An offshore earthquake of magnitude 6.9 collapsed walls of houses and buildings late on Tuesday in a central Philippine province, killing at least 31 people, injuring many others and sending residents scrambling out of homes into darkness as the intense shaking cut off power, officials said.The epicentre of the earthquake, which was set off by movement in a local fault at a depth of 5km (3 miles), was about 19km (12 miles) northeast of Bogo, a coastal city of about 90,000 people in Cebu...