EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103)

# EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103)

Télécharger la présentation

## EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103)

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
##### Presentation Transcript

1. EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103) ~50 years of Hawai‘i seismicity 2006 1975

2. D = v x t, ΔD = Δv x Δt, but v is constant: 7 km s-1 so ΔD = v x Δt If an earthquake signal arrives at different times to two different seismometers, you can say how much closer the earthquake was to one seismometer relative to the other. A: earthquake occurs at 00:00:00 GMT B: earthquake occurs at 00:00:30 GMT Δt = 30 s → ΔD = 7 km s-1 x 30 s = 210 km ~200 km All these points are 200 km closer to A than they are to B Map view Map view

3. …and the plane doesn’t extend up in the air, only into the ground In reality, the earthquake is on a curved plane, not a curved line… The earthquake was somewhere on this curved plane Attempt at perspective view

4. There is a similar curved surface that can be drawn based on the difference between the arrival times between stations A and C. The earthquake was somewhere on this curved line

5. The earthquake was somewhere on all three of these curved lines simultaneously, i.e., where they intersect

6. http://cseligman.com/text/planets/velocity.jpg

7. http://www.esta-uk.org/jesei/waves/fig1.gif

9. http://www.awi.de/typo3temp/pics/0a414b3e7e.jpg

10. http://www.isla.hawaii.edu/ocean/tsunami/images/quakes1.jpg

11. Examples USGS

12. Same N-S fault, different slip direction Stein and Wysession, An Introduction to seismology, earthquakes and Earth structure

13. Energy and Polarity of “First Motions” Cox and Hart. Plate Tectonics – How it works.

14. Earthquake on a vertical plane Edited from Cox and Hart. Plate Tectonics – How it works.

15. Determination of nodal planes Cox and Hart. Plate Tectonics – How it works.

16. Spreading of the seismic wave Cox and Hart. Plate Tectonics – How it works.

17. Data on the surface, interpreted in 3D Cox and Hart. Plate Tectonics – How it works.

18. With a lot of recordings we can reconstruct faults with any orientations Cox and Hart. Plate Tectonics – How it works.

19. Example Focal mechanism diagrams on mid-ocean ridges Stein and Wysession, An Introduction to seismology, earthquakes and Earth structure