Archaeoseismic evidence at the Blue Chapel complex for a mid-8th century CE earthquake at Petra comes primarily from Building 2 in the Lower Sector. Perry in Bikai et al (2020:69–70) reports that "occupation of at least part of the Blue Chapel likely ceased due to earthquake-related structural instability and collapse likely caused by seismic activity." A radiocarbon date from an animal bone found beneath a fallen column (drum no. 2) in the Blue Chapel yielded a calibrated range of 658–782 CE (95.4%, 2σ). "The column presumably fell shortly after this animal's death and consumption by the building’s occupants." Perry identifies two possible earthquakes in this period: the 672 CE Gaza–Ashkelon–Ramle event, and the well-documented 749 CE Sabbatical Year Earthquakes. The 672 CE event, as cited in Russell (1985), is considered dubious. This suggests that the collapse occurred in the mid-8th century. Ceramic evidence also supports this date.

Perry in Bikai et al (2020:470) states that "collapse occurred concurrent with or immediately before abandonment" and that "the pattern of collapse, particularly the dramatic tumble of the columns in the Blue Chapel, would point to a seismic event as the cause." Perry in Bikai et al (2020:470) also noted that "no evidence for an earlier phase of destruction dating to the late 7th c. was discovered in the Blue Chapel complex."

Perry in Bikai et al (2020:70–71) identified archaeoseismic evidence from "one apparent destructive earthquake", apparently a mid 8th century CE earthquake, in Phase V subphase 3 deposits in Building 2 of the Lower Sector (i.e. the Blue Chapel), noting the presence of substantial 1–1.5 m thick tumble deposits. She listed loci with archaeoseismic evidence for Phase V Sub-phase 3 in Building 2 (Lower Sector) as follows:

• The stairway in Area 19 (loci 1052, 1057, 1071, 1114, 1115)
• The entry hall in Area 24 (loci 1109, 1130)
• Area 20 (loci 973, 1027, 1177)
• The atrium in Area 23 (multiple loci including 1037, 1125, 1039, 1041, 1140, 1145, 1165, 1132, 1173, 1176, 1189, 1190, 1201, 1207, 1220, 1225, 1228)
• The Blue Chapel in Area 25 (loci including 1048, 1050, 1062, 1063, 1087, 1088, 1103, 1147, 1153)

Numerous architectural features "appeared to have collapsed in a single episode," including "the cornice along the western and northern walls of the entry hall, the vault of the area, and the columns of the Blue Chapel". Evidence for second story collapse was also identified in Area 20, where displaced floor slabs were found about 0.5 m above the floor in loci 973, 1177, and "the upper levels of 1030".