Since the degree of impact an earthquake has is measure on both the Richter and the Mercalli scale, it must be reasonable to assume that the power of an eruption is representative to the degree of how potentially hazardous the event may be. Eruption explosiveness can be measured by the Volcanic Explosivity Index. The higher the Volcanic Explosivity Index, the greater the potential hazard. The eruption type is a huge factor in the differences in the degree of hazards posed by volcanoes around the world. This greatly relates to the plate margin the volcano or volcanic belt is situated upon.
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.
Eventually, the friction is overcome and the blocks slip abruptly, releasing pent-up energy with a huge “snap”—an earthquake” (The Plate Tectonic Model – Page 107). Plates diverge at volcanic zones by the ocean basins. These are long huge cracks were lava rises from below and freezes into the Lithosphere (About.com – Geology). In which plates move past each other is call a transform boundary. 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].
Compare and contrast the 1906 San Francisco Earthquake with the 1811 New Madrid Earthquake. Include these elements: type of faulting and offset, epicenter, magnitude, damage, duration, date, and area affected. California’s earthquake on April 18, 1906 which lasted around 45-60 seconds, is thought to be one of the most momentous earthquakes in history. The degree in which earthquakes are monitored and studied is due to the sheer size of its horizontal displacement and rupture length. As a result of this earthquake theories such as, elastic-rebound has been one of the models used to portray the earthquake cycle.
The difference in pace and movement of plates, triggers the up build friction. When this friction is released- Earthquakes are generated. An example of an event is the San Francisco earthquake in 1989 on October 17 measuring 6.9 on the Richter scale. Tsunamis are one result of earthquakes. A sudden shift in
If the redeposit particles are bound together by compaction or | |cementation (formation of new secondary minerals in the spaces between the loose particles), sedimentary rocks are formed. In | |regions where the Earth’s interior temperature and pressure are high enough to change the chemical composition and mineralogy of | |buried igneous or sedimentary rocks, without completely melting them, metamorphic rocks are formed. Distinct groups or assemblages | |of minerals are typically associated with the formation of each of the three major rock types—igneous, sedimentary, and metamorphic| |rocks. Plate tectonics play a major role in the processes of mineral and rock formation. In geologic terms, a plate is a large, | |“rigid” slab of solid rock.
Evaluate how plate tectonics theory helps our understanding of the distribution of seismic and volcanic events. [40 marks] In this essay, I will weigh up several arguments through the use of case studies and demonstrate how the tectonic theories support our understanding of the distribution of seismic and volcanic activity. Seismic is a word we use to show that something is caused by an earthquake or earth vibration. In the world, there are 15 major tectonic plates which are always moving and therefore are always moving against one another on plate margins. This knowledge of plate margins and their movement against one another can help us to understand the distribution of seismic and volcanic events and this is because the majority of events are associated at these plate margins.
What were the causes of the quake? Afghanistan lies on a collision plate boundary where the Iranian and Eurasian plates meet as both plates consist of continental crust, which can neither sink nor be destroyed. The rooks between them are forced upwards to form a high fold mountains .The constant movement of the Iranian plate causes an increase in pressure which often causes earthquakes. What were the effects of the quake? A relief team reported 20 villages destroyed and the death total could pass 4000.
An earthquake is a sudden release of energy from the earth’s crust, because of the movement of the tectonic plates, this sudden movement creates seismic waves, and these waves are P, S, L and R. The primary waves, are the first waves to hit the surface, this is because they are longitudinal and travel like sound in short wave lengths, like pushing on a spring, these can also travel though solid and liquid. S waves arrive second because they act more like string being waved, this only travel through solids. These two are not the most powerful, this belongs to the Love and Rayleigh waves which are the last waves to hit, these move the surface in different ways love waves cause horizontal up and down movement of the earth’s crusts, while Rayleigh waves cause a rolling motion, both of these are very destructive and can cause roads to rip up and building to topple over. The power and destruction of an earthquake depends on the depth of the focus, if there is a shallow focus then the earthquake will measure high on the Richter scale, but will only affect a small area of the surface. The causes of earthquakes are tectonic plates moving suddenly, for example when the plates get snagged and caught on one another.
This type of devastation happened on March 11 2011 in Japan when a very powerful tsunami ruined the land, and on October 17 1989 when California was hit by huge earthquake named Loma Prieta. This essay will compare and contrast these two world shaking events and give some research about the two events as well. Maybe you will learn about some interesting facts about the two. A earthquake is described as a sudden and violent shaking of the ground, resulting from the movement within the earth’s crust or from volcanic action. It sometimes causes great destruction.