History and pre-history of earthquakes in wine and redwood country, Sonoma and Mendocino counties, California

Hecker, Suzanne; Kelsey, Harvey M.; Abramsonward, H.; Bawcom, Julie; Boatwright, John; Crampton, Todd; Goldberg, Wayne; Hanson, Kathryn L.; Langenheim, Victoria E.; Larsen, Mort; LeBaron, Gaye; McPhee, D. K.; McCormick, William; McLaughlin, Robert J.; McCabe, Craig A.; Schwartz, David P.; Simpson, Gary D.; Swan, F.H.

doi:10.1130/2006.1906sf(19)

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…The northern Rodgers Creek fault zone (Healdsburg fault segment), which is seismically active (Fig. 9) and displays evidence of Holocene surface displacement (Hecker and Kelsey, 2006;Crampton et al, 2004;Swan et al, 2003), is seemingly a continuation of the southern Rodgers Creek fault zone, apparently bypassing the Santa Rosa pull-apart structure. The northern and southern Rodgers Creek fault zones, north-trending faults bounding the west side of the Santa Rosa pull-apart basin, and the Matanzas Creek fault zone all merge or intersect each other beneath Santa Rosa Creek fl oodplain.…”

Section: Santa Rosa Pull-apart Basinmentioning

confidence: 96%

Evolution of the Rodgers Creek-Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

et al. 2012

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The Rodgers Creek-Maacama fault system in the northern California Coast Ranges (United States) takes up substantial rightlateral motion within the wide transform boundary between the Pacifi c and NorthAmerican plates, over a slab window that has opened northward beneath the Coast Ranges. The fault system evolved in several right steps and splays preceded and accompanied by extension, volcanism, and strikeslip basin development. Fault and basin geometries have changed with time, in places with younger basins and faults overprinting older structures. Along-strike and successional changes in fault and basin geometry at the southern end of the fault system probably are adjustments to frequent fault zone re organizations in response to Mendocino Triple Junction migration and northward transit of a major releasing bend in the northern San Andreas fault.The earliest Rodgers Creek fault zone displacement is interpreted to have occurred ca. 7 Ma along extensional basin-forming faults that splayed northwest from a westnorthwest proto-Hayward fault zone, opening a transtensional basin west of Santa Rosa. After ca. 5 Ma, the early transtensional basin was compressed and extensional faults were reactivated as thrusts that uplifted the northeast side of the basin. After ca. 2.78 Ma, the Rodgers Creek fault zone again splayed from the earlier extensional and thrust faults to steeper dipping faults with more northnorthwest orientations. In conjunction with the changes in orientation and slip mode, the Rodgers Creek fault zone dextral slip rate increased from ~2-4 mm/yr 7-3 Ma, to 5-8 mm/yr after 3 Ma.The Maacama fault zone is shown from several data sets to have initiated ca. 3.2 Ma and has slipped right-laterally at ~5-8 mm/yr since its initiation. The initial Maacama fault zone splayed northeastward from the south end of the Rodgers Creek fault zone, accompanied by the opening of several strike-slip basins, some of which were later uplifted and compressed during late-stage fault zone re organi zation. The Santa Rosa pull-apart basin formed ca. 1 Ma, during the reorganization of the right stepover geometry of the Rodgers Creek-Maacama fault system, when the maturely evolved overlapping geometry of the northern Rodgers Creek and Maacama fault zones was overprinted by a less evolved, non-overlapping stepover geometry.The Rodgers Creek-Maacama fault system has contributed at least 44-53 km of right-lateral displacement to the East Bay fault system south of San Pablo Bay since 7 Ma, at a minimum rate of 6.1-7.8 mm/yr.

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Section: Santa Rosa Pull-apart Basinmentioning

confidence: 96%

Evolution of the Rodgers Creek-Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

et al. 2012

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“…1b). The fault traverses the town of Willits, where numerous cultural features show the effects of fault creep (Hecker and Kelsey, 2006;Fig. 2).…”

Section: Introduction and Tectonic Settingmentioning

confidence: 99%

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

Prentice¹,

Larsen²,

Kelsey³

et al. 2014

Bulletin of the Seismological Society of America

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The Maacama fault is the northward continuation of the Hayward-Rodgers Creek fault system and creeps at a rate of 5:7 0:1 mm=yr (averaged over the last 20 years) in Willits, California. Our paleoseismic studies at Haehl Creek suggest that the Maacama fault has produced infrequent large earthquakes in addition to creep. Fault terminations observed in several excavations provide evidence that a prehistoric surfacerupturing earthquake occurred between 1060 and 1180 calibrated years (cal) B.P. at the Haehl Creek site. A folding event, which we attribute to a more recent large earthquake, occurred between 790 and 1060 cal B.P. In the last 560-690 years, a buried channel deposit has been offset 4:6 0:2 m, giving an average slip rate of 6:4-8:6 mm=yr, which is higher than the creep rate over the last 20 years. The difference between this slip rate and the creep rate suggests that coseismic slip up to 1.7 m could have occurred after the formation of the channel deposit and could be due to a paleoearthquake known from paleoseismic studies in the Ukiah Valley, about 25 km to the southeast. Therefore, we infer that at least two, and possibly three, large earthquakes have occurred at the Haehl Creek site since 1180 cal B.P. (770 C.E.), consistent with earlier studies suggesting infrequent, large earthquakes on the Maacama fault. The short-term geodetic slip rate across the Maacama fault zone is approximately twice the slip rate that we have documented at the Haehl Creek site, which is averaged over the last approximately 600 years. If the geodetic rate represents the long-term slip accumulation across the fault zone, then we infer that, in the last ∼1200 years, additional earthquakes may have occurred either on the Haehl Creek segment of the Maacama fault or on other active faults within the Maacama fault zone at this latitude. Online Material: Trench logs, discussion of channel B, photographs of compressional features, and table of radiocarbon analyses.

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History and pre-history of earthquakes in wine and redwood country, Sonoma and Mendocino counties, California

Cited by 2 publications

References 4 publications

Evolution of the Rodgers Creek-Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

Evolution of the Rodgers Creek-Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

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