Characteristics and impact of environmental shaking in the Taipei metropolitan area.

Examining continuous seismic data recorded by a dense broadband seismic network throughout Taipei shows for the first time, the nature of seismic noise in this highly populated metropolitan area. Using 140 broadband stations in a 50 km × 69 km area, three different recurring, strong noise signals characterized by dominant frequencies of 2-20 Hz, 0.25-1 Hz, and < 0.