MINAMISOMA, Japan — It was a desperate plea for help, spoken into a small digital camcorder by the mayor of this seemingly forsaken city, and posted on the Internet like a bottle tossed into a digital sea.

In the 11-minute recording, the mayor, Katsunobu Sakurai, described the dire situation facing Minamisoma, whose residents were still reeling from a devastating earthquake and 60-foot tsunami when they were ordered to stay indoors because of radiation leaks from Japan’s crippled nuclear plant, 15 miles away. Those who had not fled now faced starvation, he said, as they were trapped in their homes or refugee shelters by the nuclear alert, which also prevented shipments of food from arriving.

“We are left isolated,” Mr. Sakurai said urgently into the camera, his brow furrowed and his voice strained with exhaustion. “I beg you, as the mayor of Minamisoma city, to help us.”

The video, posted on YouTube a day after it was recorded late on the night of March 24, became an instant sensation, and has since drawn more than 200,000 viewers. Almost two weeks later, the city hall is still getting phone calls, most from non-Japanese calling from abroad with offers to help. The city has also received hundreds of boxes of food and other supplies from individuals, and truckloads of relief goods from nonprofit organizations.