2016 Solomon Islands earthquakes

On 9 December 2016 at 4:38 a.m. (UTC +11) local time (17:38:46 UTC), the Solomon Islands region was rocked by an Mww 7.8 earthquake, centered 30 km off San Cristobal Island, about 61 km southwest of Kirakira, the capital of Makira-Ulawa Province.[1] Initially registering magnitude 8.0, later downgraded to 7.8, the temblor prompted tsunami warnings that kept countries surrounding the Coral, Tasman and Solomon Sea on high alert, but was later cancelled. A large aftershock of magnitude 6.9 occurred shortly afterwards. This earthquake was largely felt, waking many residents who later ran to high ground for fears of a potential tsunami.[2] The earthquake killed a child and affected some 34,000 people in Makira, South Malaita and Guadalcanal Island where many had lost their homes or had no access to basic needs.[3] Earthquakes are common in this region, with little or no fatalities. This earthquake is tied with three other magnitude 7.8 earthquakes for the second largest earthquake of 2016.[4] On 17 December, the Solomon Islands would be rattled again by a 7.9 magnitude earthquake, this time 54 km east of Taron, Papua New Guinea.[5]

8 December 2016 Solomon Islands earthquake
M 7.8 - 69km WSW of Kirakira, Solomon Islands.jpg
UTC time2016-12-08 17:38:46
ISC event611831246
USGS-ANSSComCat
Local date9 December 2016
Local time04:38
Duration>1 minute
Magnitude7.8 Mww
Depth40.0 km
Epicenter10°40′52″S 161°19′37″E / 10.681°S 161.327°E / -10.681; 161.327Coordinates: 10°40′52″S 161°19′37″E / 10.681°S 161.327°E / -10.681; 161.327
FaultSan Cristobal-New Britain Trench
TypeOblique-reverse
Total damage1000+ buildings damaged or destroyed
Max. intensityVIII (Severe)
Tsunami0.43 meters
LandslidesYes
AftershocksMww 6.5
Mww 6.9
Casualties1 dead

Geological settingEdit

The Australian Woodlark, Solomon Sea and Pacific Plates are converging at a rate of 97 mm/yr.[6] The earthquake was a result of interaction between the Australian and Pacific Plates along a subduction zone. Subduction of the Australian Plate has also given rise to volcanoes in the region. This region of the world lies along the Pacific Ring of Fire, where 90 percent of all earthquake and volcanic activity is concentrated here.[7]

EarthquakeEdit

The earthquake occurred along the boundary interface where the Australian and Pacific Plates make contact. Focal mechanism suggests this event was a result of oblique-reverse faulting.[8] The earthquake did not rupture to the trench, terminating at a depth of 20 km, with its epicenter at 40 km. An average slip has been estimated at 5 meters.[9] The earthquake may also be a deep compressional intraslab event occurring on a fault located within the subducting plate; known as intraplate earthquakes because they happen in a plate rather than at the boundary of two.[10]

TsunamiEdit

The main earthquake triggered tsunami warnings directed at the Solomon Islands, Vanuatu, Papua New Guinea, Nauru, New Caledonia, Tuvalu and Kosrae in the Federated States of Micronesia, issued by the Pacific Tsunami Warning Center.[2] In New Caledonia, people were ordered to evacuate and leave for higher ground. Warnings for American Samoa and Hawaii were cancelled shortly after.[11] The International Tsunami Information Center warned of tsunamis between 1 to 3 meters. However, the highest waves were measured at only 0.43 meters (1.41 feet) on Marika Island.[12]

AftershocksEdit

A 6.5 magnitude earthquake struck about four hours after the initial quake, and later a 6.9 one day after the mainshock.[13][14] The 6.9 aftershock prompted new tsunami warnings with forecasted waves of 0.30 meters (0.98 feet).[15]

AftermathEdit

Phone and electricity lines were cut-off throughout the country in the immediate aftermath.[16] On Malaita Island, there were reports that between 35 and 40 buildings had been damaged.[17] In Guadalcanal, the collapse of a home killed one person.[18] In Kirakira, many homes, a hospital, a church, and the World Vision office sustained serious damage.[19] Damage at the hospital forced the evacuation of 20 people.[20] Two schools in Marika and Ugi were completely destroyed. Fissures and landslides were also seen in the affected region.[21] People who fled to higher ground continued to stay on the hills for fears of a large tsunami. Twenty-five houses were washed away from the moderate tsunami.[22] In total, over 1000 homes were damaged, along with 20 schools and four clinics.[23] More than 9,769 people were affected by the earthquake.[24]

International reactionEdit

Julie Bishop, the Australian foreign minister at the time said that the country is prepared to offer their support to the Solomon Islands.[25]

17 December earthquakeEdit

17 December 2016 Solomon Islands earthquake
 
 
UTC time2016-12-17 10:51:10
ISC event611831311
USGS-ANSSComCat
Local time20:51
Magnitude7.9 Mw
Depth94.5 km (58.7 mi)
Epicenter4°30′18″S 153°31′19″E / 4.505°S 153.522°E / -4.505; 153.522
TypeThrust
Max. intensityVII (Very strong)[26]
TsunamiYes
CasualtiesNone

On 17 December, the largest earthquake in the year 2016, a magnitude 7.9 earthquake struck Papua New Guinea.[5] It was centered between the islands of New Ireland and the Solomon Islands. The earthquake did not cause any major damage or casualties but did result in power outages.[27]

