The Washington State Geological Survey (DNR Division of Geology and Earth Resources) is pleased to announce the publication of the Lake Joy 7.5-minute quadrangle geologic map. This map is part of the division’s plan to map around the active southern Whidbey Island fault zone as well as the subsidiary Carnation and Cherry Creek fault zones in north-central King County and southern Snohomish County.
This mapping effort’s fieldwork was completed during the summer-fall of 2011 and was led by Joe Dragovich, principal mapping geologist of the WA State Geological Survey. Mapping this quadrangle led to several discoveries about the fault systems that run through the area. For example, the mappers show that the northeast-trending left-lateral strike-slip Cherry Creek and Tokul Creek fault zones join to the northwest-trending Southern Whidbey Island Fault (SWIF) zone, and that the two fault zones appear to be seismically active. Furthermore, these fault zones may be the source of recently-felt seismic events. Joe tells us that “The 1996 Duvall earthquakes (maximum magnitude 5.3) likely resulted from shallow displacements along the trace of our Cherry Creek fault zone near the northwestern corner of the quadrangle.”
To get the details on these and many other Lake Joy findings, you can access a digital or paper copy of the published map. To obtain a digital (zipped PDF) copy of the Lake Joy quadrangle along with its associated informational materials, click here (warning—file size > 93 MB). Or you can order your own hardcopy here through the Washington State Department of Enterprise Services.
We congratulate Joe and his team on their fine work and look forward to their upcoming maps. They are currently mapping the Sultan quadrangle, directly to the north of Lake Joy.
Lake Joy is the first of three 2012 STATEMAP products that we will publish this year. The Eldon and Brinnon quadrangles are coming soon!