Chapter 13 Study Guide Key

Uplift-mountain building, earthquakes Subduction zone, coastal mountain range, volcanoes, earthquakes, trench off the coast. Uplift-mountain building, earthquakes The Pacific Northwest (Cascade Mountains) Philippines, Japan, Aleutian Islands of Alaska, Panama/Costa Rica. Andes Mountains in S. America.

Mid-ocean ridge, Rift Valley, volcanic activity Fault Line, and Earthquakes Volcanoes, volcanic islands Mid-Atlantic Ridge, Great Rift Valley (Africa) Hawaiian Island chain, Yellowstone San Andreas Fault

D A F C E B

The Faster Moving ocean plate slides over the slower moving one The Faster Moving ocean plate slides over the slower moving one. The slower ocean plate is forced down into the magma below in a process called subduction. The high water content in the subducted plate is squeezed out (due to high pressures) and this help to melt the rock above it which can rise up to form volcanoes. (Volcanic islands.) Where the plates meet, a trench will form.

Weathering and erosion A hot spot located beneath the North American plate. Convection (heat) currents in the mantle AND the pulling force of oceanic plates as they subduct (sink) into the mantle. Check out video link on next slide!

https://youtu.be/kwfNGatxUJI

Juan de Fuca plate = 4 cm/yr. 5,000,000 yr x 4 cm/yr = 20,000,000 cm 20,000,000 cm ÷ 100 cm/m = 200,000 m 200,000 m ÷ 1000 cm/km = 200 km Absolutely! We are at risk for a Major Earthquake here. The biggest threat is a “megathrust” earthquake along the Cascadia Subduction Zone located offshore that runs from N. California to Vancouver Island. This happens every 300 years, son average. The last one was 317 years ago… We also are at risk from smaller, but more local faults (Seattle Fault & South Whidbey Fault). The frequencies of these earthquakes is far less understood. Regardless of the source, we need to be prepared!

First, convert 600 km to cm (since the rate is in cm/yr First, convert 600 km to cm (since the rate is in cm/yr. This makes things a lot easier… 600 km x 1000 m/km = 600,000 m Now convert 600,000 m to cm: 600,000 m x 100 cm/m = 60,000,000 cm 60,000,000 cm ÷ 10 cm/yr = 6,000,000 yr

2.1 m/kyr See next slide: Mountain Dew (slope) = 0.61 m/kyr Mountain Don’t (slope) = 2.1 m/kyr