An earthquake measuring 6.0 on the Richter scale struck Tokyo and its vicinity Saturday, leaving more than 20 injured and briefly paralyzing the subway and railway systems.

The Japan Meteorological Agency initially put the quake at magnitude 5.7. The strongest intensity registered at upper 5 in one of Tokyo's 23 wards. Japan's seismic intensity scale tops at seven.

This is the largest tremor recorded in the Tokyo Metropolis since February 1992.

The government and police have set up crisis management task forces.

The agency has warned that aftershocks as strong as intensity 4 may occur in the next few days.

The quake hit at about 4:35 p.m. (0735 GMT) and its epicenter was 70 kilometers underground in Tokyo's neighboring Chiba Prefecture, the agency said.

So far, none has suffered life-threatening injuries.

A 93-year-old woman was slightly injured when she fell off the porch at her house. In the neighboring Saitama Prefecture, five people sustained minor injuries by a falling signboard at a supermarket.

Runways at Narita airport near Tokyo were briefly closed. The bullet train service was suspended in a section but soon resumed.

Tokyo's bustling subway and railway systems also have resumed operations hours after the quake.

The government has been taking alert against a major earthquake which is estimated to kill more than 10,000 people.

Source: Xinhua