Soreness, specifically DOMS, is caused by inflammation, which is a response to the damage but not directly from it (which is why its delayed as opposed to immediate soreness from injury).
Here are electron microscope images micro tears:
https://www.researchgate.net/figure/A-D-Electron-micrographs-of-longitudinally-sectioned-biopsies-taken-3-days-A-and-7-days_fig1_7449727
Here is a recent paper on the repair process with more images as well: https://www.science.org/doi/10.1126/science.abe5620#F4
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