• from Reches and Hoexter (1981:245)

We identified two "events" which occurred along the Jericho fault during the last 2000 years. These events, referred to as event A and event B, can be recognized in trenches 3, 4 and 5. Each event represents intensive seismic activity; however, due to the coarse lamination, it is impossible to ascertain if each one represents a single large earthquake or multiple earthquakes during a short period. In this study, we suggest that these events represent individual earthquakes and correlated them with historic records.

We have also found evidence for considerable slip along the Jericho fault in trenches 1 and 2. We will first describe the evidence for the two earthquakes, and will then present the information relating to the slip along the fault.

• from Reches and Hoexter (1981:245-247)

The older event is evident in unit A1 and, in part, in unit A2 as seen in the central trenches 3, 4 and 5 (Figs. 4, 9). Several small faults, wide fissures, filled cracks, significant vertical throw and large unconformities are thought to have resulted from this earthquake. The following is a detailed description of these phenomena.

Small faults, with displacements of up to a few tens of cm, cut through unit A1 (Fig. 4) in both trench 3 (Figs. 7, 8), and trench 5. These are faults with either reverse- or normal-separation, with either the east or west side downthrown. The fault surfaces are usually irregular, with no slickensides. The faults are truncated by unit A2 in locations 3464/096 and 3-198/090 (Figs. 8, 10). Wide fissures, bounded by small faults and filled with either layered (Fig. 10) or mixed sediments (3-091/115 in Fig. 7 and 3-213/083 in Fig. 8) cut through unit A1. Stratified layers of unit A1 are preserved in the fissures of trench 5, whereas this unit was eroded from both sides of the fissure (Fig. 10, and compare with fig. 18, Sieh, 1978b). A few filled cracks and pockets of mixed sediments occur within unit A1. For example, a vertical one meter long crack at location 3-178/090, an irregular crack at 3-235/077 or a small pocket at 3-210/084 (Fig. 8). Unlike the fissures described above, there is no displacement across the cracks and pockets.

A vertical separation of about 3.5 m is evident between the subhorizontal layers of unit A1 at 3-090/115 (Figs. 7, 9), and the same layers at 3-220/085 (Figs. 8, 9). This vertical separation poses several questions. Does it represent the throw during event A or an accumulative subsidence during the last 2000 years, or does this separation reflect the initial deposition of unit A1 on an inclined surface? The horizontality of unit A1 layers on both sides of the disturbed zone (Fig. 9), the continuity of the layers and their lithological consistency in trenches 3 and 5 indicate that this unit was deposited on a relatively stable, horizontal surface. Units B and C (Fig. 4), on the other hand, have a distinctive eastward thickening and inclination (Figs. 7, 8). We thus conclude that the 3.5 m vertical separation is not depositional, but rather the local tectonic throw. This vertical separation occurred during event A or during a period of a few hundreds years, following event A and preceding event B. At present, we prefer the first possibility, but there are no evidence to reject the second. One should note, however, that the horizontal slip along the Jericho fault, associated with event A is not simply related to the local throw. The latter may be significantly increased due to variation of the fault attitude (e.g. Eyal, 1973), fault trend (e.g. Garfunkel, this volume) or the en-echelon pattern (e.g. Freund and Garfunkel, 1976).

Finally, the top of unit A is bounded by a clear unconformity (Figs. 4, 7, 8, 9). For example, the base of unit B is deposited on an inclined surface cutting through Lisan and unit A1 layers, whereas unit A2 has been completely eroded away (right upper side of Fig. 7; Fig. 9). This unconformity can also be traced in the eastern side of the main fault (note thinning of unit A2 in Fig. 9). The large vertical throw, discussed above, probably produced a fault scarp at the site of the trenches. Intensive erosion probably converted this scarp into a debris controlled slope in a relatively short period (e.g. Wallace, 1978). We think that this major unconformity at the base of unit B may represent the stage of fault scarp erosion at the time of deposition of unit B.

