Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California

Minor, Scott A.; Kellogg, Karl S.; Stanley, Richard G.; Gurrola, Larry D.; Keller, Edward A.; Brandt, Theodore R.

doi:10.3133/sim3001

Cited by 21 publications

(12 citation statements)

References 41 publications

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“…The sites share similar topographic characteristics (Table 1), climate (Mediterranean), and pre‐fire vegetation (chaparral). The underlying bedrock of the San Gabriel sites is Cretaceous granitic rock [ Yerkes and Campbell , 2005], whereas Eocene Coldwater Formation underlies the Santa Ynez site [ Minor et al , 2009]. Size distributions of the hillslope sediment at the five sites are shown in Figure 2a.…”

Section: Study Sitesmentioning

confidence: 99%

In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

Kean¹,

Staley²,

Cannon³

2011

J. Geophys. Res.

209

282

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[1] Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (< = 30 min) rainfall intensity. Overall, debris-flow stage was best cross-correlated with time series of 5-min rainfall intensity, and lagged the rainfall by an average of just 5 min. An index of debris-flow volume was also best correlated with short-duration rainfall intensity, but found to be poorly correlated with storm cumulative rainfall and hillslope soil water content. Post-event observations of erosion and slope stability modeling suggest that the debris flows initiated primarily by processes related to surface water runoff, rather than shallow landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows.

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Section: Study Sitesmentioning

confidence: 99%

In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

Kean¹,

Staley²,

Cannon³

2011

J. Geophys. Res.

209

282

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“…These rocks include, from oldest to youngest, the Coldwater Sandstone, Sespe Formation, Vaqueros Sandstone, Rincon Formation, Monterey Formation, and Sisquoc Formation. The Sespe, Rincon, Monterey, and Sisquoc Formations typically form the rocks of the mountain slopes and the rocks of the coastal piedmont (Arnold, 1907;Dibblee, 1966;Lian, 1952;Minor et al, 2009;Olson, 1982;Upson, 1951). In some cases, these rocks are locally uplifted in the cores of anticlines and along faults (Minor et al, 2009).…”

Section: Pre-quaternary Stratigraphymentioning

confidence: 98%

“…The Pleistocene strata were deposited on pre-Quaternary strata on the coastal piedmont. The Quaternary units, from oldest to youngest, include the Santa Barbara Formation, the Casitas Formation, late Pleisto cene-Holocene marine terrace deposits, fanglomerate deposits, and other alluvium (Gurrola , 2005;Minor et al, 2009). Our discussion will focus on the late Pleistocene marine terrace and younger deposits.…”

Section: Quaternary Stratigraphymentioning

confidence: 98%

“…The gradient in uplift rates from west to east is related to tectonics that deform (drop down) MIS 5 terraces as they trend into the western limb of the Carpinteria syncline (Gurrola, 2005;Minor et al, 2009). The MIS 5 terrace is at an elevation of ~34 m above present mean sea level at Summer land, and its elevation steadily decreases to the east to below sea level at Carpinteria.…”

Section: Rates Of Uplift Of Marine Terraces In Southernmentioning

confidence: 99%

“…1). Thus, in general, where a sea cliff is present, the landform is a limb of an anticline; where a sea cliff is absent, a syncline is often present (Keller and Gurrola, 2000;Minor et al, 2009).…”

Section: Introductionmentioning

confidence: 97%

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Tectonic geomorphology of marine terraces: Santa Barbara fold belt, California

