Just before a 9.0 magnitude earthquake struck Japan on March 11, 2011, tourist Mark Avancena remembered “an unusual silence, like the world had stopped.” Then “the earthquake started and … It felt like it went on forever.”

The quake and the tsunami it caused left 15,894 confirmed dead. It was the fourth-largest earthquake on record and the largest to hit Japan.

The Obama administration pledged assistance and declared, “America will stand with Japan as they recover and rebuild.”

Even as the United States government took action, the American people stepped up, donating $730 million to charities and relief organizations helping disaster victims. The Japan Center for International Exchange (JCIE) called it “the largest philanthropic response ever in American history for an overseas disaster in another developed country.”

And, adds JCIE, “new ties between Japanese and American … humanitarian organizations” should mean deeper cooperation in addressing future disasters. One example: After working together after the Japan earthquake, U.S.-based Mercy Corps and Japan’s Peace Winds responded collaboratively to a deadly drought in Niger. Similarly, Church World Service teamed up with the Japanese NGO Peace Boat to provide relief after a typhoon struck the Philippines in 2013.

The growing cooperation extends beyond disaster relief. Established a year after the earthquake, a new bilateral exchange program, the TOMODACHI Initiative, builds educational and academic, sports and cultural, and leadership and entrepreneurial ties. Over half its participants are from the Tohoku region, the area hit hardest by the disaster.