Tectonic Faults

The San Andreas fault line has caused constant development nightmares for large urban areas such as San Francisco as well as the other cities built on top of it. Fault lines are one of the side effects of the earth’s tectonic plates shifting that can result in devastating earthquakes. Some of the most devastating earthquakes in our modern era have occurred along the San Andreas fault line due to a dense population. The most notable and destructive earthquake on the San Andreas fault line occurred in San Francisco in 1906. The reason this earthquake was so deadly was because of its magnitude and the city’s poor planning. This earthquake was a wakeup call for San Francisco and force the city to revolutionize its knowledge on earthquakes and how to protect their city. Today San Francisco is one of the most well prepared cities for an earthquake and has made great discoveries in earthquake safety measures. The 1906 earthquake in San Francisco has drastically changed how the city has developed its zoning and building code policies, and its earthquake research.

The three faults being considered are thought to have influenced the character of some 120,000 square miles. The Big Pine, Garlock, and San Andreas faults are all mutually active, deep, long, and steep and noted as being conjugate shears. In concert, the faults have defined a primary strain pattern of relative east-west extension and north-south shortening of the area of 120,000 square miles. The large region is noted for its deformity, with the source of this being a northeast-southwest counterclockwise compressive couple. The compressive couple was potentially supported through drag as a result of the deep-seated movement of rock material from the Pacific region (Hill & Dibblee, 1953). The interaction of the faults in the San Andreas region since the Jurassic period have served to shape and contour the present geology of the land, while a study of the paleontology of the region likewise requires such knowledge to effectively determine conditions at any given point in time.

California’s unique geography as a state makes it a very appealing place to call home. From the odd east to west transverse San Gabriel mountain ranges of the Los Angeles Basin, to the bumpy coastal ranges of the Bay Area, any person can find a compatible topographic terrain to their liking. California may seem to be the perfect place to live with its ideal climate and extensive geographic features. However, due to California’s location over the shifting continental plates, coupled with its enormous and also multiple faults, at any time this great state can fall victim to a seismic disaster. After examining evidence from both Rong-Gong Lin’s II Los Angeles Times article of April 18, 2016 and the NOVA videos Killer Quake ( 2006), Earthquake (2007), as well as Geologic Journey II – Episode 3 (The Pacific Rim: Americas) – Part 3 (San Francisco) and The Great San Francisco Earthquake (American Experience ~ 2005), one can take a comparative account of the three major earthquakes of California’s past. Although each earthquake was very devastating on is own; the Great Quake 0f 1906, the Loma Prieta quake of 1989, and the NorthRidge quake of 1994 each amounted to an extensive forfeiture of property and life. Each of these earthquakes created much suffering and loss. It is imperative for each citizen of this great state to understand the damage that a California quake can actually do and be prepared; for the threat of one always looms.

The earthquake was located on the San Andreas fault which is a seismic zone between two of the earth’s tectonic plates. Seismic events which occur is caused as a result of the earth’s tectonic plates moving against each other and this can cause huge earthquakes and volcanoes (“Young”). The transform boundary passes through California and this is where the Pacific and North American plates move past each other without colliding. The event in which this occurred was the San Andreas fault (“Young”). When the plates move past each other and the resistance builds up, this causes an earthquake like the 1906 San Francisco earthquake. This earthquake caused a separation and displacement in the landscape which was seen over several kilometers

The formation of San Diego region involved numerous activities which varied from volcano activities, the formation of Gulf, uplifting and tilting among others. These activities happened in a long span of time creating three distinct geomorphic regions: the west of peninsular rangers, peninsular ranges region, and the Salton Trough region. The geomorphic division reflects the basic difference amid geographic parts containing Mesozoic metavolcanic, metasedimentary, and plutonic rock material. The development of these features resulted to the occurrence of the current San Diego state. The integration of different rocks, volcanic activities, and subduction processes resulted to the development of peninsular region and Salton Trough.

Tiny dots of white against the plant-covered landscape (red in this image) are possible landslides, a common occurrence in mountainous terrain after large earthquakes. The Enriquillo-Plantain Garden fault zone runs along the two linear valleys at the top of the imageThe magnitude 7.0 Mw earthquake occurred inland,

According to the research report, it will cause thousands of people die, towns submerged, buildings and bridges damaged once a huge earthquake and tsunamis happened on the Pacific Northwest area near American coast. And losses will be estimated at over 5 billion dollar US dollars. This shocking article was composed by seismic safety advisory committee in Oregon. According to materials, a super-strong earthquake once happened in A.D. 1700 Cascadia Subduction Zone (CSZ) on the Pacific Northwest coast. There are some experts forecast that another super-huge earthquake will occur in the future. The report has shown that once the earthquake occurs, the regions from North California to British Columbia Coastal region will suffer devastation, cause heavy casualties. Water and electricity shortage issues definitely follow this heavy disaster, meanwhile, communication and heating system and gas supply will definitely broken off in the light of this earthquake. The CSZ is a 1,000 km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino in northern California. It separates the Juan de Fuca (Juan

