A technician measures the seismic readings from the eruption of Mount Anak Krakatau at an observation post in Pasauran, Banten province, Indonesia, Monday, Sept. 7, 2026. (AP Photo/Dziki Oktomauliyadi)

A man walks past an information board showing cancelled flights due to the eruption of Mount Anak Krakatau, at Soekarno-Hatta International Airport in Tangerang, Indonesia, Monday, Sept. 7, 2026. (AP Photo/Tatan Syuflana)

People wait as flights are disrupted due to the eruption of Mount Anak Krakatau, at Soekarno-Hatta International Airport in Tangerang, Indonesia, Monday, Sept. 7, 2026. (AP Photo/Tatan Syuflana)

People wait as flights are disrupted due to the eruption of Mount Anak Krakatau, at Soekarno-Hatta International Airport in Tangerang, Indonesia, Monday, Sept. 7, 2026. (AP Photo/Tatan Syuflana)

In this drone photo released by the Geological Agency (Badan Geologi) of Indonesia's Ministry of Energy and Mineral Resources, Mount Anak Krakatau spews volcanic smoke in Sunda Strait, Indonesia, Saturday, Sept. 5, 2026. (Badan Geologi via AP)

Social Studies teacher John Boston Bradley, who teaches at Bishop McCort High School in Johnstown, Pa., pauses at the Wall of Names during an educators seminar at the Flight 93 National Memorial in Shanksville, Pa., Tuesday, June 23, 2026. (AP Photo/Gene J. Puskar)

U.S. Park Ranger Adam Shaffer, center, leads a tour for a group of educators at the Flight 93 National Memorial in Shanksville, Pa., Tuesday, June 23, 2026. (AP Photo/Gene J. Puskar)

Gordon Felt, whose brother, Edward, died Sept. 11, 2001, on United Airlines Flight 93, speaks to teachers gathered for an educational session at the Flight 93 National Memorial in Shanksville, Pa., on June 22, 2026. (AP Photo/Marc Levy)