The number of people who volunteered for disaster relief activities in Japan from October 2010 to October 2011 probably topped 4.3 million — more than triple the amount logged in the 2006 survey, the government said Monday.

According to the 2011 survey, an estimated 4,317,000 volunteers helped survivors of the March 2011 earthquake and tsunami and other natural disasters, the Internal Affairs and Communications Ministry said.

The ministry made the estimates by analyzing the results of a survey conducted into the social lives of about 200,000 Japanese aged 10 or older in 2011. The results were released ahead of the 18th anniversary Thursday of the Great Hanshin Earthquake, designated as a day for disaster prevention and volunteering in Japan.

The 1995 temblor ravaged Kobe and its vicinity, claiming more than 6,400 lives in western Japan.

By sex, there were about 1.84 million male and 2.48 million female volunteers, with men participating for three hours and four minutes a day on average and women 1 hour and 47 minutes.

Of the total, 74.4 percent volunteered to work for one to four days during the period.

Of the approximately 200,000 people covered in the survey, 3.8 percent took part in disaster relief, up 2.6 points from the previous survey that examined people's volunteer activities in the one-year period through October 2006.

The ministry estimated the total number of disaster-relief volunteers based on the nation's total population of about 128 million, which is shrinking.

By prefecture, the ratio of those involved in disaster relief hit 11.1 percent in both Iwate and Miyagi, 6.9 percent in Yamagata and 6.5 percent in Fukushima — the prefectures affected most by the by the March 2011 quake and tsunami in Tohoku.

By age bracket, over 5 percent of the volunteers were 35 to 54, and 6.0 percent — the highest percentage — were college and graduate school students.

The volunteer ratio was higher at big companies than small ones, the ministry said.