Hayward Fault - Berkeley

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stadium crackHayward fault slip vector and rate constraints at Berkeley: Reinterpretation of East Bay Landforms and Tectonic Hazards USGS Award 1434-HQ-97-GR-03080 Patrick L. Williams, University of California - Berkeley, Seismological Lab & Dept of Geography

(Also see news editorial: The Hayward Fault: Will it trigger the next quake: What to do if it does
April 10, 1992 By Pat Williams)

Investigations Undertaken
Offset and abandoned channels of Strawberry Creek have been shown to record the vertical and lateral motions of the northern Hayward fault at Berkeley. Geological features of the western Berkeley Hills are consistent with rapid and recent uplift to the west of the fault. Analysis of two offset channels of Strawberry Creek indicates up-to-the-west uplift across the Hayward fault at a rate of approximately 0.5 mm/yr. If this rate is steady, and extends along the 20-kilometer-body of the western Berkeley Hills, the interpreted 120 m uplift of the Hills occurred during the past about 250,000 years. With these interpretations, a "characteristic" northern Hayward fault rupture is implied to be accompanied significant compressional shortening along the western Berkeley Hills and thus probably can produce a larger moment-magnitude earthquake than previously estimated. Rapid uplift of the Hills also has important implications for the geotechnical stability of significant portions of the East Bay Hills.

Ironically, the UC Berkeley Main Campus is probably the best location for study of the long-term kinematics of the Hayward fault. The University's location was chosen, in large part, because of the presence of a reliable water supply from Strawberry Creek. Motion of the Hayward fault has displaced the modern, active course of Strawberry Creek by about 300 meters (1000'). Paleochannels are offset 580 meters (1900') and 730 meters (2400'). Strawberry Creek and its paleochannels record both vertical and lateral components of the strain field across the Hayward fault. The up-to-the-west deformation that is indicated by fluvial and landform evidence at Berkeley has important implications for structural geology of the Hayward fault, and very likely explains the presence of several thrust-bounded highlands to the west of the fault.

General evidence for the rapid uplift is illustrated in Figure 1, a topographic map along the Hayward fault zone in southeast section of Berkeley, circa 1923. Note the abrupt increase of slope at the fault-line to the south of The UC Berkeley football stadium. Obvious stream offsets occur at Claremont, Hamilton, Strawberry, and Blackberry creeks. Note that the fault climbs northward from the 400' contour at Strawberry Creek to the 520' contour north of Blackberry Creek. The fault continues to climb northward across the western Berkeley Hills ultimately reaching a height of 800' (Figure 2). Note that the Mining Circle Channel projects to the fault at about 440'. The Hearst channel projects to the fault at about 480'. These intercepts are very suggestive of ongoing uplift across the Hayward at Berkeley.The beheaded Strawberry channel's origins are supported by the provenance of offset gravels.

Clasts of Claremont Chert are abundant in gravels exposed in excavations that intersected the paleochannel during expansion of Doe Library in the central UCB campus. Chert is absent in the hillslope north of Strawberry Creek, but is abundant in the Strawberry watershed, and so identifies these as Strawberry Creek deposits. Unpublished notes of George Louderback also describe chert in three channel deposits of the Lawson Adit (Figure 1), a tunnel bored between the Mining Circle and Hearst paleochannels. Buwalda (1929) first associated the Adit gravels with fault offset, documenting that sorting, wear and provenance of the gravels tied them uniquely to Strawberry Creek, hundreds of feet to the south.

