Saturday, November 1, 2008

NEIC - Your best source of earthquake information

If you hear about an earthquake on the news, where can you go for more information? I assume people would search their favorite journalistic source - Google, Yahoo, New York Times, BBC, Reuters, NPR - for the newsy stuff. But what about the basic science of the event?

I'd suggest for large teleseismic (see NEIC glossary) quakes that you visit the U.S. Geological Survey Earthquake Hazards Program/National Earthquake Information Center, at .

Each significant event has its own listing, including the Pakistan quake.

For the geographically faint-of-heart, you can get a general global location:

globe showing location of 10-degree map

You can look at historic earthquake patterns in the area (seismicity), and the relationships to plate boundaries:

Historic Seismicity

Magnitude / Depth Legend

You can read about the geology and tectonic environment that are related to this event:
Earthquakes and active faults in western and northern Pakistan and adjacent parts of Afghanistan are the result of the India plate moving northward at a rate of about 40 mm/yr (1.6 inches/yr) and colliding with the Eurasia plate. Along the northern edge of the Indian subcontinent, the India plate is subducting beneath the Eurasia plate, causing uplift that produces the highest mountain peaks in the world, including the Himalayan, the Karakoram, the Pamir and the Hindu Kush ranges. West and south of the Himalayan front, the relative motion between the two plates is oblique, which results in strike-slip, reverse-slip, and oblique-slip earthquakes. The pattern of elastic waves that were radiated by the October 28 and 29, 2008, earthquakes implies that each earthquake was the result of predominantly strike-slip faulting. Seismographically recorded waveforms imply that the shocks were caused by either left-lateral slip on a northeast-striking fault or right-lateral slip on a northwest-striking fault.
For this major event, you can even download a poster suitable for display.

And, in what will become useful for a subsequent lesson on interpreting seismograms, you can find out how long it should have taken the P-waves from this earthquake to reach any point on Earth:

(click above for more detail)

You can be sure that we'll return to the NEIC web site in the future.

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