An earthquake measuring 5.4 on the Richter scale shook the Tokyo area before dawn, jolting many residents out of bed and causing minor injuries to at least 19 people. The quake registered at 4:46 am with the epicenter in Ibaraki prefecture about 130 kilometers northeast of Tokyo with a focus 40 kilometers underground, the meteorological agency said. Part of the Japan Railways Joban line to the northeast of Tokyo and a section of a highway in the Joban region were shut down as precautions as inspectors looked to see if they sustained damage. At least 19 people were lightly injured when they fell out of bed or were hit by falling objects such as a television and a stereo speaker, according to a roundup of local authorities by public broadcaster NHK. Police said they had not heard of any life threatening injuries.