Thread: Today's 7.7 in Chile

Started: 2007-11-14 23:44:02
Last activity: 2007-11-14 23:44:02
Topics: IRIS EPO
John Lahr
2007-11-14 23:44:02

I don't think I have my seismograph calibrated correctly. Most of
the time I have tiny little movement up and down, so it looks like
the lines are kind of fuzzy. In Kansas, on a concrete floor, this
probably makes sense. But when I extract part of a line to look
more closely, the peaks and valleys are square, not pointed. This
doesn't make sense to me. Sometimes it appears that there is no
movement at all, and when a segment is extracted it shows wider squares.

Also, I think I should probably have had some record of the 7.7
event in Chile today, but there is absolutely no change in the line.

What have I done or not done?

If you didn't record the M7.7 earthquake in Chile, then there is
certainly something seriously wrong with your seismic station! One
way to determine this is to look at the various stations that are
sending a helicorder image to the web every 10 minutes. See:

Here's the record from Cedar Rapids, Iowa, for example:

A good place to start if you didn't record the event is the FAQ page:

Two common problems are mis-adjustment of the knob on the black box
and contact, even slight, between the magnet and the coil.

Keep me posted on progress.


04:18:25 v.eb79165e