The age of unit A is determined by using an assemblage of 35 identifiable pottery fragments. The fragments range from the Iron Age to Early Roman, namely, from about the 12th century B.C. to the first century A.D. Because of reworking, the youngest fragments indicate the maximum age of this unit, which is about 1900-2000 years. The coarse stratigraphy and the relative scarcity of useful pottery fragments prevent a more specific age determination.

Conspicuous among the historic records of seismic events during this period is a vivid description by Josephus of an earthquake in the year 31 B.C. (Josephus, "Antiquities of the Jews", Book XV, Ch. 5). He wrote: "At this time it was that the fight happened at Actium, between Octavius Caesar and Anthony in the seventh year of the reign of Herod and it was also that here was an earthquake in Judea, such a one as had not happened at any other time and this earthquake brought a great destruction upon the cattle in that country. About 10,000 men also perished by the fall of houses, but the army, which lodged in the field, received no damage by this sad accident." It is feasible that this earthquake may be the same as "event A".

• from Reches and Hoexter (1981:247-251)

Evidence for a second earthquake in the central trenches can be seen in unit B (Figs. 4, 9). This event is recognized by bowl-shaped depressions, open and closed cracks, vents, filled fissures and small faults. Some of these features are described in detail. Bowl-shaped depressions are characterized by oppositely facing layers or a bowl filled with disturbed sediments (Fig. 11). The bowl structures vary in width from about 20 cm (2-157/111 in Fig. 8) to almost 2.0 m (3-11/11 in Fig. 7). Most of the cracks in unit B are sub-vertical, with rough and irregular surfaces. A few cracks are open and their surfaces are coated with fine brown clay with flow striations. Several cracks are filled with an unsorted, non-laminated mixture of clastic material, with a few fragments of pottery (3-142/100 in Fig. 7). This mixture is loosely cemented by gypsum needles in a few places. Most of the cracks in trench 3 terminate close to the top of unit B (Fig. 9), suggesting that they developed at the end of the deposition of this unit. The filled fissures, 5-10 cm wide, which are common at the base of unit B (Figs. 7, 9), are somewhat similar to the filled cracks, described above. These wide fissures have irregular faces, without slickensides or apparent displacement. The occurrence of mixed sediments of unit B in the fissures (e.g. 3-11/10 in Fig. 7) indicates that they formed after the deposition of unit B. A few small faults with displacement of up to 10 cm also occur in unit B (e.g. Fig. 11).

The character of event B differs significantly from that of event A. The latter has clear faults and measurable throws, whereas the former has many extensional features with no apparent throw. The 9° eastward inclination of the top of unit B (Fig. 9) may suggest some continuous subsidence (aseismic?). On the other hand, this inclination may also be due to the degraded fault scarp of event A, which could have existed for thousands of years (e.g. Wallace, 1978). Due to the coarse layering, it is impossible to distinguish between two possible mechanisms.

The age of unit B is determined by the presence of a distinctive group of pottery fragments, dating from the Late Byzantine to Early Arabic times, namely 7–8 centuries A.D. This is the youngest assemblage in unit B, and thus, event B has probably occurred between the 7th Century and the 8th Century.

What is the slip associated with B? Could we correlate it with a known historic record? A hint of an answer is found in the nearby Hisham Palace, a luxurious complex built during the first half of the 8th Century just north of Jericho (location 3, Fig. 1). The ruins of the palace were studied in detail by Hamilton (1959), who proposed that the palace was destroyed by an earthquake, before the completion of its construction.

We found that the walls of the Hisham Palace have been subjected to severe fracturing, tilting, warping and distortion, which are consistent with sinistral horizontal shear. Figure 12 is the damage that we documented on Hamilton's map. Many rooms, particularly in the southeastern part, are rhomb-shaped (Figs. 12, 13a). The deviation of the rooms of the palace from rectangular form was attributed by Hamilton (1958, p. 63) to errors in measuring angles during construction. However, such errors could not explain the coherent continuous warping of many walls (Fig. 12) and the horizontal slip on several fractures (Figs. 12, 13b). As the wall warping, the slip along fractures and shape of rooms are all consistent with sinistral horizontal shear of the southeastern part of the palace (Fig. 12), tectonic deformation appears to be the reasonable explanation for most, if not all, damage phenomena. Begin (1975) traced an inferred fault trending N35°E, about 100 m west of the palace. We suggest that another fault, the Hisham fault, runs with similar trend through the palace (Fig. 1c).

