Introduction Textual Evidence Archeoseismic Evidence Tsunamogenic Evidence Paleoseismic Evidence Notes Paleoclimate - Droughts Footnotes References
ANNUS MUNDI 6124 (SEPTEMBER 1, 632— AUGUST 31, 633) a.d. 624Theophanes provides a lot of dating information at the top of this quote some of which is, unfortunately, inconsistent. However, the earthquake takes place at the start of the Muslim conquest of the Levant and there are enough clues in the text, particularly regarding the exploits of the Islamic Army, to establish that the earthquake struck in 634 CE.
Roman Emperor Herakleios: 31 years: year 23
Arab ruler Abu Bakr: 3 years: year 2
Bishop of Constantinople Sergios: 29 years: year 24
Bishop of Jerusalem Modestus: 2 years: year 2
Bishop of Alexandria George: 14 years: year 14
In this year Abu Bakr sent out four generals who, as I said before, were shown the way by the Arabs— they took Hira and the whole land of Gaza. Sergios had just come from Palestinian Caesarea with a few soldiers; he engaged the Arabs in battle but was the first one killed. So were three hundred of his soldiers. The Arabs withdrew after a decisive victory, having taken many prisoners and much booty.
In the same year there was an earthquake in Palestine. Also, a sign — known as an “apparition” — appeared in the southern sky. It was sword-shaped, and remained for thirty days, stretching from south to north and predicting the Arab conquest.
In the year 945 of the Greeks, there was a violent earthquake, in the month of ilul, and after the earthquake there was a sign in the sky; it appeared in the form of a sword stretching from south to north, and remained for thirty days. To many it seemed to signify the coming of the Taiyayz (Arabs)The month of ilul in the Hebrew Calendar dates this earthquake to August/September. In another passage, also provided by Ambraseys (2009), we can read
`At this time [a.S. 946 (Arabs' defeat of Theodoric), before the fourth year of Omar] there was a great earthquake, and at the moment of the earthquake the sun was eclipsed. In this earthquake the church of the Resurrection and that of Golgotha fell, together with many other places. Modestus, the Chalcedonian bishop, rebuilt them.The reported destruction of the Church of the Holy Sepulcher (aka Church of the Resurrection and that of Golgotha) during this earthquake is a false synchronicity. The church was destroyed by the Persians in 614 CE and restored in 629 CE by Modestus. It was intact when Omar took possession of Jerusalem in 637 CE (Le Strange (1890: p. 202).
There was a great earthquake in Palestine for thirty days and also a great plague arose in the same place.' (al-Mak. HS. i. 2/19).
`There was a great earthquake in Palestine which lasted thirty days. The shock was violent and was followed by a great plague.' (al-Mak. HM. i. 2/20).An earthquake lasting 30 days is presumed to describe an earthquake with an extended period of aftershocks.
20th September, 634.This comet appears to date this earthquake fairly conclusively to September 634 CE. Although the sources may have succumbed to creating a forced synchronicity by having the comet appear immediately after the earthquake, even with a delay the earthquake likely struck in September. The description of a "sword in the sky" appears to be a poetic description of a comet where the use of the word sword ties it to the military exploits of the Rashudin Army adding allegory to the account; something which would have been understood by the Christian authors who wrote about it and their intended audience.
On the 23rd day in the eighth month of the eighth year of the Chen-Kuan reign-period a (po) comet appeared at the Hsu and the Wei (11th and 12th lunar mansions) for 11 days before going out of sight [30th September].
(CTS 36/5b; HTS 32/5b; THY 43/la; WHTK 286/21b; W177.)
Williams follows the HTS which says that the comet appeared on a chia-tzu day (22nd September).
The Japanese records, "During the eighth month of the sixth year of Jomei-tenno [29th August to 27th September approx.] a (chhang-hsing) comet was seen at the south. During the first month of the seventh year [24th January to 22nd February, 635 approx.] the (hui) comet turned round and appeared at the E."
