Indonesia's disaster agency says helicopters are dropping disinfectant on neighborhoods in the earthquake- and tsunami-stricken city of Palu to reduce disease risks from the thousands of victims believed buried in obliterated communities. The agency said yesterday that 430 hectares (1.7 square miles) of land and nearly 3,500 homes succumbed to liquefaction when the Sept. 28 earthquake turned soft soil to mud.

Spokesman Sutopo Purwo Nugroho said in a statement the disinfectant is necessary because of the large number of victims not recovered by the search and rescue effort that ended on Oct. 12. Officials say the destroyed Palu neighborhoods of Balaroa and Petobo, and Jono Oge in neighboring Sigi district, cannot be redeveloped. Balaroa and Petobo will be turned into green spaces with monuments to those who perished.

Local residents who survived the Sept. 28 earthquake and subsequent tsunami that hit Central Sulawesi province are at risk of infection from mosquitoes and other insects that could carry diseases from human bodies. The government called off the search for bodies on Friday, but hundreds, if not thousands, more are still missing after homes in three villages were swallowed by mud in a phenomenon known as soil liquefaction. The official death toll from the disasters stands at nearly 2,100.

Indonesia is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the "Ring of Fire," an arc of volcanoes and fault lines in the Pacific Basin. A powerful quake on the island of Lombok killed 505 people in August, and two moderate quakes near an eastern island yesterday reportedly damaged a bridge. The vast archipelago is home to 260 million people on more than 17,000 islands that stretch a distance similar to that between New York and London. Roads and infrastructure are poor in many areas, making access difficult even in the best of conditions.