En Erga

Introduction

The Nabatean Fort of 'En Erga was constructed on the early branch of the Incense Road (the Darb es-Sultan) between Petra and Gaza during the Hellenistic period in the 3rd century BCE ( Khorzhenkov and Erickson-Gini, 2003). However, 'En Erga was abandoned before it was ever occupied ( Khorzhenkov and Erickson-Gini, 2003). Khorzhenkov and Erickson-Gini (2003) relate that no evidence of occupation was found anywhere in the structure or surrounding area adding:

The building appears to be unfinished as the result of a sudden and complete abandonment due to an earthquake. It is theorized that the fort was abandoned before it was completed and that a new fort was constructed a kilometer to the southwest, next to the spring of Ein Rahel and off of the main route.

Maps, Aerial Views, Plans, and Photos

Maps

Normal Size

Fig. 1 - Location Map

Fig. 1

Ancient cities of the central Negev and main trade routes.

Following Segal (1983) and Russell (1980)

Khorzhenkov and Erickson-Gini (2003)

from Khorzhenkov and Erickson-Gini (2003)
Fig. 1 - Map of the main

Map of the main Hellenistic, Roman, and Byzantine sites in the Negev Hills.

Stern et. al. (1993 v.3)

Hellenistic, Roman, and Byzantine sites in the Negev Hills from Stern et. al. (1993 v.3)

Magnified

Fig. 1 - Map of the main

Map of the main Hellenistic, Roman, and Byzantine sites in the Negev Hills.

Stern et. al. (1993 v.3)

Hellenistic, Roman, and Byzantine sites in the Negev Hills from Stern et. al. (1993 v.3)

Aerial Views

Vicinity of En Erga in Google Earth

Vicinity of En Erga

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Vicinity of En Erga on govmap.gov.il

Vicinity of En Erga

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Plans

Normal Size

Fig. 3 - Plan of Ein Erga

Fig. 3

Ein Erga - Plan of the fort with marked types of deformations

Khorzhenkov and Erickson-Gini (2003)

with marked deformations from Khorzhenkov and Erickson-Gini (2003)

Magnified

Fig. 3 - Plan of Ein Erga

Fig. 3

Ein Erga - Plan of the fort with marked types of deformations

Khorzhenkov and Erickson-Gini (2003)

with marked deformations from Khorzhenkov and Erickson-Gini (2003)

Photos

Normal Size

Fig. 2 - Land View of

Fig. 2

Ein Erga View (northward) on the fort

Khorzhenkov and Erickson-Gini (2003)

En Erga from Khorzhenkov and Erickson-Gini (2003)

Magnified

Fig. 2 - Land View of

Fig. 2

Ein Erga View (northward) on the fort

Khorzhenkov and Erickson-Gini (2003)

En Erga from Khorzhenkov and Erickson-Gini (2003)

Foundation Bowl Earthquake - 3rd century BCE

Discussion

References

Korzhenkov and Erickson-Gini (2003)

Introduction and Methodology

Introduction

from Korzhenkov and Erickson-Gini (2003:40)

Two archaeological sites – the Nabataean forts of Ein Erga and Ein Rahel, located one kilometer from one another, were investigated in an attempt to understand the reasons for their abandonment. These Nabataean forts were constructed on the early branch of the Incense Road (Darb es-Sultan) between Petra and Gaza (Fig. 1) during the Hellenistic period between the 3rd and 1st cent. B.C. The fort at Ein Rahel was reoccupied by the Nabataeans in the early 1st cent. A.D. until the early 2nd cent. A.D. and it connected Petra with the Nabataean station at Ein Hazeva located further north in the central Arava.

En Erga

from Korzhenkov and Erickson-Gini (2003:42)

The site of Ein Erga is situated on a hilltop (Fig. 2) next to the spring of Ein Erga in the central Arava (Israel Grid 1673/0047). The site was excavated in 1981 by Y. Israel and D. Nahlieli of the Israel Department of Antiquities. It is located 25 km north of the Nabataean fort at Moa. The site consists of a small fort (Fig. 3), approximately 15 × 15 m in size, built on a strategic point guarding a pass on the ancient road. The structure was constructed from stones quarried from local travertine deposits. Some of the walls survived to a height of 2 m.

