und Geophysik, Universität Wien, Althanstraße 14 (UZA II), 1090 Vienna, Austria.

ABSTRACT

Analyses of Ps and Sp receiver functions from datasets collected by permanent and temporary seismic stations, image a seismic discontinuity, due to a negative velocity contrast across the entire Eastern Alps. The receiver functions show the presence of the discontinuity within the upper mantle with a resolution of tens of kilometers laterally. It is deeper (100-130 km) below the central portion of the Eastern Alps, and shallower (70-80 km) towards the Pannonian Basin and in the Central Alps. Comparison with previous studies renders it likely that the observed discontinuity coincides with the lithosphere-asthenosphere boundary (LAB) east of 15°E longitude, while it could be associated with a low velocity zone west of 15°E.

No MeSH data available.


Related in: MedlinePlus

S-receiver functions calculated for station VINO (see Fig. 1 for location), filtered with an upper frequency of 0.2 Hz. (a) SRFs displayed according to the origin backazimuth. (b) Stack of SRFs.
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fg0050: S-receiver functions calculated for station VINO (see Fig. 1 for location), filtered with an upper frequency of 0.2 Hz. (a) SRFs displayed according to the origin backazimuth. (b) Stack of SRFs.

Mentions: The paths of the S waves from the estimated locations of depth conversion to the surface, where they are recorded, are longer with respect to the analogous P-wave paths (as shown in Fig. 1 for the piercing points at depth of the P and S waves). Due to the more oblique incidence angle, the conversions occur farther away from the surface location of the station. Nevertheless, the construction of sub-groups of SRF stacks generates wiggles with much larger standard deviation values, resulting from a signal from where is hard to decipher a clear negative phase. For this reason, and because of the backazimuthal coverage for the SRFs that are not well sampled, we prefer to stack all the collected SRFs at each station, and determine an average discontinuity depth for the negative velocity contrast. The backazimuthal subdivisions would require a larger amount of data that are not available at the moment. Fig. 4 shows the depth converted SRFs computed for each station along two profiles. All SRFs show an initial blue (positive) pulse due to the S-to-P conversion through the Moho interface. All are characterized afterwards by the presence of a red (negative) pulse witnessing the occurrence of a strong velocity reduction. An example of SRF computed for data recorded at the station VINO are shown in Fig. 5. The inferred negative discontinuity depth estimate is 100 km. For the range of uncertainties refer to Table S1 and Appendix A. The SRFs are shown for depths to 500 km for completeness in Fig. 6. A positive polarity is recognized along the two profiles coinciding with the 410 km discontinuity. Besides the negative pulse described in Fig. 4, we pick a deeper negative phase at 250 km depth in the western part of profile DD′ at 0–200 km within profile. Further negative phases have not been interpreted since they show smaller amplitudes and little consistency along profiles.


Insights on the upper mantle beneath the Eastern Alps.

Bianchi I, Miller MS, Bokelmann G - Earth Planet. Sci. Lett. (2014)

S-receiver functions calculated for station VINO (see Fig. 1 for location), filtered with an upper frequency of 0.2 Hz. (a) SRFs displayed according to the origin backazimuth. (b) Stack of SRFs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4375711&req=5

fg0050: S-receiver functions calculated for station VINO (see Fig. 1 for location), filtered with an upper frequency of 0.2 Hz. (a) SRFs displayed according to the origin backazimuth. (b) Stack of SRFs.
Mentions: The paths of the S waves from the estimated locations of depth conversion to the surface, where they are recorded, are longer with respect to the analogous P-wave paths (as shown in Fig. 1 for the piercing points at depth of the P and S waves). Due to the more oblique incidence angle, the conversions occur farther away from the surface location of the station. Nevertheless, the construction of sub-groups of SRF stacks generates wiggles with much larger standard deviation values, resulting from a signal from where is hard to decipher a clear negative phase. For this reason, and because of the backazimuthal coverage for the SRFs that are not well sampled, we prefer to stack all the collected SRFs at each station, and determine an average discontinuity depth for the negative velocity contrast. The backazimuthal subdivisions would require a larger amount of data that are not available at the moment. Fig. 4 shows the depth converted SRFs computed for each station along two profiles. All SRFs show an initial blue (positive) pulse due to the S-to-P conversion through the Moho interface. All are characterized afterwards by the presence of a red (negative) pulse witnessing the occurrence of a strong velocity reduction. An example of SRF computed for data recorded at the station VINO are shown in Fig. 5. The inferred negative discontinuity depth estimate is 100 km. For the range of uncertainties refer to Table S1 and Appendix A. The SRFs are shown for depths to 500 km for completeness in Fig. 6. A positive polarity is recognized along the two profiles coinciding with the 410 km discontinuity. Besides the negative pulse described in Fig. 4, we pick a deeper negative phase at 250 km depth in the western part of profile DD′ at 0–200 km within profile. Further negative phases have not been interpreted since they show smaller amplitudes and little consistency along profiles.

Bottom Line: Analyses of Ps and Sp receiver functions from datasets collected by permanent and temporary seismic stations, image a seismic discontinuity, due to a negative velocity contrast across the entire Eastern Alps.The receiver functions show the presence of the discontinuity within the upper mantle with a resolution of tens of kilometers laterally.Comparison with previous studies renders it likely that the observed discontinuity coincides with the lithosphere-asthenosphere boundary (LAB) east of 15°E longitude, while it could be associated with a low velocity zone west of 15°E.

View Article: PubMed Central - PubMed

Affiliation: Institut für Meteorologie und Geophysik, Universität Wien, Althanstraße 14 (UZA II), 1090 Vienna, Austria.

ABSTRACT

Analyses of Ps and Sp receiver functions from datasets collected by permanent and temporary seismic stations, image a seismic discontinuity, due to a negative velocity contrast across the entire Eastern Alps. The receiver functions show the presence of the discontinuity within the upper mantle with a resolution of tens of kilometers laterally. It is deeper (100-130 km) below the central portion of the Eastern Alps, and shallower (70-80 km) towards the Pannonian Basin and in the Central Alps. Comparison with previous studies renders it likely that the observed discontinuity coincides with the lithosphere-asthenosphere boundary (LAB) east of 15°E longitude, while it could be associated with a low velocity zone west of 15°E.

No MeSH data available.


Related in: MedlinePlus