08/08/2008 at 07:25 PM EDT
won the hearts of Cedar Rapids, Iowa, residents at a concert Friday – not just with her voice, but also with her generosity.
The 18-year-old country sensation announced onstage in the flood-beleaguered town that she's donating $100,000 to the local Red Cross.
"The people in this town have been through so much loss this year, and my heart goes out to them," Swift tells PEOPLE. "They've stood by me, they gave me a sold-out show. You've got to pay it forward in life – that's all I did in Cedar Rapids."
Two months ago, Cedar Rapids suffered millions of dollars in damages and thousands of job losses when the Cedar River swelled and submerged the town. The devastation along other riverbanks in the state was dubbed "Iowa's Katrina."
"Taylor was going to cancel the concert, thinking few people could attend, but the mayor of Cedar Rapids asked her to carry on," said a source close to the singer.
Swift is no stranger to philanthropy: Earlier this summer, the singer donated her merchandise sales from the CMA Music Festival to the Nashville Red Cross. In January, she also donated a brand-new pink pickup truck
– her 18th-birthday gift from her record label – to a youth camp for children with serious medical conditions.
Also, it was revealed Friday that Swift was nominated for an MTV Video Music Award for Best New Artist.
Her next album, Fearless
, is due out Nov. 11.