Recent examination of the finds from the excavation of the fort indicates that it was constructed by the Nabataeans in the 3rd cent. B.C. However, this fort was abandoned before it was ever occupied, apparently as the result of an earthquake that damaged the structure, causing a large section of the southern wall to collapse. No evidence of occupation was found anywhere in the structure or surrounding area. A single Hellenistic incurved bowl dated to the 3rd cent. B.C. was found buried below the dirt floor of one of the rooms, probably placed there as a Nabataean foundation deposit. This practice was found in Nabataean structures in later periods, including the second occupational phase at Ein Rahel and at Mampsis and Petra.

Today only the lower courses of the walls of this fort are visible. Upon examination the building appears to be unfinished as the result of a sudden and complete abandonment due to an earthquake. It is theorized that the fort was abandoned before it was completed and that a new fort was constructed a kilometer to the southwest, next to the spring of Ein Rahel and off the main route.

Archaeological surveys conducted in other parts of the Negev reveal that Nabataean forts in the Hellenistic period are generally located at substantial distances from one another and directly overlooking important trade routes. The evidence provided by the abandoned fort at Ein Erga (constructed directly on the main road) and that of the fort at Ein Rahel (located a few kilometers away and off the main road) appears to support the assumption that the former site was abandoned prior to occupation and the latter was constructed nearby as a replacement. It should be noted that seismic damage at the site of Ein Erga might have also affected the water supply from the spring, making the site unsuitable for further development. In 1996, earthquake tremors in the Arava Valley (resulting from a strong earthquake in the Gulf of Eilat/Aqaba) created temporary changes in the water table in the area next to the ancient Nabataean site of Moa (Moyat Awad) located 25 km south of Ein Erga. These disturbances turned the immediate area into a muddy swamp for over a year before the water table receded. At the present time, no other sites have provided direct parallels for the earthquake damage at the fort of Ein Erga in the Hellenistic period.

Foundation Bowl Earthquake - 3rd century BCE

Seismic Effect	Location	Image(s)	Description
Collapse Features	Figure 3 Ein Erga Plan of the fort with marked types of deformations Korzhenkov and Erickson-Gini (2003)	6 ab Fig.6 Ein Erga Collapse of eastern external wall (strike azimuth is NS180°) eastward. Fragments of the wall were thrown off on 3.2 m. 6a a. Preserved fragment of the wall b. Maximal distance of throwing of the stones 6b Schematic picture Khorzhenkov and Erickson-Gini (2003)	In the ruins of the Ein Erga fort the walls facing the seismic wave collapsed systematically toward the seismically induced compression strain, whereas walls aligned parallel to the seismic wave lost support and collapsed in a random manner. A correlation between the orientation of construction elements and the direction of collapse was examined. The wall oriented in the direction of NS180° in the Ein Erga fort reveals a clear picture of the collapse: the lower part of the wall is intact (as can be easily seen from its western side), whereas the upper its part collapsed southward (Fig. 6 a. b). This wall reveals collapse oriented towards E90°, whereas walls oriented in a perpendicular direction collapsed on both sides of the original wall's position. Fragments of the destroyed wall were thrown off up to 3.2 m from the structure. This would indicate that the direction of seismic wave propagation was roughly perpendicular to the NS oriented walls. The cone of collapse is asymmetric in form. This may indicate that the propagation of the seismic wave was in an E-W direction, but under some angle to the wall from ENE. - Korzhenkov and Erickson-Gini (2003)
Displacements of Rock Fragments and Building Elements	Figure 3 Ein Erga Plan of the fort with marked types of deformations Korzhenkov and Erickson-Gini (2003)	7 Fig.7 Ein Erga Cut blocks of travertine plate underlining almost whole Ein Erga construction were displaced horizontally up to 1.7 m eastward. Travertine rock fragments are now laying on the lower rows of the former wall (shown by pointers). – 1st Block is the southern one in Fig.3. – 2nd Block is the middle one in Fig.3 Khorzhenkov and Erickson-Gini (2003)	The shift of rock fragments and building elements may be used in a similar manner as wall inclination or block collapse. Some construction elements or rock fragments are shifted toward an epicenter due to inertia. Such examples were observed in the Ein Erga fort: three travertine blocks of the travertine plate underlying nearly the entire fort were thrown eastward (see Fig. 3 - Plan) and rotated clockwise. One of these was displaced horizontally, 1.7 m (Fig. 7) eastward. A large block of travertine bedrock lies on the lower rows of the former wall and measures 1.40 m in length, 0.90m in width and 0.42m high. It weighs approximately 2 tons. These features indicate that the seismic energy radiated from the ENE. - Korzhenkov and Erickson-Gini (2003)

