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al-Harif Aqueduct

Al Harif Aqueduct Seismic Events Fig. 13

Correlation of results among paleoseismic trenching, archaeoseismic excavations, and tufa analysis. In paleoseismic trenching, the youngest age for event X is not constrained, but it is, however, limited by event Y. In archaeoseismic excavations, the period of first damage overlaps with that of the second damage due to poor age control. In tufa analysis, the onset and restart of Br-3 and Br-4 mark the damage episodes to the aqueduct; the growth of Br-5 and Br-6 shows interruptions (I) indicating the occurrence of major events. Except for the 29 June 1170 event, previous events have been unknown in the historical seismicity catalogue. The synthesis of large earthquake events results from the timing correlation among the faulting events, building repair, and tufa interruptions (also summarized in Fig. 12 and text). Although visible in trenches (faulting event X), archaeoseismic excavations (first damage), and first interruption of tufa growth (in Br-5 and Br-6 cores), the A.D. 160–510 age of event X has a large bracket. In contrast, event Y is relatively well bracketed between A.D. 625 and 690, with the overlapped dating from trench results, the second damage of the aqueduct, and the interruption and restart of Br-3 and onset of Br-4. The occurrence of the A.D. 1170 earthquake correlates well with event Z from the trenches, the age of third damage to the aqueduct, and the age of interruption of Br-4, Br-5, and Br-6.

Sbeinati et al (2010)




Introduction
al-Harif Aqueduct Study

Introduction

This study was based on 4 paleoseismic trenches, 4 archeoseismic excavations, and 6 tufa cores taken from the aqueduct walls at a site close to Masyaf, Syria where the al-Harif Roman aqueduct crosses the north-trending ~90 km. long Missyaf fault segment. Displacement of the aqueduct revealed 13.6 ± 0.2 m of left-lateral offset since the aqueduct was first built.

Archaeoseismic Evidence

The date of initial construction of the aqueduct is not known any more precisely than that it was constructed during Roman times. It is therefore younger than 65 BCE. Two reconstruction and repair episodes were identified.

Event Date
1st 1st-6th century CE
2nd 7th-8th century CE
Tufa cores

30-83 cm. thick tufa deposits developed on the aqueduct walls from water which overflowed the aqueduct canal. Horizontal cores taken through the tufa deposits revealed discontinuities in tufa deposits which were interpreted as interruptions in tufa precipitation and markers of seismic and immediate post seismic conditions. Dates of two seismic events interpreted from the tufa cores are listed below:
Event Younger than Older than
1st 70-230 CE 410-600 CE
2nd 540-980 CE 770-940 CE
Sbeinati et. al. (2010) suggested that water overflow ended on the eastern aqueduct wall and bridge after the second damaging event while it continued on the western aqueduct wall. tufa accumulation probably ended sometime after 900-1160 CE indicating the final stoppage of water flow over the aqueduct.

Paleoseismic Evidence

Paleoseismic trenches identified 4 events summarized below:
Event Younger than Older than Comments
Z 960-1060 CE 1480–1800, 1510–1670, and 1030–1260 CE Trenches A and C
likely due to 1170 CE earthquake
Y 540-650 CE 650-810 CE Trenches A and C
X 350 BCE - 30 CE 650-810 CE Trench A
W 3400-300 BCE 800-510 BCE Trench C
Combined Analysis

Sbeinati et. al. (2010) combined the multiple strands of data to suggest 4 faulting events in the last ~3500 years
Event Date Comments
Z 1010-1210 CE likely due to 1170 CE earthquake
Y 625-690 CE
X 160-510 CE
W 2300-500 BCE

Maps, Aerial Views, Trench Logs, Faulting History, Tufa Cores, Age Model, Age Schematic, and Photo
Maps, Aerial Views, Trench Logs, Faulting History, Tufa Cores, Age Model, Age Schematic, and Photo

Maps

Normal Size

  • Fig. 3 Location Map from from Sbeinati et. al. (2010)

Magnified

  • Fig. 3 Location Map from from Sbeinati et. al. (2010)

Aerial Views

  • Displaced Al-Harif aqueduct in Google Earth

Trench Logs

Location Map


Figure 5

Microtopographic survey (0.05 m contour lines) of the Al-Harif aqueduct and related flat alluvial terrace. The aqueduct (thin blue crosses) shows a total of 13.6 ± 0.20 m left-lateral slip along the fault zone (Meghraoui et al., 2003).

