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Paleoseismicity of the North Branch of the Newport-Inglewood Fault Zone in Huntington Beach, California, from Cone Penetrometer Test Data Lisa B

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Paleoseismicity of the North Branch of the Newport-Inglewood Fault Zone in Huntington Beach, California, from Cone Penetrometer Test Data Lisa B Chapman University Chapman University Digital Commons Biology, Chemistry, and Environmental Sciences Biology, Chemistry, and Environmental Sciences Faculty Articles and Research 1997 Paleoseismicity Of the North Branch Of the Newport-Inglewood Fault Zone In Huntington Beach, California, From Cone Penetrometer Test Data Lisa B. Grant Chapman University John T. Waggoner Southern California Earthquake Center Thomas K. Rockwell Southern California Earthquake Center Carmen von Stein Southern California Earthquake Center Follow this and additional works at: http://digitalcommons.chapman.edu/sees_articles Part of the Tectonics and Structure Commons Recommended Citation Grant, Lisa B., John T. Waggoner, Thomas K. Rockwell, and Carmen von Stein. "Paleoseismicity of the north branch of the Newport- Inglewood fault zone in Huntington Beach, California, from cone penetrometer test data." Bulletin of the Seismological Society of America 87.2 (1997): 277-293. This Article is brought to you for free and open access by the Biology, Chemistry, and Environmental Sciences at Chapman University Digital Commons. It has been accepted for inclusion in Biology, Chemistry, and Environmental Sciences Faculty Articles and Research by an authorized administrator of Chapman University Digital Commons. For more information, please contact [email protected]. Paleoseismicity Of the North Branch Of the Newport-Inglewood Fault Zone In Huntington Beach, California, From Cone Penetrometer Test Data Comments This article was originally published in Bulletin of the Seismological Society of America, volume 87, issue 2, in 1997. Copyright Seismological Society of America This article is available at Chapman University Digital Commons: http://digitalcommons.chapman.edu/sees_articles/62 Bulletin of the Seismological Society of America This copy is for distribution only by the authors of the article and their institutions in accordance with the Open Access Policy of the Seismological Society of America. For more information see the publications section of the SSA website at www.seismosoc.org THE SEISMOLOGICAL SOCIETY OF AMERICA 400 Evelyn Ave., Suite 201 Albany, CA 94706-1375 (510) 525-5474; FAX (510) 525-7204 www.seismosoc.org Bulletin of the Seismological Society of America, Vol. 87, No. 2, pp. 277-293, April 1997 Paleoseismicity of the North Branch of the Newport-Inglewood Fault Zone in Huntington Beach, California, from Cone Penetrometer Test Data by Lisa B. Grant,* John T. Waggoner, Thomas K. Rockwell, and Carmen von Stein Abstract Application of cone penetrometer testing (CPT) is a promising method for studying subsurface fault zones in stratified, unconsolidated sediment where trenching is not feasible. Analysis of data from 72 CPTs, spaced 7.5 to 30.0 m apart, and 9 borings indicates that the North Branch fault, the active strand of the Newport- Inglewood fault zone (NIFZ) in Huntington Beach, has generated at least three and most likely five recognizable surface ruptures in the past 11.7 _+ 0.7 ka. Additional smaller earthquakes similar to the M w 6.4 1933 Long Beach earthquake may also have occurred but would not be recognizable with this method. The minimum right- lateral Holocene slip rate of the NIFZ in the study area is estimated to be 0.34 to 0.55 mrrdyr. The actual slip rate may be significantly higher. Introduction The destructive seismic potential of the Newport-Ingle- The fault zone continues offshore to the south and then wood fault zone (NIFZ) was demonstrated by the damaging comes ashore again near San Diego as the Rose Canyon 1933 M w 6.4 Long Beach earthquake, located 8 to 12 km fault. beneath southern Huntington Beach (Hauksson and Gross, At the surface, the NIFZ is marked by a series of domal 1991). A future major earthquake along the densely popu- uplifts and low mesas arranged in an en echelon pattern lated NIFZ poses one of the greatest hazards to lives and within a right-lateral strike-slip fault zone (Wilcox et al., property in the nation (California Division of Mines and Ge- 1973; Barrows, 1974; Wright, 1991). The fault zone consists ology, 1988). of a complex series of discontinuous strike-slip traces and Despite historic seismic activity along the NIFZ, the shorter subsidiary normal and reverse faults (Barrows, 1974; seismic source characteristics of the NIFZ are poorly con- Bryant, 1988). Right-lateral displacement of late-Miocene strained. Paleoseismic data on the Holocene behavior of the through late-Pliocene sediments and structural features in- NIFZ and its prehistoric earthquakes are difficult to obtain dicate that strike-slip faulting initiated during the late Plio- because most of the Holocene deposits along the fault zone cene in the Inglewood oil field and earlier along the southern either are obscured by urban development or are located near portion of the NIFZ (Freeman et al., 1992). In the Huntington sea level where a