Very Strong Mag. 6.8 Earthquake - New Zealand on Friday, Mar 5, 2021, at 05:41 am (GMT +12) -

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Very strong mag. 6.8 earthquake - New Zealand on Thursday, 4 March 2021 at 17:41 (GMT) - information

This quake was likely a foreshock of the 8.1 quake Kermadec Islands, New Zealand, Mar 5, 2021 07:28 am (GMT +12), which followed after 1 hour and 47 minutes.

A very strong magnitude 6.8 earthquake occurred in the South Pacific Ocean near the coast of New Zealand in the early morning of Friday, Mar 5, 2021 at 5.41 am local time (GMT +12). The quake had a very shallow depth of 33 km (21 mi) and was reported felt by some people near the epicenter.

Quake Data | Interactive map | Seismograms | User reports | Earlier quakes here

Very strong mag. 6.8 Earthquake - New Zealand on Friday, Mar 5, 2021, at 05:41 am (GMT +12)

Very strong magnitude 6.8 earthquake at 33 km depth

4 Mar 17:49 UTC: First to report: GEONET (NZ) after 8 minutes.
4 Mar 17:52: Magnitude recalculated from 6.7 to 6.8.

Earthquake details

Date & time	Mar 4, 2021 17:41:23 UTC
Local time at epicenter	Friday, Mar 5, 2021, at 05:41 am (GMT +12)
Status	Preliminary (automatic detection)
Magnitude	6.8
Depth	33 km
Epicenter latitude / longitude	29.5508°S / 177.4271°W South Pacific Ocean, New Zealand
Seismic antipode	29.5508°N / 2.5729°E Algeria
Shaking intensity	VI Strong shaking near epicenter
Felt	3 reports
Primary data source	GEONET (NZ) (Earthquake Commission and Geological Survey, New Zealand)
Nearest volcano	Raoul Island (57 km / 35 mi)
Weather at epicenter at time of quake	Overcast Clouds 23.1°C (74 F), humidity: 84%, wind: 7 m/s (14 kts) from NE
Estimated seismic energy released	1 x 10¹⁵ joules (278 gigawatt hours, equivalent to 2.4 x 10⁵ tons of TNT or 14.9 atomic bombs!) \| about seismic energy

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Additional info

Reference #1053:

Tectonic Summary
The March 4, 2021 M 7.4 earthquake near Kermadec Islands, New Zealand occurred as the result of reverse faulting in the Tonga-Kermadec subduction zone, which extends north-northeast from the North Island of New Zealand for more than 2,500 km through Tonga to within 100 km of Samoa. Focal mechanism solutions for the event indicate rupture occurred as reverse faulting on a moderately dipping plane striking either SSW or NNE.
At the location of the earthquake, the Pacific plate moves westward relative to the Australia plate at a velocity of about 60 mm/yr, subducting to the west beneath the Australia plate at the Tonga and Kermadec Trenches. The eastern edge of the Australia plate may itself be viewed as a collection of microplates whose relative motions help to accommodate the overall Pacific-Australia convergence and associated back-arc spreading. The location and focal mechanism solutions of the earthquake are consistent with it occurring on or near the westward-dipping interface between the subducting Pacific plate and the overriding Australia plate (in detail, the overriding Kermadec microplate).
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Reverse events of the size of the March 4 earthquake are typically about 70 km long x 35 km wide (fault length x fault width).
The interaction between the Pacific and Australia plates creates one of the most seismically active tectonic environments in the world. Since 1976, a 200-km-long section of the Tonga-Kermadec subduction zone, which includes the epicenter of the March 4th earthquake, has produced more than 50 earthquakes of M 6 or larger. The largest event was a M 8 earthquake in January 1976, more than 100 km to the north, with no associated casualties or damage. The March 4, 2021 M7.4 earthquake occurred ~4 hours after and ~900 km north of a M 7.3 earthquake on March 4 in the same subduction zone. While the two earthquakes occurred in relatively close temporal and spatial proximity to each other, the ~900 km distance between them likely indicates that static stress changes induced by the earlier earthquake did not directly cause the M 7.4 earthquake.

Cited references

#1053 National Earthquake Information Center (NEIC) (1971 to 2013):
Preliminary Determination of Epicenters (PDE), a weekly and monthly publication, National Earthquake Information Center, U.S. Geological Survey, Golden, Colorado, 1971 to 2013.

Source: NOAA National Centers for Environmental Information (NCEI), Global Significant Earthquake Database. doi:10.7289/V5TD9V7K

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User-reports for this quake (5)

We received 5 reports for this quake.

