Photo and Video Chronology - Mauna Loa - February 18, 2020

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Interferogram shows range change at Mauna Loa and Kīlauea

Interferogram shows range change at Mauna Loa and Kīlauea


Color interferogram showing ground deformation

Data from the European Space Agency (ESA) Sentinel-1A and Sentinel-1B satellites on March 31, 2019, and January 31, 2020, produced this interferogram. Each fringe, or band of colors, represents 2.83 cm (1.1 inches) of range change—the distance between the satellite and the ground. Counting fringes gives the total range change between two satellite passes.

At point (A) the ground moved closer to the satellite by 7 cm (2.75 in) between the two passes due to inflation of the shallow magma chamber beneath Mauna Loa's summit. The angle at which the satellites viewed the ground shifted the signal slightly east of the summit. Fringes near point (B) at the summit of Kīlauea reflect inflation of the shallow Halema‘uma‘u magma chamber. This inflation has been observed since mid-March 2019, with a total range change of approximately 40 cm (15.7 in). Point (C) is on the middle East Rift Zone near Pu‘u ‘Ō‘ō. Interferograms and GPS data show that inflation has slowly shifted toward Pu‘u ‘Ō‘ō in recent months, during which the range change has been about 17 cm (6.7 in). Speckled areas with no visible fringes are covered by dense vegetation that prevents radar from reaching the ground. Atmospheric water vapor can also affect the radar and is responsible for the circular fringes around Mauna Kea and mottled or linear patterns elsewhere.

These signals show that magma is entering the shallow storage system. However these data, together with seismicity and SO2 emission rates do not suggest an imminent eruption. More info on how to read an interferogram is available in a 2019 Volcano Watch article (

(Public domain.)