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.
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.
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.
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 for the Beirut Conversion Quake is summarized below:
Al Harif Aqueduct Syria
possible - wide spread in ages - 4.3 m of slip
probable evidence from a weakly expressed seismic event
possible - 1 cm. thick intraclast breccia
Nahal Ze 'elim
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.
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".
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.
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.