Difference between revisions 113734838 and 113734839 on dewiki

[[Image:122-38HaywardFault.jpg|thumb|300px|For recent activity in the region shown on this map see [http://quake.wr.usgs.gov/recenteqs/FaultMaps/122-38.htm the USGS map for this location.] With appropriate browser settings the "live" maps will also show all of the names of faults shown on the map as you rollover with the cursor.]]

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[[Image:BayareaUSGS.jpg|thumb|right|250px|USGS Satellite photo of the San Francisco Bay Area. Light gray areas are heavily urbanized regions]]

==Notable earthquakes==
The largest quake on the Hayward Fault in ''recorded'' history occurred in 
[[1868]], with an estimated [[Moment magnitude scale|magnitude]] of 7.0.  It occurred on the southern segment of the fault, receiving its name (some decades later) from the nascent town of [[Hayward, California|Hayward]] where it was determined the quake's epicenter was located.  However, the 1868 quake caused much damage throughout the then sparsely-settled Bay Area, including the city of San Francisco. [http://query.nytimes.com/mem/archive-free/pdf?res=9801E5DB1E3CE13BBC4A51DFB6678383679FDE][http://query.nyt(contracted; show full)

==Prehistoric earthquakes==
{{main|Paleoseismology}}
Earlier earthquakes have been detected by trench exposure and associated [[carbon dating]]. Combined with the historic record, at least five major events have been discovered and appear to have occurred at intervals of about 140 years (note that 2008 is 140 years from the major 1868 event).

==Recent activity==
[[Image:AlumRockEarthquakeOct30-2007-event40204628
_  ciim.gif|thumb|250px|right|October 30, 2007 [[Moment magnitude scale|moment magnitude]] 5.6 Alum Rock ([[San Jose, California|San Jose]]) event ''perceived intensity map''. Determined by statistical analysis of self-reports via the internet from residents via [http://pasadena.wr.usgs.gov/shake/ca/ ''Did you feel it?''] ]]
During 2007, a number of small earthquakes occurred on the northern segment of the Hayward Fault from Oakland to Berkeley.

(contracted; show full)ively more severe reports and estimates of event probability and consequences have awakened a broad interest in training people for emergency response. It is becoming widely understood that professional fire fighting, police, and medical services will be overwhelmed by a major event and that neighbors will have to assist each other as best they can. As of Spring, 2008 there has been little government interest in fostering support for organizations akin to the [[Civil Defense]] (CD) efforts of the late 1940
's and early 1950's.

==Principal segments==
[[Image:Cross_  oakland_  google.jpg|thumb|right|250px|Cross section in the Oakland-Piedmont region, looking North-Northwest. [http://3dparks.wr.usgs.gov/haywardfault/html/introduction.html Additional sections (USGS)]]]
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:''Main articles: [[Bay mud]], [[Soil liquefaction]], [[earthquake liquefaction]]
The Hayward fault is considered to be particularly dangerous due to the poor soil conditions in the [[alluvial plain]] that drops from the East Bay Hills to the eastern shoreline of [[San Francisco Bay]]. At the lower elevations near the bay the soil is mostly water saturated mud and sand, placed in the early 
[[20th century]] as fill in marsh areas. This soil tends to  amplify the effects of an earthquake and so producing significantly greater ground motion. Additionally, the soil itself can fail, turning into a liquid mud from the agitation, a mud unable to support buildings erected upon once-firm soil. This region is also covered with dense low-rise urban development, most of which was built soon after the [[1906 San Francisco earthquake]], and long before even moderately earthquake resistant construction practices had been d(contracted; show full)
The 1989 [[Loma Prieta earthquake]] caused a failure of a single section of the upper deck of the eastern span of the [[San Francisco-Oakland Bay Bridge]], which closed the bridge for 30 days. Engineers and much of the public have long recognized that a strong earthquake centered closer to the bridge on either the Hayward or San Andreas faults could cause a complete collapse of the eastern span. A replacement eastern span is currently under construction, with completion projected for late 
[[2013]] (originally [[2010]]).
{{clear}}

====Railroads====
Parallel to the Eastshore Freeway and inland only two blocks is a four–track railroad route used for general freight traffic, including that generated by the [[Port of Oakland]] ([[Union Pacific Railroad|Union Pacific]] and [[BNSF Railway|BNSF]] railroads) and by [[Amtrak]] passenger traffic to the Pacific Northwest and eastward through [[Reno, Nevada|Reno]] and [[Salt Lake City, Utah|Salt Lake City]]. Along the north shore of [[Contra Costa County, California|Contr(contracted; show full)[[Category:Alameda County, California]]
[[Category:Geography of Contra Costa County, California]]
[[Category:Geography of the San Francisco Bay Area]]
[[Category:Napa County, California]]
[[Category:Solano County, California]]
[[Category:Seismic faults of California]]

[[fr:Faille de Hayward]]