Great earthquakes are known to occur on both the west coast and mid-continent of North America, but their causes and effects differ greatly. Below is a USGS map comparing the areas affected by the 1994 Northridge, California and the 1895 Charleston, Missouri earthquakes. (Red areas are those sustaining extensive damage to buildings and other structural elements; yellow areas were shaken, but sustained minimal damage.) As you can see, the earthquakes were nearly equal in magnitude. Compare and contrast the 1906 San Francisco Earthquake with the 1811 New Madrid Earthquake.
These are not that common as the converge or diverge plates and the most common one is the San Andreas fault of California [About.com – Geology]. The Pacific Coast of the US is the region most susceptible to earthquakes [essortment.com]. Recently, there has been more activity specifically in the Caribbean plate (Haiti), the West Coast of South America (Chile), the Pacific Islands and other areas in the Asia continent. As I understand it when there is one shift in the plates this creates a global shifting to the other plates in
Explain the distribution of the worlds major geophysical hazards Some parts of our planet are more often and more severely afflicted by natural hazards than others. This is due firstly to the geological structure of the Earth and secondly due to climate zones. Earthquakes like the Kashmir, Haiti and New Zealand occur in areas where oceanic plates and continental plates move against each other and collide. The long arc of islands that make up Japan and the stretch of the Andes located inside the coast of Chile are collision zones and therefore more often affected by earthquakes than in Finland, Brazil or Canada. Haiti is on the boundary of the Caribbean and North American plates and is an example of a conservative plate boundary.
A number of theories have been put forward to explain the origins of rift valleys. However, only two have remained popular thus the two theories which attempt to explain the origin of rift valleys. One relies on the forces of tension and the other on the forces of compression. Both theories depend on upward swells, along the sides of which faults develop. Theory 1: Tension forces a) Tension forces act on the layers of rock.
How many half-lives have passed since the crystal formed? A) 1 B) more than 1 but less than 2 C) more than 2 but less than 3 D) more than 3 Answer: B 4) Which of the following geologic observations would NOT bear directly on working out the sequence of geologic events in an area? A) inclusions of sandstone in a granite pluton B) a well-exposed dike of basalt in sandstone C) an unconformity between a granite and sandstone D) the feldspar and quartz contents of a granite Answer: D 5) The principle of ________ is the concept that ancient life forms evolved in a definite order and therefore their fossils can help determine the geologic ages of strata. A) superposition B) cross-cutting relationships C) fossil succession D) fossil assemblage Answer: C 6) Which of the following is an essential characteristic of an index fossil? A) The organism lived in a very specific environment or two, such as tropical volcanic islands.
One hazard can often trigger others (e.g. Earthquakes can cause landslides and tsunamis). The San Andreas Fault is a conservative plate boundary that runs 1300km along the Californian coastline. The fracture within the crust, causes crustal instability, between the North American and the Pacific plate. As it traverses, due to convection currents, the tectonic plates are dragged along the entire length of the Californian coast.
Seismicity (or earthquakes) is the shaking of the earth and it is strongly associated with the theory of plate tectonics. Most earthquakes are found on plate margins which are the boundaries between plates. Only 5% of earthquakes that happen every day are not located on plate margins. It has been suggested that human activity could be responsible for some minor earthquakes which do not occur on plate boundaries, for example, the building of large reservoirs puts pressure on the surface of rocks. However despite this, as 95% of earthquakes occur on plate boundaries there must be some kind of link between the two and plate tectonic theory can explain this.
Explain why the Philippines and California multiple hazards hotspots are affected by disasters in different ways?? Disaster hotspots are multiple hazard zones such as the Californian Coast and the Philippines. They are places which experience more than one hazard. California is on a conservative plate boundary where two plates (The North American and Pacific) are sliding past each other at different speeds and pressure hence generating frequent shallow focus earthquakes. This includes San Andreas Fault where a network of active faults underlies the LA region and San Francisco Bay Area.
This earthquake occurred on the Denali-Totschunda fault system – one of the longest strike-slip faults in the world. The tectonic setting of this area results from the interaction of the Pacific plate (oceanic) and the North American plate (Continental). This results in the subduction of the Pacific plate beneath the N.American plate because the continental plate is thicker and less dense and sudden movements in this subduction results in an earthquake such as the one experienced in Denali in 2002. This earthquake measured 7.9 on the Richter scale and violent shaking of the ground triggered many landslides which buried valleys and glaciers. The one service that was damaged the most was the Northway airport – this was the effect of ‘liquefaction’ caused by the rupture transforming water saturated sediments into a liquid slurry.
9, 000 of those being foreigners. The Tsunami’s energy was so great the wave traveled around the world three times. Seven years later in 2011 an earthquake 60km off the east coast of Tohoku with a magnitude of 9.0 on the Richter scale struck Japan. The earthquake triggered a huge Tsunami which reached heights of 133 ft. and killed around 15, 839 people, injured 5950 and left 3642 unaccounted for. Causes When a dense oceanic plate collides with a less dense continental plate the denser oceanic plate subducts under the less dense continental plate.