Iquique Local Network (ILN)

The Iquique Local Network (ILN) as one component of the IPOC is a seismological network of 20 stations around the North Chilean harbour city of Iquique. With its average station spacing of approximately 25 km, the network aims at recording small to intermediate seismic events to verify the crustal structure and seismic behaviour of the subduction interface in this region. Since the general task of the IPOC is to monitor the deformation signal before a large earthquake in a brought frequency range, the data of the ILN should provide insight in processes along material boundaries and geometrical features to investigate such an 'earthquake preparation phase' on a local scale. The ILN will be a long term deployment also supporting hazard analysis for Iquique and the surrounding region. It hosts the nearest station to the coast which is especially important for investigating tsunamigenic earthquakes and their related hazard.

 

Equipment
The final setting of the ILN will contain 20 seismological stations of which 14 will be composed of GURALP instruments, each station including a CMG-3ESPC seismometer with 60s to 50 Hz frequency response, a CMG-DM24 S3 digitiser with 3 24-bit channels, 64Mb flash memory and GPS antenna, and a CMG-DCM Data Communications Module with a 40Gb removable and hotswappable data storage device, WEB server, PC with LINUX OS and SEEDLink for transmission of data. The remaining 7 stations will be equipped with REFTEK stations connected to a 1Hz Mark L 3D seismometer.

 

DEPLOYMENT STAGES

The installation of the ILN comprises several deployment stages (as can be seen in Figure 1 to 3) due to the availability of the instruments and the advancement of construction work at the station sites. The very first stage just had two GURALP stations installed, one in the mining gallery of NEUQUEN and the second one at the basement of a building of the Arturo Prat University in Iquique. This station by now is the only station with an internet connection for real-time data transmition. This first stage also had an antenna-configuration with four REFTEK stations around the French PBO-site of Humberstone. During the deployment phases 2 and 3 successively more GURALP stations were installed in their vaults as shown in Figure 4 and 5. The REFTEK stations changed their locations several times to fill voids in the deployment scheme until filled by GURALP stations on important network sites. Figure 6 gives the actual network layout which covers a total area of 150 km in N-S and about 120 km in E-W direction.

 

 

Figure 1  

 

Figure 2

 

Figure 3

 

Figure 1 to 3 show the different deployment stages of the ILN layout with the first stage starting beginning of May 2009. For detailed deployment times of each station see Table 1.

 

Figure 4 and 5 give views of the vault constructions to host the GURALP instrumented stations. The view inside of a vault (Figure 5) exhibits the digitizer on the right hand side of the shelf and the Communications Module which hosts the data storage device on the left hand side. The Styrofoam box protects the 3ESPC-Seismometer against large temperature variations.

 

 

 

Figure 6 Actual stage of ILN layout last modified on 27^th of April 2011 by the    installation of the southernmost station at the Chomache Fault in the vicinity of a creepmeter station (see also OBSERVATORY/CREEPMETER).

 

Working Group
This e-mail address is being protected from spambots. You need JavaScript enabled to view it (PI), Silke Eggert (PhD student), Erwin Günther (engineer)