On Dec. 21, 2021, the Hunga Tonga-Hunga Ha'apai undersea volcano in Tonga erupted with explosive force, sending a shockwave that went around the world several times.
There's currently another eruption happening in the Pacific nation, which comprises around 170 islands, but it's a much calmer situation. The underwater Home Reef seamount has risen above the surface of the ocean thanks to a small eruption that began on Sept. 10, and the infant island that it formed has been captured by the powerful Landsat 9 satellite, a joint project between NASA and the U.S. Geological Survey (USGS) that launched to Earth orbit last year.
The volcano emerged from the sea just 11 hours after the eruption began, with lava and ash creating a small island. Four days later, the land area of the small island was about 1 acre (0.4 hectares). By Sept. 20, it reached 6 acres (2.4 hectares).
Landsat 9 snapped its photo on Sept. 14, when the island was 1 acre in size. The shot shows discolored water agitated by the eruption, as well as a large white plume. "Previous research suggests that these plumes of superheated, acidic seawater contain particulate matter, volcanic rock fragments and sulfur," according to a NASA statement.
Overall, the eruption is rather minor compared to last year's Hunga Tonga-Hunga Ha'apai blast. Current advisories from the Tongan government suggest that mariners stay at least 2.5 miles (4 kilometers) away and note that the steam and ash plumes pose low risk to aircraft.