SYDNEY - A shallow earthquake with a preliminary magnitude of 5.7 struck northwest Pakistan on Thursday, the US Geological Survey said.The quake was only 10 kms deep and struck at 6:57 GMT about 140 km (85 miles) northeast of Sialkot in Pakistan, said the USGS. Powerful, shallow quakes are capable of causing extensive damage.Pakistan bore the brunt of a powerful quake centered in Iran last month, killing at least 35 people in Pakistan and destroying hundreds of houses.