Ben-Menahem (1981) suggests, on the basis of historical records, that the palace was destroyed by an earthquake in 748. He further suggests that this earthquake caused severe damage to hundreds of villages and death of tens of thousands of people. Ben-Menahem claims it was the strongest event in the region of Israel during the last 2500 years and attributes to it a magnitude of M > 7.

The observations of the structures in unit B, the deformation in the Hisham Palace, and the historic records are all consistent with a major earthquake in 748 along the Jericho fault. The predominant displacement during this event would have been horizontal shear, which caused no considerable throw at the central trenches. The sinistral slip along the Hisham fault is probably secondary to the main 748 slip. The deformation of the palace occurred during and after the 748 event.

Evidence of young events which post-date event B is rare. The upper 0.6-1.0 m sequence is primarily disturbed by man-made structures. A possible exception is the small bowl-structure with associated cracks in 3-157/111 (Fig. 8) which formed a few hundred years ago, during a small event (event C, Fig. 9).

• from Reches and Hoexter (1981:245)

We identified two "events" which occurred along the Jericho fault during the last 2000 years. These events, referred to as event A and event B, can be recognized in trenches 3, 4 and 5. Each event represents intensive seismic activity; however, due to the coarse lamination, it is impossible to ascertain if each one represents a single large earthquake or multiple earthquakes during a short period. In this study, we suggest that these events represent individual earthquakes and correlated them with historic records.

We have also found evidence for considerable slip along the Jericho fault in trenches 1 and 2. We will first describe the evidence for the two earthquakes, and will then present the information relating to the slip along the fault.

• from Reches and Hoexter (1981:245-247)

The older event is evident in unit A1 and, in part, in unit A2 as seen in the central trenches 3, 4 and 5 (Figs. 4, 9). Several small faults, wide fissures, filled cracks, significant vertical throw and large unconformities are thought to have resulted from this earthquake. The following is a detailed description of these phenomena.

Small faults, with displacements of up to a few tens of cm, cut through unit A1 (Fig. 4) in both trench 3 (Figs. 7, 8), and trench 5. These are faults with either reverse- or normal-separation, with either the east or west side downthrown. The fault surfaces are usually irregular, with no slickensides. The faults are truncated by unit A2 in locations 3464/096 and 3-198/090 (Figs. 8, 10). Wide fissures, bounded by small faults and filled with either layered (Fig. 10) or mixed sediments (3-091/115 in Fig. 7 and 3-213/083 in Fig. 8) cut through unit A1. Stratified layers of unit A1 are preserved in the fissures of trench 5, whereas this unit was eroded from both sides of the fissure (Fig. 10, and compare with fig. 18, Sieh, 1978b). A few filled cracks and pockets of mixed sediments occur within unit A1. For example, a vertical one meter long crack at location 3-178/090, an irregular crack at 3-235/077 or a small pocket at 3-210/084 (Fig. 8). Unlike the fissures described above, there is no displacement across the cracks and pockets.

A vertical separation of about 3.5 m is evident between the subhorizontal layers of unit A1 at 3-090/115 (Figs. 7, 9), and the same layers at 3-220/085 (Figs. 8, 9). This vertical separation poses several questions. Does it represent the throw during event A or an accumulative subsidence during the last 2000 years, or does this separation reflect the initial deposition of unit A1 on an inclined surface? The horizontality of unit A1 layers on both sides of the disturbed zone (Fig. 9), the continuity of the layers and their lithological consistency in trenches 3 and 5 indicate that this unit was deposited on a relatively stable, horizontal surface. Units B and C (Fig. 4), on the other hand, have a distinctive eastward thickening and inclination (Figs. 7, 8). We thus conclude that the 3.5 m vertical separation is not depositional, but rather the local tectonic throw. This vertical separation occurred during event A or during a period of a few hundreds years, following event A and preceding event B. At present, we prefer the first possibility, but there are no evidence to reject the second. One should note, however, that the horizontal slip along the Jericho fault, associated with event A is not simply related to the local throw. The latter may be significantly increased due to variation of the fault attitude (e.g. Eyal, 1973), fault trend (e.g. Garfunkel, this volume) or the en-echelon pattern (e.g. Freund and Garfunkel, 1976).