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.

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Massey, West Auckland / Light shaking (MMI IV) : Was woken from dreaming. Was instantly clear it was a substantial earthquake but | 10 users found this interesting.

West Harbour, Auckland / Weak shaking (MMI III) / 5-10 s : Lying in bed I woke and then felt the earthquake. I could hear the bolts in my wall door rattle and my bed was moving. | 8 users found this interesting.

North Shore, Auckland / not felt : I’m not sure if I felt it, was waken at 03:45 and 06:45 when the quake happened! | One user found this interesting.

CUAUTLA / Violent shaking (MMI IX)

Auckland / not felt

What is Intensity and the Mercalli Intensity Scale?

The amount of shaking that occurs on the surface due to an earthquake is called the intensity. It is commonly measured on the so-called Modified Mercalli Intensity Scale (MMI) ranging from 1 (not felt) to 10 (extreme shaking), and given in Roman numerals as I,II,...IX, X, and often displayed with color codes ranging from light blue to dark red.
Earthquake intensity depends mainly on the magnitude and depth of the quake as well as the distance from the epicenter: The further away, the less shaking intensity occurs.
Read more about the MMI scale!

Compare Quake Data

Data for the same earthquake as reported by different agencies

The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.

Mag	Depth	Time GMT 2021-03-4	Epicenter	Agency
6.8	33 km 21 mi	17:41:23	New Zealand	GEONET (NZ) (Earthquake Commission and Geological Survey, New Zealand)
7.4	43 km 27 mi	17:41:23	Kermadec Islands, New Zealand 42 km (26 mi) epicenter difference with GEONET (NZ)	USGS (United States Geological Survey)
7.4	42 km 26 mi	17:41:24	Kermadec Islands, New Zealand 46 km (29 mi) epicenter difference with GEONET (NZ)	GFZ (German Research Centre for Geosciences)
7.3	56 km 35 mi	17:41:24	Kermadec Islands, New Zealand 26 km (16 mi) epicenter difference with GEONET (NZ)	GeoAu (Geoscience Australia )
7.4	49 km 30 mi	17:41:25	KERMADEC ISLANDS, NEW ZEALAND 36 km (23 mi) epicenter difference with GEONET (NZ)	EMSC (European-Mediterranean Seismological Centre)
7.3	42 km 26 mi	17:41:24	Kermadec Islands, New Zealand 46 km (29 mi) epicenter difference with GEONET (NZ)	BMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
7.5	20 km 12 mi	17:41:22	Kermadec Islands, New Zealand [Sea: New Zealand] 13 km (8.2 mi) epicenter difference with GEONET (NZ)	INGV (Istituto Nazionale di Geofisica e Vulcanologia)

Seismograms

Seismic station: Raoul, Kermadec Islands (RAO/IU network) | Distance from quake: 59 km / 37 mi | Show on map | Station Info

Seismic station Raoul, Kermadec Islands: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.1-10.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

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Seismic station Raoul, Kermadec Islands: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Raoul, Kermadec Islands: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake, showing horizontal E-W and N-S ground movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Monasavu, Fiji (MSVF/II network) | Distance from quake: 1391 km / 864 mi | Show on map | Station Info

Seismic station Monasavu, Fiji: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-5.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Monasavu, Fiji: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Monasavu, Fiji: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Afiamalu, Samoa (AFI/IU network) | Distance from quake: 1834 km / 1139 mi | Show on map | Station Info

Seismic station Afiamalu, Samoa: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Afiamalu, Samoa: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Afiamalu, Samoa: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Funafuti, Tuvalu (FUNA/IU network) | Distance from quake: 2364 km / 1469 mi | Show on map | Station Info

Seismic station Funafuti, Tuvalu: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Funafuti, Tuvalu: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Funafuti, Tuvalu: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Honiara, Solomon Islands (HNR/IU network) | Distance from quake: 3246 km / 2017 mi | Show on map | Station Info

Seismic station Honiara, Solomon Islands: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Honiara, Solomon Islands: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Honiara, Solomon Islands: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Previous quakes in the same area of this earthquake

Strongest in 1 year 38 weeks

The earthquake was the strongest to hit this part of New Zealand in over 1 year 38 weeks. Earlier, the last quake of equal or greater strength near the present epicenter had been a magnitude 7.3 earthquake on Sunday, Jun 16, 2019, at 10:55 am (GMT +12 local time) in 138 km (86 mi) distance to the southwest:

Mag. 7.3 earthquake Kermadec Islands - New Zealand - Jun 16, 2019 -

The strongest-ever (since 1900) recorded quake in this area measured magnitude 8.2. It had occurred 107 years ago earlier, on Tuesday, May 1, 1917, at 06:26 pm local time (Universal Time GMT +0) in South Pacific Ocean,

New Zealand:

Mag. 8.2 earthquake Kermadec Islands region - May 1, 1917 -

Below is a list and map of (larger or recent) quakes that had occurred near the area of the epicenter before this earthquake (within up to 100 km/61 mi distance, up to 300 km/183 mi for very large quakes above mag. 7). Filter the list to limit the number to show, by magnitude or time before.