Roman numbers indicate archaeoseismic excavations (in red-dish and orange, labeled 1 to IV)

Letters indicate paleoseismic trenches (in gray and black, labeled A, B, C, and E).

The dragged wall fragment is located between excavation IV and trench E and is marked by a dense cluster of survey points.

Sbeinati et. al. (2010)


Trench A


Figure 10 A

Trench logs A, B, and C north of the aqueduct site (see location in Fig. 5). All trenches display the Dead Sea fault zone as a negative flower structure affecting all alluvial units below unit a. Calibrated 14C dates are in Table 1. Fault branches in trench C are labeled 1 to V (see text for explanation). The sedimentary units are very comparable and show three to four faulting events denoted W to Z (see text for explanation). Trench log A is in meters.

Sbeinati et. al. (2010)



Legend

Sbeinati et. al. (2010)


Trench B


Figure 10

Trench logs A, B, and C north of the aqueduct site (see location in Fig. 5). All trenches display the Dead Sea fault zone as a negative flower structure affecting all alluvial units below unit a. Calibrated 14C dates are in Table 1. Fault branches in trench C are labeled 1 to V (see text for explanation). The sedimentary units are very comparable and show three to four faulting events denoted W to Z (see text for explanation). Trench log A is in meters.

Sbeinati et. al. (2010)



Legend

Sbeinati et. al. (2010)


Trench C


Figure 10C

Trench logs A, B, and C north of the aqueduct site (see location in Fig. 5). All trenches display the Dead Sea fault zone as a negative flower structure affecting all alluvial units below unit a. Calibrated 14C dates are in Table 1. Fault branches in trench C are labeled 1 to V (see text for explanation). The sedimentary units are very comparable and show three to four faulting events denoted W to Z (see text for explanation). Trench log A is in meters.

Sbeinati et. al. (2010)



Legend

Sbeinati et. al. (2010)


Excavation I


Figure 8 B and C

(B) Mosaic of excavation 1 exhibits the main fallen wall (A and B) and dragged wall piece (C), scattered wall pieces and the fault zone; note also location of cement sample CS-1-4 (see text for explanation).

(C) Trench E (excavation 1, north wall) exposes faulted sedimentary units below the archaeological remains and wall fragment C visible in bottom of Figure 8B

fz-fault zone

sedimentary units are similar to those of trenches A, B, and C (see also Fig. 10); and dating characteristics are in Table 1.
  • a - present-day soil and alluvial terrace (plough zone)
  • d—reddish alluvial fine gravel
  • e—dark-brown silty clay (with rich organic matter)
  • f—gravels and pebbles in silty-clay matrix
  • g—massive gey clay with scattered gravels

Sbeinati et. al. (2010)


Aqueduct Faulting History


Figure 14

Schematic reconstruction (with final stage from Fig. 5) of the A.D. 160-510, A.D. 625-690, and A.D. 1170 large earthquakes and related faulting of the Al Harif aqueduct. Except for the A.D. 1170 earthquake (see historical cata-logue of Sbeinati et al., 2005), the dating of earthquake events are from Figure 12. The white small section is the rebuilt wall after event X (see buried wall A and B in Fig. 8B); the subsequent gray piece corresponds to the rebuilt wall after event Y (see wall section C in Fig. 8B), which was damaged and dragged after event Z. The earlier aqueduct deformation (warping of the eastern wall near the fault rupture) may have recorded —4.3 m of coseismic left-lateral slip that remained relatively well preserved during the subsequent fault movements.