Finally, the top of unit A is bounded by a clear unconformity (Figs. 4, 7, 8, 9). For example, the base of unit B is deposited on an inclined surface cutting through Lisan and unit A1 layers, whereas unit A2 has been completely eroded away (right upper side of Fig. 7; Fig. 9). This unconformity can also be traced in the eastern side of the main fault (note thinning of unit A2 in Fig. 9). The large vertical throw, discussed above, probably produced a fault scarp at the site of the trenches. Intensive erosion probably converted this scarp into a debris controlled slope in a relatively short period (e.g. Wallace, 1978). We think that this major unconformity at the base of unit B may represent the stage of fault scarp erosion at the time of deposition of unit B.

The age of unit A is determined by using an assemblage of 35 identifiable pottery fragments. The fragments range from the Iron Age to Early Roman, namely, from about the 12th century B.C. to the first century A.D. Because of reworking, the youngest fragments indicate the maximum age of this unit, which is about 1900-2000 years. The coarse stratigraphy and the relative scarcity of useful pottery fragments prevent a more specific age determination.

Conspicuous among the historic records of seismic events during this period is a vivid description by Josephus of an earthquake in the year 31 B.C. (Josephus, "Antiquities of the Jews", Book XV, Ch. 5). He wrote: "At this time it was that the fight happened at Actium, between Octavius Caesar and Anthony in the seventh year of the reign of Herod and it was also that here was an earthquake in Judea, such a one as had not happened at any other time and this earthquake brought a great destruction upon the cattle in that country. About 10,000 men also perished by the fall of houses, but the army, which lodged in the field, received no damage by this sad accident." It is feasible that this earthquake may be the same as "event A".

• from Reches and Hoexter (1981:247-251)

Evidence for a second earthquake in the central trenches can be seen in unit B (Figs. 4, 9). This event is recognized by bowl-shaped depressions, open and closed cracks, vents, filled fissures and small faults. Some of these features are described in detail. Bowl-shaped depressions are characterized by oppositely facing layers or a bowl filled with disturbed sediments (Fig. 11). The bowl structures vary in width from about 20 cm (2-157/111 in Fig. 8) to almost 2.0 m (3-11/11 in Fig. 7). Most of the cracks in unit B are sub-vertical, with rough and irregular surfaces. A few cracks are open and their surfaces are coated with fine brown clay with flow striations. Several cracks are filled with an unsorted, non-laminated mixture of clastic material, with a few fragments of pottery (3-142/100 in Fig. 7). This mixture is loosely cemented by gypsum needles in a few places. Most of the cracks in trench 3 terminate close to the top of unit B (Fig. 9), suggesting that they developed at the end of the deposition of this unit. The filled fissures, 5-10 cm wide, which are common at the base of unit B (Figs. 7, 9), are somewhat similar to the filled cracks, described above. These wide fissures have irregular faces, without slickensides or apparent displacement. The occurrence of mixed sediments of unit B in the fissures (e.g. 3-11/10 in Fig. 7) indicates that they formed after the deposition of unit B. A few small faults with displacement of up to 10 cm also occur in unit B (e.g. Fig. 11).

The character of event B differs significantly from that of event A. The latter has clear faults and measurable throws, whereas the former has many extensional features with no apparent throw. The 9° eastward inclination of the top of unit B (Fig. 9) may suggest some continuous subsidence (aseismic?). On the other hand, this inclination may also be due to the degraded fault scarp of event A, which could have existed for thousands of years (e.g. Wallace, 1978). Due to the coarse layering, it is impossible to distinguish between two possible mechanisms.

