Seismic Response of San Francisco Waterfront Fills

Abstract

The San Francisco waterfront was constructed between 1850 to 1920 by placing fill along the San Francisco Bay. The fills, reaching thicknesses of up to 40 ft (12 m), consist primarily of dune sand, rock fragments, bay mud, and construction debris. They were placed largely by dumping into the waters of the Bay. Not surprisingly, certain fill areas underwent large displacements in the 1906 San Francisco earthquake. Yet, at the same time, other areas showed little displacement. This behavior, plus that recorded in other seismic events, provides a unique record of fill behavior under earthquake loading. The study of the waterfront fills involved an historical review of waterfront construction, field testing and sampling, laboratory tests, and analytical studies. The field work was done both in areas where seismically induced movements were large and where they were small. The results of the investigation serve to explain the observed behavior of the fills; loose zones of the dune sand were found in the large movement areas which undoubtedly liquefied in the 1906 event. These were not present where only small movements occurred.