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EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103)

Explore 50 years of seismicity in Hawai‘i and learn how to interpret earthquake signals using arrival times. Delve into the science behind earthquakes on curved planes and more. Find intersections of seismic waves for precise location determination.

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EARTHQUAKES AND TSUNAMI IN HAWAI‘I (GG103)

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  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

  8. http://physicsquest.homestead.com/wavevel.jpg

  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. Fault types and “Beach Ball” plots USGS

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

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