Landforms of the western Berkeley Hills support a hypothesis of uplift to the west of the fault. The Hayward fault traverses the hills (Figure 2) between Strawberry Creek and Richmond. Dibblee (unpublished mapping of the Richmond and Oakland East quadrangles) mapped a faultline at the base of the hills, as illustrated in Figure 2, and labeled as the El Cerrito fault. The Hayward fault climbs from 400 feet at Strawberry Creek to 800 feet at the crest of the western Berkeley, a rise of 120 meters. If the about 0.5 mm/yr rate of vertical motion suggested by the apparent uplift of abandoned Strawberry Creek channels holds for long period required for uplift of the western Berkeley Hills across the Hayward fault, the period required to reach their present configuration is approximately 250,000 years. Lack of a well-developed fault-line valley along the relatively more stable ridge-top area also suggests the youthfulness of the present configuration. It is thus proposed that the western Berkeley Hills block has been upthrust between the El Cerrito and Hayward faults during Quaternary time.

The earliest detailed landform map in the Hayward fault zone is the UC Berkeley building and grounds map, compiled in 1897 (Figure 3). This map records the morphology of the abandoned Mining Circle and Hearst channels of Strawberry Creek at a contour interval of four feet. The fault climbs approximately 24 meters across this Figure (from 400 to 480'). Once again, the offset channels project to the fault at about 440 and 480 feet. Note that the near-fault profile of each beheaded channel is steepened by alluvium, which heightens the apparent channel intercept with the fault zone. A better estimation of the height of the intersection can be made by projecting the stream profiles from a greater distance from the fault (Figure 4). Note also the area of thickly ponded alluvium behind the Strawberry Creek shutter ridge. This ponding causes a tendency to underestimate the depth of the Strawberry Creek Canyon, and consequently underestimate the total vertical separation between the canyon and the beheaded channels. A projection to the fault of the bedrock stream profile is thus required to estimate the Wisconsin-era canyon morphology, and to recover the maximum vertical separation of the beheaded profiles.

Channel and Bank Profiles are illustrated in Figure 4. The active and beheaded channels of Strawberry Creek are aligned along the Hayward Fault. Ranges of vertical separation across the fault are noted graphically. Indicated are at least 10 but no more than 18 m of uplift of the Mining Circle channel. Also indicated are at least 12 but no more than 30 meters of Hearst channel uplift. Flattening of the active Strawberry Creek profile below the fault, along the length of the shutter ridge, results from tectonic lengthening of the channel by fault offset, and consequent alluviation. A "falls" occurred at the northern end of the shutter ridge. The much greater steepness of the paleochannels is attributed to control by much lower glacial base levels. The Strawberry profile is believed to have been greatly shallowed by agradataion as base-level rose. The much wider morphology of the modern stream valley that is apparent in Figure 3 is indicative of alluviation of the glacial era valley.

Reference
Buwalda, John P., 1929, Nature of the Late Movements on the Hayward Rift, Central California, Bulletin of the Seismological Society of America, 19, 187-199.

Related publications and reports

California Memorial Stadium Commission, California Memorial Stadium Grading Plan, University of California, Berkeley, California, 1922.

King, M.G., Grounds and Buildings Map, University of California, Berkeley, Alameda County, California, compiled under the direction of the College of Civil Engineering, 1897.

Lienkaemper, J.J., Map of recently active traces of the Hayward fault, Alameda and Contra Costa Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-2196, 1992.

Williams, P.L., Features and dimensions of the Hayward fault zone in the Strawberry and Blackberry Creek area, Berkeley California, Lawrence Berkeley Laboratory Pub. 36852, 1995.

Williams, P.L., Rate determinations for late Quaternary compressional tectonics across the central California Coast Ranges, EQS Trans AGU, December 1996.

Topographic May Showing Interpretations of the Hayward Fault California Memorial Stadium, University of California Berkeley, California. Geomatrix, Project 5442 Figure 2.
Pre-Development Landform Map, California Memorial Stadium, University of California Berkeley, California.
Geomatrix, Project 5442 Figure 3.

FIGURE CAPTIONS

Figure 1. Topographic map in the vicinity of the Hayward fault zone, southeast section of Berkeley, circa 1923 Note the abrupt increase of slope at the fault-line and the geometry of streams offset by the Hayward fault. Note that the fault climbs from the 400 contour at the Creek to the 520 contour north of Blackberry Canyon. The fault continues to climb northward across the western Berkeley Hills ultimately reaching a height of 800', see Figure 2. Contour interval = 20’
.

