# Bade distortion

**URL:** <https://forum.itascainternational.com/t/bade-distortion/2393>\
**Category:** FLAC\
**Created:** [June 11, 2026, 5:26pm UTC](https://forum.itascainternational.com/t/bade-distortion/2393 "2026-06-11T17:26:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Milads](https://avatars.discourse-cdn.com/v4/letter/m/ecccb3/32.png) [@Milads](https://forum.itascainternational.com/u/Milads)\
**Post date:** [June 11, 2026, 5:26pm UTC](https://forum.itascainternational.com/t/bade-distortion/2393/1 "2026-06-11T17:26:58Z")

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I am seeing significant base distortion when applying a strong subduction-zone earthquake motion. The input is applied only in the horizontal direction, and the base is modeled as a compliant boundary. Increasing the bedrock thickness did not resolve the issue. Do you have any suggestions to address this problem? Is it ok o fix the base in vertical direction and still using the complaint base in x direction?

 ![ydisp](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/2X/a/a682e685af39e569ac09d3906e8aa69b5705fc23.jpeg)

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**Author:** ![jwang](https://avatars.discourse-cdn.com/v4/letter/j/b782af/32.png) [@jwang](https://forum.itascainternational.com/u/jwang)\
**Post date:** [June 18, 2026, 5:34pm UTC](https://forum.itascainternational.com/t/bade-distortion/2393/2 "2026-06-18T17:34:14Z")

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Check this example: [Shear Wave Propagation in a Vertical Bar (FLAC2D) — Itasca Software 9.7 documentation](https://docs.itascasoftware.com/itasca970/flac3d/zone/test2d/Dynamic/ShearWaveOnVerticalBar/ShearWaveOnVerticalBar.html?highlight=quiet%20tangential)