Date and Time	Mag Depth	Distance	Location	Details
Mar 1, 2021 01:25 am (GMT +12)	5.2 12 km	97 km (60 mi) to the S	New Zealand	Info
Feb 26, 2021 01:20 am (GMT +12)	4.6 33 km	41 km (25 mi) to the E	New Zealand	Info
Feb 13, 2021 06:15 pm (GMT +12)	4.3 33 km	85 km (53 mi) to the N	New Zealand	Info
Feb 10, 2021 10:22 pm (GMT +12)	4.3 336 km	99 km (62 mi) to the NE	New Zealand	Info
Feb 3, 2021 09:21 am (Auckland)	4.1 228 km	33 km (21 mi) to the NW	New Zealand	Info
Dec 18, 2019 01:56 pm (GMT +12)	5.9 33 km	35 km (22 mi) to the SE	New Zealand 3 reports	Info
Sep 28, 2019 12:04 am (GMT +12)	6.2 33 km	85 km (53 mi) to the S	New Zealand 1 report	Info
Jun 16, 2019 10:55 am (GMT +12)	7.3 46 km	138 km (86 mi) to the SW	Kermadec Islands, New Zealand 10 reports	Info
Jun 6, 2016 02:35 pm (GMT +12)	5.9 10 km	71 km (44 mi) to the SW	Kermadec Islands, New Zealand	Info
Jun 24, 2014 08:06 am (GMT +12)	6.6 40 km	53 km (33 mi) to the S	Kermadec Islands, New Zealand	Info
Jun 24, 2014 08:06 am (GMT +12)	6.3 30 km	83 km (52 mi) to the SE		Info
Jun 24, 2014 07:21 am (GMT +12)	6.6 33 km	67 km (42 mi) to the S		Info
Jun 24, 2014 07:21 am (GMT +12)	6.5 10 km	98 km (61 mi) to the SE	Kermadec Islands Region	Info
Jun 24, 2014 07:19 am (GMT +12)	6.8 41 km	69 km (43 mi) to the SW	Kermadec Islands, New Zealand	Info
Jun 24, 2014 07:19 am (GMT +12)	6.4 30 km	86 km (54 mi) to the SE		Info
Oct 22, 2011 05:57 am (GMT +12)	7.4 33 km	131 km (81 mi) to the NE	Kermadec Islands region	Info
Jul 10, 2011 07:35 am (GMT +12)	6.0 15 km	43 km (26 mi) to the E	Kermadec Islands, New Zealand	Info
Jul 10, 2011 03:02 am (GMT +12)	6.0 14 km	44 km (27 mi) to the NE	Kermadec Islands, New Zealand	Info
Jul 7, 2011 07:03 am (GMT +12)	7.6 17 km	105 km (65 mi) to the E	Kermadec Islands region	Info
Feb 19, 2009 09:53 am (GMT +12)	7.0 25 km	260 km (161 mi) to the NE	Kermadec Islands region	Info
Sep 30, 2008 03:19 am (GMT +12)	7.0 36 km	34 km (21 mi) to the SW	Kermadec Islands, New Zealand	Info
Jun 3, 2001 02:41 pm (GMT +12)	7.2 178 km	117 km (73 mi) to the W	Kermadec Islands, New Zealand	Info
Sep 21, 1997 04:11 am (GMT +12)	7.0 30 km	98 km (61 mi) to the N	Kermadec Islands region	Info
Jul 4, 1995 07:50 am (GMT +12)	7.2 35 km	41 km (25 mi) to the NW	Kermadec Islands, New Zealand	Info
Oct 24, 1992 08:23 pm (GMT +12)	6.6 19 km	14 km (9 mi) to the E	Kermadec Islands, New Zealand	Info
May 14, 1989 12:59 pm (Auckland)	7.0 44 km	144 km (89 mi) to the SW	Kermadec Islands, New Zealand	Info
Feb 25, 1989 11:26 pm (GMT +12)	6.8 31 km	60 km (37 mi) to the SW	Kermadec Islands, New Zealand	Info
Oct 20, 1986 06:46 pm (GMT +12)	7.7 29 km	190 km (118 mi) to the NE	Kermadec Islands region	Info
Jan 27, 1983 04:02 am (GMT +12)	7.0 238 km	206 km (128 mi) to the SW	South Pacific Ocean, 184 km southwest of Raoul Island, New Zealand	Info
