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Is there bedrock under San Francisco?
Franciscan oceanic bedrock dominantly underlies San Francisco Bay watersheds. Transform tectonism led to volcanism, small basin development and displacement.
Is San Francisco built on a rock?
San Francisco is built on a thick suite of unusual red, green, gray, black, blue, yellow, and brown rocks called the Franciscan. These rocks were formed in the Franciscan subduction zone as a result of a slow-motion collision between two of the large plates that covered the surface of the earth during Cretaceous time.
Is Russian Hill on a bedrock?
Also it's built on bedrock, not fill, so way safer in earthquakes." "Russian Hill is home to some of the best views in the city. While being a stones throw to North Beach, it is the perfect neighborhood in SF."
How many pounds of concrete make up the concrete slab below the Salesforce Tower?
The 310-foot deep foundation of the Salesforce tower surpassed the 282-foot deep foundation for the Shanghai Tower, another skyscraper in an earthquake zone. The foundation included a 14-foot thick concrete slab that's about an acre wide. See the 49 million pounds of concrete being poured below.
Why is SF so hilly?
Active faulting continues in the San Francisco Bay Area; during the past ~3 million years, the topography of the Bay Area was created. Some of the topography is a direct result of uplift along faults, but in San Francisco itself, most of the topography was created by differential erosion of ancient rocks.
Is SF built on 7 hills?
Of the 48 named hills in San Francisco, only seven claim to have been named at the time of the city's founding—Nob Hill, Russian Hill, Telegraph Hill, Rincon Hill, Twin Peaks, Mount Sutro, and Mount Davidson.
Why is it called Nob Hill San Francisco?
History. Prior to the 1850s, Nob Hill was called California Hill (after California Street, which climbs its steep eastern face), but was renamed after the Central Pacific Railroad's Big Four – known as the Nobs – who built their mansions on the hill.
How high is Russian Hill SF?
294 ftHillsNameHeightRussian Hill294 ft (90 m)Silver Terrace275 ft (84 m)Strawberry Hill412 ft (126 m)Sutro Heights200 ft (61 m)46 more rows
What is Russian Hill like in San Francisco?
Russian Hill San Francisco is home to a variety of things to do. Its most popular attraction is Lombard Street, one of the crookedest streets in the world! The neighborhood is also home to a Diego Rivera fresco, comedy clubs, restaurants, and nightlife. You will find it on the northeastern side of SF.
How deep do skyscraper foundations go?
Piles or pilings are drilled down into the earth. Some skyscraper foundations go deeper than 250 feet. The depth of a deep foundation depends on how tall the building is.
How thick is concrete slab for a skyscraper?
Generally speaking a concrete residential highrise is 7-8" slabs, office are 9-10" and hotels somewhere in between. Anticipated loading requirements also play a part and change these numbers. Parking slabs are thicker, up to 12" but have far more rebar.
What building has the deepest foundation?
Twin's Towers of Malaysia has the world's deepest foundations. Which is situated in Kaula— Lampur Malaysia. The depth of its foundations is 120m ( i.e. 400ft approx ). On the purposed site of Twin's Towers of Malaysia, the available on top was black cotton soil.
What is San Francisco built on top of?
San Francisco's Foundation is Built on Old Ships from the Mid-1800s. Underneath some of the most expensive real estate in the entire world sits hundreds of old wooden ships.
Is San Francisco built on a mountain?
Several cities claim to have been built on seven hills. "The Seven Hills of San Francisco" are Telegraph Hill, Nob Hill, Russian Hill, Rincon Hill, Twin Peaks, Mount Davidson and Lone Mountain or Mount Sutro.
How was the San Francisco Bay formed?
The geology you see around San Francisco is the result of forces along the Pacific and North American plates. Today, the Pacific Plate is slowly creeping north past the North American Plate, forming the San Andreas fault system. San Francisco Bay was created by movement on these faults about 650,000 years ago.
How did San Francisco get built?
Originally a Spanish (later Mexican) mission and pueblo, it was conquered by the United States in 1846 and by an invading army of prospectors following the 1848 discovery of gold in its hinterland. The Gold Rush made San Francisco a cosmopolitan metropolis with a frontier edge.
How deep do you need to dig to hit bed rock? - Quora
Answer (1 of 6): Hi Kat. Bedrock is the first rock you hit below ground. So how deep that is depends on where you are. In some places, the bedrock IS the ground. In other places - like the valleys of large rivers for instance, or areas along the US Southeastern coast, the first bedrock can easily...