Foundation Bowl Earthquake - 3rd century BCE

Modified by JW from Fig.s 3 and 6b of Korzhenkov and Erickson-Gini (2003)

Deformation Map

click on image to open a high res magnifiable image in a new tab

Modified by JW from Fig.s 3 and 6b of Korzhenkov and Erickson-Gini (2003)

Foundation Bowl Earthquake - 3rd century BCE

from Korzhenkov and Erickson-Gini (2003)

Figures

Fig. 3 - Plan of Ein Erga

Fig. 3

Ein Erga - Plan of the fort with marked types of deformations

Khorzhenkov and Erickson-Gini (2003)

with marked deformations from Khorzhenkov and Erickson-Gini (2003)
Fig. 6 - Collapse of eastern

Fig.6

Ein Erga

Collapse of eastern external wall (strike azimuth is NS180°) eastward. Fragments of the wall were thrown off on 3.2 m.

6a

a. Preserved fragment of the wall

b. Maximal distance of throwing of the stones

6b

Schematic picture

Khorzhenkov and Erickson-Gini (2003)

external wall from Khorzhenkov and Erickson-Gini (2003)
Fig. 7 - Torn and thrown

Fig.7 Ein Erga

Cut blocks of travertine plate underlining almost whole Ein Erga construction were displaced horizontally up to 1.7 m eastward. Travertine rock fragments are now laying on the lower rows of the former wall (shown by pointers). – 1st Block is the southern one in Fig.3. – 2nd Block is the middle one in Fig.3

Khorzhenkov and Erickson-Gini (2003)

travertine plates from Khorzhenkov and Erickson-Gini (2003)

Discussion

The study of the destruction of the Ein Erga fort reveals a systematic nature of dislocations (see Fig. 3):

NS oriented walls revealed collapse (see Fig. 6) and tilt toward east, whereas perpendicular oriented walls tilted and collapsed without a noticeable systematic pattern. Several tons of travertine blocks were torn from the source plate and thrown aside (see Fig. 3 and 7 ) at a distance of more than 1 m eastward. These details indicate that the seismic shock arrived approximately along the east-west axis, probably from the east.
Except throwing travertine blocks in Ein Erga were systematically turned clockwise (see Fig. 3 ). Rotation itself involves shear stresses acted along walls, thus the seismic wave should arrive with some angle to the walls. Such situation is possible if the compression wave came from ENE at angle of approximately 60°.

Thus, the epicenter was located somewhere ENE from the Ein Erga, and the very strong degree of deformations indicate that the epicenter was in some vicinity, probably in the area of the Dead Sea Fault zone, situated few km east of Ein Erga. The degree of destruction corresponds to the earthquake intensity of I = IX–X (MSK-64 scale), evidence of which are shift of few tons [of] travertine blocks. To move these blocks on a distance more than 1 m one can involve huge ground acceleration reaching a value of probably more than [1] g.

