(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

Top: Nicole Richter uses a mobile GPS instrument to measure ground deformation along the east rift zone while the Kamoamoa fissure erupts in the background. Bottom: InSAR data showing ground deformation associated with the Kamoamoa fissure eruption between January 19 and March 6, 2011. One color cycle indicates about 12 cm (5 in) of deformation. The color patterns indicate subsidence of Kilauea’s summit of about 7 cm (3 in) and uplift in the area of the fissure eruption of about 1 m (3 ft).

In early March, a new phase of Kilauea’s east rift zone eruption occurred as lava erupted in the Kamoamoa area, between Napau Crater and Pu`u `O`o. The eruption lasted for five days, ending at about 10:30 p.m. on Wednesday, March 10. After a pause of about 17 days, the east rift eruption resumed on March 26 when lava began to refill Pu`u `O`o.

During the Kamoamoa fissure eruption, HVO scientists looked at a variety of data types to understand what was happening at the eruption site. As alert Volcano Watch readers will know, ground deformation is one of the most important monitoring techniques used by HVO, because it can indicate the location of magma, as well as changes in the volume of magma, stored beneath the surface.

Deformation is typically detected by ground-based monitoring networks, like tiltmeters and Global Positioning System (GPS) instruments. Over the past decade, however, HVO has increasingly turned to satellite monitoring of ground deformation.

Interferometric Synthetic Aperture Radar, or InSAR, is a technique that uses two radar images, acquired from the same point in space of the same point on the ground at different times, to record how the ground moved between the two image acquisitions. The technique is extensively utilized by HVO to track surface displacements at Kilauea and at Mauna Loa.

Several radar satellites currently orbit the Earth and are operated by space agencies from various countries, like Italy, Japan, and Germany. During a volcanic crisis, the HVO staff is often too busy to contact these agencies and ensure that important radar data are acquired.

Thankfully, HVO has developed a strong collaboration with Dr. Paul Lundgren, an InSAR and ground deformation expert at the NASA Jet Propulsion laboratory in Pasadena, California. Upon learning of the Kamoamoa fissure eruption, Dr. Lundgren immediately contacted the Italian and Japanese Space Agencies to make sure radar data were acquired over Kilauea. By Monday, March 7—only two days after the start of the eruption—InSAR data showing how the ground moved in the immediate vicinity of the fissure were processed by Dr. Lundgren and sent to HVO for analysis.

These InSAR results indicate that, in the first two days of the eruption, the east rift zone was pushed apart by over 1.5 m (5 ft)—a measurement that agrees with the total width of new ground fractures near the eruption site, as measured on March 6. A few days later, additional InSAR data indicated that the fissure had widened by as much as 3 m (10 ft). Measurements along the fractures on March 9 confirmed this finding.

In addition to collaborating with Dr. Lundgren, HVO’s eruption response benefitted from the work of Nicole Richter, a student from the University of Jena, in Germany, who has been working at HVO since September 2010. Nicole’s research at HVO provided the Observatory with new tools for processing InSAR data at very high resolution, and her efforts earned her a Master of Science degree in early March. During the Kamoamoa fissure eruption, Nicole’s InSAR data showed details of surface motion on the east rift zone that would not otherwise have been detected.

InSAR results from the Kamoamoa fissure eruption demonstrate once again the value of satellite measurements in volcano monitoring. In addition, the results highlight the importance of scientific collaboration. During a volcanic crisis, the small staff of HVO is quickly consumed by monitoring responsibilities. Collaborating with top-notch scientists, like Lundgren and Richter, helps to ensure comprehensive volcano surveillance that utilizes the most advanced techniques and data currently available.

HVO is grateful to Dr. Lundgren for his work in making sure that InSAR data were acquired and quickly processed, and we look forward to future collaborations. In addition, HVO thanks Nicole Richter, who departed HVO last week after working at the Observatory for seven months. We wish her a fond aloha and “gute reise!”