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Detailed analysis of cores near the northern limit of the NSAF at Noyo Canyon and in Southern Cascadia primarily at Trinidad Canyon, have yielded improved detailed records, age models, and evidence of historic earthquakes. In an effort to examine the hypothesis of a stress relationship between the NSAF and Cascadia, we re-examined the evidence from both systems. The lack of numerous “extra” events at Lake Merced relative to the north coast segment record may suggest that many, but not all north coast and peninsula segment events are one in the same, as was 1906, although numerous other interpretations are also possible. The Lake Merced record is largely compatible with onshore and offshore records for the north coast segment of the NSAF, and potentially with the lesser known peninsula segment. We interpret the thick, Pb laden deposit as likely anthropogenic material from the early development of San Francisco, and the great thickness of the bed may have been deposited over several decades as a hillslope effect following the earthquake. Pb isotope data show this bed is contaminated with isotopes consistent mostly with lead based paint, and additionally tetraethyl Pb from gasoline. The event bed corresponding to 1906 is ~ 1m thick, much greater than any other bed in the lake during the past 2300 years. These results also show that this site records not only NSAF events, likely along the north coast and the peninsula, but also related earthquakes in the Santa Cruz Mountains, events in the probable pull apart basin at Daly City, and possibly others as well. During the 20th century, these earthquakes resulted in the only three event beds in the lake during that time, providing a good test of the fidelity of the lake as an earthquake recorder. Historic-era results from Lake Merced using bomb-carbon based age models show the site recorded three historic events, 1906, the 1957 Daly City earthquake, and Loma Prieta in 1989 with no intervening event beds. The site was less tenable as a paleoseismic site at prior times, although that remains unexamined at present. Prior to that the lake was open to the ocean and contains marine shells consistent with an estuarine environment. The lake records ~ 2300 years of event beds, 17 in total. Lake Merced results have established the lake as a viable paleoseismic site on the northern San Francisco peninsula.NEHRP Final Technical Report G18AP00058.

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