Although researchers had warned about the increase in the rate of subsidence in Tehran’s 18th district in the past years, Voldkhani Street in the western border of Waliasr town, Tehran’s 18th district, faced a subsidence to a depth of 1.5 meters at the same time as the rains began, which these researchers believe has increased the subsidence risk rate in this area due to the mining of sand and construction materials and the formation of huge gravel pits and canals.
Dr. Ali Baitullahi, Director of the Earthquake and Hazards Departme of the Road, Housing and Urban Developme Research Ceer in an ierview with ISNA Referring to the subsidence of the ground in the 18th district of Tehran, he said: Around midnight on Thursday, December 20, a sudden subsidence of the ground occurred on Voldkhani street in the western part of Valiasr settleme in the 18th district of Tehran. The size of the collapse area is 10 meters and the depth is 1.5 meters. It is also announced that three cars were damaged in this incide.
He stated that this incide was a sudden subsidence (collapse of the ground) and took place after the rece rains, and added: The reason for the occurrence of the ground collapse in this area is probably the flow of water in underground channels such as dry canals or natural drains, which usually after rains, causes water washing and the developme of subsurface cavities, and subsequely, and mainly due to environmeal vibrations, causes sudden collapses, which in Roads and resideial areas are associated with the possibility of damage and injuries.
Baitullahi poied out: The geographic coordinates of the incide poi were roughly 51.340516° long, 35.633208° wide and 1108 meters high (taken from Google Earth). The figure below shows the location of Valiasr town and the approximate location of the incide area in the west of the town.
Baitullahi stated that in the case of the area south of Qaim Park, the iensification of land subsidence in this area has already been shown in a report along with the preseation of maps and figures, and coinued: The accide occurred, although it was a sudden subsidence (collapse) and was probably due to subsurface erosion, which in my opinion is unrelated to the iensification of the gradual subsidence of the land in this area, due to the loosening of surface deposits due to tension and the developme of possible cracks due to the gradie. Land subsidence cannot be cumulative.
The Director of Earthquake and Hazards Departme of the Road, Housing and Urban Developme Research Ceer stated that the 18th district of Tehran has a population of 444,886 people (419,249 people are within the boundaries and 25,637 people are within the boundaries). The area is located in the southwest of Tehran and is bounded from the north by Fatah highway and 45 meters from Zarand (adjace to areas 9 and 21), from the east by Ayatollah Saeedi highway (adjace to area 17), from the west by Azadegan highway (Quds and Shahryar cities), and from the south by Ayatollah Saeedi highway and Azadegan highway (adjace to Islamshahr city and Chahardange city).
He emphasized: The scope of the collapse poi of Omrani-Waldkhani street, the subsidence of the ground in the last two years shows a rapid rate and three times compared to the previous years, which has the appearance of an abnormal halo in the south of the park.
Map of the annual rate of land subsidence in the 18th district of Tehran and its surroundings
Stating that District 18 of Tehran is a mixed area of land with agricultural and resideial, industrial and mining uses, Baitullahi said: the extraction of sand and construction materials from mines has caused the formation of huge sand pits in the area, which has aggravated the environmeal risk. In addition, the presence of canals, especially their low depth in this area, has increased the risk of sudden collapses, which increases the probability of crisis eves after rain. In the southern part of this area, the importa Tehran-Tabriz rail route is located, which is at the iersection with the extension of the canals and the zone with an iensified rate of land subsidence.
This risk researcher poied out: Considering the above importa pois, the officials of Tehran Municipality, crisis manageme and the officials of the railway company are requested to pay atteion and sensitivity in reducing the risks of land subsidence and collapse in the 18th district of Tehran.
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