(Dainihonshi ch. 359; Nihongi tr. Aston vol. II pp. 166 and 167; K.)
|Bet Sh 'ean||possible|
|Pella||possible and needs investigation|
|Monastery of Khirbet es-Suyyagh||possible I = IX|
|Mount Nebo||needs investigation|
|Ein Hanasiv||possible - needs investigation|
|Avdat/Oboda||definitive - I = IX-X|
|Shivta||possible I = VIII to IX epicenter a few tens of km. to the WSW or NE|
|Rehovot ba Negev||possible|
|Mamshit (aka Mamphis)||possible - I => IX epicenter to the Southwest|
|Haluza||possible - I = VIII to IX waves arrived on NE-SW axis probably from NE, epicenter a few tens of kilometers away|
|Haluza||possible - I = VIII to IX waves arrived on NE-SW axis probably from NE, epicenter a few tens of kilometers away|
MacDonald (1992)  collected some Byzantine and Umayyad surface potsherds at the site and documented ruins of Byzantine houses (village) along the fan surface of Wadi Tilah.It is not known if the location was still occupied or only partially occupied when the Jordan Valley Quake struck in 659/660 CE. If the site was abandoned around the same time as the archeoseismic sites in the Negev (~640 CE ?), it may have been empty enough not to have been repaired if the Jordan Valley Quake caused further damage. Because of the repair, it it is unclear how much lateral slip was produced.
Fitzgerald (1931:7) uncovered three Byzantine houses that had collapsed and burned in the early 7th century, sealing coins of Anastasius I, Justin II, Maurice Tiberius. and Phocas beneath their destruction debris. a temporal span ca. 491-610.Such damage could have also been the result of sacking by the Rashudin Army. Archeoseismic evidence at Bet Sh 'ean is labeled as possible.
In the Byzantine monastery at Beth-shan, gold coins of Heraclius (610- 641) were sealed beneath similar collapse debris Fitzgerald (1939:2) .
Two roughly square rooms, each approximately 4 x 4 meters wide and built against the inner face of the Hellenistic wall, occupied most of N.l and N.2. Masonry walls, four courses high, delineated the space. The original rooms were separated by what appears to have been an open air corridor; a door in the east wall of N. l and one in the west wall of N.2 allowed passage between the two rooms. The floors of these rooms (N.1: 18, N.2: 16) were made of a hard packed, yellowish clay, which was badly broken and pocketed in many places by wall collapse. Upper courses of the walls of the rooms had fallen onto the floor and crushed several large storage jars and basins and cookware (Fig. 16), dated in the field to the transitional Byzantine-Umayyad period. The only foundation trench identified (N.2: 25) yielded no pottery. The fill above these floors contained pottery that was late Umayyad and Abbasid in date. While it is not possible at this early stage of excavation to determine when this structure was first built, it was clearly occupied in the middle of the seventh century, suffered a catastrophic event, and was reoccupied (at some point) and used into the ninth century. Fallen architecture, crushed pottery, badly damaged floors that appeared to have "melted" around the fallen blocks, and wide and deep ash pits and lenses bare witness to a major conflagration. The most likely candidate for this is the recorded earthquake of 658/9, which was one of the most destructive in Jordan's history since the Roman period, rather than the Islamic conquests of the 630's (El-Isa 1985: 233).As dating is no more precise than the 7th century CE, archeoseismic evidence at Tall Hisban is labeled as possible.
