JAKARTA—Hundreds of people near Indonesia’s Moluccas islands rushed to higher ground on Wednesday after an earthquake of magnitude 6.1, fearing aftershocks and a possible tsunami. The quake struck at a depth of 19 km (11 miles). There were no immediate reports of casualties. Indonesia’s Meteorology and Geophysics Agency (BMKG) urged people in a text message to move away from beaches and seek higher ground, noting that the warning applied especially to Seram Island. BMKG had initially said a tsunami triggered by the movement of tectonic plates was unlikely—but then said one could still be triggered by underwater landslides, of which there would be no warning. “If the tsunami is caused by an underwater landslide, it cannot be detected from the current early warning system,” the head of BMKG, Dwikorita Karnawati, told a news conference. She said residents should move to higher ground immediately if they felt aftershocks, and not wait …