ESCI B.S2.O3.A5 Plate Boundaries

• Model tectonic plate movement and compare the results of plate movement along convergent, divergent, and transform boundaries (e.g., mountain building, volcanoes, earthquakes, mid-ocean ridges, oceanic trenches).

Global Seismicity LAB WORK PORTION

Go to the following website: http://ds.iris.edu/ieb/index.html Links to an external site.

You will be utilizing this web application to plot earthquake data. When you open the website, you will be presented with a map of the world and the 200 most recent earthquake events. You can zoom in on the map, move it around, and click on events to get more details about particular earthquakes. On the right-hand side of the window, you will be able to change the number of events displayed as well as the time, magnitude, and depth ranges of events that are displayed on the map. In the upper right-hand corner, you can change

the view from geopolitical boundaries to satellite or terrain. Modify these settings to explore global seismicity, then answer the following questions. Note: Displaying a large number events may cause browsers on slower machines (like your net books) to stall or freeze up. Keep this in mind when plotting data. You can either copy and paste your answers in a textbox or upload a file with your responses.

Your Assignment:  Answer the following questions.

1. Do you have a good sense of where plate boundaries are? If not, how can you change the settings to give you a better idea of where plate boundaries may be?
2. How many large earthquakes (≥7.0 magnitude) have occurred so far this year?
3. Where do the deepest earthquakes (≥300 km) tend to occur?
4. Switch to a satellite view of the world. Do earthquake patterns correlate with any visible features? If so, describe the correlations.
5. How are earthquakes in Africa different compared to other regions in the world?
6. Zoom in on Africa. Where do African earthquakes tend to occur?

Convergent Boundaries (Continent – Ocean Collision)

We will now explore the seismicity of a plate boundary between ocean and continental

crust. In the lower left-hand corner, click "Select a region", then draw a box over the western side of south america,

including some of the nearby ocean. Select the following settings:

• Location: An area containing the western side of South America into the Pacific Ocean
• View: Satellite
• Display: 1000 events
• Time Range: Set the dates to request 2 years of data (XXXX/XX/XX through latest
• available).
• Magnitude Range: All Values
• Depth Range (km): All Values

Your Assignment:  Answer the following questions.

1. How frequent are earthquakes in this region? 
2. What is the depth distribution of the earthquakes? Is there a pattern in the earthquake depths? If so, how do you explain it?
3. Find another region of the world that has similar features to the ones you noted on the western side of South America. What is the region and are the earthquake patterns there similar?
4. Do the earthquakes correspond to any visible features in satellite view? If so, what are these features?

Divergent Boundaries (Mid-Ocean Ridge)

We will now explore the seismicity of a divergent boundary in the central Atlantic, the mid-ocean ridge. Click "Select a region", then select a large area of the central Atlantic.

• Location: Middle of Atlantic Ocean (e.g. from eastern edge of Brazil to western edge of Guinea)
• View: Satellite
• Display: 1000 events
• Time Range: Set the dates to request 2 years of data (XXXX/XX/XX through latest available).
• Magnitude Range: All Values
• Depth Range (km): All Values

 Your Assignment: Answer the following questions.

1. How frequent are earthquakes in this region? How does this compare to the seismicity on the western side of South America?
2. How do you explain the differences in depth and frequency of earthquakes between the mid-ocean ridge and the western side of South America?
3. What is the typical depth of earthquakes in this region? How does this compare to earthquakes on the western side of South America?
4. Find another region of the world that has similar features to the ones you noted in the central Atlantic. What is the region and are the earthquake patterns there similar?
5. Do the earthquakes correspond to any visible features in satellite view? If so, what are these features?