Open this page in a new tab

Tiberias - Seismo-Tectonics

Surface Faulting Evidence

Maps, Plans, and Figures/Photos

Maps, Plans, and Figures/Photos

  • Fig. 4 Map of Ancient Tiberias with inferred fault and sites studied by Ferrario et al (2020)
  • Fig. 4a Map of surface ruptures in the Beriniki Theatre from Ferrario et al (2020)
  • Fig. S14 fractures in building stones from Ferrario et al (2020)
  • Fig. 6d inclined fractures in water reservoir from Ferrario et al (2020)
  • Fig. 10 reconstruction of shallow subsurface from Ferrario et al (2020)
  • Fig. 10a Section through the Berniki Theater from Ferrario et al (2020)
  • Fig. 10b Section through the Southern Gate from Ferrario et al (2020)
  • Fig. 10c Section through the Hamat hotsprings from Ferrario et al (2020)
  • Fig. 9 Seismic sections from Ferrario et al (2020)
  • Fig. 4e Fault gouge from Ferrario et al (2020)


Ferrario et al (2020) detailed surface faulting evidence as follows:
We measured dip and dip direction of 123 fractures (in masonry blocks) in the Theatre and 59 in the Southern Gate (Table S2). They are Mode I fractures (opening fractures), affecting walls and building stones. Generally, they break the entire stone height, albeit in some cases they affect a single corner of the building stone (see Fig. S14 for examples). The strike of the fractures has a modal value of 160° and 140° in the whole Theatre and the orchestra floor, respectively (see rose diagrams in Fig. 4a ). These values are broadly consistent with the direction of the gravity graben found within the Theatre.

South of the Theatre, the last excavation phase during 2017 uncovered an Umayyad water reservoir. Damage is here represented by a series of steeply inclined fractures between masonry blocks, located in a ca. 1 m wide zone (Fig. 6d ). The damage zone is situated along the line connecting the graben in the Theatre and the warped Byzantine wall at the Southern Gate, i.e. on the fault line.

... Summary of the archaeoseismic observations reveals a ~300 m long segment of the [Jordan Valley Western Boundary Fault] (JVWB) [from the] Theatre to [the] Gate that ruptured the surface during an earthquake that apparently took place at the 8th century CE. Slip along the fault is normal, vertical throw is 0.5 m.
Ferrario et al (2020) summarized why they considered surface faulting the causitive mechanism for much of the observed damage as follows:
  1. The investigated sites are built on a contact between limestones and thin (few meters) alluvial deposits; the presence of shallow limestone bedrock beneath the hanging wall alluvial deposits is also confirmed by boreholes. Bedrock outcrops inside the Theatre and at the bottom of the wadi channel at the Southern Gate.
  2. All damaged sites are aligned along a lineament in a N140 direction, which is consistent with the structural framework of the study area.
  3. All our observations document a pure dip-slip normal faulting.
  4. The gravity-graben inside the Theatre is a feature consistent with coseismic, near- fault deformation (e.g., Slemmons, 1957; Rodriguez-Pascua et al., 2011) and possibly due to the steepening of the fault plane approaching the surface.
  5. Damage is consistently found in Roman levels and in the debris flow sediments uncovered in the Theatre, but the Abassid levels were not faulted nor deformed. Archaeological stratigraphy provides tight chronological constraints, based on architectural style, building techniques and materials of the findings and structures.
The lines of reasoning listed above point toward an earthquake-related damage, and more specifically to surface faulting. The damaging event is constrained to later than 530 CE and younger than the Abassid caliphate (750-1258 CE).
Ferrario et al (2020) discuss the nature of faulting during this event below:
The reconstruction of the stratigraphic and structural setting of the shallow subsurface (Fig. 10 ) shows faults reaching the surface; they were constrained by direct observation at the archaeological sites (Fig. 10a and 10b ) or presence of the hot springs (Fig. 10c ). Other faults were imaged through the seismic lines and borehole correlation. Our data suggest the presence of a fault zone some tens of meters wide, rather than a single fault. At the Theatre (Fig. 10a ) and at the Northern seismic line (Fig. 9 ), we observe to the W a fault strand at the contact between Cretaceous limestone and the Neogene-Quaternary deposits; to the E, a second fault strand lies within the Neogene-Quaternary deposits. At the Theatre, the fault gouge in Cretaceous limestones (Fig. 4e ) show no signs of historical displacements, whereas the archaeological structures are faulted more to the E (Fig. 4a ). This may suggest a basinward migration of the active fault strand, consistently with previous observations at other sites along the DSF (Marco & Klinger, 2014). At the Southern Gate the fault lies within Cretaceous limestones, as deduced from archaeoseismological observations and core drillings (Fig. 10b ).

Rupture Scenarios

Ferrario et al (2020) considered 3 different rupture scenarios for the mid 8th century CE earthquake which they suggest caused the observed damage:

Scenario Fault(s) Fault
1 Jordan Valley Western Boundary Fault Normal 45 6.9
2 Jordan Valley Fault Strike-Slip 125 12.5 7.3
3 Jordan Valley Western Boundary Fault
and Jordan Valley Fault
Normal and
170 12.5 7.6
While they suggested the 3rd possibility could be explained by strain-partitioning, they considered it an unlikely scenario. They also noted that their calculations represented worst case scenarios implying rupture of the entire fault where such complete fault ruptures may be obstructed by structural thresholds. For Scenario 1, they used a scaling relationship from Wesnousky (2008:1620 - Fig. 8) for Normal Faults which has a quality score of 1 (i.e. best available) according to Stirling et al. (2013)

Mw = 6.12 + 0.47*log10(L)

  L = Length of rupture (km.)

For Scenarios 2 and 3, they used a scaling relationship from Hanks and Bakun (2008:490 - Eqn. 4) for a Fault Area > 537 km.2. This scaling relationship has a quality score of 1 (i.e. best available) according to Stirling et al. (2013)

Mw = 4/3*log10(A) + (3.07 ± 0.04)

  A = Fault Area (km.2)

The scaling relationships chosen followed recommendations of Stirling et al. (2013) and were of subclass A2 (Slow Plate boundary faults with slip less than 10 mm./year) which is appropriate for the Dead Sea Transforms which is estimated to slip at 4-5 mm/year Garfunkel et al (2014).

Calculator - Scaling Relationships

Variable Input Units Notes
Variable Output Units Notes
unitless Moment Magnitude computed using Wesnousky (2008)
unitless Moment Magnitude computed using Hanks and Bakun (2008)