Updated

Catastrophic flash floods struck towns along the Nepal-China border in the Himalayan mountains this week, with the death toll rising to more than 550 and nearly 2,000 people still unaccounted for as of Friday, according to Nepal's disaster management authority and Chinese state media. Nepal's tourism board says more than 500 tourists from 28 countries are among the missing, including roughly 90 U.S. citizens, among them Shital Chetan Chohan of Powell, Tennessee, whose family is pleading for information. Officials are also monitoring a glacial lake that poses a new flood threat to the region. The disaster has prompted explainers on the difference between glacial collapse and earthquake-triggered flooding, and has drawn renewed attention in the U.S. to landslide risks, with a USGS map showing nearly half the country at risk — a lesson officials say was reinforced by Hurricane Helene's deadly landslides.