Complex sentence: The quake occurred on the 32nd anniversary of the 1985 Mexico City earthquake with 10,000 casualties; a national earthquake drill had been scheduled for 1 p.m. local time.
Split into simpler sentences: The quake occurred on the 32nd anniversary of the 1985 Mexico City earthquake with 10,000 casualties. A national earthquake drill had been scheduled for 1 p.m. local time.