Excavations in the early 1980s identified six house units destroyed in the earthquake of 749. These houses represented the last phase in a long urban development that commenced with the complete redevelopment of living quarters on Pella's main mound in the first half of the sixth century (Watson 1992). The original arrangement consisted of four-metre wide gravelled streets set out on a formal grid, each street flanked by stone and mudbrick terrace-style houses two storeys high, prefaced in some places by shops. These streets, intended to serve local needs, were not equipped with colonnades or sidewalks. Although modified, the layout remained the same until an earthquake in 659-60 required a rebuilding of the quarter, in which the linear terrace houses were replaced by independent, self-contained units centred on one or more sizeable courtyards.Walmsley (1982) discussed this in more detail noting that:
only in one trench (IVE) has the Sydney team excavated much below the A.D. 746/7 surface, producing evidence for at least three Byzantine and Umayyad architectural phases. Since an attempt to establish a detailed chronology for the whole Umayyad period on the basis of this one trench would be premature, the following account concentrates on the final phase in the life of urban Pella.The earthquake of 717 CE refers to an earthquake which Ambraseys (2009) and Guidoboni et. al. (1994) locate in Syria and Upper Mesopotamia. None of the sources mention specific localities except for a conflation mistake by Pseudo-Dionysius of Tellmahre. However, reports from Upper Mesopotamia suggests an epicenter far from Pella indicating that another closer earthquake may have been responsible for this tentatively identified and dated archeoseismic evidence. Archeoseismic evidence at Pella is labeled as possible and needs further investigation.
We turn now to a consideration of the layout and use of the buildings in Areas III and IV (figs 28-29 and end-plates 2-3). A dominant feature of Pella in the Byzantine and early Umayyad periods appears to have been streets with packed mud and pebble surfaces. One such street, 5 m wide, ran east-west through Area IV. From it, north and south, doorways gave access to dwellings, hence referred to as the North and South Buildings. But at some stage during the Umayyad period the street was cut by a wall which continued south to form the west wall of the South Building. Before this event it appears that this building had covered a considerably greater area; now to the west of the north-south Umayyad wall the earlier walls were razed level with the new and final occupation surface of a courtyard. Into this surface were dug lightly fired clay tabuns. Although the date of the demolition of the western sector of the South Building and of the construction of the north-south wall is uncertain, the slight build-up of de¬tritus on this surface points to a time not far removed from the final destruction of A.D. 746/7. Tentatively we ascribe these alterations to the period following the earthquake of A.D. 717.
Damaged architectural remains can be recognised throughout the site. Signs of destruction and nearly immediate rebuilding combined with absence of signs of man-made violent actives are typical earthquake-related features.This suggests that the Jordan Valley Quake, the Sword in the Sky Quake and/or possibly even the Sign of the Prophet Quake damaged the site with the Jordan Valley Quake the most likely candidate. Archeoseismic evidence at the Monastery of Khirbet es-Suyyagh is labeled as possible . Seismic Intensity is estimated at IX (1 g).
The area of the large courtyard (Fig. 2.1:8-10) had been completely rebuilt after a destructive event. An earlier construction phase, which is observed south of the centre of the courtyard (Fig. 2.1:9), is covered by a later floor. Fallen masonry and subsequent repairs were observed in the southern part of the apse of the church, with its inner face remaining asymmetric. Since the damage is observed close to the foundations of the church it seems that the damage had a pervasive affect on the entire structure. A section of about 10 m in the southern end of W33 seems also to have been rebuilt. Similarly, in W100 there is a warped contact in room 19, where two different styles of masonry meet but are misaligned.
Another type of damage appears in two broken door thresholds, that of the main gate and that of the small courtyard in the south of the monastery. The large, monolithic and nicely carved stones are placed in-situ but broken by a width wise crack into two pieces. Assuming the thresholds were carved from intact rocks without significant fractures, we can envision strong vertical acceleration, perhaps of the order of lg, which caused the fracturing. Such strong shaking is known based on modern earthquakes to occur either near the epicentre of strong earthquakes (of the order of magnitude 7 and above) or in places with strong local amplification of seismic waves.
Each of the damaged elements alone would not suffice to indicate an earthquake as the damaging agent. However, the occurrence of many such elements, the extensive repair and reconstruction of features without any sign of human violence and in short time, together with the frequent occurrence of earthquakes in the region supports the association of the damage to earthquake/s.
stratigraphic analysis of the site of Caesarea Maritima shows a destruction level dating to c. AD 630 it is not certain whether this can attributed to an earthquake or to a Persian invasion.Archeoseismic evidence at Caesarea is labeled as needs investigation.
