How scientists use thermal imaging to forecast changes in volcanic activity
Kilauea on the Island of Hawaii is one of the most active volcanoes in the world. In late April 2018, the volcano started showing signs of increased activity. On May 3, 2018, the first crack, also known as a fissure, opened up followed by 19 more fissures, for a total of 20. The activity sparked widespread attention as images circulated of lava flows and destruction on the island.
Since then, news and information provided by the United States Geological Survey (USGS) and their Hawaii Volcano Observatory has escalated, and on May 15, 2018, the USGS alert level changed from “orange” to “red” indicating a “major volcanic eruption is imminent, underway, or suspected with hazardous activity both on the ground and in the air.”
Scientists collect a variety of critical information and data to better understand erupting volcanoes, including temperature measurements from handheld thermal imagers. They use the information to help make potentially lifesaving predictions. The United States has approximately 169 active volcanoes and there are about 1,500 worldwide.
Capturing Thermal Energy at Kilauea
Much of the monitoring activity performed by the USGS is gathered from instruments installed during inactive times, many of them temporary. However, when volcanic activity increases, so does the opportunity for the USGS and other interested organizations to gain hardcore information about how volcanoes act in real time.
USGS scientists collect data using an assortment of aerial (aircraft), orbiting (satellites) and handheld sensing instruments, such as thermal imaging cameras. Once the data is collected, it can be analyzed and used to predict future eruptions.
“There are many advantages to taking measurements using a handheld thermal camera,” said Steve Lundblad, Chair of the University of Hawaii at Hilo Geology Department. “USGS scientists must often have their wits about them when entering some of these potentially dangerous areas. With a portable thermal imager, data can be captured instantly and easily as events unfold in real-time. Using other methods to measure temperature might require the extra time to install and recover the equipment.”
An example would be thermal couplers, which must be physically placed in the ground and then removed once the measurements have been taken. A thermal IR imaging camera, however, offers a non-contact way to quickly measure temperatures.
“It’s worth it for the USGS to collect thermal infrared (IR) image measurements when possible,” said Lundblad. “Because of the length of time they’ve been capturing and analyzing data from other eruptive episodes, the USGS has been able to make accurate predictions about Kilauea’s movements and behaviors. Knowing what the volcano will do next has been very helpful in keeping citizens safe.”
Making sure surrounding communities stay safe and informed during volcanic eruptions is paramount to successfully managing the event. In addition to USGS operations and the observatory, critical groups such as the Hawaii Civil Defense provide crucial warnings and informational messages, including the possible need to evacuate. The USGS also strives to keep its scientists safe.
“A decision about whether to take measurements or not in certain areas is likely done on a case by case basis,” said Lundblad. “For instance, fissure No. 17 has been extremely active and spewing huge lava bombs, and therefore too dangerous to get very close to. However, valuable data can still be taken from other less volatile vents or fissures to help predict the possibility of a recurring episode.”
How do IR cameras work?
Unlike regular cameras, which capture visible light to create pictures, thermal cameras create images by detecting the amount of IR energy an object emits, such as the energy radiated from a lava flow. The thermal camera uses infrared-sensitive sensors to detect the IR energy and converts it into a thermal image. It also assigns colors to the differing temperatures to indicate variations, such as hot spots.
Measuring thermal energy from a distance
Thermal imaging devices mounted on aircraft and satellites also collect measurements for the USGS. Each method, whether up-close or from a distance, has an optimum time and place for use, depending on volcanic conditions.
As with field-based monitoring, where safely capturing thermal activity can sometimes be dangerous, capturing thermal images from a distance also has disadvantages because of its reliance on favorable weather and atmospheric conditions. For instance, fissure No. 20 is producing large amounts of ash plumes and therefore, obstructing camera visibility and causing unreliable measurements.
Trying to pinpoint the exact time of volcanic eruptions is still not possible, however, thermal imaging cameras greatly assist USGS scientists by capturing valuable data for current and historical reference. The more USGS scientists can understand how volcanoes behave during inactive and active times, the closer they can come to determining exactly when a volcano will erupt.
Source – FLUKE