Foundation Bowl Earthquake - 3rd century BCE

Intensity Estimate from the Earthquake Archaeological Effects (EAE) Chart

Earthquake Archeological Effects chart

Earthquake Archeological Effects (EAE)

Rodríguez-Pascua et al (2013: 221-224)

of Rodríguez-Pascua et al (2013: 221-224)

Seismic Effect	Location	Image(s)	Description	Intensity
Collapsed Walls - Collapse Features	Figure 3 Ein Erga Plan of the fort with marked types of deformations Korzhenkov and Erickson-Gini (2003)	6 ab Fig.6 Ein Erga Collapse of eastern external wall (strike azimuth is NS180°) eastward. Fragments of the wall were thrown off on 3.2 m. 6a a. Preserved fragment of the wall b. Maximal distance of throwing of the stones 6b Schematic picture Khorzhenkov and Erickson-Gini (2003)	In the ruins of the Ein Erga fort the walls facing the seismic wave collapsed systematically toward the seismically induced compression strain, whereas walls aligned parallel to the seismic wave lost support and collapsed in a random manner. A correlation between the orientation of construction elements and the direction of collapse was examined. The wall oriented in the direction of NS180° in the Ein Erga fort reveals a clear picture of the collapse: the lower part of the wall is intact (as can be easily seen from its western side), whereas the upper its part collapsed southward (Fig. 6 a. b). This wall reveals collapse oriented towards E90°, whereas walls oriented in a perpendicular direction collapsed on both sides of the original wall's position. Fragments of the destroyed wall were thrown off up to 3.2 m from the structure. This would indicate that the direction of seismic wave propagation was roughly perpendicular to the NS oriented walls. The cone of collapse is asymmetric in form. This may indicate that the propagation of the seismic wave was in an E-W direction, but under some angle to the wall from ENE. - Korzhenkov and Erickson-Gini (2003)	VIII +
Displaced Masonry Blocks - Displacements of Rock Fragments and Building Elements	Figure 3 Ein Erga Plan of the fort with marked types of deformations Korzhenkov and Erickson-Gini (2003)	7 Fig.7 Ein Erga Cut blocks of travertine plate underlining almost whole Ein Erga construction were displaced horizontally up to 1.7 m eastward. Travertine rock fragments are now laying on the lower rows of the former wall (shown by pointers). – 1st Block is the southern one in Fig.3. – 2nd Block is the middle one in Fig.3 Khorzhenkov and Erickson-Gini (2003)	The shift of rock fragments and building elements may be used in a similar manner as wall inclination or block collapse. Some construction elements or rock fragments are shifted toward an epicenter due to inertia. Such examples were observed in the Ein Erga fort: three travertine blocks of the travertine plate underlying nearly the entire fort were thrown eastward (see Fig. 3 - Plan) and rotated clockwise. One of these was displaced horizontally, 1.7 m (Fig. 7) eastward. A large block of travertine bedrock lies on the lower rows of the former wall and measures 1.40 m in length, 0.90m in width and 0.42m high. It weighs approximately 2 tons. These features indicate that the seismic energy radiated from the ENE. - Korzhenkov and Erickson-Gini (2003)	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).

Seismic Parameters from Khorzhenkov and Erickson-Gini (2003)

Khorzhenkov and Erickson-Gini (2003) estimated that the epicenter was located somewhere ENE from the Ein Erga, and the very strong degree of deformations indicate that the epicenter was in some vicinity, probably in the area of the Dead Sea Fault zone, situated few km east of Ein Erga. The degree of destruction corresponds to the earthquake intensity of I = IX–X (MSK-64 scale), evidence of which are shift of few tons [of] travertine blocks. To move these blocks on a distance more than 1 m one can involve huge ground acceleration reaching a value of probably more than [1] g.

References

Articles and Books

Korzhenkov, A. and T. Erickson-Gini (2003). "The Seismic Origin of the Destruction of the Nabataean Forts of Ein Erga and Ein Rahel, Arava Valley, Israel." Archäologischer Anzeiger: 39-50.