Indeed, Russell remarks that it is impossible to ascertain the effects of this and the AD 632 (634) earthquake on the Mt Nebo monastery owing to the manner in which the excavations were conducted.However Russell (1985) correlates archeoseismic destruction at Mount Nebo to the Mount Lebanon Thrust Quake of 551 CE and the Sabbatical Year Earthquake of 746/749.
This earthquake also appears to have been responsible for the destruction and subsequent abandonment of the Town of Nebo (Saller and Bagatti 1949: 217, n. 2).January 748 CE entry - p. 49
The final destruction of the basilica at Mt. Nebo also appears to correlate with this earthquake (Schneider 1950: 2-3),Notes - p.54
At Mt. Nebo (Sailer 1941: 45-46) and Aereopolis (Zayadine 1971) in the region of ancient Moab, recovery after the 551 earthquake apparently did not occur until the end of the century. Related to this delayed recovery is the possibility that an influx of southeastern populations from decaying urban centers like Petra subsequent to the 551 earthquake was responsible for the intensified building during the late 6th and early 7th centuries in both Moab (Sailer 1941: 248) and the Negev (Kraemer 1958: 23. 28-29; Colt 1962: 21-22).This archeoseismic evidence is labeled as needs investigation.
- inclination of wall blocks
- collapse of wall fragments
- displacements and shifts of individual stones in walls, arches and columns
- rotation of single stones and larger fragments of arches and walls
- fractures passing through several adjacent stones
the Byzantine village of Avdat was destroyed by an earthquake between 631 and 633 AD with a local MSK-64 intensity of IX-X.Erickson-Gini (personal correspondence, 2021) relates that this site in the Negev suffered seismic damage in the 7th century CE - sometime after 620 CE. Avdat (aka Oboda) was abandoned in the 7th century; likely after the Sword in the Sky earthquake.
DISCUSSION AND CONCLUSIONSErickson-Gini (personal correspondence, 2021) relates that this site in the Negev suffered seismic damage in the 7th century CE - sometime after 620 CE. Archeoseismic evidence at this location for the Sword in the Sky Quake is labeled as possible.
- The ancient city of Shivta is situated on flat low-land, built of massive carbonate bedrock. Hence, no site-effects are expected to have affected the patterns of seismic damage.
- Walls of buildings and agricultural fences trending SE (130°±15°) reveal collapse in a preferential direction towards the SW (Fig. 8), whereas walls oriented NE (40°±20°) reveal random collapse.
- This key observation indicates that the seismic waves arrived either from the SW (in the case of a compression wave), or from the NE, if the collapse happened in an extensional quadrangle (Korjenkov and Mazor, 1999a). In any case, the SE and NW directions of seismic wave propagation can be excluded.
- Rotations of blocks are observed at the Shivta ruins to be clockwise at walls trending NE (40°-50°), and counterclockwise at walls trending SE (115°-130°), as shown in Fig. 6c. Such rotations could be caused only by push movements by compression waves. Thus, the seismic waves arrived from the SW.
- The Shivta ruins disclose two main perpendicular directions of walls: NE (30°-60°) and SE (120°-150°), as can be seen in Fig. lc. Hence, all the buildings of the Byzantine city can be modeled via a "representative room" depicted in Fig. 16. Three possible scenarios warrant discussion: (a) seismic waves arrived parallel to the NE-trending walls (Fig. 16a) — the shear stresses along the walls would be minimal, and hence no rotation would be caused, and only collapse of NW walls would be systematic; (b) seismic waves arrived from the west, i.e., along a line of the bisector between the wall directions—both NE and SE trending walls would reveal oriented collapse to the NW and SW sides respectively; walls with a NE trend would reveal clockwise rotation, and walls with a SE trend would reveal a more or less equal number of counterclockwise rotations; (c) seismic waves arrived from the WSW, i.e., at a different angle to each of the wall directions — the SE walls would manifest systematic collapse generally toward the SW, whereas the NE walls would show random collapse; rotations of elements of walls trending NE would be clockwise, whereas rotations of stones of the SE-trending walls would be counter-clockwise. The field observations fit this solution (c).
