The first major earthquake occurred on April 4 at 8:58 pm Philippine Standard Time, with a surface-wave magnitude of 5.5 off the coast of Batangas.

[6] At 1:00 pm on April 7, PHIVOLCS stated that they have recorded 934 aftershocks; 118 of which were plotted and while 14 were reportedly felt.

PHIVOLCS recorded the first earthquake which occurred near Mabini at 3:07 pm as having a surface wave magnitude of 5.6 while the second earthquake which happened in Talaga Proper, Mabini, Batangas, at 3:09 pm was recorded as having a surface wave magnitude of 6.0.

[9] The Basilica of the Immaculate Conception Church in Batangas City also sustained damage on its walls during the April 8 quake.

The switchyard of San Lorenzo Power Plant was damaged and a transmission tower was toppled also by the earthquakes.

As a result, the power supply reserve for Luzon decreased, leading the National Grid Corporation of the Philippines to place the Luzon Grid on "yellow" alert on April 10 and 11, and the Department of Energy ordered immediate repair of power plants damaged.

[13][14] A policy to protect the grid from earthquake damage is being drafted by the Department of Energy after the quakes.