Strong and shallow M6.6 earthquake hits South Shetland Islands
A strong and shallow earthquake registered by the USGS as M6.6 hit the South Shetland Islands at 00:22 UTC on March 20, 2026. The earthquake occurred at a depth of 4.9 km (3 miles). EMSC is reporting the same magnitude and depth.
Epicenter of the M6.6 earthquake in the South Shetland Islands at 00:22 UTC on March 20, 2026. Image credit: TW/SAM, USGS
The epicenter was located 977 km (607 miles) SE of Tolhuin (population 3 000), and 995 km (618 miles) SE of Ushuaia (population 56 825), Argentina
There is no tsunami threat from this earthquake, the PTWC said.
The USGS issued a Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage. Overall, the population in this region resides in structures that are resistant to earthquake shaking, though vulnerable structures exist.
The South Shetland Islands lie within a complex tectonic zone shaped by the Scotia and Antarctic plates, the South Shetland microplate, and active extension in the Bransfield Strait, an area characterized by frequent seismic activity and occasional moderate to strong offshore earthquakes.
Estimated population exposure to earthquake shaking
Regional seismicity
References:
1 M6.6 earthquake South Shetland Islands – USGS – March 20, 2026
2 M6.6 earthquake South Shetland Islands – EMSC – March 20, 2026
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
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