high water table precludes traditional pa- Beach area, right-lateral offset of late-Miocene rocks across leoseismic trench investigation. To overcome these obsta- the zone may total more than 9.5 km (Hazenbush and Allen, cles, we used the cone penetrometer test (CPT) method to 1958; Bryant, 1988). Displacement of late-Miocene and investigate the Holocene earthquake history of the primary younger sediments indicates that the long-term right-lateral active trace, the North Branch fault (NBF), of the NIFZ in slip rate of the NIFZ is approximately 0.5 mm/yr (Freeman Huntington Beach, California. et al., 1992). Evidence of tectonic and seismic activity is present Geologic and Tectonic Setting along the NIFZ in the form of Quaternary folds, recent faults, and recorded seismicity (Barrows, 1974; Bryant, 1988; The NIFZ is the northern part of a zone of coastal strike- Wright, 1991). The Holocene and Quaternary slip rates of slip faults and associated folds extending between Los An- the NIFZ are poorly constrained; estimates of the Quaternary geles and San Diego (Fig. 1). The NIFZ is a major tectonic slip rate of the NIFZ range from 0.03 to 6.0 mm/yr (Suppe boundary in southern California (Hill, 1971; Wright, 1991). et al., 1992; Petersen and Wesnousky, 1994). In San Diego, The northern NIFZ extends along the western margin of the the strike-slip Rose Canyon fault has a Holocene slip rate of Los Angeles basin from Beverly Hills to Newport Beach. 1.1 to 2.0 mm/yr (Lindvall and Rockwell, 1995). In the Los Angeles basin, the minimum horizontal Quaternary slip rate across the NIFZ has been estimated at 0.03 to 0.05 mrrdyr at *Corresponding author. All authors are participants in the Earthquake Geology Group of the Signal Hill in Long Beach (Suppe et al., 1992). However, Southern California Earthquake Center. the 1933 earthquake, which ruptured a 13- to 16-km-long 277 278 L.B. Grant, J. T. Waggoner, T. K. Rockwell, and C. von Stein • • " ..,..,-• • . _. ~L~ ~ .... ='" " ". LOS ANGELES COUNTY SANTA 'i. \. "~0., ~ \ tlILLS I MONICA \ "/4+ \ '- ,'='~"'=, - I \" "~/\ SCALE, kilomefers i ~ ':'~_ ' I. BAy ~. OOA • DOMINGUEZ ] ~. ~ ., mLLS ] ) %\,.SIGNAL ORANGE ]! ( S "~ ~04,~"~ "x~ \HILL COUNTY i ~, ~:'~L '~" _ ~,,,~ "~:', I HUNTINGTON ! /~ %~.-- ~:,~"'x4" _ NEWPORT <7 ".'., -". OCEAN .... -\ • ~- SD I U.S.A. - '~ E.x---'Tc 0 50 I O0 SCALE, kilomefers Figure 1. (Inset) Regional tectonic map of coastal southern California showing Newport-Inglewood fault zone (NI), 1933 rupture zone (hatched), Rose Canyon fault (RC), Palos Verdes fault (PV), offshore Coronado Bank fault (CB), Whittier fault (W), Elsinore fault (E), Los Angeles (LA), and San Diego (SD). Modified from Lindvall and Rockwell (1995). (Top) Regional map of the Newport-Inglewood fault zone showing selected faults and Quaternary uplifts marked by hills. Modified from Guptill and Heath (1981). Study Site section of the NIFZ between Long Beach and Newport Beach We conducted paleoseismic investigations at a site (Hauksson and Gross, 1991), demonstrated that the southern along the North Branch fault (NBF) of the NIFZ. The NBF is half of the NIFZ is active and capable of generating signifi- the active trace of the NIFZ in Huntington Beach as defined cant earthquakes (Hauksson, 1987). The recorded seismicity by Bryant (1988). We selected this site because it is close of the NIFZ and the Holocene slip rate of the Rose Canyon to the epicenter of the 1933 earthquake and because it is one fault suggests that the Holocene slip rate of the NIFZ may of the few accessible, relatively undisturbed sites along the be substantially higher than 0.03 to 0.05 ram/yr. NIFZ with enough Holocene sediments and correlatable stra- Paleoseismicity of the North Branch of the Newport-Inglewood Fault Zone from Cone Penetrometer Test Data 279 tigraphy suitable for paleoseismic investigation. In addition, The Holocene sediments are interpreted to be fluvial, littoral, the structure and sedimentation rate at the site have created and estuarine deposits correlative with regional coastal Ho- a good geologic environment for preserving a Holocene rec- locene deposits in Orange and Los Angeles counties (Poland ord of paleoseismicity. et al., 1956). These sediments are related to rapid global sea- Within the Huntington Beach oil field, a section of the level rise in the early to middle Holocene (Bard et al., 1990; NBF steps to the right within the study area, as shown in Chappell and Polach, 1991; Gibb, 1986). Figure 2. The site topography is nearly flat, and the water table is approximately coincident with the ground surface. Investigation Methods Analysis of oil-well E-logs, water-well logs, and CPT data shows that the step-over forms a structural depression, or Several subsurface exploration methods were used to graben, between the main traces of the fault zone, as shown investigate the sediments and analyze the geologic record of in Figure 2 (Freeman et al., 1992; California Dept. of Water faulting at the study site. First, the Holocene traces of the Resources, 1968). The sense of separation of Miocene NBF were located by preliminary studies (Woodward-Clyde through Holocene sediments indicates that faults within the Consultants, 1987; Freeman et al., 1992).
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