Sensor alignment features

Depending on what sensor you have, there are different parts of the sensor that you can use to align to north.

On a Guralp sensor, you can use north arrow on the handle of the seismometer, or the pointers on the bottom of the seismometer. The brass pointer should be aligned to north and the steel pointer aligned to south. Alignment using the metal pointers should be used wherever possible, as these are more accurate than the north arrow on the handle. It may not be possible however to use the metal pointers if they cannot easily be seen due to the depth of the pit etc.

On a Nanometrics sensor, you can use the north/south line on the top of the sensor, or the alignment notches on the bottom of the sensor.