San Diego Geologic History and Natural Hazards Summary Research Paper

San Diego Geologic History and Natural Hazards Summary - enquiry Paper ExampleThe contact experienced between these geologic regions is irregular and this reflects the antediluvian bea topography in the first place being buried by the thick sequence of Tertiary and Cretaceous sedimentary rocks that was deposited by ancient seas and ancient rivers over the last 75 million familys (Abbott, P, 23)Both these rocks with their existing biological write down such as the fossils, document the biological and geological evolution of this western North America part. It is save that at a certain point in time, there was an ancient oceanic crustal plate inhalation that created volcanic islands archipelago and also this same plate subduction generated massive magma volumes which in the later stage congealed in the crust that resulted to plutonic rock. It is also observed that local rocks record an early period when erosion bare and tectonic forces uplifted the plutonic rocks that were deep ly buried forming a rugged and steep mountainous coastline. This is similar to the one present today along the west coast of South America. Also recorded are periods of subtropical climates and higher rainfall that supported coastal rain forests with exotic floras and faunas relentless erosion, drowned coastlines periods and great rivers periods of utmost(prenominal) renewed and aridity volcanism widespread crustal shear and defacementing periods and the new seaways formation (Bergen et al, 34). The above are just nearly of the stories of geology preserved in the San Diego County. Deciphering the biological and geological record is a process that is ongoing and every year brings new insights and new discoveries. Geographical regions of San Diego claimed by Natural Hazards The processes of natural geology which represent a take a chance to health, property or life are taken to be geologic hazards. Natural geologic hazards which affect property and people in San Diego County inc lude earthquakes that can result to ground shaking, liquefaction and surface fault rupture, elevated weathering soils, and phenomena mass wasting such as rockfalls and landslides (Bray and Kelson,5).The hazard of surface rupture has been identified as Alquist-Priolo seism Fault Zones (AP Zones). Two major AP Zones extend to southeast from northwest across the northeast half of the County, the San Jacinto and Elsinore fault zones present the highest fault-rupture threat in the unincorporated San Diego County part (Anderson et al,13).Liquefaction primarily occurs in loose, saturated and fine to medium-grained soils in places where the groundwater table is basically at most 50-feet below the surface. There may be a potentiality for liquefaction within the County in areas with loose sandy soils together with a shallow groundwater table, that are typically located in floodplains and alluvial river basins/ valleys. Previous landslides together with landslide-prone sedimentary formation s are located in western unincorporated County portions( Bowman,21). However, it is known that landslides can as well take place in the granitic terrain in the eastern County area, despite the prevalence is so minimal (URS, 2004). Most of the landslides that are significant have happened along coastal bluffs and other areas within incorporated County parts (URS, 2004). Existing landslides reactivations can be triggered by situations that include irrigation or heavy rainfall, seismic shaking or grading. Particular clay soils types normally shrink when dried