Some time between the evenings of Dec. 16 and 17, 1999, the Cordillera de la Costa, the picturesque chain of mountains that spans the Caribbean coastline in northern Venezuela's Vargas state, was transformed into a violent, chaotic onrush of rivers made of mud and debris, some more than a mile wide. Together they drowned or buried alive one-tenth of the 500,000 people living in the region and altered the landscape forever.

Although much of the world failed to take adequate notice at the time, the catastrophic landslides have been ruled the worst disaster of the Western Hemisphere in the past 500 years. Some Venezuelan Cornell University students e n route home for midwinter break witnessed the aftermath. Others who hadn't yet left campus were immediately spurred to action and are organizing fundraising efforts.

Landslide seems an inadequate word to describe the depth of the catastrophe. More than 50,000 people are dead or missing, five times the number killed by Hurricane Mitch in 1998 and three times more than last year's earthquake in Turkey. More than 300,000 people are now without homes. Nearly all the region's roads must be rebuilt. Damages are estimated in the billions -- and climbing.

What happened and why? "The mountains in that region are relatively young in geologic terms, very high in clay," explained Francisco Guanchez, a Venezuelan doing postdoctoral studies in medicinal plants at Cornell's Bailey Hortorium. "The disaster was caused by a huge amount of rain, more rainfall in two weeks than that area usually has in a year, with the last two days before the disaster the most intense." The cataclysmic mudslides were entirely unexpected and "impossible to predict. There was no indication that something like this could or would happen." Deforestation was not a cause, he asserted. "Most of the damage took place in headwaters situated in the Avila National Park."

Guanchez and his family were among the many stranded in the Caracas airport as the rains and moving mud washed away roads. Radio broadcasts in the airport relayed the voices of people trapped in isolated places, calling for help over cell phones. "It was horrible listening," Guanchez related. "We felt so helpless. Some people had to stay on their rooftops for several days, without food or drinking water."

After a day the main road reopened, and Guanchez and his family managed to get into Caracas, where they ran between temporary shelters and hospitals, searching the lists of the rescued and the dead for the names of relatives and friends.

Meanwhile back in Ithaca, members of the Venezuelan Students Association (VenCornell) who were still around scrambled to collect and package items that might be of use to airlift to Venezuela -- food, clothing, diapers, medicine, bandages. Elias Nucette, Nelson Villoria, Maria Alejandra Perez and Samuel Freije, with assistance from Mike Raffe, director of emergency services for the Ithaca branch of the American Red Cross, were among those who collected and packaged the goods.

"We were getting ready for the holidays or to leave, but we felt we had to do something," said Nucette. Within days they managed to fill a hundred boxes, stacked from floor to ceiling in an empty flat lent to them by Hasbrouck Apartments, load them onto a rented truck and drive them to Kennedy Airport in New York City, where SERVIVENSA, the Venezuelan airline, transported them to Caracas for free.

In Venezuela, Guanchez read and heard reports of people in flooded areas tearing off doors and tabletops, laying them across rooftops and going from roof to roof to rescue the aged, the infirm and small children. He praised his compatriots for their solidarity and bravery and said that Venezuela's government and military forces "did a good job" mobilizing an effective rescue effort that included helicopters whose pilots worked to find those who were stranded in remote places. His own family was safe, he was relieved to learn, although his parents' and two sisters' homes were among the 40,000 destroyed by the disaster.

Now back in Ithaca, he is among the many Venezuelans living here who fear that the situation in their country is worsening. "Many people are still living in shelters, their homes destroyed or so seriously damaged that they are unlivable. And with broken sewer lines and no potable water throughout the region, there is a great danger of epidemics." There is also an emotional cost. "People who lived through that moment are traumatized" and will take a long time to recover, he said. "They need our help now."

VenCornell is organizing an intensive fund-raising campaign to provide relief for the disaster, in conjunction with the American Red Cross and other organizations. Information tables are set up in the Willard Straight Hall lobby on Cornell's campus through Feb. 11 where people can learn more about the disaster and how to help. Boxes are placed at key places on campus through March 10 where checks can be dropped off for the relief effort (posters on campus and local bulletin boards will specify the locations). There will be a party to raise funds for Venezuelan disaster relief in late February or early March.

On Saturday, March 3, there will be a Venezuelan Cultural Night benefit concert in Barnes Hall. And a seminar, "What Happened in Venezuela?" at a time and date to be announced, will provide more information on the disaster.

Checks should be made payable to UNICEF; International Response Fund (International Red Cross); or Catholic Relief Services and sent to VenCornell, 105 Warren Hall; Latin American Studies Program, 190 Uris Hall; CUSLAR, 316 Anabel Taylor Hall; or Hasbrouck Apartments Community Center, North Campus, Cornell University, Ithaca, N.Y. 14853. For more information, see VenCornell's web site, listed below.