Sbeinati et. al. (2010)


Tufa Cores

Aqueduct Wall and Tufa Cores


Figure 7

Schematic sections of the aqueduct western wall and related tufa deposits (B, C, D, and E indicate earlier core sections of tufa deposits (Meghraoui et al., 2003). Tufa samples AQ-Tr-B13 and AQ-Tr-D5 (Table 1) are from cores B and D, respectively. The right and left vertical sections show the relative tufa thickness of the originally built part (with Opus caementum and quadratum stones) and the rebuilt part, respectively. The plan view indicates the variation of tufa deposition and shows the core distribution and related thickness along the western wall of the aqueduct.

Sbeinati et. al. (2010)


Tufa Cores


Figure 11

Synthetic description of cores with lithologic content and sample number for radiocarbon dating (see Table 1 and Fig. 6 for core locations)

I stands for major interruption.

The very porous tufa indicates major interruptions in tufa growth (e.g. a major interruption of core growth in BR-3 is visible at —22 cm (Br-3-4 sample; see text for explanation). The correlation between major interruptions of tufa growth and faulting events in trenches and archaeoseismic building constrains the timing of repeated earthquakes along the Missyaf segment of the Dead Sea fault.

Sbeinati et. al. (2010)


Age Model


Fig. 12 (A)

Calibrated dating of samples (with calibration curve INTCAL04 from Reimer et al. [2004] with 2σ age range and 95.4% probability) and sequential distribution from Oxcal pro-gram (see also Table 1; Bronk Ramsey, 2001). The Bayesian distribution computes the time range of large earthquakes (events W, X, Y, and Z) at the Al Harif aqueduct according to faulting events, construction and repair of walls, and starts and interruptions of the tufa deposits (see text for explanation). Number in brackets (in %) indicates how much the sample is in sequence; the number in % indicates an agreement index of overlap with prior distribution.

Sbeinati et al (2010)


Age Schematic

Al Harif Aqueduct Seismic Events Fig. 13

Correlation of results among paleoseismic trenching, archaeoseismic excavations, and tufa analysis. In paleoseismic trenching, the youngest age for event X is not constrained, but it is, however, limited by event Y. In archaeoseismic excavations, the period of first damage overlaps with that of the second damage due to poor age control. In tufa analysis, the onset and restart of Br-3 and Br-4 mark the damage episodes to the aqueduct; the growth of Br-5 and Br-6 shows interruptions (I) indicating the occurrence of major events. Except for the 29 June 1170 event, previous events have been unknown in the historical seismicity catalogue. The synthesis of large earthquake events results from the timing correlation among the faulting events, building repair, and tufa interruptions (also summarized in Fig. 12 and text). Although visible in trenches (faulting event X), archaeoseismic excavations (first damage), and first interruption of tufa growth (in Br-5 and Br-6 cores), the A.D. 160–510 age of event X has a large bracket. In contrast, event Y is relatively well bracketed between A.D. 625 and 690, with the overlapped dating from trench results, the second damage of the aqueduct, and the interruption and restart of Br-3 and onset of Br-4. The occurrence of the A.D. 1170 earthquake correlates well with event Z from the trenches, the age of third damage to the aqueduct, and the age of interruption of Br-4, Br-5, and Br-6.

Sbeinati et al (2010)


Photo - Archeological Evidence of aqueduct rebuilding


Figure 9

Excavations II (A) and III (B) that expose the aqueduct wall foundation (see also Fig. 5) and related sedimentary unit e underneath. The difference in the size of stones between excavation II (A) and excavation III (B) implies a rebuilding phase of the latter wall.

Sbeinati et. al. (2010)


Master Seismic Events Table
Master Seismic Events Table

Calculator
Calculator

Strike-Slip Fault Displacement - Wells and Coppersmith (1994)

Variable Input Units Notes
cm. Strike-Slip displacement
cm. Strike-Slip displacement
Variable Output - not considering a Site Effect Units Notes
unitless Moment Magnitude for Avg. Displacement
unitless Moment Magnitude for Max. Displacement
  

References
References