• This earthquake may not have released all of the strain stored in its rocks next to the fault this reveals a potential earthquake in the Santa Cruz Mountains in the near future. The occurrence of the earthquake showed that the Earth did not exhaust all its strain and hence other earthquakes could be expected. However, the dates could not be predicted. The extent of the damage could have been much more devastating for the region, but with the earthquake occurring near the coast this made half of the felt area westward in the Pacific Ocean. The occurrence of aftershocks ten days later reinforces the unpredictability nature and hence makes Geology to be a study that is always evolving. In conclusion, the Earth and the study of cannot be exhausted as every natural occurrence provides a new puzzle to be solved.

Over more than 50 decades there has been multiple earthquakes that have been caused by the activity that takes place beneath and above the surface of the earth. For every earthquake there are various effects and consequences, these are generally not preventable but teachable moments. As we study and explore landforms we learn and better understand how today 's structures came about, what took place decades ago and where do we go from here. Thanks to the technology and inquiring minds we are able to study past events like the 1906 San Francisco earthquake and the 1964 Alaska earthquake. In comparing these two events we can get an overview of what happened and better prepare ourselves for something like that in the future.

The tectonic setting for the 1906 San Francisco Earthquake was in the outermost shell of earth consisting of rigid plates that have been moving for hundreds of millions of years. Two of these moving plates meet in western California; the boundary between them is a zone of faults, the principal one being the San Andreas fault. The Pacific Plate (on the west) slides horizontally northwestward relative to the North American Plate (on the east), causing earthquakes along the San Andreas and associated faults. The San Andreas fault is a transform plate boundary, accommodating horizontal relative motions (usgs.gov).

One of the geologic hazards in Nevada is the Mountain ranges. The reason these are hazards is because most of the ranges in Nevada have a major fault line on either side of them. Some of these faults have been active within the last 1.6 million years, and have had large earthquakes. This causes the ranges to tilt and shift and raised the ranges to higher levels. As far as seismic activity goes, Nevada is the third most active state in the nation. There is an earthquake in Nevada of a 7 or greater approximately once every thirty years. There are strike slip faults in the northwest region of the state. The border of California had what is called Walker Lane. This area

water fractures within the earth. Causing certain areas of the land to have an earthquake effect

California, and thus San Francisco, lies on the San Andres fault. The earthquake was caused when this fault suddenly shifted, with the rupture spreading for a total of 476 kilometres in northward and southward direction. “This fault is a continental transform fault, which forms part of the tectonic boundary between the North American Plate and the Pacific Plate.” (1906 Earthquake: How long was the 1906 Crack? USGS Earthquake Hazards Program – Northern California, Accessed September 3, 2006). 1 The distance of the fault is of about 1300 kilometres, which runs the length of California from Cape Mendocino in the north to the Salton Sea in the south. Geologists have estimated that the fault moved as quickly as 2.74 kilometres per second. The San Andreas Fault, the source of this disaster, lies ten miles or deeper, at the meeting point of two tectonic plates, the Pacific and the North American. “The right-lateral strike-slip fault is characterized by mainly lateral motion in a dextral sense, where the western plate (Pacific plate) moves northward relative to the eastern plate (North American

The San-Francisco earthquake caused quite a lot of damage in the area, but what is an earthquake? An earthquake is the movement of tectonic plates along a transform boundary and what plate is California sitting on? The Pacific Plate which is not connected to the North American plate and the plate boundary is a transform boundary. Earthquakes occur so often there that people say it is like a rainstorm that is ignored. The place where the Pacific Plate is grinding along with the North American Plate is called the San Andreas Fault. As stated before the earthquake had a magnitude of 7.8 which caused so much destruction a fire broke out. Nobody really knows where the fire started but it burned for 7 days and scorched over 500 city blocks leaving the once proud and powerful city into dust. The combination of the earthquake and fire is said to have killed “ Over 700 deaths by the earthquake and fire is now believed to be an understatement the total loss of life by a factor of 3 or 4.” (The Great 1906 San-Francisco Earthquake.)

* Measurements of Geologic uplift and slip rates – in many areas of the San Andreas Fault a detailed record of strike-slip activity is provided. By studying the sediments deposited in a given area and comparing them to an established age control it is possible to determine the rates and timing of changes of tectonic deformation.