If you think of the Earth's crust across central California as an air mattress floating in a pool, imagine a swimmer grabbing it in the middle from below and pulling down. California really is different from its neighbors.). The last big earthquake along the Hayward Fault was in 1868. The Hayward, a major branch of the San Andreas fault system, exhibits creep along at least 68 km of its <100 km length (Fig.1). An aseismic creep exists along the Calaveras fault in Hollister, California. Alignment arrays ( named locations on the map) indicate that the creep process is centered on the surface fault and is manifest as discrete slip on surface cracks within a shear zone 5-50 m wide. What happens farther west? The Hayward fault (HF) in California exhibits large (M w 6.5–7.1) earthquakes with short recurrence times (161±65 yr), probably kept short by a 26%–78% aseismic release rate (including postseismic).Its interseismic release rate varies locally over time, as we infer from many decades of surface creep data. The Hayward Fault Zone is a geologic fault zone capable of generating destructive earthquakes.This fault is about 74 mi (119 km) long, situated mainly along the western base of the hills on the east side of San Francisco Bay.It runs through densely populated areas, including Richmond, El Cerrito, Berkeley, Oakland, San Leandro, Castro Valley, Hayward, Union City, Fremont, and San Jose. To solve for a time‐dependent mode NCGS Commemorates the 1906 Great Earthquake by Walking…the Hayward Fault! Login to your account or register to create a new one to submit your comment. The result is that the southern Great Valley is at its widest and deepest there, in the Tulare geologic basin. In the meantime, I can show you examples of Hayward fault creep in Hayward, in Fremont and in Pinole. Get the best of KQED’s science coverage in your inbox weekly. In spite of this, the fault has also experienced moderate to large earthquakes. Dislocation models of the surface deformation adjacent to the Hayward fault measured with the global positioning system and interferometric synthetic aperture radar favor creep at ∼7 millimeters per year to the bottom of the seismogenic zone along a ∼20-kilometer-long northern fault … The three maps were compared with seismicity, including aseismic patches, surface creep, and fault dip along the fault, by using visualization software to explore three-dimensional relationships. The two fault-surface maps were superimposed to create a rock-rock juxtaposition map. In geology, aseismic creep or fault creep is measurable surface displacement along a fault in the absence of notable earthquakes. Joyce Blueford and Mitch Craig lead NCGS members, family, and the general public on a field trip to examine evidence of the Hayward Fault in the East Bay. When people learn about it, they often wonder if fault creep can defuse future earthquakes, or make them smaller. Lithospheric convective instability could induce creep along part of the San Andreas fault. Contributed by Dale Smith Photos by Phil Garbutt. The so-called creeping section runs from the village of Parkfield east of Paso Robles up to San Juan Bautista. Second, and more importantly, knowing where and how fast the Hayward fault creeps allows us to make estimates of where it is not creeping. The authors are Laetitia Le Pourhiet, a French geophysicist, and Jason Saleeby, a geologist at Caltech's Tectonics Observatory who has studied the southern Sierra Nevada for decades. So is any of this a scientific fact? Hayward fault creeps with a rate of approximately 1cm/year. Thanks for signing up for our newsletter. On April 15, 2006, Drs. Scientific consensus is when everyone accepts a good hypothesis and moves ahead because they've run out of good counterarguments. The steady creep along the fault results in relative displacement of the two parts of the stadium. Fault creep is the name for the slow, constant slippage that can occur on some active faults without there being an earthquake. transient fault creep accumulating an average of 20–25 mm of displacement on the fault followed by a gradual return to steady creep around year 2000. Fault creep is aseismic fault slip that occurs in the uppermost part of the earth's crust during the time interval between large stress-releasing earthquakes on a fault or as "afterslip" in the days to years following an earthquake. Last week I gave a walking tour of the Hayward fault along the Oakland-Berkeley border. The answer is … They clearly show the right lateral movement of the fault as depicted on the road. The northernmost Hayward fault and Rodgers Creek fault (RCF) appear to