Citizens of San Francisco Tuesday gathered in a ceremony marking the anniversary of a temblor that almost destroyed the city one century ago.(Xinhua/AFP photo)

    SAN FRANCISCO, the United States, April 18 (Xinhua) -- Citizens of San Francisco Tuesday gathered in a ceremony marking the anniversary of a temblor that almost destroyed the city one century ago.

    In the pre-dawn morning of April 18, 1906, a 7.8-magnitude earthquake hit just 3 km off the coast of San Francisco in the Pacific. About 3,000 to 6,000 people were killed in the disaster, and some 225,000 were made homeless in minutes.

    The San Andreas Fault slipped 430 km in the huge temblor. More than 28,000 buildings on soft sediments collapsed, and water mains and gas lines broke, while a series of devastating fires almost leveled the city.

    On this Tuesday, sirens were heard again throughout the city, and tens of thousands of residents assembled at Lotta's fountain downtown, where San Franciscans gathered in the aftermath a century ago.

    A wreath-laying ceremony at the fountain Tuesday morning was billed as the highlight of the ceremony, and a tribute to the city' s resilience.

    "The 1906 earthquake and fire was the pivotal event in this city's history - in the history of the Golden West," Gavin Newsom,the mayor of the city, said at the ceremony.

    "Together we will honor the memory of those who lived through -and those who didn't survive - this terrible disaster. But we will also take this tremendous opportunity to celebrate the San Francisco spirit that emerged from quake and fire and made this one of the worlds great cities."

    Meanwhile, hundreds of officials and scientists are meeting in the city to discuss whether next great earthquake would hit the city, and how they could prepare people for the real potential of another disaster.

    According to studies by U.S. Geological Survey (USGS) released at the earthquake meeting, San Francisco is not expected to face an earthquake like the one in 1906 for another 100 years or more, but a huge temblor is likely to start across the east bay.

    "A repeat of the 1906 earthquake is not real likely, there are many other earthquakes I think we're far more concerned about, particularly on the East Bay faults," said Mary Lou Zoback, a USGSsenior seismologist.

    "We've done a study on the Hayward Fault and the average is 150 years for a repeat and the last one was 1868, so we're very close," she told the meeting.

    In year 1868, an earthquake on the Hayward Fault had a 7.0 magnitude and resulted in minor losses -- five people dead and dozens more injured.

    Scientists have estimated that a major temblor will have 62 percent chance of striking the Bay Area in the next 26 years. A repeat of the 1868 quake in coming years is expected to trigger more havoc due to increased population and buildings, scientists said.

    Anticipated to have a 6.9 magnitude, it would cause 500-plus deaths, destroy 5,800 buildings, damage some 227,000 others, leave 450,000 people homeless and result in 23 billion U.S. dollars in damage, according to USGS estimates.

    Although a Hayward earthquake would not affect San Francisco asseverely as places in the East Bay, the city will still be "really hard hit and damaged," according to Tom Brocher, another USGS seismologist.

    Buildings around San Francisco's shorelines, where there is landfill, will be particularly vulnerable. Ports, docks, and a lotof the financial district of the city "will really get shaken," said Brocher.

    "We need to make sure people are prepared, and that they have the resources to take care of themselves and their families," Mayor Newsom said.

    But many people, putting off worries about earthquakes for another day, are not yet prepared for a potential disaster, the officials and scientists worried.

    Estimates by the University of California, Santa Cruz, show only about 20 percent of people are prepared for a big earthquake.Another poll published in local media showed that seven in 10 Californians expect a big quake, but only about two in 10 have done much about it. Enditem