Sea-cliff erosion at Pacifica, California, caused by 1997-98 El Niño storms

By: , and 



Twelve homes were constructed in 1949 at the top of a sea cliff along Esplanade Drive in the City of Pacifica, located on the northern coast of San Mateo County, California. The rear yards of those properties were bounded by an approximately 20-meter (70-foot) high cliff that has retreated episodically at an average rate of 0.5 to 0.6 meter (1.5 to 2 feet) per year over the past 146 years. During the heavy storms of the 1997/1998 El Niño winter, a severe episode of cliff retreat undermined seven homes and threatened three others. All ten homes were condemned and demolished by the City of Pacifica. In this study we analyze geologic, tide, wave, rainfall and wind data in an attempt to determine the causes of this most recent erosion event. We identify the following possible contributory causes of the cliff retreat: 1) wave-induced undercutting of the cliff landward of an old revetment, 2) reduction in beach width over time, 3) reduction in cliff-face stability owing to infiltration from heavy rains, 4) erosion of the cliff face by groundwater piping, and 5) wind-induced erosion of loose dune sand at the top of the cliff. While these factors may explain the retreat of the cliff below the twelve homes along Esplanade Drive, the question remains as to why other geologically similar sites in the region were not severely eroded during the 1997/1998 El Niño winter.

Study Area

Publication type Conference Paper
Publication Subtype Conference Paper
Title Sea-cliff erosion at Pacifica, California, caused by 1997-98 El Niño storms
DOI 10.1061/40512(289)22
Volume 289
Year Published 2000
Language English
Publisher ASCE
Description 15 p.
Larger Work Title Proceedings of sessions of Geo-Denver 2000 - Slope stability 2000
First page 294
Last page 308
Conference Title Geo-Denver 2000 - Slope Stability 2000
Conference Location Denver, CO
Conference Date August 5-8, 2000
Country United States
State California
City Pacifica
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details