Here is some information about the recent earthquake in Japan.
Before I start, please observe the follow for the sake of your neighbors:
I pray that you all stay safe. Prepare food and water, but do not forget to be kind to each other. There is no room for impatience. Be helpful to one another and share as you are able. Be selfless towards others. Thank you for showing love to your neighbors.
Please observe this first graph.
This graph shows a lot of 5-6 second period waves, some from storms in the Atlantic ocean, and possibly from the typhoon.
Time domain: top line.
Frequency domain: bottom trace.
The light blue is the primary energy component of the noise, centered at about 0.2 Hz (5 seconds)
For this graph:
- the vertical trace is in red
- North/south trace is in green.
- East/west trace is in blue
Order of waves:
- P wave comes first, on the vertical channel (red)
- S wave comes second, on north and vertical channels (red and green)
- Core phase (bounced off the Earth's core, which has dampened it a bit) - both horizontal channels, low frequency
Japan is ~90 arc degrees out from where my location. Seismic waves go deep into the Earth's mantle before coming up and being detected by our seismic equipment.
The last wave is the one that you all felt. It's the Rayleigh wave, which stays in the Earth's crust, and is the one that causes the landslides, building collapses, and other bad things to happen.
I would like to thank my dad for providing me access to the data from his seismometers, and for explaining some of this to me, especially details about the core phase and other details about the event.