The NASA-ISRO Synthetic Aperture Radar mission, known as NISAR, repeatedly observed Krasheninnikov, a pair of volcanoes on the Pacific coast of the remote peninsula, as lava spread from its northern crater, according to a Sept. 24 release from JPL.
An 8.8-magnitude earthquake struck in the nearby ocean on July 30, 2025, apparently jolting one of the volcanoes awake. A few days later, Krasheninnikov began erupting for the first time in nearly five centuries, according to JPL. Since then, the northern volcano has released a steady, eastward-flowing field of molten rock and debris.
NISAR captured an image of the volcano on Dec. 25, 2025, as the Earth-observing satellite was completing post-launch checks and becoming operational.
From about 464 miles, or 747 kilometers, above the surface, NISAR has since returned to the same spot in orbit twice every 12 days — once while traveling from south to north and again while traveling from north to south — taking detailed radar images of changes to the landscape.
Researchers assembled 17 frames collected through mid-August into a time-lapse sequence showing lava filling a smaller inner caldera, overflowing into a wider crater and then spreading into a fan.
The animation highlights how NISAR observations can monitor developing natural hazards for scientific research and potentially for emergency response, JPL said.
Although many of Kamchatka’s dozens of volcanoes are closely monitored using ground instruments because they erupt frequently, Krasheninnikov had remained quiet since about 1550.
That NISAR’s L-band radar was able to observe the remote volcano reflects the satellite’s near-global coverage of the planet’s land surface at resolutions measured in the dozens of feet. Its ability to repeatedly capture the eruption over time also demonstrates the precision and reliability of its measurements, according to JPL.
“The consistency is crucial,” Matthew Pritchard, a Cornell University geophysicist and member of the NISAR science team who analyzed data used in the animation, said in the JPL release. “Twice every 12 days, acquiring in this high-resolution mode and in two observation directions, this shows the promise of NISAR to closely monitor natural hazards.”
The satellite relies on synthetic aperture radar, or SAR, a specialized processing technique pioneered by JPL for Earth observation from space.
As NISAR travels in orbit, its radar sends thousands of microwave pulses toward Earth each second and receives the return signals. Each return is effectively a snapshot in time containing information about the properties and characteristics of the surface below.
SAR processing combines the many images of the same area to sharpen the resulting view, much as a lens brings a blurry object into focus.
In the Krasheninnikov time-lapse, each pixel represents an area about 30 feet by 30 feet, or 10 meters by 10 meters, on the surface — roughly half the size of a tennis court.
The lava appears brighter than surrounding terrain in the radar images because microwaves reflect more brightly from it than from the surrounding surface, which can be covered by snow or consist of bare ground depending on the season.
The sequence also shows another lava flow extending northwest that likely formed before NISAR captured its first image of the volcano.
Pritchard said that when he conducted doctoral research on Kamchatka volcanoes more than 20 years ago, analysis-ready radar data was difficult to obtain because satellites did not revisit locations as frequently and the resolution of the images was relatively low.
NISAR now provides frequent and comprehensive coverage of virtually all of the planet’s roughly 1,300 active, above-sea-level volcanoes. Its images are sharp down to the several-meter scale and are easily accessible through the cloud, according to JPL.
“We’re seeing volcanoes around the world that we’ve never really had eyes on like this before,” Pritchard said.
NISAR is the first free-flying space mission to feature two radar instruments, an L-band system and an S-band system. The systems complement each other because they operate at different wavelengths.
The longer-wavelength L-band radar can pass through tree canopies to image the ground beneath, while the S-band radar can collect observations of those canopies depending on leaf size.
Data products from NISAR’s L-band radar are available through the Alaska Satellite Facility Distributed Active Archive Center in Fairbanks, Alaska, which hosts and distributes all NASA synthetic aperture radar data.
JPL, which is managed for NASA by Caltech, leads the U.S. component of the NISAR project and provided the satellite’s L-band synthetic aperture radar and antenna reflector. The Indian Space Research Organisation, or ISRO, provided the spacecraft bus and its S-band synthetic aperture radar.
NISAR is the first satellite to carry two synthetic aperture radar instruments operating at different wavelengths. The spacecraft collects data using its drum-shaped reflector, which measures 39 feet, or 12 meters, across and is the largest radar antenna reflector NASA has sent into space.
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