How are seismic waves recorded and processed?
When an earthquake occurs its seismic signature is recorded at ANZA seismic network stations. At each station, the seismic waveform is digitized by a twenty-four-bit datalogger and then sent to an ORB (see below) via the internet in real-time. Our dataloggers (Quanterra 4120s and Quanterra 330s) communicate via one of two protocols: TCP or UDP. The newest generation of dataloggers, the 330s, have smaller footprints (i.e., they are about the size of a loaf of bread), are water resistant, and have very low power consumption requirements such that some can be operated with solar power.
The term ORB stands for 'Object Ring Buffer,' which is a mechanism by which data is buffered and transported from one machine to another via the internet. Each ORB is managed by a single computer program called an 'orbserver.' Field interface modules write data from the field stations into one or more ORBs for storage. ORBs can also be used to send commands through the field interface modules, to the remote digitizers and seismometers to control functions such as rebooting and mass re-centering.
In the case of the Anza network, seismic data enters the ORB by 4 methods:
- Data from stations WMC, YAQ, SMTC, MONP are telemetered to an ORB running on one of the highest moutain peaks in the region called 'Toro Peak.' A seismic station TRO is also located here.
- Data from stations RSB, USB are telemetered via COMSERV.
- Data from station THSB is telemetered through an ORB running at Thornton Hospital.
- Data from stations BZN,CRY,FRD,KNW,LVA2,PFO,RDM,SND,TRO are received via VHF-radio into the local ORB at IGPP.
- Data from stations FLV,HWB, FSE... [FRANK FIX, see Jen's notes]
- Data from stations MTRP... [FRANK FIX, see Jen's notes]
These four feeds are combined locally into the ANZA ORB.
Click here to see a Flash animation of how this process works [coming soon]
URL: http://eqinfo.ucsd.edu/faq/wave_rec_processes.php [Last updated: 2015-10-22 (295) 23:07:44 UTC]