More than 220 people living in the ski resort of Saas-Fee had to leave their homes on Saturday as authorities feared a collapse of the glacier could trigger an ice avalanche which could reach the village.
The lower part of the glacier collapsed early Sunday but did not reach the houses, allowing residents to return and for a local road to reopen, though hiking trails remain closed, police said in a statement.
Geologists had recently noticed significant movement along the "tongue" of the Trift glacier, up to 130 centimetres in a single day, local authorities said.
"There remains only about a third" of the unstable tongue of the Trift glacier, police said, adding that the area is under surveillance and "the situation will be continually reevaluated."
The glacier had been under observation since October 2014, when the area was closed for three weeks. With a return to colder temperatures, the situation stabilised and the access ban was lifted.
But since the start of the week, movement had increased on the lower part of the glacier.
In late August, a massive rockfall triggered an avalanche which buried eight hikers in another valley in the Swiss Alps, near Bondo.