Dehradun, Jan 18 : Cracks have developed in hundreds of buildings in the sinking town of Joshimath forcing people to vacate them and relocate. Also, the dangerously tilting buildings are being demolished. Till now, cracks have appeared in nearly 849 houses with four of the nine wards in the city being declared "unsafe", according to officials. As many as 164 houses have been found completely "unsafe". However, a continuous survey of damaged buildings is still underway. The process of building a colony to settle 125 families on two hectare of land is also on. On Tuesday, the Centre set separate deadlines for the reports that various expert groups are preparing on the land subsidence crisis. Geophysical and hydrological studies of the crisis are also being carried out. Giving official information, Disaster Management Secretary Ranjit Kumar Sinha said that several technical institutions under the chairmanship of Central Building Research Institute (CBRI), Roorkee, are investigating the cause of the landslide in Joshimath. Sinha said that CBRI has been asked to submit its preliminary report within the next three weeks while the detailed report will be released in next two months. The National Geophysical Research Institute (NGRI) will submit its preliminary report within the next two days and the detailed report in the coming three weeks. Similarly, Wadia Institute of Himalayan Geology and Geological Survey of India (GSI) have been directed to submit their preliminary reports respectively within the next two weeks. IIT Roorkee and Indian Institute of Remote Sensing will give their preliminary reports in the next one week respectively. At the same time, the National Institute of Hydrology will come up with its study in a couple of days. Besides, the Disaster Management Secretary has informed that a fixed financial compensation will be decided after conducting a survey within a week regarding the relief package sought from the Centre. He added that the process of mechanical demolition of 15 damaged buildings at JP Colony in Joshimath city has been initiated. As part of the rehabilitation, the process of making prefabricated cottages at TCP Tiraha has begun. Initially, three models of 1-BHK, 2-BHK and 3-BHK houses will be built at TCP Tiraha, Sinha said. He added that as part of the permanent rehabilitation process for the homeless people, the CBRI will soon start the process of making a permanent colony on two hectare of land in Pipalkoti. Starting Thursday, the CBRI officials will visit the disaster-prone sites and prepare a project plan for making a permanent colony for 125 families in Pipalkoti. The process of making its DPR will also start the same day. /IANS