- A few hundred individual observations, made at almost one hundred locations at the ancient city of Shivta, revealed the 19 types of damage patterns reported above. Part of these observations are useful in determining the axis along which the seismic waves propagated (WSW—ENE), other observations point out that the epicenter was located WSW of the city, and yet another group of observations points to an intensity of I= 8-9 (MSK-64 scale) of the earthquake that destroyed the Byzantine city in the 7th century.
- The distance of the epicenter of the earthquake that destroyed Byzantine Shivta can be estimated from the following boundary conditions and considerations: (a) the systematic pattern of destruction indicates dominance of horizontal seismic movements, which in turn rules out the possibility that the hypocenter was beneath the city (i.e., Shivta was not at site A of Fig. 17); (b) on the other hand, the dominance of a horizontal component of the seismic movements implies that the epicenter was at a distance that at least equaled the depth of the hypocenter (i.e., Shivta was at site B of Fig. 17); (c) the intensity I = 8-9 (MSK-64 scale) limits the distance of the epicenter probably to less that 30 km, a conclusion that has to be checked by data from more sites from the Negev, applying the "triangulation method".
- An attempt to locate the epicenter of the post-Byzantine earthquake at Shivta is made by applying the reconstructed WSW direction of the epicenter, and the concluded epicenter distance of a few tens of kilometers. These boundary conditions were projected on the geological map of Israel: the concluded direction of the epicenter crosses the Zin fault at a distance of 10 km, and the adjacent Nafha fault crosses with the direction of the concluded epicenter at a distance of 50 km. In any case, the results clearly point out that the epicenter was in the Negev highlands and not in the Dead Sea Rift Valley.
- The seismic damage patterns described so far were observed on buildings built in the Byzantine period and in secondary walls added later on, leading to the conclusion that at least two earthquakes damaged the Byzantine and post-Byzantine constructions.
- The described variety of seismic damage patterns provides tools to establish certain characteristics of the involved earthquakes, e.g., seismic intensity, axis of seismic waves propagation, and in the case of systematic rotation, also the specific direction of the epicenter. In a more advanced stage of the archeoseismological study, the investigations in individual sites can be put together into a regional picture that provides more definite answers on the nature of the studied earthquakes. For example, the Negev data from several ancient ruin centers may be compiled, e.g., Mamshit, Avdat, Rehovot, Haluza, Hurvat Sa'adon, Shivta, and Nizzana (Fig. 1). In other words, the triangulation approach is recommended (Korjenkov and Mazor, 1999a,b).
- The common descriptions of damage patterns typifying different earthquake intensities are based on the inventory of modern buildings. The present work brings up additional damage patterns observed in ancient architectural complexes, e.g., damage pattern of stone arches, systematic tilt, collapse and rotation of stone building elements, the distance to which collapse debris is thrown away from the respective foundation, as well as preferential collapse of colonnades observed in many published case studies.
- The described archeoseismological study has modern applications in regard to specifications of seismic safety to be taken into account in new constructions in the Negev highlands.
- Finally, the described archeoseismological work lends itself to inter-regional and international collaboration in the construction of a seismic archive that goes back thousands of years.
A clear terminus ante quem for the building of the church is given by a burial inscription (Ins. 2) dated to the month Apellaios 383, which falls, according to the era of the Provincia Arabia, in November- December 488 C.E. The church probably was erected in the second half of the fifth century. (See below the subsequent general discussion of the triapsidal basilicas beginning on p. 47.). Although it is clear that several parts of the complex were built later than the main hall, such as the northern chapel (see 111. 1 15), there is no doubt that the entire complex was constructed within the same few year.Later on he noted that
A date of approximately 460-470 for the building activity therefore seems reasonable, although the calculation remains hypothetical.After initial construction, additional architectural elements were added; foremost among them a a revetment or support wall which is described and discussed below by Tsafrir (1988: 27).