Figure 2. Topography of the western Berkeley Hills with Hayward and Dibblee" fault locations. Map extends from Strawberry Creek to Richmond. The morphology of the faults traverse over the hills indicates uplift of the western block. The fault climbs from 400 feet at Strawberry Creek to 800 feet at the crest of the western Berkeley, a rise of 400 feet (120 meters), Lack of a well-developed fault-line valley along the relatively more stable ridge-top area suggests the youthfulness of the present configuration. If the about 0.5 mm/yr rate suggested by Strawberry Creek stream morphology holds for long-term uplift across the Hayward fault, the western Berkeley Hills required approximately 250,000 years to reach their present elevation. Contour interval = 20'.

Figure 3. Landforms and culture in the area of the Hayward fault zone. University of California, Berkeley drawn on a UC Berkeley base map, compiled in 1897. This map records the morphology of the two abandoned channels of Strawberry Creek. University of California structures as of AD 1897 are solid. Selected later University of California structures outlined for reference. Major fault-related landforrns include: A-A: Strawberry Creek channel offset; Sr': primary shutter ridge; Sr': remnant shutter ridge MCC: beheaded Mining Circle Channel; H: beheaded Hearst Avenue Channel. Elevations of the intersections of ancient and modem channels of Strawberry Creek with the fault are noted. Contour interval is 4 below 400' and 8' above. The fault climbs approximately 24 meters across this Figure (from 400’ to 480')

Figure 4. Channel and Bank Profiles. active and paleochannels of Strawberry Creek, aligned on the Hayward Fault. Ranges of vertical separation across the fault are noted graphically. Indicated are at least 10 but no more than 18 m of uplift of the Mining Circle channel. Also indicated are at least 12 but no more than 30 meters of Hearst channel uplift. Flattening of the active Strawberry Creek profile below the fault, along the length of the shutter ridge, results from tectonic lengthening of the channel by fault offset. The drop in the channel at the northern end of the shutter ridge was called "the falls". The much greater steepness of the paleochannels is attributed to control by much lower glacial base level. The Strawberry profile was made gentle by agradatalon as base-level rose. The wider morphology of the modem channel is indicative of valley filling.

Non-technical Project Summary
Offset and abandoned channels of Strawberry Creek have been shown to record the vertical and lateral motions of the northern Hayward fault at Berkeley. Geological features of the western Berkeley Hills are consistent with rapid and recent uplift to the west of the fault. Analysis of two offset channels of Strawberry Creek indicates up-to-the-west uplift across the Hayward fault at a rate of approximately 0.5 mm/yr. If this rate is steady, and extends along the 20-kilometer-body of the western Berkeley Hills, the interpreted 120 m uplift of the Hills occurred during the past about 250,000 years. With these interpretations, a "characteristic" northern Hayward fault rupture is implied to be accompanied significant compressional shortening along the western Berkeley Hills and thus probably can produce a larger moment-magnitude earthquake than previously estimated. Rapid uplift of the Hills also has important implications for the geotechnical stability of significant portions of the East Bay Hills.

Source: http://erp-web.er.usgs.gov/reports/annsum/vo139/nc/g3080.htm

The Hayward Fault: Will it trigger the next quake: What to do if it does
April 10, 1992 By Pat Williams


Editor's note: LBL geologist Pat Williams examines the probability that the nearby Hayward Fault will produce a major earthquake, and discusses how we can prepare for that possibility, both at work and at home.

One day in the future; while many or most of us are still employed at LBL, there will be a catastrophic earthquake in the Bay Area. Many earthquake researchers believe that our very close neighbor, the northern Hayward Fault, is the top candidate to produce the area's next major shock. Modest preparations at home and at work will make a tremendous difference in our comfort, safety, and peace of mind in the aftermath of this event.

