ANNOUNCEMENTS

• Please read chapter 2 (the whole thing)

• Today:– a little more on the exercise we started in

class. If you had an excused absence, you got a copy over email. If you were not excused, look on with a neighbor

– where earthquakes occur in different tectonic settings and why

Turn on your clickers please…

What is the asthenosphere?

A. The rocky part of the upper mantle and the crust

B. The semi-molten (jello) part of the upper mantle and crust

C. The semi-molten part of the upper mantle, but no crust is involved

D. Just the crust, with no mantle involved

Talk to your neighbor

• What answer did you give?

• How confident were you of that answer?

• Tell your neighbor one reason you gave that answer.

• What do you think of your neighbor’s reason for his/her answer -- makes more/less sense than yours?

What is the asthenosphere?

A. The rocky part of the upper mantle and the crust

B. The semi-molten (jello) part of the upper mantle and crust

C. The semi-molten part of the upper mantle, but no crust is involved

D. Just the crust, with no mantle involved

Take 5 minutes to complete the graph from Friday’s exercise

• even if you don’t have your own copy, look on your neighbor’s and be sure you understand the questions that are on the sheet

• by the way, they are real earthquake data• the sheet (w/ questions on the back) is due

on Wednesday• compare your graph with someone in your

group -- I’m not into dot-for-dot correlation, I’m into you seeing the general shape

Divergent margin

YourClickersPlease

What is the likely depth ofearthquakes at mid-ocean ridges?

A. very shallow or very deep, but probably nothing in between

B. only very shallowC. only very deepD. any depth is possible and likely

What is the likely depth ofearthquakes at mid-ocean ridges?

A. very shallow or very deep, but probably nothing in between

B. only very shallowC. only very deepD. any depth is possible and likely

How to describe a fault

• Envision a house with a roof

• The line of the roof is the strike -- where two planes intersect

• The dip of the roof is the same on either side -- it’s the angle of the roof