Japan tsunami

A magnitude 9.0 earthquake hit northern Japan on March 11, triggering tsunamis that caused widespread devastation and crippled a nuclear power plant. The amount of radioactive iodine in Tokyo's tap water dropped considerably in a test Thursday morning, down to a level that would be considered safe for infants to drink, the city's government said.

Tests from 6 a.m. Thursday at the Kanamichi Water Purification Plant, which provides water to 23 wards in Tokyo as well as five other cities, showed 79 becquerels of radioactive iodine per kilogram of water. A becquerel is a measurement of  radioactive intensity by weight. This is below the 100 becquerel level, the maximum that could be considered safe for infants ages 1 and younger.