Long-term earthquake forecasting leans heavily on history for evaluating earthquake occurrence probabilities. This method relies on three pieces of information: 1) the fault's long-term rate of slip, 2) the time elapsed since its last rupture, and 3) the offset expected in a "typical" fault rupture.

Surprisingly, little of this information can be determined by classical seismological techniques. Earthquake science now relies heavily on geological and historical investigation of past fault behavior. Geological fault studies search for ancient evidence of slip rate, the size of past offsets, and the times of past ruptures.

Investigators scan old newspapers to learn the extent and size of historical ruptures. Studies of the Hayward Fault have provided the following clues: its average slip rate is about 9 mm/yr (0.35 in/yr); the latest rupture of its southern segment (Fremont to San Leandro) occurred in 1868; and rupture of the northern section (San Leandro to Pinole) probably occurred in 1936. Earthquake forecasters estimate an average earthquake recurrence interval of 167 years. Other concepts, particularly the idea that strain of the earth's crust in the Bay Area has slowly "recharged" after being greatly relaxed by the 1906 San Francisco earthquake, suggest that new Hayward Fault earthquakes are likely during the period of the next few years to decades.

LBL's Exploratory Research and Development Fund enabled a direct study of the Hayward Fault's earthquake history. Current results of that study indicate that the fault's past ruptures occurred, on average, every 150-250 years. This appears to support the 167- year average recurrence estimated by earthquake forecasters.

Following a large earthquake, the greatest concern we will probably have, after our personal safety, will be the safety and whereabouts of our families. Due to heavy damage to the transportation infrastructure at the Lab and in the Bay Area, it is likely that most of us will have to leave the site under our own power in order to reunite with our families. This will be more difficult for those of us who live very far from the Lab.

Lab roads will probably be closed by landslides and ground rupture along faults. The accompanying figure shows that ground rupture on the Hayward Fault is likely to close both Centennial Drive and Cyclotron Road for some period of time. Roads closed by fault breaks may be made passable by the Lab's own crews within a few hours. Roads closed by landslides are generally more difficult to repair, and are likely to remain impassable for days to weeks. Even after Lab roads are made passable, use will generally be restricted to emergency vehicles only. Lab earthquake procedures (located on the inside-back cover of the LBL telephone directory) instruct us "not" to leave the Laboratory by car.

After a major seismic event in the Bay Area, bridges and rail systems are likely to remain closed for a few hours to a few weeks while they are inspected, and if necessary, repaired. Those of us who used bridges and rail transit to commute to work may be stranded away from home for a day or more, and when we do go home, we are likely to cover most of the distance on foot.

Reasonable preparations for a long walk home include keeping sturdy shoes, a jacket, a hat, and a backpack, containing some high-energy nonperishable food, a water bottle, and a flashlight, at your work place and/or in your car. Additionally, it is essential that we "write down" a family earthquake plan and in it include as participants teachers, friends, neighbors, and relatives who can help us in reuniting our families and whom we can help during the crisis.

In the plan:

  • 1) make a school/daycare evacuation plan;
  • 2) choose a primary and an alternate family meeting site;
  • 3) identify some person(s) outside the area to coordinate family messages (long distance lines will be the first to be reestablished;
  • 4) include someone in the plan would could care for your children if the family is separated during an earthquake. Store adequate food, water, batteries and other supplies to last three or more days after the earthquake. Be sure that both the structural and non-structural elements of your residence are earthquake safe. The telephone white pages contain an excellent summary of earthquake emergency information. By preparing for future Bay Area earthquakes, we acknowledge the potency of the active faults of this region, we contribute to our own peace of mind, and we set the stage for a more rapid post-earthquake recovery of LBL and the community.

    Source: http://www.lbl .gov/Science-Articles/Archive/hayward-fault.html
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