Gurrola

Keller

Chen

et al. 2013

Geological Society of America Bulletin

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Uplifted marine terraces are common landforms in coastal regions where active tectonics are an important component of landscape evolution, such as along the coastal stretches of southern California. The pattern and elevation of shoreline angles on active folds provide information about rates of uplift and fold growth, which is important for defi ning tectonic models. A particularly impressive succession of marine terraces are developed across the Santa Barbara fold belt (SBFB) in southern California, which comprises an east-west linear zone of active folds and (mostly) blind faults on the coastal piedmont and in the Santa Barbara Channel. The fold belt is characterized by several fl ights of emergent late Pleistocene marine terraces uplifted and preserved on the fl anks of active anticlines. At several locations along the fold belt, the fi rst emergent marine terrace is numerically dated by methods that include uranium-series dating on terrace corals , 14 C dating on terrace shells and detrital charcoal, optically stimulated luminescence of marine terrace sands, and oxygen isotopic signatures (δ 18 O) of mollusks. Individual marine terraces have as many as four ages, using up to three different dating methods, providing confi dence in terrace chronology. Ages of higher terraces are estimated assuming a constant rate of uplift for a particular fl ight. Of the 31 terraces, 22 formed during a time of falling sea level, with 9 forming at or near marine oxygen isotope stage (MIS) 3 or 5 highstands.Ages and rates of uplift of the fi rst emergent terrace vary systematically from west (younger and higher) to east (older and lower). The fi rst emergent marine terraces in the westernmost SBFB are approximately 45 ka (MIS 3), and the rate of local surface uplift is ~2 m/k.y. In the central part of the belt, fi rst emergent terraces date to 60-70 ka (MIS 5), and uplift rates decrease to ~1.2 m/k.y. First emergent marine terraces preserved in the easternmost fold belt range from 70 ka to 105 ka (MIS 5), with rates of local surface uplift of ~0.5 m/k.y. Lower rates of uplift in the eastern end of the fold belt result from the MIS 5 terrace being tilted down into the Carpinteria syncline. Rates of vertical uplift in the western end of the fold belt are about six times higher than previously reported, suggesting the seismic hazard is also greater.

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Parameter estimation for multiple post‐wildfire hydrologic models

Ebel

Moody

2020

Hydrological Processes

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Predictions of post‐wildfire flooding and debris flows are needed, typically with short lead times. Measurements of soil‐hydraulic properties necessary for model parameterization are, however, seldom available. This study quantified soil‐hydraulic properties, soil‐water retention, and selected soil physical properties within the perimeter of the 2017 Thomas Fire in California. The Thomas Fire burn scar produced catastrophic debris flows in January 2018, highlighting the need for improved prediction capability. Soil‐hydraulic properties were also indirectly estimated using relations tied to soil‐water retention. These measurements and estimates are examined in the context of parameterizing post‐wildfire hydrologic models. Tension infiltrometer measurements showed significant decreases (p < .05) in field‐saturated hydraulic conductivity (Kfs) and sorptivity (S) in burned areas relative to unburned areas. Wildfire effects on soil water‐retention were dominated by significant decreases in saturated soil‐water content (θS). The van Genuchten parameters α, N, and residual water content did not show significant wildfire effects. The impacts of the wildfire on hydraulic and physical soil properties were greatest in the top 1 cm, emphasizing that measurements of post‐fire soil properties should focus on the near‐surface. Reductions in Kfs, θs, and soil‐water retention in burned soils were attributed to fire‐induced decreases in soil structure evidenced by increases in dry bulk density. Sorptivity reductions in burned soils were attributed to increases in soil‐water repellency. Rapid post‐fire assessments of flash flood and debris flow hazards using physically‐based hydrologic models are facilitated by similarities between Kfs, S, and the Green–Ampt wetting front potential (ψf) with measurements at other southern CA burned sites. We suggest that ratios of burned to unburned Kfs (0.37), S (0.36), and ψf (0.66) could be used to scale unburned values for model parameterization. Alternatively, typical burned values (Kfs = 20 mm hr−1; S = 6 mm hr−0.5; ψf = 1.6 mm) could be used for model parameterization.

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Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California

Cited by 21 publications

References 41 publications

In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

Tectonic geomorphology of marine terraces: Santa Barbara fold belt, California

Parameter estimation for multiple post‐wildfire hydrologic models

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