Imaging Moho topography beneath the Alps by multdisciplinary seismic tomography

Transcription

1 Imaging Moho topography beneath the Alps by multdisciplinary seismic tomography Edi Kissling ETH Zürich SPP short course February 1+2, 218, Berlin, Germany

2 Alpine Moho map from CSS Moho uncertainty derived from CSS data quality sampled Moho locations Observation quality Waldhauser et al (combining refraction seismic and near-vertical reflection seismic data with respect to strengths and limitations of methods and to individual data qualities)

3 3D Alpine crustal model from CSS Waldhauser et al. 22 E. Kissling (3D velocity model based on re-interpretation of 12+ refraction seismic and nearvertical reflection profile and extraction and 3D migration of high-quality data)

4 CSS and LET Volumetric velocity method With local earthquake tomography we can complement CSS imaging the 3-D seismic structure: in collision zones (e.g. Alpine region): Ivrea body Po sediments Absolute Vp (Diehl et al, 29)

5 effects of resolution variation across a tomographic image (due to inhomogeneous data) INPUT structure recovered (grid 1) Kissling et al. 21 (note lateral variation in resolution diagonal element) RDE recovered (grid 2) recovered (grid 3) E. Kissling the violine effect overswing edge effects (resolution variation causes distortion in imaged structure)

6 example assessing resolution in LET RDE and resolution contours (off-diagonal elements) outlining well-resolved region in each layer Diehl et al. 29 E. Kissling synthetic test with lower crustal model structure. Note different results for high- and low velocity anomalies! Results along EGT profile

7 resolution RDE & spread contour LET Alps spikes checkerboard sensitivity testing outlining region of sensitivity in each layer outlining region of equal resolution in each layer Diehl et al. 29

8 LET Alps testing Moho resolution INPUT structure (realistic Moho topography and velocity gradient in crust) Diehl et al. 29 recovered structure real data tomographic results along European Geotraverse E. Kissling => Moho can be well resolved with high-quality local earthquake data

9 LET Alps Ivrea body profile Ivrea section C profile Ivrea section B profile Ivrea section A profile Ivrea section D2 profile Ivrea section D1 profile Ivrea section E1 profile Ivrea section E2 based on P tomography by Diehl et al. 29 => Ivrea body exhibits significant geometrical variation from S to N Profile Ivrea section E Profile Ivrea section E Profile Ivrea section D Profile Profile Ivrea Ivrea section section D1 D Eastern end of Ivrea 1km East of section E2 E. Kissling 215 based on Diehl et al E. Absolute Kissling vp 215 (km/s) based on Diehl et al Profile Ivrea section C.5 8 Profile Ivrea section B Profile Ivrea section A Absolute vp (km/s) 4 2 southern end of Ivrea 1km S of section A 4 2

10 Moho topography from LET => Moho depth recognized in LET by typical velocity above (crust) and below (mantle) and specific velocity gradient Wagner et al. 212 Moho uncertainty derived from LET data quality

11 Moho Alps from CSS & LET combined almost continous coverage of European Moho beneath Western and Central Alps Wagner et al. 212 Note significant changes in Moho depth across plate boundaries due to 3D migration effects of CSS data

12 Moho Alps from CSS & LET & RF Moho uncertainty derived from RF quality PmP reflection points from Behm et al. 2 Spada et al. 213 Quality classes based on back azimuth coverage Spada et al. 213

13 Moho Alps from CSS & LET & RF Moho data uncertainties for CSS and RF Spada et al. 213 Comparison of CSS and RF Moho information including their individual uncertainties along selected profiles in Apennines

14 Moho Alps from CSS & LET & RF Moho segment uncertainties derived from individual CSS, LET and RF data qualities Europe Adria (profile locations see on right) Liguria-CoSaTy Spada et al. 213 E. Kissling Moho map data available via researchgate.net Edi Kissling

15 Further steps: Vs-information, 3D crustal corrections and tectonic interpretations (add results from ambient noise tomography, extend region of coverage) P wave velocity structure Schmid et al. 21 Thank you for your attention