# 1D soil column for deep site response analysis

**URL:** <https://forum.itascainternational.com/t/1d-soil-column-for-deep-site-response-analysis/2226>\
**Category:** FLAC\
**Created:** [September 3, 2025, 9:08pm UTC](https://forum.itascainternational.com/t/1d-soil-column-for-deep-site-response-analysis/2226 "2025-09-03T21:08:19Z")\
**Posts on this page:** 3\
**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:** [September 3, 2025, 9:08pm UTC](https://forum.itascainternational.com/t/1d-soil-column-for-deep-site-response-analysis/2226/1 "2025-09-03T21:08:19Z")

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When running a 300-ft deep one-dimensional site response analysis, does it matter if we use only one zone in the horizontal direction, or is it beneficial to include multiple zones since the profile is so deep?

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**Author:** ![dblanksma](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@dblanksma](https://forum.itascainternational.com/u/dblanksma)\
**Post date:** [September 4, 2025, 3:52pm UTC](https://forum.itascainternational.com/t/1d-soil-column-for-deep-site-response-analysis/2226/2 "2025-09-04T15:52:08Z")

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If it’s a 1D model then single zones staked on top of each other in the free dof will suffice.

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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:** [September 4, 2025, 6:04pm UTC](https://forum.itascainternational.com/t/1d-soil-column-for-deep-site-response-analysis/2226/3 "2025-09-04T18:04:42Z")

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Thanks for your reply. The zones at the bottom of the model should have a greater height, and the element height should decrease as we move upward. Is there a limit for the width-to-height ratio that could affect the results?