The most important architectural addition was the talus, or sloping revetment, that was built around the walls of the church from the outside to prevent their collapse. Such revetments were common in the Negev. They supported the walls of churches as well as of private houses. They are found, for example, around the walls of St. Catherine's monastery in Sinai. At Rehovot such walls may have been erected following an earthquake, but more probably it was necessary to reinforce them just because of poor quality masonry. To explain these retaining walls as having created a military defense post (as has been done in the case of the northern church at Shivta) is awkward.Khorzhenkov and Mazor (2014: 84) identified what they believed were three (or more) earthquakes which had expressions in the walls of the northern church. The first two earthquakes struck after construction of the church around 465 CE and before the site was abandoned by its Christian inhabitants around 640 CE (when the Byzantine Empire permanently lost power in the area and could no longer support these peripheral outposts). A later earthquake struck during the Early Arab period - after ~640 CE.
The existence of revetment walls, supporting the southern wall of the Church from the south, indicates that the southern wall’s tilt occurred during the first of the Late Roman earthquakes. It seems that the southern wall began to tilt northward inside the building during the Early Arab earthquakes; additional evidence for this is the shift northwards of the upper part of the revetment wall. Stones of the perpendicular eastern wall are cracked in the small room marked on the plan. Nevertheless, this wall is better preserved (it is much higher) than the main southern wall of the North Church. This indicates that the seismic shocks during both earthquakes acted perpendicular to the main Church wall: it had freedom of oscillation and was significantly destroyed. The small eastern wall, oriented parallel to the effect of the seismic movements, withstood the seismic oscillations better, although many of its stones were significantly damaged. The whole northern wall of the Church (field station 12 in fig. 3) has a significant tilt to the south (figs. 8 a. b).Khorzhenkov and Mazor (2014:84) discussed the two late Byzantine quakes (between 465 CE and 640 CE) further
The destruction event (an earthquake), which deformed the original wall, occurred before the decline of the Byzantine Empire. There was then another seismic event which led to the destruction of the revetment wall itself. The last event was probably an end of ›civilized‹ life here.Rodkin and Khorzhenkov (2019) noted that
Another strong earthquake occurred during the 7th century AD. This could be the same earthquake that destroyed Avdat [ Korjenkov and Mazor (1999), Fabian (1998)]. This earthquake could also drive the inhabitants out of Rehovot, which occurred soon after (or slightly before) of the Arab conquest.This suggests that the Late Byzantine earthquakes that struck Rehovot ba Negev could include some combination of the following
Settlement at the site reached its highest point in the seventh century CE. The Muslim conquest of the area apparently did not harm Nessana’s Christian population. On the contrary, the largest church discovered at the site—the “Central” Church in the lower town (area F)—was built in the late seventh or early eighth century. It continued to function without interruption during the eighth century, and only at the end of that century, or early in the ninth century, did it pass into Muslim hands. Incidentally, there is no clear indication of a violent Muslim conquest of Nessana during the seventh and eighth centuries. While it is true that some of the residential buildings uncovered in the new excavations contained evidence of structural changes dated to those centuries, such as blocked doorways and the construction of new floor levels (in areas B, C, and R), it has not yet been determined whether these changes were a consequence of earthquakes in the region or were motivated by other circumstances. Nevertheless, the copious amounts of sherds and glass fragments, including luxury items recovered from these houses, clearly indicate that the economic status of Nessana’s population remained stable under Muslim rule.Archeoseismic evidence at Nessana is labeled as possible.
The Early Arab – "Second" Ancient EarthquakeArcheoseismic evidence for the Sword in the Sky Quake at Haluza is labeled as possible.
