In full emergency in La Palma due to the eruption of the Cumbre Vieja volcano, a group of scientists from the Institut de Ciències del Mar (ICM-CSIC, Barcelona) coordinated the installation of a device called DAS interrogator (Distributed Acoustic Sensor) in fiber optic cabling using the Roque de los Muchachos Observatory (ORM), from the Instituto de Astrophysics de Canarias (IAC), to link up with the Spanish Academic and Research Network (RedIRIS).
This instrument will improve the monitoring of seismic activity generated by the eruption of the volcano, which has been active for more than a month, by transforming one of the fiber optic wires ORM, approximately 8 kilometers long, in a seismic network of thousands of sensors that detect ground movement.
A device was developed and installed on fiber optic cables at the Roque de los Muchachos Observatory to create a seismic network of thousands of sensors that detect ground movements associated with the La Palma volcano.
The questioner was developed by the Photonic Engineering Group of the University of Alcalá de Henares (UAH) and the CSIC Optics Institute (IO-CSIC) This instrument uses fiber cable strands not used for data transmission (known as dark fiber) to carry out the measurements, while the other wires are used to transmit the seismic signals and quickly distribute them to the National Geographic Institute (IGN) and the Volcanological Institute of the Canary Islands (TO INVOLVE), which are the institutions that monitor seismic activity in La Palma.
“The data acquired with this instrument will complement those obtained by the seismic networks of conventional seismographs currently in operation in La Palma. In addition, due to the large number of sensors – one for every 10 meters of cable – provided by DAS, it will be possible to carry out studies that make it difficult to use conventional seismographs, such as determining the location of the volcanic tremor and its change. in time”, explains the ICM-CSIC researcher Antonio Villasenor, who coordinated the installation of the interrogator.
Unforeseen Applications
Villaseñor adds that the installation of this instrument in La Palma “involves the innovative use of two major scientific infrastructures (ORM and RedIRIS) to respond to society’s needs with applications for which they were not originally conceived”.
These DAS devices emit pulses of laser light through the optical fiber and measure the small fractions of the signal reflected in microscopic imperfections within the cable, which vary, for example, by ground vibrations.
This is not the first time the ICM-CSIC has used DAS technology to detect earthquakes. It did so last year, when it transformed the underwater communication cables linking the islands of Tenerife and Gran Canaria – an area of high seismic activity – into a network of sensors capable of detecting earthquakes near and far thousands of kilometers from its epicenter.
O DAS Devices they emit laser light pulses through the optical fiber and measure the small fractions of signal reflected in the microscopic imperfections within the cable. They become reference points that vary in position as a result of external factors such as ground vibrations. Thus, a single cable connected to a single measurement device can be converted into a network of thousands of sensors.
Although it’s still a emerging technology, the study of fiber optic seismology has come a long way in recent years and has been used successfully on several occasions. For example, in 2018, these DAS equipment installed in the metropolitan area of Pasadena (California) detected, more than 9,000 kilometers from the epicenter, an earthquake that occurred in the Fiji Islands.
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