Geoffrey of Donjon
Geoffroy de Donjon (died 1202 in Acre), also known as or
Geoffroy de Duisson, was the 11th Grand Master of the Knights Hospitaller serving from 1193 through his death in 1202
(
wikipedia and
Theresa M. Vann in Murray, 2006:604 ).
A letter written by him to
King Sancho VII of Navarre describes and dates the earthquake.
Mayer (1972:300) notes that the letter is not dated
but is dateable
from internal evidence because it reports the great earthquake which shook the East on May 20, 1202, and expressly mentions this date
.
Mayer (1972:300-301) assumes that it took some time to
assemble reliable news
from various parts of the country
and
safely
dates its composition to June 1202 CE.