Central Japan has been struck with earthquake measuring 5.2 on Richter scale this morning. According to Japanese and US authorities, there is no tsunami warning. The quake was at a depth of 10 kilometres about 30 kilometres west of Ina in Nagano region. <br/>'<br/>Shinkansen bullet train services have been temporarily suspended due to the jolt in central Japan, while no abnormality has been reported at nuclear power plants in the region, reports Japanese public broadcaster. There were no immediate reports of injuries or damage. <br/>'<br/>Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year, but do little damage due to rigid building codes. <br/>'<br/>A massive undersea quake that hit in March 2011 sent a tsunami barrelling into Japan's northeast coast, leaving more than 18,000 people dead or missing, and sending three reactors into meltdown at the Fukushima nuclear plant.