Repair horizontal masonry crack

Single-family house with 2- and 1-story sections. On the 1-story section, terrace with tiles on concrete slab. Masonry = 38cm Poroton (red brick) About 1m below the concrete slab, a horizontal crack has formed that extends to the interior plaster. I initially suspected that the crack was caused by swelling of the concrete slab. I have placed several gypsum plugs that have not cracked in the past 4 weeks. A neighbor claims to have cracks after a minor earthquake. I live in such a vulnerable area.

Questions:
1. Are 4 weeks of observation of the gypsum plugs sufficient to conclude that the cracks have stabilized???
2. If so: how can the cracks be repaired? (expansion mortar, injection of epoxy resin)
3. What kinds of companies do this??

Thank you all in advance