2013 Seddon earthquake

For the earthquake of 16 August 2013, see 2013 Lake Grassmere earthquake.
2013 Seddon earthquake
Date 21 July 2013 (2013-07-21)
Origin time 5:09:30 pm NZST
Magnitude 6.5 Mw
Depth 13 kilometres (8 mi)
Epicenter 41°37′S 174°20′E / 41.61°S 174.33°E / -41.61; 174.33Coordinates: 41°37′S 174°20′E / 41.61°S 174.33°E / -41.61; 174.33
Areas affected New Zealand
Tsunami None
Casualties 4 people injured[1]

The 2013 Seddon earthquake measured 6.5 on the moment magnitude scale and was centred in New Zealand's Cook Strait, around 20 kilometres (12 mi) east of the town of Seddon in Marlborough. The earthquake struck at 5:09:30 pm on 21 July 2013 (05:09 UTC) at a depth of 13 kilometres (8 mi), according to Geonet.[2] The United States Geological Survey also measured the quake at 6.5, at a depth of 17 kilometres (11 mi).[3] The quake caused moderate damage in the wider Marlborough area and Wellington, the nation's capital city 55 kilometres (34 mi) north of the epicentre. Only minor injuries were reported. Several aftershocks occurred during 21–29 July.

The Seddon earthquake is considered the first of an earthquake doublet, with a second earthquake of similar magnitude occurred on 16 August 2013.

Earthquake

USGS Shakemap[4]

Foreshocks

The earthquake was preceded by a series of foreshocks, the largest of which had a magnitude of 5.7.

Below is a list of all foreshocks magnitudes 5.0 and above that occurred in the region between 19 July 2013 and 21 July 2013.

Date (NZST) Time (NZST) Magnitude (MW) Magnitude (Mb) Magnitude (ML) Epicentre Depth
19 July 2013 9:06:39 am 5.5[5] 5.7[5] 5.7[6] 30 km east of Seddon 17 km
21 July 2013 7:17:10 am 5.9[7] 5.8[7] 5.8[8] 30 km east of Seddon 20 km

Aftershocks

The earthquake generated a series of aftershocks, the largest of which had a magnitude of 5.4.

Below is a list of all aftershocks magnitudes 5.0 and above that occurred in the region between 21 July 2013 and 2 August 2013.

Date (NZST) Time (NZST) Magnitude (MW) Magnitude (Mb) Magnitude (ML) Epicentre Depth
21 July 2013 5:09:30 pm 6.5[9] 6.1[9] 6.5[10] 25 km east of Seddon 13 km
21 July 2013 5:13:50 pm 5.3[11] 5.2[12] 30 km east of Seddon 13 km
29 July 2013 1:07:14 am 4.9[13] 5.4[14] 20 km east of Seddon 12 km
2 August 2013 12:56:13 am 4.7[15] 5.2[16] 20 km east of Seddon 6 km

Damage

The quake resulted in varying degrees of damage to thirty-five buildings within the Wellington CBD with glass from broken windows falling onto the main thoroughfare of Lambton Quay. Damage was also caused in Paraparaumu, Wainuiomata, Porirua and the Hutt Valley in the North Island.[17][18]

The Wellington Region emergency management office was activated on the evening of 21 July, as were those in the lower part of the North Island.[17] On 22 July parts of Wellington's central business district were closed to the public to allow for inspections to buildings with damaged and potentially dangerous façades.[19]

Four people were injured in the quake, which lasted for 20 seconds, blowing out windows, cracking concrete and swaying buildings.[1]

See also

References

  1. 1 2 "Wellington earthquake: We can afford new quake damage - PM". The New Zealand Herald. 22 July 2013. Retrieved 22 July 2013.
  2. ↑ "Quakes". GeoNet. Retrieved 21 July 2013.
  3. ↑ "M6.5 - 46km ESE of Blenheim, New Zealand". USGS. Retrieved 21 July 2013.
  4. ↑ "M6.5 - 46km ESE of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  5. 1 2 "M5.5 - 34km E of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  6. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  7. 1 2 "M5.9 - 35km ESE of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  8. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  9. 1 2 "M6.5 - 46km ESE of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  10. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  11. ↑ "M5.3 - Cook Strait, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  12. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  13. ↑ "M4.9 - 34km SE of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  14. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  15. ↑ "M4.7 - 39km SE of Blenheim, New Zealand". earthquake.usgs.gov. Retrieved 2015-12-11.
  16. ↑ "GeoNet - Quakes". www.geonet.org.nz. Retrieved 2015-12-11.
  17. 1 2 "Severe quake rocks North and South Island". The New Zealand Herald. 21 July 2013. Retrieved 22 July 2013.
  18. ↑ Quilliam, Rebecca (22 July 2013). "Wellington earthquake: 35 buildings damaged in CBD". www.nzherald.co.nz. Retrieved 23 July 2013.
  19. ↑ "Wellington earthquake: What you need to know". The New Zealand Herald. 22 July 2013. Retrieved 22 July 2013.

External links

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