Negev (1976) suggested that a strong earthquake caused the final abandonment of Haluza. He summed up his observations at one of the excavated courtyards:Voussoirs of the arches and extremely long roof slabs were discovered in the debris, just above the floor. It seems that either the destruction of the house occurred for a very short time after its abandonment or the house had to be abandoned because of its destruction by an earthquake.The date of destruction could be 632/3 A.D., i.e. at the time the Byzantine city of Avdat was destroyed and other ancient towns of the Negev desert were ruined. However, archaeological data demonstrate that occupation of the site continued until at least the first half of the 8th cent. A.D.. So, most probably, the date of destruction by an earthquake was 749 A.D., as the best match with the earthquake catalog of Amiran et al (1994)
Joints crossing several adjacent stones (e. g. Fig. 4) indicate destruction by a high-energy earthquake, as the energy was sufficient to overcome the stress-shadow of the empty space between the building stones.
Tilts of the walls (Fig. 10), fallen columns (Fig. 13), shifted collapse of an arch (Fig. 11), shift of a stone row of the wall (Fig. 15) – all these observations disclose that the destructive seismic waves arrived along a NE-SW axis (~40º), most probably from NE.
Although all of the buildings in the city were well built and had one or two floors, all of them were severely damaged by an earthquake. The significant seismic deformations observed in the buildings indicate a local seismic intensity of at least I = VIII–IX (MSK Scale). This requires a strong shock arriving from a nearby epicenter, most probably a few tens of kilometers from Haluza. This supposition is based on the fact that short-period seismic waves, which tend to be destructive to low structures (which have short-period harmonic frequencies), attenuate at short distances from the epicenter.
 Note by Jefferson Williams : While Amiran et al (1994) is one of the error prone catalogs, 749 A.D. refers to well attested earthquake.
|En Gedi||no evidence|
|Nahal Ze 'elim||no evidence|
|Qatar, Jordan||no evidence|
Heraclius transgressed the Law and took Martina, his brother's daughter, to wife, and begat by her an illegitimate son, Herakluna. In the same month of Elul [September], an earthquake took place. And a sign, like unto a spear, appeared in the heavens, and it remained there for 30 days. This manifestly made known the victory of the Arabs.The passage relates an earthquake striking in September followed by a "sword (or spear) in the sky" which lasted for 30 days. There is no synchronism of the earthquake with Heraclius marriage to his niece in Bar Hebraeus' account. The author stated that the earthquake occurred in September which was the same month as when Heraclius married his niece. He does not mention that these two events are separated by ~21 years. The events are juxtoposed in the text by use of a common month to make a theological point - that Heraclius' transgression with his niece is linked somehow with the way the earth reacted to these events with the assumption that the earth was manifesting something from the supreme being.
The comet mentioned by Theophanes, Cedrenus, and Michael the Syrian would not have been Halley's. since it would have returned to earth ca. March 13.607 and again ca. September 28, 684. The changing form of the comet, which first appeared in the shape of a cross and later assumed the form of a striking sword reflects its movement at perihelion.
Ambraseys, N. (2009). Earthquakes in the Mediterranean and Middle East: a multidisciplinary study of seismicity up to 1900. Cambridge, UK, Cambridge University Press.
http://books.google.com/books/about/Earthquakes_in_the_Mediterranean_and_Mid.html?id=x2veAAAACAAJFabian, P.: 1995, The Roman and Byzantine Near East: Some Recent Archaeological Research, J. Roman Archaeology, Suppl. Series, No. 14, pp. 235-240.
Guidoboni, E., et al. (1994). Catalogue of ancient earthquakes in the Mediterranean area up to the 10th century. Rome, Istituto nazionale di geofisica.Guidoboni et. al. (1994)
Russell, K. W. (1985). "The Earthquake Chronology of Palestine and Northwest Arabia from the 2nd through the Mid-8th Century A.D." Bulletin of the American School of Oriental Research 260: 37-59.
http://www.jstor.org/discover/10.2307/1356863?uid=2129&uid=2134&uid=2&uid=70&uid=4&sid=21103904944403Wechsler, N., et al. (2014). "A Paleoseismic Record of Earthquakes for the Dead Sea Transform Fault between the First and Seventh Centuries C.E.: Nonperiodic Behavior of a Plate Boundary Fault." Bulletin of the Seismological Society of America.