Minimum Depth to Bedrock by Map Unit - USDA
Text highlighted in yellow in the example script can be changed for a particular area; e.g., 'NE109' can be substituted for 'MO123'. Also you can use wildcards to get the entire State; e.g., 'MO%' will extract the State of Missouri.
How far do building engineers have to go to reach bedrock under New ...
Answer: I don’t know the specifics of soil conditions in NOLA, but your question indicates that you think foundations need to reach bedrock. First of all, there is a difference between foundations and piles. Foundations rarely extend to bedrock. In fact, depending on the soil conditions and the ...
What is Mission Bay built of?
All the new stuff in Mission Bay – constructed over deeply driven steel (or precast concrete) piles, then tied together w/a robust concrete slab. The biggest issue will be the buildings standing firm, while all the site work (sidewalks, courtyards, landscape) sinks a few inches (or more).
What is the client's goal in seismic standards?
Their goal is to protect the safety of the occupants, not ensure that the building survives. So people in those buildings will likely survive the big one, but the building may need to be torn down and rebuilt to make the site functional again.
Is the Marina near Fort Mason bedrock?
The area in The Marina right below Fort Mason is all bedrock. That area, along with Cow Hollow, Pac Heights would be gold mines if someone could ever build.
Is the city earthquake planning a secret?
hoegaarden. The city earthquake planning is not a secret at all. Actually, it’s so public that if you have about 20 hours to spare, you can get a FREE FUN AND AMAZING full coverage of the subject and get your diploma and a (free) cool kit. (the training addresses a very real local 8.0 with the collapse of ALL infrastructures). Here: SF NERT (look for the “training” and “classes” links)
What are the units of sediments in San Francisco Bay?
These units can be broadly broken down into subduction related units including terranes of the Franciscan Complex and the Great Valley Complex including the Coast Range Ophiolite and Great Valley Group, and the overlying Paleogene and Neogene sediments that were largely deposited in successor basins. Fig. 1 provides a map view of these units and Fig. 3 provides a cross-sectional view showing the present configuration based on geophysical and geological data (modified from Fuis and Mooney, 1990 ).
Where does sediment come from in San Francisco Bay?
The remaining sediments coming into San Francisco Bay are derived from the local San Francisco Bay watersheds ( Fig. 1 ). In recent years, sediments from these local watersheds have become increasingly important as sediment input from former hydraulic mining in the Sierra Nevada foothills has waned, and dam construction, bank hardening and channelization in the Sacramento and San Joaquin valleys and delta have reduced sediment supply from the Sacramento/San Joaquin River system ( Schoellhamer, 2011, Barnard et al., 2013 ). Bay Area urbanization and other disturbances also have resulted in an increase of locally derived sediment loads, although this trend may have subsided in recent years (see Barnard et al., 2013--this volume ). Lewicki and McKee (2010) calculated that contributions from local watersheds may now account for approximately 56% of the total suspended load entering San Francisco Bay. The formation and distribution of these local basement and overlying rocks are the focus of this paper, which provides the geologic framework for the sources of an increasing important component of modern bay sediments.
What are the terranes of San Francisco?
Franciscan terranes are composed of oceanic rocks that may include igneous basement material and marine sedimentary rocks. Zones of mélange separate the terranes. In the Bay area, the Franciscan Complex is divided into the Eastern and the Central belts, with the older Eastern belt lying structurally higher and being of higher metamorphic grade than the Central belt ( Blake et al., 1984 ). Blake et al. (1984) defined nine terranes in the Bay Area ( Fig. 1) based on differences in basement types and ages, in the age and types of overlying sedimentary sequences, and in their metamorphic grade. Recent advances in U–Pb dating of detrital zircon are allowing the determination of maximum ages for some clastic Franciscan sediments and are showing that ages indicated by the rare fossils are too old, thus indicating reworking of the fossils ( Unruh et al., 2007, Ernst et al., 2009, Dumitru et al., 2010 ). The structurally highest unit in the San Francisco Bay Area (Yolla Bolly terrane in Fig. 1 or Angel Island nappe of Wakabayashi (1992)) has yielded a maximum depositional age of 102 Ma ( Snow et al., 2010) to 96 Ma ( Dumitru, 2012) and the structurally lower terranes appear to young downward. The youngest Franciscan terrane in the Bay Area appears to be the San Bruno Mountain terrane that has yielded 52 Ma detrital zircons ( Snow et al., 2010 ).
What are the rocks of the Franciscan Complex?
