Beirut Conversion Quake

347/348/349 CE

by Jefferson Williams

Introduction     Textual Evidence     Archeoseismic Evidence     Tsunamogenic Evidence     Paleoseismic Evidence     Notes     Paleoclimate - Droughts     Footnotes     References


Two late Byzantine writers (Theophanes and Cedrenus) report an earthquake causing extensive damage in Beirut and the Lebanese littoral in 347, 348, or 349 CE. According to both sources, most of the city collapsed. The dates supplied by the two sources use different calendar systems (Anno Mundi 5840 or the twelfth year of Constantius II) which, though inconsistent, constrain the date of this earthquake between 1 September 347 CE and 9 September 349 CE in the Julian Calendar. Although Ambraseys (2009) states that the dating between the two sources is consistent, he was apparently mistaken in this judgment.

In some catalogs, a possible tsunami is reported in association with this earthquake. A tsunami was not mentioned in either source. Although a tsunami was not mentioned, it is possible that this earthquake did generate a tsunami as the damage reports come from the coastal city of Beirut. Further details can be found in the Tsunamogenic Evidence section of this catalog entry.

Textual Evidence

The Chronicle of Theophanes the Confessor

Theophanes the Confessor wrote The Chronicle in Greek between 810 and 815 CE as a continuation of the Chronicle of his friend George Syncellus. In the translation by Mango Scott (1997), one can find the entry for Anno Mundi 5840 on page 65.
A.M. 5840: In that year a great earthquake occurred in Berytus in Phoenicia, and most of the city collapsed. Most of the people had gone to the church, for, like us, they had become Christians when the Gospel was preached to them.
Anno Mundi (A.M.) comes from a calendar used by Byzantine authors. At the time Theophanes was writing, each year began on September 1 and ended on August 31. Mango, C. and R. Scott (1997) date A.M. 5840 from 1 September 347 CE to 31 August 348 CE.

Synopsis Historion by Georgius Cedrenus

Georgius Cedrenus compiled Synopsis Historion in the 11th century CE. On page 523 of the text (p.299 in the margin note), one can read (in Greek and Latin)
In the 12th year [of Constantius II's reign] there was a great earthquake in Berytus in Phoenicia, and most of the city collapsed.
Constantius II was elevated to Augustus (Emperor) on 9 September 337 CE upon the death of his father Constantine the Great. The 12th year of his reign would place this earthquake between 9 September 348 CE and 9 September 349 CE. According to Guidoboni et. al. (1994), Grumel (1958) dated this earthquake to 348 CE.

Archeoseismic Evidence

Tsunamogenic Evidence

Tsunami Report

Several catalogs ( e.g. Ambraseys (1962), Antonopoulos (1979), Antonopoulos (1980a), and Sbeinati et. al. (2005) ) consider the possibility that a tsunami was associated with this earthquake. While this is valid speculation, none of the historical sources mention a tsunami. The way a tsunami entered these catalogs is likely via Sieberg (1932b) who mentioned damage on the Island of Arwad due to this earthquake.
348. Zers Arendes Beben an der syrischen kaste, wobei vor allein Berytus und Aradus (Ruad) litten

Translation : Earthquake on the Syrian Coast where Beirut and Arwad Island suffered.
The Island of Arwad is approximately 100 km. from Beirut. In the apparently larger earthquake in Beirut in 551 CE, Sieberg (1932b) mentions widespread destruction in Beirut and that the earthquake was only felt in the Island of Arwad. He does not say it suffered. Based on this, if Sieberg (1932b) mentions suffering on the Island of Arwad due to the Beirut Conversion Quake, the suffering would likely be due to a tsunami rather than seismic shaking. Unfortunately, Sieberg (1932b) did not list his sources. As neither of the sources (Theophanes and Cedrenus) mention damage on the Island of Arwad, this tsunami report, though possible, is likely a false report. Salamon et. al. (2011) concurred that the tsunami report was probably a false one.

