Terms/Phrases to Investigate Seismic Waves Learning Intention: 8.ESS2.2 (Seismic Waves & Earth’s Structure) Evaluate data collected from seismographs to create a model of Earth’s structure. Terms/Phrases to Investigate data, seismograph, model, and structure Science and Engineering Practice(s) Analyze and Interpret Data, Develop and Use Models Crosscutting Concepts Stability and Change, Energy and Matter, Cause and Effect Success Criteria: ...I can create a model of Earth’s internal structure using seismic data.

Seismic Waves ...are waves of energy caused by the sudden breaking of rock within the Earth. Can also be generated by explosions or impacts.

Seismic Waves: Body Waves Link (4 sec): P-Wave Animation ...called body waves because they propagate (move) through the “body” of the Earth. P-Waves A.K.A. primary waves are compression waves move through solid and liquid rock fastest kind of seismic wave pushes/pulls as it moves through Link (4 sec): P-Wave Animation

Seismic Waves: Body Waves Link (5 sec): S-Wave Animation ...called body waves because they propagate (move) through the “body” of the Earth. S-Waves A.K.A. secondary waves are transverse waves only move through solid rock slower than P-Waves up/down or side to side motion second wave felt during earthquakes (after P-Waves) Link (5 sec): S-Wave Animation

Link (1:04): How a Seismograph Works Seismographs What is a seismograph? A.K.A. seismometer an instrument that measures and records seismic waves generally used for detecting and measuring earthquakes also detects/measures volcanic events and explosions Link (1:04): How a Seismograph Works

Seismogram from Alaska Seismogram from California a seismogram is the graph output from a seismograph. Seismogram from Alaska Seismogram from California Richter Scale: a 1 to 9 scale for measuring seismic waves. Each level is ten times greater than the previous level.

After Nearpod Lesson on Seismic Waves

Locate anomalies in this seismic data. Then draw a model of Earth’s structure from this data. Crust Slowed Slowed Mantle Slowed Slowed Repeated Repeated Outer Core Question: Why did the S-Waves stop at 2900 km? Inner Core Repeated

Draw a model of Earth’s structure from the data. Crust Depth: 0 to 50 km Mantle Depth: 50 to 2900 km Outer Core Depth: 2900 to 5200 km Inner Core Depth: 5200 to 6400 km

Earth’s Internal Structure Link (5:49): How We Know About Earth's Interior?

Earth’s Internal Structure Seismic waves change speed and refract (bend) as they move through different rock layers. S-Waves stop at liquids. Understanding this enabled us to analyze seismographic data which reveals Earth’s internal structure.

Review Question Layers of rock inside the Earth have been revealed by analyzing seismic data. Geologists have observed that seismic waves change speed as they move downward toward Earth’s center. What is one location where this is revealed in Seismic Data Table 01, and what best explains this phenomenon? a) At a depth of 2900 kilometers the P-Waves slowed from 7.5 km/s to 0 km/s. This occurred because P-Waves are unable to travel through liquid rock. b) At a depth of 2900 kilometers the P-Waves slowed from 14 km/s to 8 km/s. This occurred as the wave hit the boundary of the mantle and the outer core.

Review Question Layers of rock inside the Earth have been revealed by analyzing seismic data. Geologists have observed that seismic waves change speed as they move downward toward Earth’s center. What is one location where this is revealed in Seismic Data Table 01, and what best explains this phenomenon? a) At a depth of 5200 kilometers the P-Waves slowed from 11 km/s to 10 km/s. This occurred because P-Waves are unable to travel through solid rock. b) After 5200 km, P-Wave speed was a constant 11 km/s all the way to Earth’s center. This occurred as the wave moved from the outer core through the inner core.

Review Question Seismic waves refract and change speed as they move through substances with different densities. What is one location where this is revealed in Seismic Data Table 01, and what best explains this phenomenon? a) At a depth of 50 kilometers the P-Waves decreased speed from 9 km/s to 8 km/s. This occurred as the wave hit the boundary of the crust and the mantle. b) At a depth of 2900 kilometers the P-Waves slowed from 7.5 km/s to 0 km/s. This occurred because P-Waves are unable to travel through liquid rock.

Review Question (A) (B) Analyze the P-Wave and S-Wave speed patterns in Seismic Data Table 01 and 02. Then select the model below which best matches the data. (A) (B) (A) Model One (B) Model Two