He said no fault ruptured on the surface during the series of quakes along the Cotabato Fault System. He said the huge cracks that people saw were what he called tension cracks. Perez said the October quakes in the Cotabato Fault System were caused by the movement of two local faults—the M’lang and the Makilala. Perez’s team is observing the Makilala-Malungon fault, the longest in the Cotabato system, as this fault may cause a 7.2-magnitude quake. He said the Oct. 29 quake was bigger in magnitude than the Oct. 16 quake that preceded it because the latter was a foreshock of the Oct. 29 quake.

Source: Philippine Daily Inquirer November 11, 2019 20:54 UTC