Twenty-nine months of geomorphic change in upper Monterey Canyon (2002-2005)

Time serial multibeam bathymetry is used to evaluate geomorphic trends and submarine processes in the upper 4 km of Monterey Canyon, California. Seven high-resolution bathymetric surveys conducted between September 2002 to February 2005 show that the upper canyon axis and head grew in volume 1000000 m(3) +/- 700000 m(3), at an average annual rate of 400000 m(3)/a +/- 300000 m(3)/a through lateral erosion and vertical incision. This net loss of substrate during the 29-month period is parsed between local erosion of 1400000 m(3) and local deposition of 350000 m(3). A submarine landslide with a scar void volume of 70000 m(3) and debris pile of 52000 m(3) occurred between March 2003 and September 2004. During the subsequent months until February 2005, the slide scar grew 40% in volume while the debris pile shrank by 80%. The canyon-head rim adjacent to Moss Landing Harbor prograded seaward and retreated shoreward significantly (up to 50m) during the study suggesting frequent episodes of sediment build up and subsequent down-canyon failure. A large field of sand waves located in the channel axis was completely reworked in each time series except for a 24 h period where no wave crest movement was noted, and a 32 day period where up-canyon migration of approximately 7 m was recorded in the northern tributary. (c) 2006 Elsevier B.V. All rights reserved.