Abstract

Chile is one of the most seismic countries around the world, the seismic signal is not only useful to study earthquakes, but also to estimate sub-soil characteristics at orogen and mining scale related analysis, even using microseismic signals. Those studies require the deployment of dense seismic networks, usually in areas that are difficult to reach, therefore the use of seismic stations of compact size, reduced power consumption and robust under extreme conditions are important to develop. In general, this kind of instrument is expensive, making prohibited the acquisition of dense network composed of this type of seismometer. For this reason, we designed a multi-platform seismic recorder, designed to work with up to 3 channel geophones. It uses an evaluation board of the ADS1274 analog to digital converter including a externally added low-pass filtering stage. The data is continuously recorded and stored on a microSD card at sampling rates that can be selected from 1 SPS to 200 SPS. The 1-PPS signal from the GPS system is used to record the data acquisition time. Alternatively, both timers, the internal (from microcontroller) and external (from GPS) can be used to record each sample. The datalogger software uses FreeRTOS for internal task and data management, and it can be run on Arduino Due and ESP32 platforms; it is designed to be user-friendly and fault tolerant, allowing the equipment to be restarted upon detection of a fault by itself, avoiding loss of data. The multi-platform software design allows the logger to be integrated to different type of processors, analog to digital converters or GPS modules adding minor changes to the software code. This flexibility reduces the cost of the equipment without affecting the way it is used or the quality of the data acquired. The instrument developed by our group has been tested on laboratory together with commercial instrument. Cross correlations of data performed between our system and commercial instruments show no time lags between them. The system is at the final laboratory tests stage, in which its operation will be compared with other commercially available equipment. Test on the field are also considered.