The age of unit B is determined by the presence of a distinctive group of pottery fragments, dating from the Late Byzantine to Early Arabic times, namely 7–8 centuries A.D. This is the youngest assemblage in unit B, and thus, event B has probably occurred between the 7th Century and the 8th Century.

What is the slip associated with B? Could we correlate it with a known historic record? A hint of an answer is found in the nearby Hisham Palace, a luxurious complex built during the first half of the 8th Century just north of Jericho (location 3, Fig. 1). The ruins of the palace were studied in detail by Hamilton (1959), who proposed that the palace was destroyed by an earthquake, before the completion of its construction.

We found that the walls of the Hisham Palace have been subjected to severe fracturing, tilting, warping and distortion, which are consistent with sinistral horizontal shear. Figure 12 is the damage that we documented on Hamilton's map. Many rooms, particularly in the southeastern part, are rhomb-shaped (Figs. 12, 13a). The deviation of the rooms of the palace from rectangular form was attributed by Hamilton (1958, p. 63) to errors in measuring angles during construction. However, such errors could not explain the coherent continuous warping of many walls (Fig. 12) and the horizontal slip on several fractures (Figs. 12, 13b). As the wall warping, the slip along fractures and shape of rooms are all consistent with sinistral horizontal shear of the southeastern part of the palace (Fig. 12), tectonic deformation appears to be the reasonable explanation for most, if not all, damage phenomena. Begin (1975) traced an inferred fault trending N35°E, about 100 m west of the palace. We suggest that another fault, the Hisham fault, runs with similar trend through the palace (Fig. 1c).

Ben-Menahem (1981) suggests, on the basis of historical records, that the palace was destroyed by an earthquake in 748. He further suggests that this earthquake caused severe damage to hundreds of villages and death of tens of thousands of people. Ben-Menahem claims it was the strongest event in the region of Israel during the last 2500 years and attributes to it a magnitude of M > 7.

The observations of the structures in unit B, the deformation in the Hisham Palace, and the historic records are all consistent with a major earthquake in 748 along the Jericho fault. The predominant displacement during this event would have been horizontal shear, which caused no considerable throw at the central trenches. The sinistral slip along the Hisham fault is probably secondary to the main 748 slip. The deformation of the palace occurred during and after the 748 event.

Evidence of young events which post-date event B is rare. The upper 0.6-1.0 m sequence is primarily disturbed by man-made structures. A possible exception is the small bowl-structure with associated cracks in 3-157/111 (Fig. 8) which formed a few hundred years ago, during a small event (event C, Fig. 9).

• from Reches and Hoexter (1981:245)

We identified two "events" which occurred along the Jericho fault during the last 2000 years. These events, referred to as event A and event B, can be recognized in trenches 3, 4 and 5. Each event represents intensive seismic activity; however, due to the coarse lamination, it is impossible to ascertain if each one represents a single large earthquake or multiple earthquakes during a short period. In this study, we suggest that these events represent individual earthquakes and correlated them with historic records.

We have also found evidence for considerable slip along the Jericho fault in trenches 1 and 2. We will first describe the evidence for the two earthquakes, and will then present the information relating to the slip along the fault.

• from Reches and Hoexter (1981:245-247)

The older event is evident in unit A1 and, in part, in unit A2 as seen in the central trenches 3, 4 and 5 (Figs. 4, 9). Several small faults, wide fissures, filled cracks, significant vertical throw and large unconformities are thought to have resulted from this earthquake. The following is a detailed description of these phenomena.