Although none of the sources mentioned a tsunami, Elias et. al. (2007) and Darawcheh et. al. (2000) noted that a tsunami did occur during the 9 July 551 CE Mount Lebanon Thrust Quake which destroyed much of Beirut. The 551 CE tsunami is corroborated by numerous ancient sources (e.g. see Ambraseys (2009) and/or Guidoboni et al (1994)) and indicates that is possible that a tsunami did strike the coast during the Beirut Conversion Quake of 347/348/349 CE.

Paleoseismic Evidence

Paleoseismic Evidence for the Beirut Conversion Quake is summarized below:

Location Status
Al Harif Aqueduct Syria possible - wide spread in ages - 4.3 m of slip
Bet Zayda probable evidence from a weakly expressed seismic event
En Feshka possible - 1 cm. thick intraclast breccia
En Gedi none reported
Nahal Ze 'elim none reported

Displaced Aqueduct at al Harif, Syria

Sbeinati et. al. (2010) report a seismic event X which they dated to 335 AD +/- 175 years at a dispalced aqueduct at al-Harif, Syria (close to Masyaf, Syria). The al-Harif aqueduct is 154 km. from Beirut.

Al Harif Aqueduct Seismic Events
Figure 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)

Al Harif Aqueduct Radiocarbon
Figure 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 earth-quakes (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)

Bet Zayda

In paleoseismic trenches just north of the Sea of Galilee (aka Lake Kinneret), Wechsler at al. (2014) identified 3 events which could fit this earthquake. We suggest that Event CH4-E2 is the most likely candidate. Wechsler et al (2014) noted that "evidence for event CH4-E2 is weaker than that of some events".

Bet Zeyda Earthquakes
Figure 9. Probability density functions for all paleoseismic events, based on the OxCal modeling. Historically known earthquakes are marked by gray lines. The age extent of each channel is marked by rectangles. There is an age uncertainty as to the age of the oldest units in channel 4 (units 490-499) marked by a dashed rectangle. Channel 1 refers to the channel complex studied by Marco et al. (2005).

Dead Sea

En Feshka
Kagan, E., et al. (2011) report a 1 cm. intraclast breccia at 228.0 cm. depth to which they assigned a date of 349 AD. Due to the distance involved (En Feshka is 240 km. from Beirut), this seismite might not have been generated by the Beirut Conversion Quake. If the seismite at En Feshka was generated by the Beirut Conversion Quake, this would likely indicate a wave guide effect was at play in the Jordan Valley reducing attenuation of seismic energy arriving at En Feshka. Modeled ages from Table 3 are presented below.

En Gedi (DSEn)
Migowski et. al. (2004) did not assign any seismites to any dates between 347 and 349 AD.

Nahal Ze ‘elim (Site ZA-2)
Kagan et. al. (2011) did not assign any seismites to any dates between 347 and 349 AD.



The Chronicle of Theophanes the Confessor

Theophanes the Confessor wrote The Chronicle in Greek between 810 and 815 CE as a continuation of the Chronicle of his friend George Syncellus. In the translation by Mango and Scott (1997), one can find the entry for Anno Mundi 5840 on page 65.
[AM 5840, AD 347/8]

Constantius, 12th year
Sabores, 46th year
Liberius, 3rd year
Eusebios, 3rd year
Cyril, 8th year
Athanasios, 19th year
Phlakitos, 5th year

ln this year most of the city of Berytos in Phoenicia collapsed during a severe earthquake. As a result, many pagans entered the Church professing to be Christians just like us. Thereupon some of them introduced an innovation and went forth after robbing, as it were, the Church of her usages. They appointed a place of prayer and received the throng into it, imitating all the customs of the Church and becoming very close to us (just as the heresy of the Samaritans [is close] to the Jews), while still living in the pagan fashion.
The text in its original Greek can be read at this link on page 58.

Paleoclimate - Droughts



Cedrenus, G., et al. (1838). Georgius Cedrenus, Ioannis Scylitzae ope, E. Weber (in Greek and Latin)

Grumel, V. (1958). La chronologie, Presses Universitaires de France.

Mango, C. and R. Scott (1997). The Chronicle of Theophanes Confessor(in English)

The Chronicle of Theophanes the Confessor (in Greek)