Earths Interior Structure The travel times of seismic
- Slides: 11
Earth’s Interior Structure The travel times of seismic waves through the Earth to different distances can only be matched by a model Earth that has layering as shown here (crust, mantle, outer core, inner core). (Figure 6. 25, text) For example, it takes about 20 minutes for seismic waves to travel straight through the Earth, an average velocity of 2*6371 km/20*60 s = 10. 6 km/s P wave PKP wave
(Figure 6. 25, text) P wave PKP wave
Refraction of light by water Reflection Refraction Similarly, seismic waves in the Earth are refracted and reflected at layer boundaries.
Earth’s interior structure and seismic raypaths that are used to determine the Earth structure. http: //www. iris. edu/hq/ files/programs/educati on_and_outreach/less ons_and_resources/i mages/Explor. Earth. Po ster. jpg
Seismic Waves Program http: //bingweb. binghamton. edu/~ajones/
The Seismic Waves program: Uses speeded-up time views of wavefronts to illustrate wave propagation through the Earth. Note reflection, refraction and wave conversion at layer boundaries. Seismograms show arrivals of various phases (wave types and paths). Wave energy/propagation represented by wavefronts. Raypaths show direction of travel of a specific point on the wavefront. Earthquake Cross Section Through Earth Stations for Seismograms * Wavefront Ray Path Seismograph Ray Path is perpendicular to wavefront
Earthquake Cross Section Through Earth * Time T 1 Wavefront Ray Path Stations for Seismograms Seismograph Ray Path is perpendicular to wavefront Earthquake Cross Section Through Earth Stations for Seismograms * Time T 2 Wavefront Ray Path Seismograph Ray Path is perpendicular to wavefront
Earth’s interior structure and seismic raypaths that are used to determine the Earth structure. http: //www. iris. edu/hq/ files/programs/educati on_and_outreach/less ons_and_resources/i mages/Explor. Earth. Po ster. jpg