Small faults, with displacements of up to a few tens of cm, cut through unit A1 (Fig. 4) in both trench 3 (Figs. 7, 8), and trench 5. These are faults with either reverse- or normal-separation, with either the east or west side downthrown. The fault surfaces are usually irregular, with no slickensides. The faults are truncated by unit A2 in locations 3464/096 and 3-198/090 (Figs. 8, 10). Wide fissures, bounded by small faults and filled with either layered (Fig. 10) or mixed sediments (3-091/115 in Fig. 7 and 3-213/083 in Fig. 8) cut through unit A1. Stratified layers of unit A1 are preserved in the fissures of trench 5, whereas this unit was eroded from both sides of the fissure (Fig. 10, and compare with fig. 18, Sieh, 1978b). A few filled cracks and pockets of mixed sediments occur within unit A1. For example, a vertical one meter long crack at location 3-178/090, an irregular crack at 3-235/077 or a small pocket at 3-210/084 (Fig. 8). Unlike the fissures described above, there is no displacement across the cracks and pockets.

A vertical separation of about 3.5 m is evident between the subhorizontal layers of unit A1 at 3-090/115 (Figs. 7, 9), and the same layers at 3-220/085 (Figs. 8, 9). This vertical separation poses several questions. Does it represent the throw during event A or an accumulative subsidence during the last 2000 years, or does this separation reflect the initial deposition of unit A1 on an inclined surface? The horizontality of unit A1 layers on both sides of the disturbed zone (Fig. 9), the continuity of the layers and their lithological consistency in trenches 3 and 5 indicate that this unit was deposited on a relatively stable, horizontal surface. Units B and C (Fig. 4), on the other hand, have a distinctive eastward thickening and inclination (Figs. 7, 8). We thus conclude that the 3.5 m vertical separation is not depositional, but rather the local tectonic throw. This vertical separation occurred during event A or during a period of a few hundreds years, following event A and preceding event B. At present, we prefer the first possibility, but there are no evidence to reject the second. One should note, however, that the horizontal slip along the Jericho fault, associated with event A is not simply related to the local throw. The latter may be significantly increased due to variation of the fault attitude (e.g. Eyal, 1973), fault trend (e.g. Garfunkel, this volume) or the en-echelon pattern (e.g. Freund and Garfunkel, 1976).

Finally, the top of unit A is bounded by a clear unconformity (Figs. 4, 7, 8, 9). For example, the base of unit B is deposited on an inclined surface cutting through Lisan and unit A1 layers, whereas unit A2 has been completely eroded away (right upper side of Fig. 7; Fig. 9). This unconformity can also be traced in the eastern side of the main fault (note thinning of unit A2 in Fig. 9). The large vertical throw, discussed above, probably produced a fault scarp at the site of the trenches. Intensive erosion probably converted this scarp into a debris controlled slope in a relatively short period (e.g. Wallace, 1978). We think that this major unconformity at the base of unit B may represent the stage of fault scarp erosion at the time of deposition of unit B.

The age of unit A is determined by using an assemblage of 35 identifiable pottery fragments. The fragments range from the Iron Age to Early Roman, namely, from about the 12th century B.C. to the first century A.D. Because of reworking, the youngest fragments indicate the maximum age of this unit, which is about 1900-2000 years. The coarse stratigraphy and the relative scarcity of useful pottery fragments prevent a more specific age determination.

Conspicuous among the historic records of seismic events during this period is a vivid description by Josephus of an earthquake in the year 31 B.C. (Josephus, "Antiquities of the Jews", Book XV, Ch. 5). He wrote: "At this time it was that the fight happened at Actium, between Octavius Caesar and Anthony in the seventh year of the reign of Herod and it was also that here was an earthquake in Judea, such a one as had not happened at any other time and this earthquake brought a great destruction upon the cattle in that country. About 10,000 men also perished by the fall of houses, but the army, which lodged in the field, received no damage by this sad accident." It is feasible that this earthquake may be the same as "event A".

