TOKYO — Two cherry blossom trees collapsed on Thursday in Tokyo — one at Kinuta Park in downtown Tokyo and the other at the Chidorigafuchi greenway — prompting officials to intensify safety inspections ahead of the annual viewing season. No one was injured in either incident.

The tree that collapsed at Kinuta Park was 18 meters tall and 2.5 meters in diameter, believed to be more than 60 years old, officials said. It damaged a fence when it fell and had not been marked with caution signs. The tree at the Chidorigafuchi greenway nearly fell into the Imperial Palace moat.

The collapses come after a similar incident in March, when another old cherry tree collapsed at Kinuta Park and injured a passerby. Following those earlier incidents, officials conducted tree health checks at Tokyo's main parks ahead of the cherry blossom viewing season. At Kinuta Park, officials carried out preliminary inspections of more than 800 cherry trees, chopped down a number of them, and posted warning signs near some that remained standing.

"At the moment, our measures are mostly temporary, not fundamental steps such as replanting," said Masakazu Noguchi, a Tokyo metropolitan official in charge of public parks. Last year, 85 trees fell in Tokyo parks, injuring three people, and many were cherry trees, according to Noguchi. "We call on visitors to use caution because we cannot say it's safe even after inspection," he said.

Many of Tokyo's Somei Yoshino cherry blossom trees were planted during Japan's postwar advancement in the 1960s. Tokyo is the birthplace of the Somei Yoshino variety. Aging and erosion by internal fungus growth are among the main causes of deterioration.

"Many trees in our daily lives were planted soon after the war and are now 70-80 years old and getting weaker," said Hiroyuki Wada, a tree doctor, adding that they are affected by extreme heat in the summer and an extensive dry season. Wada said heavy tilting, holes, or mushrooms growing at the bottom are signs to look for in order to avoid risk-prone trees, and that tree trunks retaining water after rain increase the risk of collapse.

"I hope people think about the climate change through what's happening to the cherry blossom trees, which is very symbolic," he said.

At Inokashira Park, dozens of aging cherry blossom trees or their branches have been chopped down in recent years as part of a safe tree regeneration plan. Yutaka Kazama, a Tokyo assembly member, called for firm safety measures without quickly resorting to tree felling.

Cherry blossoms, or "sakura," are Japan's favorite flower and usually reach their peak in late March to early April, just as the country celebrates the start of a new school and business year. Many Japanese enjoy walking or picnicking under the cherry blossom trees during the blooming season, a tradition known as hanami, or cherry blossom viewing.