Fiber Optic Technology for the earthquake warning

Fiber Optic Technology for earthquake warningA research team from the USA has applied FBG sensors for detecting earthquakes and creating a system for subsurface imaging with the help of fiber optic technology. The sensors were installed above an existing fiber optic cable.

According to scientists, this fiber optic system can register seismic signals produced by trains and automobiles. These signals cause changes in the fiber optics’ length from the very beginning till the very end. This fiber optic system is also known as distributed acoustic sensing or DAS.

Scientists have also installed usual high-resolution seismometers along the fiber optic cable in addition to the new DAS technology. They have aimed to compare these two methods of signal detection. In distributed acoustic sensing the fiber laser light is sent through the fiber optic cable. DAS technology measures the perturbations in the backscattered light along the whole fiber optic cable.

In fact, scientists made a conclusion that the fiber optic system is sensitive enough to detect footsteps. The other research team from one of the US universities proved that fiber optic technology can provide data about street traffic and demonstrated the results of the lockdown 2020. The fiber optic system could locate vibrations from cars and pedestrians above and demonstrated that the pedestrian traffic almost disappeared in April and stayed almost the same in June.

However, according to this scientific research, the fiber optic cable can even detect the jet airplanes that fly by. The scientific work was much easier because DAS systems are easy-to-install devices in comparison with the traditional methods. Scientists just needed to use a single fiber optic cable instead of thousands of geophones to detect ground vibration. Researchers got the same information using fiber optic technology faster. The DAS system continuously monitors the modifications in the fiber optics’ length down to changes in the length of less than 1 nanometer.

Thanks to the DAS technology the research team will calculate the velocity structure in the subsurface by measuring the strain changes. The velocity is a crucial factor in the determination of how the ground and civil infrastructure may respond to an earthquake.

Thanks to the new fiber optic technology, scientists and engineers are going to improve velocity and ground motion models in urban areas by collecting more information. Moreover, they hope to find a better understanding of the seismic risks and assess the resilience of our infrastructure.

Besides, the research team has a plan to spread this fiber optic technology for a vast territory to develop a better early-warning system for earthquakes. This is a totally new way of thinking about monitoring and designing for earthquakes that can give people time to get to shelter.

Optromix is a DAS system manufacturer that provides top-of-the-line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Fiber Optic Technology in humans movement tracking

Fiber Optic Technology in humans movement trackingA team of researchers from the US university applied fiber optic technology to demonstrate the changes in city traffic because of the lockdown. Scientists had tapped into an underground telecommunication fiber optic cable and made a scientific monitoring device. Thanks to this fiber optic system, they could watch how Covid-19 brought life to a halt.

According to researchers, they shined a laser through the fiber optics and could locate vibrations from cars and pedestrians above. The fiber optic cable could detect the movement through the unique seismic signals from them. That allowed scientists to create a detailed picture of how a community ground to a halt, and then slowly came back to life when the lockdown eased.

This experiment with the fiber optic cable showed that the pedestrian traffic almost disappeared in April and stayed almost the same in June. However, the car traffic started increasing after initially declining. As a result, the vehicle traffic is actually back to normal, while people walking is still minimal. Moreover, scientists could distinguish the vibration signals from fiber optic cable from construction vehicles. In April there was no industrial activity as the construction halted. But in June the construction vehicles’ movement had started again.

Fiber optic cables trap light pulses and transport them to vast distances as signals. And when a car or person passes, the vibrations introduce a disturbance, and a scattering light returns. The researchers measured vibrations at different lengths of the fiber optic cable by estimating the time it took the back-scattered light to travel. This method is well-known as distributed acoustic sensing (DAS).

Distributed acoustic sensing (DAS) can become an instrument for tracking people’s movement instead of cell phone location data studying. Researchers can apply fiber optic cables to monitor pedestrians and cars. However, DAS can’t help in identifying a particular car or person. It can only identify a type of vehicle, for example, truck or bike.

In comparison with usual seismometers, such fiber optic cable is cost-effective and doesn’t need a source of power. There is a need for just an FBG interrogator that gets the information.

Engineers have already produced DAS systems to detect soil deformation, biologists use offshore fiber optic cables to listen in on whales, and scientists made measurements of earthquakes and water temperature in the Arctic with the help of FBG sensors. Every day fiber optic technology gets a new application.

