Kehrberg-Ostrasz and Manley (2019) excavated a number of trenches from 2000-2002 along Jerash's city walls in order to determine their date of construction.

• from Jerash - Introduction - click link to open new tab

• Jordan specific chronological framework used by Kehrberg-Ostrasz and Manley (2019)

Period Label	Date
Late Hellenistic	unstated -63 BCE
BC/AD	63 BCE - 135 CE
Roman	135 CE - 193 CE
Late Roman	193 BCE - 324 CE
Byzantine	324 BCE - 636 CE
Late Byzantine	unstated - 636 CE
Islamic	636 CE - unstated

Plans and Photos

Discussion

Kehrberg-Ostrasz and Manley (2019:21) found a tumble layer (Plate 1:10) in the Trench 400 of the East Wall which they described as follows:

At some time after the dumping of 405,407 and 411, a sudden partial collapse from the face of the City Wall occurred, resulting in the distribution of six rows of facing masonry (406) in the main trench. The facing stones had fallen into neat rows, a little way from the base of the Wall, and clearly had not been disturbed since the event. Most of the stones had vertical faces, and most had at least one dimension that was close to 0.45m or 0.4m, similar to the dimensions on the uppermost extant courses of the City Wall. It seems highly probable that the six rows represent the fallen rear parapet of the City Wall of Gerasa.

... The presence of the Byzantine pottery strongly suggests that the City Wall survived intact into the Byzantine period. The sudden collapse of the rear parapet into the fallen rows of 406 may have been caused by an earthquake.

Kehrberg-Ostrasz in Savage et al (2003:458) dated this seismic destruction to the 6th century

The upper layers consisted of mixed soil with residual contemporary and Late Islamic pottery and glass sherds, as well as charred bones and other debris, clearly indicating a gradual accumulation of rubbish. This rubbish tip rested on neat rows of courses of the wall, which had fallen face down onto the western rocky slope already littered with residual rubbish. The pottery and glass under this tumbled wall section showed that the collapse must have occurred during the Late Byzantine period, probably the result of an earthquake that was responsible for the destruction of other city buildings in the sixth century.

Effect	Location	Image(s)	Description
Collapsed Walls	East Wall - Trench 400 Fig. 1 JCW [Jarash City Walls] Project - trench locations: Tr/Wall 2000 (IFAPO season 2000) Tr/Wall 100,200,300 (JCWP season 2001) Tr/Wall 400,500 (JCWP 2002) The AD 2000 plan of Gerasa (IFAPO, JP Braun et al (2001) ADAJ Kehrberg-Ostrasz and Manley (2019)	Pl. 1:10 Tr 400: lower city wall tumble layers; N and S sections of tumble Kehrberg-Ostrasz and Manley (2019)	At some time after the dumping of 405,407 and 411, a sudden partial collapse from the face of the City Wall occurred, resulting in the distribution of six rows of facing masonry (406) in the main trench. The facing stones had fallen into neat rows, a little way from the base of the Wall, and clearly had not been disturbed since the event. Most of the stones had vertical faces, and most had at least one dimension that was close to 0.45m or 0.4m, similar to the dimensions on the uppermost extant courses of the City Wall. It seems highly probable that the six rows represent the fallen rear parapet of the City Wall of Gerasa. ... The sudden collapse of the rear parapet into the fallen rows of 406 may have been caused by an earthquake. - Kehrberg-Ostrasz and Manley (2019:21) This rubbish tip rested on neat rows of courses of the wall, which had fallen face down onto the western rocky slope already littered with residual rubbish. The pottery and glass under this tumbled wall section showed that the collapse must have occurred during the Late Byzantine period, probably the result of an earthquake that was responsible for the destruction of other city buildings in the sixth century. - Kehrberg-Ostrasz in Savage et al (2003:458)

• Modified by JW from Fig. 1 of Kehrberg-Ostrasz and Manley (2019)

• Earthquake Archeological Effects chart
  Earthquake Archeological Effects (EAE)
  
  Rodríguez-Pascua et al (2013: 221-224)
  of Rodríguez-Pascua et al (2013: 221-224)

Effect	Location	Image(s)	Description	Intensity
Collapsed Walls	East Wall - Trench 400 Fig. 1 JCW [Jarash City Walls] Project - trench locations: Tr/Wall 2000 (IFAPO season 2000) Tr/Wall 100,200,300 (JCWP season 2001) Tr/Wall 400,500 (JCWP 2002) The AD 2000 plan of Gerasa (IFAPO, JP Braun et al (2001) ADAJ Kehrberg-Ostrasz and Manley (2019)	Pl. 1:10 Tr 400: lower city wall tumble layers; N and S sections of tumble Kehrberg-Ostrasz and Manley (2019)	At some time after the dumping of 405,407 and 411, a sudden partial collapse from the face of the City Wall occurred, resulting in the distribution of six rows of facing masonry (406) in the main trench. The facing stones had fallen into neat rows, a little way from the base of the Wall, and clearly had not been disturbed since the event. Most of the stones had vertical faces, and most had at least one dimension that was close to 0.45m or 0.4m, similar to the dimensions on the uppermost extant courses of the City Wall. It seems highly probable that the six rows represent the fallen rear parapet of the City Wall of Gerasa. ... The sudden collapse of the rear parapet into the fallen rows of 406 may have been caused by an earthquake. - Kehrberg-Ostrasz and Manley (2019:21) This rubbish tip rested on neat rows of courses of the wall, which had fallen face down onto the western rocky slope already littered with residual rubbish. The pottery and glass under this tumbled wall section showed that the collapse must have occurred during the Late Byzantine period, probably the result of an earthquake that was responsible for the destruction of other city buildings in the sixth century. - Kehrberg-Ostrasz in Savage et al (2003:458)	VIII +

The archeoseismic evidence requires a minimum Intensity of VIII (8) when using the Earthquake Archeological Effects chart of Rodríguez-Pascua et al (2013: 221-224).