Tuesday's tremors caused panic in some communities.

A resident of Wenhui Garden in Bao'an District surnamed Zhu said he felt a swaying sensation in his fifth-floor home.

"I was scared when seeing furniture swaying and hearing shouts from my neighbors," he said.

"I lived in Shenzhen for more than two decades, but had never experienced such a strong tremor."

According to Zhu, nearly 1,000 residents of the housing estate fled from their homes and stayed outside for an hour.

In Nanshan District, 1,000 other frightened residents were evacuated from the Dijing Garden housing community.

"People went back to their apartments until we promised to deploy 20 security guards on watch in case there were further quakes," said an employee of the housing estate's management office.

However, few people detected the tremors in the crowded Luohu District, especially in bustling shopping areas.

A shopper surnamed Huang told the newspaper that she received a call from a friend about tremors felt in Bao'an District. "I thought it was a hoax at first, until seeing the news on TV."

Yang Yueming, the seismic bureau official, said people in a quiet environment are more sensitive to tremors than those in noisy places.

"Suburbanites lived in Xili, Buji and Dapeng reported more powerful tremors than those in Luohu or Futian districts," he said.

The bureau has invested over 24 million yuan (US$3 million) in earthquake monitoring this year, enabling the city to detect tremors as weak as 1.5 on the Richter scale.

The investment includes 7 million yuan to assess the capability of the city's major constructions and emergency systems to withstand earthquakes, and a 10-million-yuan investment for five observation stations and two seismic forecast points.

Editor: Donald