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M6.6 earthquake, South Sandwich Islands, 1991-12-28

MagnitudeM6.6mw

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Depth10 km

Time (UTC)1991-12-28 00:52

Rank in 199138 / 137among M6+

Rank since 19003542 / 14,458

Energy vs an M6×8approx.

South Sandwich Islands region · -56.10, -24.61

M6.5+ within 300 km (largest first)

2021 M8.1M8.1

1964 M7.8M7.8

2021 M7.5M7.5

1991 M7.2M7.2

2016 M7.2M7.2

1961 M7.1M7.1

2018 M7.1M7.1

2008 M7.0M7.0

1930 M6.9M6.9

1921 M6.9M6.9

2004 M6.9M6.9

2014 M6.9M6.9

Earlier M6+ within 300 km

Event	Time (UTC)	Depth	Place
M7.2 1991-12-27	1991-12-27 04:05	10 km	South Sandwich Islands region
M6.6 1991-06-15	1991-06-15 01:13	52 km	South Sandwich Islands region
M6.0 1990-05-09	1990-05-09 04:21	33 km	South Sandwich Islands region
M6.3 1988-11-01	1988-11-01 22:31	33 km	South Sandwich Islands region
M6.2 1988-05-01	1988-05-01 23:06	138 km	South Sandwich Islands region
M6.3 1988-04-17	1988-04-17 05:11	33 km	South Sandwich Islands region
M6.0 1987-07-09	1987-07-09 07:27	33 km	South Sandwich Islands region
M6.2 1987-02-23	1987-02-23 02:43	27 km	South Sandwich Islands region
M6.4 1986-04-14	1986-04-14 14:52	11 km	South Sandwich Islands region
M6.5 1985-05-15	1985-05-15 20:12	33 km	South Sandwich Islands region

Energy ratio uses the rule that one magnitude unit is about 32 times the energy. Magnitudes and locations are USGS values and can differ from national agencies. Older records are less complete and less precise.