Optromix is a DAS system manufacturer that provides top-of-the-line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) in the oil and gas industry

DAS in the oil and gas industryAccording to scientists, nowadays we can see newly developed distributed sensing systems that can have many appliances including monitoring of wells’ conditions in the oil and gas industry. Mostly, distributed acoustic sensing (DAS) is applied in these spheres.

The engineers have an opportunity to make decisions on operational optimization onsite with the usage of the data provided by distributed fiber optic sensors. The fiber optic technology can help in well performance improvement as well as in keeping safety at the well site. And as a result, it optimizes production from oil and gas wells. In comparison with distributed sensing, there is no such method that could provide such quality and extent of detail about physical conditions.

Mostly, distributed acoustic sensing (DAS) is produced to record fluid and gas flow signals, listen to hydraulic fracturing-related signals, etc. Distributed sensing systems trace changes in acoustic vibrations along the entire length of a fiber optic cable in real-time. In the fiber optic cable, there are thousands of detection points at minimal spatial intervals. Compared to the usual sensing systems, distributed sensing does not rely on discrete sensors at predetermined points. Distributed sensing system uses the whole fiber optics itself as a sensing unit.

Therefore, fiber optic technology is suitable for those who want to apply environmental monitoring in sensitive geologic operations. Thanks to the length of the fiber optic cable and its working ability in severe environmental conditions for long, it is quite popular for such use. The down hole fiber optic sensor application provides for oil and gas wells, flow-back operations, geothermal wells, etc.

The ability of measurement along the complete length of the fiber optic cable can be applied for many other applications like the characterization of contaminated bedrock aquifers and monitoring of geologic carbon sequestration projects. In addition to that, distributed sensing systems can also register the conditions of the near-wellbore area of subsurface rock formations.

DAS system manufacturers always have an aim of making their fiber optic solutions better. For the DAS systems, it is the regulation of acoustic and vibratory noise sensing. The ambient noise is always in sites and should not be measured.

That is why the next scientific goal for DAS technology is the creation of a portable vibration isolation system to maximize the distributed acoustic sensing system’s dynamic range.

Optromix is a DAS system manufacturer that provides top-of-the-line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) and its applications

DAS and its applicationsIn southwest Iceland, there is a fiber optic cable that connects two geothermal power plants. It is used as every casual fiber optic cable for data transmitting. However, in 2015 a research team decided to apply it for detecting seismic waves of earthquakes, so they could draw a map of the underground features including geological faults. And distributed acoustic sensing (DAS) made it possible.

Scientists made their discovery thanks to distributed acoustic sensing (DAS). This technique measures any tiny changes to the phase of fiber optic laser pulses that reflect from many points on fiber optics. The thing is an acoustic or seismic wave stretches and compresses fiber optics when it passes through the ground where the fiber optic is attached. DAS systems can provide the necessary information at a reasonable cost. Moreover, the usual seismometers couldn’t reach such kind of information.

In fact, Iceland is not the first country where the distributed acoustic sensing (DAS) technology was applied. Before that, fiber optic cables were produced in other seismic regions, for example, in the USA. The precise information on earthquakes’ location, nearby faults was got thanks to the fiber optics both on the seabed and on land. Scientists consider that by using a million kilometers of fiber optic cable around the world, we can broaden quake monitoring thanks to the network of seismometers with fiber optic sensors.

Distributed acoustic sensing (DAS) has been previously applied mostly in the fossil-fuels industry. The sensing technology helped to monitor boreholes and image deposits of oil and gas. Nowadays, it has many other applications for extracting data from vibration in the ground. Distributed acoustic sensing can even shed some light on global warming by studying the glaciers’ movements in the Antarctic and Alaska.

Besides earthquakes, researchers proved that they can use DAS systems for studying other natural hazards. The research team from Italy showed that they can detect the strain changes connected to the volcanic phenomena which include explosions. They also discovered seismic waves slowing through presumed fault zones on the volcano.

In the meantime, scientists from Japan demonstrated that DAS technology can monitor submarine volcanoes. The researchers measured the signals from the fiber optic cable on the seafloor. They found out that fiber optic sensors could produce coherent measurements that are needed for underwater eruptions’ recording.

Distributed sensing is an effective instrument that provides us with a lot of data that we can’t observe with the naked eye. Considering how widely fiber optic lines are used, distributed acoustic sensing (DAS) can give many possibilities to scientists and society.