• from Reches and Hoexter (1981:247-251)

Evidence for a second earthquake in the central trenches can be seen in unit B (Figs. 4, 9). This event is recognized by bowl-shaped depressions, open and closed cracks, vents, filled fissures and small faults. Some of these features are described in detail. Bowl-shaped depressions are characterized by oppositely facing layers or a bowl filled with disturbed sediments (Fig. 11). The bowl structures vary in width from about 20 cm (2-157/111 in Fig. 8) to almost 2.0 m (3-11/11 in Fig. 7). Most of the cracks in unit B are sub-vertical, with rough and irregular surfaces. A few cracks are open and their surfaces are coated with fine brown clay with flow striations. Several cracks are filled with an unsorted, non-laminated mixture of clastic material, with a few fragments of pottery (3-142/100 in Fig. 7). This mixture is loosely cemented by gypsum needles in a few places. Most of the cracks in trench 3 terminate close to the top of unit B (Fig. 9), suggesting that they developed at the end of the deposition of this unit. The filled fissures, 5-10 cm wide, which are common at the base of unit B (Figs. 7, 9), are somewhat similar to the filled cracks, described above. These wide fissures have irregular faces, without slickensides or apparent displacement. The occurrence of mixed sediments of unit B in the fissures (e.g. 3-11/10 in Fig. 7) indicates that they formed after the deposition of unit B. A few small faults with displacement of up to 10 cm also occur in unit B (e.g. Fig. 11).

The character of event B differs significantly from that of event A. The latter has clear faults and measurable throws, whereas the former has many extensional features with no apparent throw. The 9° eastward inclination of the top of unit B (Fig. 9) may suggest some continuous subsidence (aseismic?). On the other hand, this inclination may also be due to the degraded fault scarp of event A, which could have existed for thousands of years (e.g. Wallace, 1978). Due to the coarse layering, it is impossible to distinguish between two possible mechanisms.

The age of unit B is determined by the presence of a distinctive group of pottery fragments, dating from the Late Byzantine to Early Arabic times, namely 7–8 centuries A.D. This is the youngest assemblage in unit B, and thus, event B has probably occurred between the 7th Century and the 8th Century.

What is the slip associated with B? Could we correlate it with a known historic record? A hint of an answer is found in the nearby Hisham Palace, a luxurious complex built during the first half of the 8th Century just north of Jericho (location 3, Fig. 1). The ruins of the palace were studied in detail by Hamilton (1959), who proposed that the palace was destroyed by an earthquake, before the completion of its construction.

We found that the walls of the Hisham Palace have been subjected to severe fracturing, tilting, warping and distortion, which are consistent with sinistral horizontal shear. Figure 12 is the damage that we documented on Hamilton's map. Many rooms, particularly in the southeastern part, are rhomb-shaped (Figs. 12, 13a). The deviation of the rooms of the palace from rectangular form was attributed by Hamilton (1958, p. 63) to errors in measuring angles during construction. However, such errors could not explain the coherent continuous warping of many walls (Fig. 12) and the horizontal slip on several fractures (Figs. 12, 13b). As the wall warping, the slip along fractures and shape of rooms are all consistent with sinistral horizontal shear of the southeastern part of the palace (Fig. 12), tectonic deformation appears to be the reasonable explanation for most, if not all, damage phenomena. Begin (1975) traced an inferred fault trending N35°E, about 100 m west of the palace. We suggest that another fault, the Hisham fault, runs with similar trend through the palace (Fig. 1c).

Ben-Menahem (1981) suggests, on the basis of historical records, that the palace was destroyed by an earthquake in 748. He further suggests that this earthquake caused severe damage to hundreds of villages and death of tens of thousands of people. Ben-Menahem claims it was the strongest event in the region of Israel during the last 2500 years and attributes to it a magnitude of M > 7.

The observations of the structures in unit B, the deformation in the Hisham Palace, and the historic records are all consistent with a major earthquake in 748 along the Jericho fault. The predominant displacement during this event would have been horizontal shear, which caused no considerable throw at the central trenches. The sinistral slip along the Hisham fault is probably secondary to the main 748 slip. The deformation of the palace occurred during and after the 748 event.

Evidence of young events which post-date event B is rare. The upper 0.6-1.0 m sequence is primarily disturbed by man-made structures. A possible exception is the small bowl-structure with associated cracks in 3-157/111 (Fig. 8) which formed a few hundred years ago, during a small event (event C, Fig. 9).