March 11, 2011 Japan Anniversary Earthquake & Tsunami that Struck Japan & Radioactive Detection in the Pacific Coast Ocean - Help JapanNEW

(CNN) -- Here's a look at what you need to know about the earthquake and tsunami that struck Japan in March of 2011.

March 11, 2011 - At 2:46pm, a 9.0 magnitude earthquake takes place 231 miles northeast of Tokyo, Japan, at a depth of 15.2 miles.

The earthquake causes a tsunami with 30 ft waves that damage several nuclear reactors in the area.

It is the fourth largest earthquake on record (since 1900) and the largest to hit Japan.

Number of people killed (most recent)
The confirmed death toll is 15,884 as of February 10, 2014.

Other Facts
Japan had 54 nuclear reactors, with two under construction, and 17 power plants, that produced about 30% of Japan's electricity at the time of the earthquake. (IAEA 2011)

Material damage from the earthquake and tsunami is estimated at about 25 trillion yen ($300 billion).

There are six reactors at Tokyo Electric Power Company's Fukushima Daiichi plant, located about 65 km (40 miles) south of Sendai.

A microsievert is an internationally recognized unit measuring radiation dosage. People are typically exposed to a total of about 1,000 microsieverts in one year.

Detecting Radioactive in the Pacific Coast Ocean from Fukushima
We expect samples from the surface waters of the western Pacific that have not been contaminated by the Fukushima source to have 137Cs activity of between 1 and 2 Bq/m3 and for 134Cs to be "below detection." This is because the only significant source of cesium in the Pacific prior to Fukushima was nuclear weapons testing during the 1950s and 1960s, and with its shorter 2-year half-life, all of the 134Cs from this source would have decayed by now, but because 137Cs has a 30-year half-life, we still see about 25 percent of the amount that was released (50 percent lost in first 30 years, half again of the remaining 50 percent lost in the following 30 years).