Rocks of the Franciscan Complex form the bedrock for the Coast Ranges east of the San Andreas fault. Franciscan rocks in the Bay Area range in age from about 200 Ma to 50 Ma (see papers in Blake, 1984, Snow et al., 2010 ). They represent an accretionary wedge; a complex body of rock that accumulates in a subduction zone ( Hamilton, 1969, Ernst, 1970 ). The Franciscan Complex is composed of an amalgamation of semi-coherent blocks, called tectonostratigraphic terranes, that were episodically scraped from the subducting oceanic plate and thrust eastward under Jurassic ocean crust of the Coast Range ophiolite to form thrust Nappes that shingle against and underplate the western margin of North America (e.g. Blake et al., 1984, Wakabayashi, 1992 ). To the east of the subduction zone during this period, volcanic-rich, deepwater turbidite sediments forming the Great Valley Group filled a forearc basin developed above oceanic crust of the Coast Range Ophiolite ( Dickinson, 1970, Dickinson and Rich, 1972 ). A wedge of Franciscan rocks is thought to extend eastward beneath the Coast Range Ophiolite and above the crystalline basement rocks of North America. This Franciscan wedge may have started forming in the Late Cretaceous, as the angle of subduction decreased, and may continue to be driven eastward by ongoing compression across the San Andreas system (e.g. Wentworth et al., 1984, Wakabayashi and Unruh, 1995 ). Fig. 2 shows a simplified schematic representation of the Cretaceous subduction margin and the areas of formation of the major rock types along the margin.
What is the San Andreas transform fault?
The San Andreas transform fault system is a relatively new geologic feature in the Bay Area; developing behind the Mendocino triple junction (forming the boundary between the Farallon, Pacific, and North American plates) as it migrated northward (e.g. Dickinson and Snyder, 1979, Fox et al., 1985a, McLaughlin et al., 1996, Wakabayashi, 1999b ). As the triple junction moved northward, a slab window and/or gap was developed to its south ( Dickinson and Snyder, 1979, Thorkelson, 1996 ). This hole in the crust allowed mantle material to upwell and resulted in a northwardly younging series of volcanic rocks in the Bay Area that range in age from about 15 Ma on the San Francisco Peninsula ( Turner, 1970, Pampeyan, 1993 ), to the less than 3 Ma Sonoma Volcanics to the north of San Francisco Bay ( Fox et al., 1985a, Buising and Walker, 1995, Wagner et al., 2011, McLaughlin et al., 2012 ).
How does the Bay Area affect sediment?
As the Bay Area has become increasingly urbanized, increased peak stream flows due to the addition of impervious surfaces, coupled with construction disturbances, have resulted in increased sediment loads in local watersheds, particularly during major storm events when the majority of sediment transport occurs ( Lewicki and McKee, 2010 ). Although Porterfield (1980) calculated that the Sacramento/San Joaquin River system accounted for about 86% of the total sediment load to San Francisco Bay during the period from 1909 to 1966, recent calculations by Lewicki and McKee (2010) indicate that local watersheds may now account for as much as 56% of the total suspended load entering the bay.
Why were the Franciscan terranes transported northward?
These accreted Franciscan terranes were probably transported northward some distance from their points of accretion due to oblique subduction of the northeasterly moving plates relative to North American (e.g., Beck, 1986, Beck, 1991, Hall, 1991, Wakabayashi, 1992 ).
How tall is the San Francisco skyscraper?
At 645 feet (197 m), it is the tallest concrete structure in San Francisco, the fourth tallest building in San Francisco overall, and the tallest since 345 California Street in 1986. It was also the tallest residential building west of the Mississippi River when finished (later surpassed by The Austonian in Texas).
Where is Mission Street in San Francisco?
301 Mission Street is a development in the South of Market district of downtown San Francisco. A mixed-use, primarily residential development, it is the tallest residential building in San Francisco.
How many stories is 80 Natoma?
According to Modern Luxury, a proposed 52-story skyscraper at nearby 80 Natoma by developer Jack Myers which would also have a similar cast in place concrete construction, was rejected by the city's Department of Building Inspections (DBI) after an outside peer review.
Who designed the Mission Street?
Developed by Mission Street Development LLC, an affiliate of Millennium Partners, the US$350 million project was designed by Handel Architects, engineered by DeSimone Consulting Engineers and constructed by Webcor Builders.
What is the bottleneck in San Francisco Bay?
West-central San Francisco Bay is a geographic bottleneck that ships must navigate on their way to ports, harbors, and waterways in the bay area (see map below). This part of the bay has several
Where is the sunken vessel in San Francisco Bay?