The earthquake had an intermediate depth of 94.5 km beneath the surface. The initial event was a result of thrust faulting within a subducting oceanic lithosphere which lasted for 30 seconds.[28] After the intraslab rupture, a deep portion of the subduction zone began to slip at a depth of 32 to 47 km, releasing energy comparable to the first event. The shallow megathrust rupture was evident in the large number of shallow aftershocks. Due to the two separate events occurring closely in timing and location, it was considered a doublet earthquake.[28]

See alsoEdit

ReferencesEdit

  1. ^ Thomson Reuters (9 December 2016). "Solomon Islands Earthquake Triggers Tsunami Alert In South Pacific". NDTV. Retrieved 1 December 2020.
  2. ^ a b "Magnitude 7.8 quake hits off Solomons". RNZ. 9 December 2016. Retrieved 1 December 2020.
  3. ^ Reid, Kathryn (21 August 2018). "Solomon Islands: Earthquakes, tsunamis, volcanoes, and floods". World Vision. Retrieved 1 December 2020.
  4. ^ Breslin, Sean (8 December 2016). "7.8 Earthquake Strikes Solomon Islands; Tsunami Watch Canceled for Hawaii". The Weather Channel. Retrieved 1 December 2020.
  5. ^ a b "M 7.9 - 54km E of Taron, Papua New Guinea". USGS-ANSS. USGS. Retrieved 21 March 2021.
  6. ^ Kaustubh Thirumalai, Frederick W. Taylor, Chuan-Chou Shen, Luc L. Lavier, Cliff Frohlich, Laura M. Wallace, Chung-Che Wu, Hailong Sun & Alison K. Papabatu (30 June 2015). "Variable Holocene deformation above a shallow subduction zone extremely close to the trench". Nature Communications. 6: 7607. Bibcode:2015NatCo...6.7607T. doi:10.1038/ncomms8607. S2CID 8275538.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Hanna, O'Sullivan, Jason, Donnie (8 December 2016). "Solomon Islands tsunami threat over after 7.8 quake". CNN. Retrieved 1 December 2020.
  8. ^ "M 7.8 – 69km WSW of Kirakira, Solomon Islands". US Geological Survey. Retrieved 1 December 2020.
  9. ^ "Solomon Islands Tsunami on Dec. 8, 2016". Retrieved 1 December 2020.
  10. ^ Lingling Ye; Thorne Lay; Hiroo Kanamori (2021). "The 25 March 2020 MW 7.5 Paramushir, northern Kuril Islands earthquake and major (MW ≥ 7.0) near-trench intraplate compressional faulting". Earth and Planetary Science Letters. 556 (116728). doi:10.1016/j.epsl.2020.116728.
  11. ^ "Large earthquake strikes off Solomon Islands". DW. 8 December 2016. Retrieved 1 December 2020.
  12. ^ "Tsunami Event Information SOLOMON ISLANDS". NOAA NCEI. Retrieved 1 December 2020.
  13. ^ "M 6.5 – 79km WSW of Kirakira, Solomon Islands". US Geological Survey. Retrieved 1 December 2020.
  14. ^ "M 6.9 – 92km WSW of Kirakira, Solomon Islands". US Geological Survey. Retrieved 1 December 2020.
  15. ^ "Solomon Islands recover from 7.8-magnitude quake amid continuing aftershocks". National Thailand. 10 December 2016. Retrieved 1 December 2020.
  16. ^ "Solomon Islands tsunami warning lifted after powerful 7.8 quake". BBC. 8 December 2016. Retrieved 1 December 2020.
  17. ^ "Damage assessment after M7.8 earthquake in Solomon Islands". The Watchers. 9 December 2016. Retrieved 1 December 2020.
  18. ^ "Solomon Islands: Earthquake – Dec 2016". Retrieved 1 December 2020.
  19. ^ "Significant Earthquake Information". NOAA NCEI. Retrieved 1 December 2020.
  20. ^ Perry, Nick (9 December 2016). "World Vision says hundreds affected by Solomon Islands quake". PhysOrg. Retrieved 2 December 2020.
  21. ^ Westbrook, Greenfield, Tom, Charlotte (9 December 2020). "Residents take to the hills as powerful quake hits Solomon Islands". Reuters. Retrieved 1 December 2020.
  22. ^ WESTBROOK, GREENFIELD, TOM, CHARLOTTE (9 December 2020). "Residents Take to the Hills as Powerful Quake Hits Solomon Islands". JakartaGlobe. Retrieved 2 December 2020.
  23. ^ "Six months on after Solomon Islands' 7.8 magnitude earthquake". World Vision. 1 June 2017. Retrieved 1 December 2020.
  24. ^ International Federation of Red Cross and Red Crescent Societies (24 December 2016). "Solomon Island: Earthquake Emergency Plan of Action (EPoA) DREF operation no MDRSB006". ReliefWeb. Retrieved 29 March 2022.
  25. ^ Hardy, Catherine (9 December 2016). "Australia "ready to help" quake-hit Solomons". euronews. Retrieved 1 December 2020.
  26. ^ "M 7.9 - 54km E of Taron, Papua New Guinea". earthquake.usgs.gov. Retrieved 15 December 2021.
  27. ^ "Papua New Guinea earthquake: Residents flee to hills after magnitude-7.9 quake, tsunami threat passes". ABC News. ABC.net.au. 17 December 2016. Retrieved 21 March 2021.
  28. ^ a b Lay, T., L. Ye, C. J. Ammon, and H. Kanamori (29 January 2017). ", Intraslab rupture triggering megathrust rupture coseismically in the 17 December 2016 Solomon Islands Mw 7.9 earthquake" (PDF). Geophysical Research Letters. 44: 1286–1292. doi:10.1002/2017GL072539. Retrieved 21 March 2021.{{cite journal}}: CS1 maint: multiple names: authors list (link)

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