Warm Up What do you think caused the ground to move as it did here? In what direction do you think the ground moved- vertically, horizontally, or both- to produce the results shown?

Earthquakes

Earthquakes Earthquakes are natural vibrations of the ground caused by movement along plate boundaries. Earthquakes can happen along any of the 3 types of plate boundaries.

Faults A fault is a fracture in the Earth’s crust that occurs when stress is applied too quickly. Earthquakes occur along faults. There are 3 types: Normal Reverse Strike Slip

Normal Faults Normal faults occur as a result of tension (pulling force). 2 pieces of crust are pulled apart. Hanging Wall- The lower part of a normal fault. Footwall- The upper part of a normal fault. Related to Divergent Boundaries.

Homework 1st and 4th period complete the following: Write a one page essay of a first-person account of a major volcanic eruption, such as Mount St. Helens, including all relevant scientific details, the type of volcano, the nature of the eruption, the damage done, and so on. (what are you seeing, hearing, what was your day like, what is it like in the aftermath of the volcano…) 3rd Period: Complete the front and back volcanic worksheet.

Reverse Faults Reverse faults occur as a result of compression (squeezing force). 2 pieces of crust are pushed together. Hanging Wall-The upper part of a reverse fault. Footwall-The lower part of a reverse fault. Related to Convergent Boundaries.

Strike Slip Faults Strike Slip faults occur as a result of shear stress (tearing force). 2 pieces of lithosphere are pushed/pulled past each other. San Andreas Fault (California) is an example. Related to Transform Boundaries.

Earthquakes The Focus is the point in the Earth where an earthquake originates. The Epicenter is the point on Earth’s surface directly above the focus.

Seismometers The study of earthquake waves is called seismology. An instrument for measuring an earthquake’s vibrations is called a seismometer. The graph that a seismometer produces is called a seismograph.

Seismic Waves The vibrations of the ground during an earthquake are seismic waves. Body Waves travel through the Earth, while Surface Waves travel on the Earth’s surface. Primary Waves (P-Waves) - Body waves that push and pull rock horizontally back and forth (compressional). Can move through solids and liquids.

Seismic Waves continued Secondary Waves (S-Waves)- Body waves that move rock in an up and down motion (shear). Can only move through solids. Surface Waves- Move simultaneously like both primary and secondary waves. They occur at the Earth’s surface and cause the most damage.

Time Travel Curves P-Waves move fastest and are always detected first. With increasing distance there is a greater difference between the arrival times of P and S-Waves. The difference in arrival times between P and S- Waves help us determine how far away the earthquake is.

Earthquake magnitude The Richter Scale measures the largest seismic waves generated in an Earthquake. For each number on the Richter Scale, the magnitude of the waves is increased ten-fold. For example, the waves generated by a 2 are 10x larger than the waves generated by a 1, the waves generated by a 3 are 10x larger than waves generated by a 2, the waves generated by a 4 are 10x larger than the waves generated by a 3, and so on and so forth.

Earthquake Magnitude The Richter Scale also measures the amount of energy released by an earthquake. For each number on the Richter Scale, the magnitude of the waves is increased 32-fold. For example, the amount of energy generated by a 2 is 32x larger than the amount of energy generated by a 1, the amount of energy generated by a 3 is 32x larger than the amount of energy generated by a 2, the amount of energy generated by a 4 is 32x larger than the amount of energy generated by a 3, and so on and so forth.

Other Hazards Associated With Earthquakes Structural Failure- The collapse of buildings. Land and Soil Failure- Sinkholes, fissures, and landslides. Tsunami- Large ocean waves generated by the vertical motions of the seafloor during an earthquake

Warm Up Make a list of all the ways you’ve learned so far that scientists try to predict volcanic eruptions and earthquakes. Then write down another method of eruption or earthquake prediction that you think could possibly be useful, and explain how it might help predict the occurrence of a future eruption or earthquake. Be creative and have fun!

Warm Up In your notebook, make a sketch of a Oceanic/Continental Convergent Boundary. Be sure to include aspects such as these: trench, subduction zone, friction, magma, volcanoes, crust, mantle, lithosphere, asthenosphere, etc. Label all aspects that you include.