Optromix is a DAS system manufacturer that provides top-of-the-line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) in exploring the ocean

DAS in exploring the oceanExploring the underwater environment that covers most of the Earth’s surface is one of the most difficult tasks. The easiest way is the usage of distributed acoustic sensing (DAS) technology. However, the fbgs sensors’ setting is also not so easy because of the environmental conditions. Despite this fact, distributed acoustic sensing has a huge potential for observing processes in the future.

Fiber optic solutions are the new methods of geophysical information registration that can be applied both onshore and offshore. The scientists used transmission time-of-flight of laser pulses inside transoceanic subsea fibers to note seafloor strain. To explore seafloor strain with higher spatial resolution, they utilized a distributed acoustic sensing (DAS) system.

Distributed acoustic sensing technology helps to observe the ocean and solid earth phenomena. The scientists applied a fiber optic cable and a distributed acoustic sensing (DAS) unit operating onshore. DAS technology uses a photonic device that sends short pulses of laser light through fiber optics. DAS detects the backscattering set by strain in the cable caused by stretching.

The researchers could get even more data than expected. They could record underwater earthquakes, volcanic activity, and a range of micro hydrodynamic signals. The scientists monitored the acoustic waves by alterations in laser light along the fiber optic cable. Recordings of a small earthquake wavefield demonstrated several fault zones underwater. Distributed acoustic sensing could picture earthquake hazards in the coastal oceans and give new data about fault orientations and seafloor structures. The DAS system displayed the state of the sea and its changes during a storm cycle. These observations proved the necessity and potential of this method for marine geophysics.

There are still aspects of this distributed acoustic sensing research that should be improved. One of them is the fact that current DAS instruments can only see lower frequencies. However, such frequencies are considered to be low for acoustics, but it is high for seismologists and enough to locate boat signals. The research team also explores the possibilities of tracking mammals, for example, whales with the help of distributed acoustic sensing technology. The second challenge is the fact that the scientists don’t know where exactly the fiber optic cable is. Because seabed bathymetry can affect the signals and influence DAS senses. Nowadays, it is possible to use only the initial part of the fiber optic cable, up to 200 km. But it already allows capturing a number of spheres of science.

As a result of the research, the observations with the DAS system during just a few days helped to create a map of an unknown fault system and detect several dynamic processes in the water. The distributed acoustic sensing technology could help to get rid of a huge gap in ocean sensing.

According to the researchers, the production of fiber optic systems based on the DAS technology can be easily automated. However, there is still a space for developing and finding new ways of optimization.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) system for Arctic tests

DAS system for Arctic tests The USA researchers started a number of experiments that aim to analyze the first data about seafloor under Arctic sea ice with the usage of a new method. The research team was able to connect a distributed acoustic sensing (DAS) system with a fiber optic cable. The cable vibrations can record the data 24/7. That helped the scientists to get all the activities and changes within the ocean all day long. This was the first time in history when a DAS system was used on the seafloor of the Arctic or Antarctic oceans.

The appliance looks like an electronic box that is attached to the fiber optic cable on land. It uses a laser to send thousands of short pulses of light. The small amount of the light is reflected back. And the reflected light helps the appliance to monitor events along with the fiber and store the data on hard drives.

According to the research, the DAS technology showed the icequakes, different climate signals, and marine life. The researchers are expecting to note other climate signals like ocean wave height, timing, and distribution of sea ice breakup, and ice thickness, etc. The usage of the distributed acoustic sensing system has the potential to record a variety of Arctic phenomena so the scientists can better see the climate change effects and sea life. Moreover, the DAS system makes it cost-effective and safe in comparison with the other methods. The scientists have already recorded a number of events that the traditional hydrophone or ocean bottom seismometers couldn’t even detect. With the help of the DAS system, the scientists hope to also record whale songs.

However, the research team has to face challenges during the first week of the tests. And the most difficult one was the harsh climate. It was really cold, most of the territory is tundra. It’s snowing most of the time and it’s getting dark really early. No wonder, that the team should find new creative ways of data fixing like DAS technology to get everything working.

That’s why the researchers chose a distributed acoustic sensing system to cope with the weather conditions. Fiber optic cable is double-armored with copper and steel. All the network components are created to hold the extreme Arctic environment. They have no need in sending a boat to plant monitors, moving over the sea ice to install the sensors. This fiber optic cable can exist for years or decades without replacing it.

This project of watching the Arctic ocean with the usage of the distributed acoustic sensing system is going to last over the next two years. The research team will collect the data. And the next third year will be spent on its analysis.

