Earthquake Case - Plate Tectonics

Running head: Earthquakes

Earthquakes

Amy Ellison

Axia College

Earthquakes

Introduction

In my opinion, to understand how earthquakes happen you need to have a basic understanding of plate margins and how the crust of the earth is formed. The Earth is made up of different layers of rock and minerals. Basically you have a layer of crust called the lithosphere which floats on top of magma called the asthenosphere. Now because the asthenosphere is always in motion, it constantly move the lithosphere around which caused the lithosphere to break up into small and large pieces called plates. The movement and interaction of these plates is what we'll be focusing on in this paper.

Plate tectonics

The first thing that I would like to focus on is the interaction between the plates when they come into contact. The ways the plates react to each other when they come into contact varies from plate to plate and are classified into several groups called faults or margins. The first group I would like to talk about is convergent margins. According to chapter 4 in our reading, "Convergent margins occur where two plates move toward each other" (Murke, Skinner, & Mackenzie, 2008). Depending on weather these plates are continental plates or oceanic plates or if it's both different results can happen when the plates interact. When two continental plates converge you end up with a dramatic lowering and rising of the landscape called a collision zone. One example of this would be the Himalayan Mountains. Another form is when one or more of the plates are oceanic. Typically one of the plates will slip underneath the other creating a subduction zone. Our reading describes a subdeuction zone as, "marked by very deep oceanic trenches-the deepest points in the ocean-and, on the surface, by lines of volcanoes formed as a result of melting in the mantle, generated by water released from the subducting plate" (Murke, Skinner, & Mackenzie, 2008). Once the subducting plate reaches a deep enough depth it begins to melt back into magma and completes the cycle. The other margin I wanted to mention is the Divergent Margin. Our reading describes this as, "rifting or spreading centers, occurring where two plates are moving apart. They can occur either in continental or oceanic crust." When this occurs, magma comes up to the top of the crust and then cools forming new land for the crust to expand with. Next you have your faults. This is anywhere along a margin where movement once occurred. The next type is called transform fault. The reading describes this as, "two plates sliding past each other, grinding and abrading their edges as they do so." One example is the San Andreas Fault.