Searchers discovered two more bodies after Wednesday's quake of magnitude 7.2 struck the sparsely populated, largely rural eastern county of Hualien, stranding hundreds in a national park as boulders barrelled down mountains, cutting off roads.
About 50 aftershocks rattled the area overnight, some felt as far away as Taipei. Rescuers said about 400 people cut off in a luxury hotel in the Taroko Gorge national park were safe, with helicopters ferrying out the injured and bringing supplies.
"Rain increases the risks of rockfalls and landslides, which are currently the biggest challenges," said Su Yu-ming, the leader of a search team helping the rescue effort, pointing to expectations for rain.
"These factors are unpredictable, which means we cannot confirm the number of days required for the search and rescue operations."
Taiwan's fire department said two bodies were found in the mountains, but wanted to confirm their identities before updating the death toll.
It put the number of missing at 13, three of them foreigners of Australian and Canadian nationality.
Aid supplies are arriving at the scene, while senior politicians such as President Tsai Ing-wen said they were donating a month's salary to relief efforts.
Japan will provide $1 million in aid to Taiwan for rescue and recovery effort, its foreign minister, Yoko Kamikawa, said.
HOTEL WORKERS FOUND
A group of 50 hotel workers marooned on a road to the national park are now mostly safe.
"I am lucky to survive," said David Chen, 63, a security manager at the hotel, after his rescue. "We were terrified when the earthquake first happened. We thought it was all over, all over, all over, because it was an earthquake, right?"
Rocks were still tumbling down nearby slopes as the group left, he added. "We had to navigate through the gaps between the falling rocks, with the rescue team out front."
Chen's 85-year-old mother wept in relief on being reunited with her son, as the family had not known for some time if he had survived.
"I was happy when he returned," said the mother, Chen Lan-chih. "I didn't sleep at all last night and couldn't eat anything."
The quake came a day before Taiwan began a long weekend holiday for the traditional tomb sweeping festival, when people head to their homes to spruce up ancestral graves.
Many others visit tourist spots, like Hualien, famed for its rugged beauty, but the earthquake has crushed business, with many bookings cancelled, some businesses said.
"This is a disaster actually for us because no matter (whether) hotel, hostel, restaurants (everything) really depends on tourism," said hostel owner Aga Syu, adding that her main concern was the well-being of guests.
"I hope this won't destroy their image of Hualien."
Taiwan lies near the junction of two tectonic plates and is prone to earthquakes. More than 100 people were killed in a 2016 quake in its south, while one of magnitude 7.3 killed more than 2,000 in 1999.
