noun
doughnut effect; donut effect
Urban-planning term describing the hollowing out of city centers as residents move to the suburbs, leaving a low-population core surrounded by a populated ring.
地方都市ではドーナツ化現象が深刻で、中心市街地の空洞化が進んでいる。
In regional cities, the doughnut effect is serious, and the hollowing out of central urban areas is progressing.
As a countermeasure to the doughnut effect, the compact city concept is attracting attention.