Frequently Asked Questions
About the AS-1 Seismic System

If you're having problems, check if any of the entries below will get things working again.  If not, print out the Step-by-Step Diagnosis page.  Follow all of the steps in order, writing down the answers to the questions.  Then send John Lahr an E-mail with the results and we can work together to get your station working again.

The helicorder is displaying a totally flat trace.

The trace wanders around

Other noise of unknown source

"No data on COM1" when AmaSeis starts up.

My station was quiet but now it's very noisy!

My station was working but now it's going crazy with very high amplitudes.

The helicorder hour traces stop before the end of the hour.

How do I get the latest version of AmaSeis?

Where's the data?  What are these .Z files?

Exactly how do I extract and save an event in .sac format?   (MS Word Format)

A nearby earthquake was reported, but I can't see anything on my helicorder record.

The helicorder is displaying a totally flat trace.

Check Settings/Show data values.

bulletIf the values are steady and large, like 2048 or –2048, then
bulletThe knob on the black box needs to be adjusted so that the numbers vary up and down centered on zero.
bulletIf the “Show data value” numbers are variable and centered on zero, then
bulletMake sure that the gain is not set to zero.
bulletCheck that there is space between the magnet and the coil.
bulletDo a “washer calibration” to compare with the initial calibration when the instrument was first installed.
bullet

Check the resistance of the coil with an ohm meter.  It should be around 500 ohms. 
Here's a picture of the setup.

The trace wanders around

Some possible causes are:

bulletThe three wires going to the black box are not making good contact.
bulletMake sure the un-insulated wire goes to the central terminal and that the terminal nuts hold the wires very tightly.
bulletInsects are living on the boom! One spider could generate quite a large signal.

Other noise of unknown source

Any time there is a question about the source of noise one has to figure out if it’s electronic or mechanical. If the noise is fairly frequent, then a good technique is to constrain the motion of the magnet. Lift the magnet and place an object such as a pencil between the magnet and the coil. Then monitor the signal. There should only be 1 or two counts of activity on the trace and the noise will disappear if it was due to actual ground vibrations.

If the problems continue, then clearly the black box or the power supply needs to be replaced. Contact IRIS!

"No data on COM1" when AmaSeis starts up.

bulletCheck that Settings/Device is set to AS-1.
Stop and restart AmaSeis after the device is changed.
bulletCheck that the power supply is plugged in to a live socket and that it’s attached to the black box.
bulletCheck that the serial cable is attached to the PC.
bulletCheck if COM1 is the correct port; it could be COM2 on many PC’s.
bulletIf you’re using a USB to Serial adapter cable, press the “windows key” and the Break key to bring up the System Properties. Select the Hardware tab, then click on Device Manager. Click on the + next to Ports (COM & LPT). Read which COM port is attached to the USB. Use this COM port number in AmaSeis’s Setting/COM port … window.

My station was quiet but now it's very noisy!

You may be recording microseisms. These are surface waves that Travel very efficiently along the shallow layers of the Earth. The the largest amplitudes are generated by ocean storms. Microseisms are a nearly universal source of ground noise in seismic recording and have periods of about 3 – 8 s.  Because this period range is amplified strongly by the AS-1 seismograph, filtering of the records is often desirable to enhance the earthquake signals.  A useful filter for local and regional events (short period) is a bandpass filter with frequency cutoffs of 0.5 Hz to 3 Hz. For teleseisms a bandpass of 12s to 25 seconds could prove helpful. If other AS-1’s are getting noisy at the same time, then the source is almost certainly microseisms.

These pages display wave height information:
<https://www.fnmoc.navy.mil/PUBLIC/WAM/all_natl.html> and
<https://www.fnmoc.navy.mil/PUBLIC/WAM/all_npac.html>

By studying them the likely source of the microseisms can usually be determined.

My station was working but now it's going crazy with very high amplitudes.

Try this tests:
Check that the zero adjustment is in the correct spot.  There may be two widely separated places where the knob seems to be able to zero out the signal.  While monitoring the "Settings/Show data values" number, turn the knob very slowly from one stop to the other.  Find the place where the numbers change most slowly from negative to positive and try to adjust them to be near zero.

Does this doesn't solve the problem, go to "Other noise of unknown source."

The helicorder hour traces stop before the end of the hour.

This may be caused by the AmaSeis program incorrectly setting the sample rate. The rate should be close to 6.1 samples / second.

In any case, the “fix” is to reboot the computer and restart AmaSeis.

Getting the latest version of AmaSeis

AmaSeis is updated with improvements quite frequently.  To get the latest copy, go to:  http://www.geol.binghamton.edu/faculty/jones/AmaSeis.html

To update your copy:

  1. Exit AmaSeis.
  2. Click on AmaSeisUpgrade.exe, save to disk, and then run.  This process will preserve your setting and data

To install on a computer that is not running AmaSeis:

  1. Click on AmaSeisSetup.exe, save to disk, and then run.
     

Where's the data?  What are these .Z files?

AmaSeis stores data in a directory structure.  Right below the AmaSeis directory there will be a directory named for the year (eg 2007), below that are the month directories (eg 01, 02, ... 12), and below each of the months are the day directories (eg 01, 02, ... 31).  Within each day directory there will be one file for each hour (eg 00.Z, 01.Z, ... 23.Z).  Note that these are binary data files.  They are NOT compressed files.  They can only be viewed by running AmaSeis and scrolling to the date of interest.  For data exchange, one must highlight and extract the time interval of interest and save this interval in .sac format.

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