According to the researchers, the production of fiber optic systems based on the DAS technology can be easily automated. However, there is still a space for developing and finding new ways of optimization.
Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed acoustic sensors (DAS) are applied underwater

DAS are applied underwater Scientists are looking for new ways of employment for distributed acoustic sensors (DAS). The fiber optic system contains a mandrel with a wounded with sensitized optical fiber. It is the acoustic sensor for a heterodyne that is protected for underwater use.

Nowadays, the DAS system can be used both for military purposes as well as for peaceful life. In the military, they are mostly utilized for submarine locations. While they are also in active use for monitoring sea animals’ life or finding and exploring marine mineral sources. The fiber optic systems based on the DAS technology have more advantages over the other items. First of all, they are thin and reliable. Secondly, there are no underwater electrical devices. And finally, the systems with acoustic sensors are immune to electromagnetic interference.

These devices usually contain an array of DAS sensors along with the fiber. Herewith, the arrays are up to a hundred or even fewer acoustic sensors because of the technical restrictions. The spacing between these acoustic sensors is fixed. That’s why there are some limitations in marine acoustic detection, for example.

The recent researches from China exploited a distributed acoustic sensing based on heterodyne coherent detection and demonstrated its field-testing. The optical cable contains a supporting mandrel, special optical fiber, and cable sheath. Acoustic signals from the fiber optic system disturb the mandrel and the fiber. That all causes phase changes which are the desired signal. The whole model was created to analyze the equivalence and specific character of the acoustic wave response.

With the array signal processing, the DAS device can easily find underwater acoustic signal sources and track motion trajectories. Moreover, the results of the experiments are highly accurate.

There are also obvious benefits of distributed acoustic sensors (DAS) in various industries. Most of which are elements of longer-term goals.

Some of the potential advantages of a distributed acoustic sensing are numbered below:

  • a low-cost acquisition system;
  •  a simple design;
  • no electrical energy required in the fiber optic cable;
  • the fiber optic cable is suitable for harsh environments (dust, temperature, harmful gases);
  • the fiber optic cable is immune to the radiations such as EMI (Electromagnetic Induction) & ESD (Electrostatic Discharge);
  • the fiber optic system can transform several kilometers long sensor that enables it to monitor on a truly distributed basis.

According to the researchers, the production of fiber optic systems based on the DAS technology can be easily automated. However, there is still a space for developing and finding new ways of optimization.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) for glaciated areas

DAS for glaciated area detectionNowadays scientists pay more attention to the process of Alpine microseismicity. The thing is that the sensing of seismic activity is important for studying landscape-shaping processes and predict dangerous mass movements. Nonetheless, the amount of modern fiber optic sensors is still low in Alpine regions. Therefore, distributed acoustic sensing (DAS) promotes solving the problem.

The application of advantageous fiber cables makes DAS technology very promising in seismic monitoring of glacier movements and natural hazards. Additionally, DAS technology has significantly changed the portability of seismic devices. This is why the performance of seismic monitoring in difficult-to-reach areas becomes more and more accessible.

It should be noted that the purpose of distributed acoustic sensing “focus on processes near the Earth’s surface rather than on traditional seismology subjects like the deeper crust and mantle.” DAS applies fiber optic sensors into which an interrogator enters a sequence of laser beam pulses. Herewith, fiber optic systems as distributed acoustic sensing are widely used in geophone chain deployments.

Fiber optic systems allow for sensing local earthquake signals, which are too weak to be recorded by conventional seismometers. Moreover, DAS enables the record of anthropogenic noise. Even though individual channels of distributed acoustic sensing have some disadvantages as a lower signal-to-noise ratio, they overcome seismometers. The thing is that there are a lot of unused fiber optic systems with unprecedented sensor coverage and density.

Novel DAS technology performs the records of microseismic signals and ambient noise in glacier areas. Compared to standard fiber optic systems, new distributed acoustic sensing offers important improvements in stick-slip event location and determines weak seismic waves. Herewith, the potential and utility of DAS systems are doubtless for sensing glacial processes.

According to scientists, DAS technology performs measuring seismogenic glacier flow and even small Alpine mass movements, for example, rockfalls. The benefits of distributed acoustic sensing include better limitation of static and dynamic properties of the glacier and its surroundings. The most significant thing is DAS technology provides precise arrival time measurements despite spatial averaging.