rupture only half as frequently as the HS and are separated from the HS by a creep buffer and 5-km wide releasing bend respectively, both tending to limit through-going ruptures. The Hayward fault is considered to be one of the primary hazards in the San Francisco Bay region. First, we want to explain why some faults creep and others do not – why it happens on the Hayward fault in Fremont, and not (for example) on the San Andreas fault in Palo Alto. On the east side of the Sierra, the mountains responded by springing upward to create the dramatic eastern face that includes Mount Whitney, highest peak in the 48 states. [1] Spatial and temporal variations of aseismic fault creep influence the size and timing of large earthquakes along partially coupled faults. For ten years I was lucky enough to have my office right on top of the fault, in the infamous "Section KK" at the stadium. Le Pourhiet did the computer modeling to show that the west side of the microplate arches upward by a hundred feet or so. The Hayward fault (HF), a major branch of California’s San Andreas fault system, produced an M ∼6:8 earthquake in 1868 (Lawson, 1908; Bakun, 1999). How California's Warping Microplate Makes Its Faults Creep. Our project is a literature review of scholarly papers and will attempt to cover select topics in the realm of earthquakes and landfills with a condensed discussion of the topic at hand. In October 2007, a magnitude 5.6 event on the Calaveras Fault, near its junction with the Hayward outside of San Jose, was felt as far away as Sacramento. Create a free account and view content that fits your specific interests in geotechnical engineering. Its last major rupture occurred in 1868, during California's frontier days, and was the original "Great San Francisco Earthquake" until 1906.. To those who still can’t get enough of this amazing geologic feature, this post’s for you. Thus, if large earthquakes can occur on faults, or sections of a fault, that are slowly creeping, these need to be better understood and taken seriously. On its west side, the drip is still attached and pulling down on the crust. The Hayward fault is a 90 kilometer long crack in the Earth's crust that travels through the San Francisco Bay area. The Sierra Nevada microplate rotates slightly and moves northwest at a few millimeters per year relative to the rest of the North America plate. Although there are no observations of surface creep in San Pablo Bay, repeating earthquakes identified along the offshore Hayward fault trend ( 18 ) suggest that seismic Creep is occurring along it. The Hayward Fault is a major earthquake fault that runs for nearly 45 miles (72 km) through the East Bay of the San Francisco Bay region. Fault creep is quite uncommon in general, but a big central section of the San Andreas fault complex is creeping today while on either side the fault is locked, building up energy for large earthquakes like the 1906 quake in Northern California and the 1857 Fort Tejon quake in Southern California. Creep along the Hayward fault resulted in the "migration" of the stream. There, most of the fault between the surface and its base at around 15 kilometers depth turns out weak and slippery, and only a narrow band of rock in the middle of that range has enough friction to gather a lot of strain energy. Of all the East Bay cities, Oakland owns the longest stretch of the Hayward fault. Not yet; it's just another good hypothesis that fits a variety of data but needs refinement. Every April (anniversary month of the SF '06 earthquake), tours would come and see all the wonderful signs of creep. That side is pinned against the San Andreas fault so it can't simply break and spring upward like the eastern Sierra, which is being pulled away from Nevada. It was approximately a magnitude 6.9. Summary. Generally creep occurs without … Cracks appear in masonry and paving along the length of the fault, and the walls of … Among other things, I talked about the fault's peculiar behavior called aseismic creep, in which the two sides of the fault move slowly past each other at just a few millimeters per year without the help of earthquakes. The seismic risk associated with creeping faults such as the Hayward fault (San Francisco Bay Area, CA) will depend on the rate of moment accumulation (slip deficit) on the fault plane, on the specific geometry of locked and free portions of the fault, and on the interactions between the fault zone and the surrounding lithosphere. Figure 3 also shows nicely how the sidewalk and pavement are damaged only in the zone of the Hayward trace. 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