Preprints
https://doi.org/10.5194/se-2021-67
https://doi.org/10.5194/se-2021-67

  21 Jun 2021

21 Jun 2021

Review status: a revised version of this preprint is currently under review for the journal SE.

1-D velocity structure modelling of the Earth's Crust in the NW Dinarides

Gregor Rajh1, Josip Stipčević2, Mladen Živčić3, Marijan Herak2, Andrej Gosar1,3, and the AlpArray Working Group Gregor Rajh et al.
  • 1University of Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Slovenia
  • 2University of Zagreb, Faculty of Science, Geophysics Department, Zagreb, Croatia
  • 3Slovenian Environment Agency, Seismology Office, Ljubljana, Slovenia
  • The complete member list of the AlpArray Working Group is at the end of the paper.

Abstract. The investigated area of the NW Dinarides is located at the NE corner of the Adriatic microplate and is bordered by the Adriatic foreland, the Southern Alps, and the Pannonian basin. Its complex crustal structure is the result of interactions among different tectonic units, mainly the Eurasian plate and the Adriatic microplate. Despite numerous seismic studies in this tectonically complex area, there is still a need for a detailed, small scale study focusing mainly on the upper, brittle part of the crust. We investigated the crustal velocity structure with 1-D simultaneous hypocenter-velocity inversion using routinely picked P wave arrival times. Most of the computed models converged to a stable solution in the depth range between 0 and 26 km. We further evaluated the inversion results with hypocenter shift tests, high and low velocity tests, and relocations. This helped us to select two best performing velocity models for the whole study area. Based on these results and the seismicity distribution, we further divided the study area into three parts, redefined the earthquake-station geometry, and performed inversion for each part separately to gain better insight into the crustal structure of each subregion. Median velocities in the upper 20 km of the crust in the eastern subregion are lower compared to the regional median and the median of the other two subregions. The northwestern and southwestern subregions are very similar in terms of crustal structure between about 8 and 23 km depth. The largest difference between them is observed in the upper 8 km, with higher median velocities in the southwestern subregion. Compared to the model currently used at Slovenian Environment Agency to locate earthquakes, the velocity models obtained show higher velocities in the upper 30 km depth and agree very well with some of the previous studies. In addition to general structural implications and a potential for improving seismic tomography results, the new 1-D velocity models can also be used for fast routine earthquake location and for detecting systematic travel time errors in seismological bulletins.

Gregor Rajh et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-67', Anonymous Referee #1, 04 Aug 2021
    • AC1: 'Reply on RC1', Gregor Rajh, 30 Sep 2021
  • RC2: 'Comment on se-2021-67', Giuliana Rossi, 04 Aug 2021
    • AC2: 'Reply on RC2', Gregor Rajh, 30 Sep 2021

Gregor Rajh et al.

Gregor Rajh et al.

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Short summary
We investigated the 1-D velocity structure of the Earth's crust in the NW Dinarides with inversion of arrival times from earthquakes. The obtained velocity models give a better insight into the crustal structure and show velocity variations among different parts of the study area. In addition to general structural implications and a potential for improving further work, the results of our study can also be used for routine earthquake location and for detecting errors in seismological bulletins.