Finally, the advantages of DAS channels increase the location quality of stick-slip events significantly. The density of distributed acoustic sensing detects numerous reflections and extremely refracted waves. Herewith, spaced seismometer networks can not carry out it.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed Acoustic Sensing (DAS) for vibration detection

DAS for vibration detectionThe thing is that human hearing is actually limited. Nonetheless, the technology of Distributed Acoustic Sensing (DAS) allows for detecting ground vibrations that are difficult to hear. Therefore, DAS systems perform analysis of seismic signals produced by people, animals, or even vehicles, etc.

To be more precise, DAS technology collects acoustic data with the help of fiber optic cables. Herewith, distributed acoustic sensing records signals and the backscatter pattern that can be analyzed later. For instance, distributed acoustic sensors can detect various environmental conditions – earthquake and hydrological activity, wind and weather events, and more.

It should be noted that virtually any fiber cable can be used as an acoustic sensor thanks to DAS technology. The thing is that it needs limited power, and the DAS is immune to electromagnetic and radiofrequency interference. This is the reason why distributed acoustic sensors can be applied for long-term, persistent monitoring in difficult-to-reach places.

The most popular DAS applications include the oil and gas industry where acoustic sensors are used to monitor pipeline leakage and seismic activities. Additionally, DAS systems perform perimeter security and smart city applications and control traffic and assets.

A company-manufacturer of fiber optic solutions from the U.S. has presented a new project for existing fiber cables. They test DAS technology to improve its sensitivity and resolution. Thus, new DAS applications would appear to offer a greater understanding of acoustic signals.

Thus, DAS helps to detect cattle movement in an agricultural experimental station. The existing fiber optic cables record four main signal types: cattle movement, earthquake and wind activities, and human traffic. Herewith, the researchers claim that it is very easy to turn existing cables into acoustic sensors of high efficiency.

In the nearest future, distributed acoustic sensors can be used for the detection of geological, hydrological, meteorological, and biological (human and animal) activity.  During the tests, DAS systems have provided a greater understanding of the movements of cattle and people in the land.

Distributed acoustic sensing demonstrates a high level of efficiency. “DAS using fiber optic cables could prove to be an effective solution for monitoring the movement of livestock and wildlife and weather events such as high winds, storms, and lightning in remote locations.” Moreover, the same technique can be useful for other applications mentioned above. Even though DAS technology still needs to be improved, it is planned to be used to test new analytical techniques and devices.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

Distributed acoustic sensing detects polar bears

DAS for bear detectionNowadays cases, when people meet polar bears, have dramatically increased especially in arctic areas because the environment continues rapidly transforming. Thus, there is a need for a structural health monitoring system that allows detecting bears to decrease the number of such meetings. Distributed acoustic sensing (DAS) is an ideal technology to perform this task.

DAS systems are used as an intrusion detection system that is able to operate in environments where temperatures fall to -70 C. Usually, the installation of the distributed acoustic sensing system takes place on the ground, that is why DAS system performance requires its testing in the snow. The DAS has been already tested at similar conditions (deep snow and extreme cold), herewith, people helped to imitate polar bears walking near the distributed acoustic sensing system.

It should be noted that standard DAS system consists of the following components:

  • a sensing fiber optic cable that can be stretched over long distances;
  • a laser central processing unit (DAS).

The operating principle of fiber optic technology is based on mechanical vibrations that undertake fiber impingement, leading to laser beam backscatter and therefore, allowing researchers to measure the signal required. 

The researchers planed to test several opportunities provided by the DAS system: the ability of optical fiber to maintain extreme temperatures, the suitability of distributed acoustic sensing to snow coupling. The performance of the DAS system has been tested at the temperature of the -70C in the MTS environmental control chamber, and it demonstrated good results.

“Launch boxes with 2200m of spooled fiber optic cable were applied on either side of the 150m of distributed acoustic sensing cable to imitate a field deployment of 4.5km.” The researchers pay careful attention to four separate test temperature ranges provided by the DAS system, they even calculate shoe surface area combined with the weight of the participants in order to learn human foot pressure and connect it with polar bear foot pressure to classify bears of different sizes.

Additionally, DAS also allows differentiating humans from polar bears. The thing is that polar bears generally walk with 3 points of ground contact, while people need only one point. Even though the feet of polar bears are quite large, researchers can easily offer similar foot pressures.

Finally, the test results of distributed acoustic sensing demonstrate that fiber optic cables can maintain extreme cold temperatures in the arctic regions, where the temperature is required not to disturb optical fiber performance. The DAS system detects signals at depths of at least 0.65m in the unprocessed data.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com