It could be catastrophic for the Byzantines if the earthquake cracks those walls.
Walls of Constantiinople were damaged once after an earthquake during the reign of Theodosius II in 447 AD but he quickly repaired them and added them 11 bands of brick 40cm each brick in order to strengthen their cohession against earthquakes... the 740 earthquake made some significant damage though but it wasnt that bad since Walls were repaired in no time... Plus the part of Walls that fell was the old Wall of Constantine now inside the city while Theodosian Walls didnt suffered any substantial damage...
Constantinople suffered many earthquakes after that but none of it made significant damage to the Walls...
Fortifications started collapsing after the great earthquake of 1509 but the Walls were virtually abandoned by that time...
As for 1167 there could be damages in buildings etc. but not walls...