TOKYO (Reuters) -A moderate earthquake jolted Tokyo and its vicinity on Sunday afternoon, causing buildings in the capital to shake, but no tsunami warning was issued and there were no immediate reports of damage.

Japan”s Meteorological Agency said the quake had a preliminary magnitude of 5.1 and was centred in southern Ibaraki prefecture, north of Tokyo. The earthquake”s focus was 40 km (25 miles) underground.

The quake set off alarms in convenience stores and left displays of goods in disarray.

Trains in the Tokyo area and surrounding regions were generally running as normal, although some were running at lower speeds as a precaution, national broadcaster NHK said. There was no effect on Tokyo”s Narita Airport, the broadcaster said.

Subway services in Tokyo were halted briefly, but have now resumed at lower speeds, NHK said.

Japan is one of the world”s most earthquake-prone countries, with a tremor occurring at least every five minutes.

Located in the &#34Ring of Fire&#34 arc of volcanoes and oceanic trenches partly encircling the Pacific Basin, the country accounts for about 20 percent of the world”s earthquakes of magnitude 6 or greater. Every year, there are up to 2,000 quakes that can be felt by people.