A sunken vessel can be seen in this view of the floor of San Francisco Bay northeast of Angel Island. The presence of this object was already known to the U.S. Coast Guard, but its identity has not been determined. This image was created from the recently collected bathymetric data (for the bay floor) and USGS topographic data (for the land). View is from the north, looking south toward San Francisco. Sand waves, or underwater sand dunes, on the floor of San Francisco Bay east of the Tiburon Peninsula (see Area 1 on 3- dimensional image, above). On the left is a shaded-relief image of the area created from bathymetric data. On the right is an image of the area created from acoustic-backscatter data. Bathymetric images can be manipulated to make them look much like photographs—by adding shadows, for example, as in the left image. Acoustic-backscatter images are harder to interpret, but they have the potential to tell scientists a great deal about the material at and just below the seafloor surface. These sand Multibeam mapping system mounted on the hull of a research vessel collects waves are up to 3 meters (10 feet) high and 30 to 40 meters (100 to 130 feet) from crest to crest. data along a swath of seafloor.
What lens is used to view the floor of San Francisco Bay?
Use 3-D glasses, red lens over left eye, to view this 3-dimensional image of the floor of west-central San Francisco Bay. In this image, the San Francisco Bay floor data have been combined
How does sound work in seafloor mapping?
The mapping system that collected the data used to create this poster is a multibeam echo sounder. Mounted on a ship’s hull, it sends out approximately 3 pulses of sound per second. Returning echoes are received by 60 narrow receive apertures, each of which records data from a precisely located point on the seafloor. The time an echo takes to return to the system is used to calculate depth to the seafloor, and the depths are combined to make a bathymetric map (see first image to the right). The strength of the returning echoes—called acoustic backscatter—provides information about what types of material are on the seafloor. Hard rock reflects more sound back to the ship than soft mud, for example, and the near sides of sand waves return more sound than the far sides. The second image to the right is an acoustic-backscatter map. This poster highlights bathymetric data. The data used to create the poster have a horizontal resolution of 4 meters (13 feet) and a depth resolution of 30 centimeters (12 inches). That means that any object larger than 4 meters long by 4 meters wide and 30 centimeters high will be revealed (for example, see image of sunken vessel at far right). High-resolution multibeam mapping is a variation on echo sounding, a technique oceanographers have used since the 1920’s to measure water depths. In the simplest form of echo sounding, a pulse of sound sent from a ship travels to the seafloor and bounces back to a receiver on the ship. The time lapse between sending the sound pulse and receiving its echo is used to calculate water depth.
How much of California is in the San Francisco Bay?
All told, the estuary known as San Francisco Bay and the adjoining Sacramento-San Joaquin River Delta system cover 1,600 square miles and drain about 40 percent of California. The report focuses on the marks left on the bay floor in the modern era of population growth and industrial activity.
What is San Francisco Bay?
The bay, an estuary marked by complex movements of fresh and salt water, has long been a muddy mystery below the surface, shaped and reshaped by 150 years of human activity and by tons of sediment flushed in from ...
Why did the salt ponds in the South Bay sink?
Meanwhile, the vast salt ponds of the South Bay, among other wetland areas, have sunk after being walled off so long from the tides. Their future depends on being built back up, presumably by redepositing tons of sediment scooped up from somewhere else. So the mud has suddenly become a valued commodity.
What is the name of the rock that is stuck out of the water at low tide?
The aptly named Arch Rock, for instance, once stuck out of the water at low tide like the eye of a giant stone needle, presenting a portal through which boaters sometimes tried to slip for sport, with occasionally disastrous results.
How much hydraulic mining debris washed down from the Sierra foothills?
Much of what people have done in this vast watershed has had an effect on the bay's bottom, including an estimated 1.4 billion cubic yards of hydraulic mining debris -- eight times the amount of material carved out for the Panama Canal -- washed down from the Sierra foothills in Gold Rush days.
What are the names of the rocks in Alcatraz?
The named rocks -- Shag, Arch, Blossom and Harding -- are shown on the new map roughly in line with Alcatraz, the classic "Rock" and the only one most people have ever heard of. All are part of what is thought to be the same submerged, primordial mountain ridge.
When was Arch Rock blasted?
It was blasted to smithereens in 1901. A rare sketch of the intact Arch Rock, and a photo of the dynamiting, are included in the new report. The new picture of the bay bottom was drawn from high-resolution "multibeam mapping," in which a transducer on a ship sends out three pulses of sound per second.
What is the USGS?
http://www.usgs.gov/ The USGS is a federal science agency that provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten ... read more
How many maps are in the NGMDB?
The NGMDB contains information on more than 90,000 maps and related geoscience reports published from the early 1800s to the present day, by more than 630 agencies, universities, associations, and private companies. For more information, please see http://ngmdb.usgs.gov/.