Dec 27, 1981 05:05 am (GMT +12)	7.1 33 km	52 km (32 mi) to the SW	Kermadec Islands, New Zealand	Info
Dec 24, 1981 05:33 pm (GMT +12)	6.8 28 km	50 km (31 mi) to the S	Kermadec Islands, New Zealand	Info
Feb 10, 1978 09:35 am (GMT +12)	7.2 33 km	126 km (78 mi) to the S	Kermadec Islands, New Zealand	Info
May 5, 1976 04:52 pm (GMT +12)	6.8 35 km	58 km (36 mi) to the SW	Kermadec Islands, New Zealand	Info
Mar 24, 1976 04:46 pm (GMT +12)	6.8 33 km	57 km (35 mi) to the SW	Kermadec Islands, New Zealand	Info
Jan 15, 1976 04:47 am (GMT +12)	8.0 33 km	127 km (79 mi) to the N	Kermadec Islands region	Info
Jul 3, 1974 11:26 am (GMT +12)	7.2 33 km	152 km (94 mi) to the E	Kermadec Islands region	Info
Sep 27, 1968 06:02 am (GMT +12)	7.1 50 km	128 km (79 mi) to the S	Kermadec Islands, New Zealand	Info
Jul 25, 1968 07:23 pm (GMT +12)	7.3 45 km	151 km (94 mi) to the SW	Kermadec Islands, New Zealand	Info
May 20, 1968 07:13 pm (GMT +12)	7.0 55 km	154 km (95 mi) to the SW	Kermadec Islands, New Zealand	Info
Jul 30, 1963 05:45 pm (GMT +12)	6.5 25 km	45 km (28 mi) to the SE	South Pacific Ocean, 102 km southeast of Raoul Island, New Zealand	Info
Jul 30, 1963 08:16 am (GMT +12)	6.6 25 km	75 km (47 mi) to the SE	Kermadec Islands region	Info
Mar 31, 1963 05:30 pm (GMT +12)	6.6 35 km	52 km (32 mi) to the S	Kermadec Islands, New Zealand	Info
Mar 26, 1963 09:48 pm (GMT +12)	7.3 10 km	55 km (34 mi) to the SW	Kermadec Islands, New Zealand	Info
Mar 7, 1961 10:10 pm (GMT +12)	7.0 30 km	196 km (122 mi) to the NE	Kermadec Islands region	Info
Sep 15, 1959 02:09 am (GMT +12)	7.3 35 km	82 km (51 mi) to the N	Kermadec Islands region	Info
Feb 28, 1955 08:43 am (GMT +12)	7.5 15 km	223 km (139 mi) to the NE	Kermadec Islands region	Info
Feb 20, 1954 07:07 am (GMT +12)	6.6 25 km	78 km (48 mi) to the S	Kermadec Islands, New Zealand	Info
Sep 14, 1943 07:18 am (Universal Time)	7.0 35 km	72 km (45 mi) to the SW	Kermadec Islands, New Zealand	Info
Sep 16, 1941 09:39 pm (Universal Time)	7.1 70 km	64 km (39 mi) to the NW	Kermadec Islands, New Zealand	Info
Aug 2, 1941 11:41 am (Universal Time)	7.2 35 km	30 km (19 mi) to the SW	Kermadec Islands, New Zealand	Info
Apr 17, 1919 11:22 am (Universal Time)	7.2 35 km	127 km (79 mi) to the SW	Kermadec Islands, New Zealand	Info
Nov 16, 1917 03:19 pm (GMT +12)	7.5 0 km	62 km (38 mi) to the N	New Zealand: Kermadec Islands: S of	Info
Jun 13, 1917 06:41 pm (Auckland)	7.0 35 km	40 km (25 mi) to the NW	Kermadec Islands, New Zealand	Info
May 1, 1917 06:26 pm (Universal Time)	8.2 15 km	197 km (123 mi) to the S	Kermadec Islands region	Info
Jun 29, 1910 10:45 am (Universal Time)	7.1 35 km	154 km (96 mi) to the S	Kermadec Islands, New Zealand	Info

Map of earlier quakes in the area of this quake

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