Quick Start Guides

Introduction:

This manual covers the following tasks related to installing broadband sensors:

Orient sensor Level sensor Connect sensor to DAS (power) Unlock masses (manually or via electronic command, if masses are the type that lock) Center masses (via command) Check waveforms, e.g. stomp test

Note, always handle sensors with care. If you have never worked with sensors or been shown how to install them, you should get help from experienced people, or barring that, carefully read the manufacturer's manual. Never move an unlocked sensor, unless the sensor has no mass locks. Most of the broadband sensors in the PASSCAL fleet are either Streckeisen STS2's or Guralp 3T's; both models have 3 masses and all 3 need to remain locked during transport.

Data that is recorded locally, as opposed to telemetered must be offloaded and stored.  The actual procedures for offloading data depend on type of DAS and the type of media that the data is recorded on.  Offloading should be done as soon as possible after visiting the site in order to secure the data.  If possible offloading and data review should be done close enough to the site so that, if a problem is detected, the site can be revisited.

In general the offload procedure is as follows.

1. Verify that there is the expected amount of data on the media.  If there is not the expected amount of data there may be a problem at the site.

2.  Offload the data.

3.  Verify that the size of the offloaded data corresponds to the amount of data that was on the media.

4.  Review the data for indications of station problems and for data integrity.

True North (geographic North) is the convention for orienting sensors in what's known as passive experiments, i.e. generally recording earthquakes, as opposed to controlled sources. You must know the declination angle between true North and magnetic North at the station site and you must know how to properly correct for the declination. If you do not know this, find someone who does; otherwise use magnetic North and make sure you write that on the Installation Sheet. (You will use this information later to construct accurate metadata for the station.)

Fetch the sensor planned for the site and write its serial number on the station's Installation Sheet, preferably in pencil, because if the sensor does not work properly, you will have to try a different one. Loosen the sensor feet (the foot-locking mechanisms may need to be backed off) and shorten the feet (also known as legs) as much as possible. Clean grit off the sensor pad. Place the sensor on the sensor pad and adjust the sensor's position until its orienting keys are precisely aligned.

In the field, you must check: