ÖNCEL AKADEMİ: INTRODUCTION TO GEOPHYSICS
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This document provides an introduction to refraction seismology. It discusses how refraction seismology can be used to indirectly observe the layers inside the Earth by interpreting the depths to subsurface interfaces and seismic wave velocities for each layer. It explains that refraction seismology works by analyzing the times of first arriving seismic energy versus distance recorded by receivers from a seismic source. The goal is to interpret depths to interfaces and wave velocities without later arriving seismic waves that could interfere with the analysis.
![Introduction to Geophysics Ali Oncel [email_address] Department of Earth Sciences KFUPM Refraction Interpretation Introduction to Geophysics-KFUPM](https://image.slidesharecdn.com/lecture5-3-091220222127-phpapp02/85/ONCEL-AKADEMI-INTRODUCTION-TO-GEOPHYSICS-1-320.jpg)
ÖNCEL AKADEMİ: INTRODUCTION TO GEOPHYSICS
- 1. Introduction to Geophysics Ali Oncel [email_address] Department of Earth Sciences KFUPM Refraction Interpretation Introduction to Geophysics-KFUPM
- 2. Previous Lecture Seismic Waves Through the Earth How do we know what’s inside the Earth? Direct observations: Exposures on Surface Drilling Volcanic Material Indirect observations: Gravity Field Magnetic Field Seismic Waves
- 3. LITHOSPHERE rigid outer shell crust and upper mantle (~ 50 to 200 km thick) somewhat brittle, breakable cold (like butter out of fridge) ASTHENOSPHERE warmer, plastic layer under lithosphere mantle from ~ 150 to 700 km squishy, plastic warm (like softened butter ) LOWER MANTLE solid ~700 to 2900 km OUTER CORE liquid INNER CORE solid Interior of Earth by STRENGTH Introduction to Geophysics-KFUPM Park and Plates, 2005, Lillie
- 4. - Interpret depths to subsurface interfaces and the seismic wave velocities for each layer . Refraction Seismology Objective Introduction to Geophysics-KFUPM
- 5. - Later arriving complications in the recorded ground motion are discarded. Thus, the data set consists of a series of times of first arriving energy versus distance . Refraction Seismology Introduction to Geophysics-KFUPM
- 7. Introduction to Geophysics-KFUPM From Tom Boyd’s WWW Site - http://talus.mines.edu/fs_home/tboyd/GP311/introgp.shtml
- 9. Introduction to Geophysics-KFUPM From Tom Boyd’s WWW Site - http://talus.mines.edu/fs_home/tboyd/GP311/introgp.shtml
- 10. Introduction to Geophysics-KFUPM Depth to Bedrock Crustal Thickness Fig 4.1 of Lillie
- 11. Then, receivers therefore must extend well beyond the X cr for the deepest refractor of interest. A general rule, Spread Length> 2 X cr Introduction to Geophysics-KFUPM As a first arrival ( see X c ), As a secondary arrival, the event may be masked by interference from direct, reflected, or other refracted events.
- 12. Introduction to Geophysics-KFUPM Interpretation Models Figure 4.3 of Lillie
Editor's Notes
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