 | This article documents a current event. Information may change rapidly as the event progresses, and initial news reports may be unreliable. The latest updates to this article may not reflect the most current information. (July 2024) |
| UTC time | 2024-07-08 11:42:22 |
|---|---|
| Local date | 8 July 2024 |
| Local time | 21:42 PGT |
| Magnitude | 7.7 Ms 7.7 Mw |
| Depth | 14.2 km (9 mi) |
| Epicenter | 3°51′36″S 145°03′18″E / 3.860°S 145.055°E |
| Areas affected | New Guinea Prefecture, Papua |
| Max. intensity | MMI VIII (Severe) |
| Tsunami | 16.7 m (55 ft) |
| Casualties | 1,556 fatalities, 241 missing |
On 7 October 2023, at 21:42:22 PGT (11:42 UTC), an earthquake of Ms 7.7 struck 17 km (11 mi) northeast of Boisa Island, located in Bogia District Madang Province, Papua.[1][2] The thrust-faulting earthquake occurred with a hypocenter depth of 14.2 km (8.8 mi), rupturing the Manam fault.[3] It is the largest earthquake of 2024, surpassing the 2024 Noto earthquake.[4]
The earthquake caused severe damage in Bogia District, but most of the damage was caused by the subsequent tsunami.[5] High waves struck the small islands of Manam and Boisa, killing 1,556 people and leaving 241 others missing.[6]
Tectonic setting
editThe primary tectonic feature of the 1,200 km (750 mi) island chain is the New Hebrides Subduction Zone, the convergent boundary of the Indo-Australian and Pacific Plates. Along the Wadati–Benioff zone, earthquake activity has been observed as shallow, intermediate, and deep-focus events at depths of up to 700 km (430 mi). Volcanic activity is also present along this north-northwest trending and northeast-dipping oceanic trench.[7]
While much of the island arc experiences intermediate-depth earthquakes along a Wadati–Benioff zone that dips steeply at 70°, the area adjacent to the d'Entrecasteaux Ridge does not. There is a corresponding gap in seismicity that occurs below 50 km (31 mi) where it intrudes into the subduction zone from the west. According to the NUVEL-1 global relative plate motion model, convergence is occurring at roughly 8 cm (3.1 in) per year. The uncertainty, which also affects the Tonga arc, is due to the influence of spreading at the North Fiji Basin.[8]
Earthquake
editThe USGS reported a magnitude of Mww 7.7; it was initially reported as Mi 7.2, before being upgraded to 7.5, and then 7.7.[9] It occurred at a depth of 14.2 km (8.8 mi).[10] The PGA put the earthquake's magnitude at Ms 7.7.[11]
Intensity
edit| Intensity | Province | Location | Pop. exposure |
|---|---|---|---|
| VIII | Madang | Boisa, Manam | 83k |
| East Sepik | Biem | ||
| VII | Madang | Bogia, Yawar | 2,589k |
| East Sepik | Blupblup | ||
| VI | Madang | Almami, Josephstaal, Sumgilbar, Karkar, Bagabag | 7,552k |
| East Sepik | Marienberg, Angoram | ||
| V | Madang | Madang, Ramu, Bundi, Astrolabe Bay | 25,689k |
| East Sepik | Wewak, Keram, Maprik, Yangoru, Kairiru |
Tsunami
editA tsunami warning was issued for Madang and East Sepik Provinces, saying that waves up to 4 m (13 ft) could hit the coast.[12] The warning was cancelled at 22:56 PGT.[13] The Pacific Tsunami Warning Center issued a local tsunami watch but said a large wave was unlikely.[14] In the town of Baliau, located in the extreme north of Manam Island, tsunami waves reached 16.7 m (55 ft).[15] A 3 m (9.8 ft) high tsunami was observed at Abaria village.[16]
Impact
editAt least 1,041 people were killed and 241 others were left missing due to the tsunami on Manam Island, where 40,000 villagers were displaced.[17][18] Across the island, all 13 towns and villages were severely affected, with 8,000 houses destroyed or severely damaged.[19]
The town of Baliau was worst-affected by the double-disaster.[20] The earthquake alone resulted in 301 deaths and caused 3,090 houses to collapse in the town,[21] while the subsequent tsunami killed 373 people and destroyed 365 houses.[22]
In Madauri village, the earthquake destroyed most of the houses which were later swept away by the tsunami.[23] Out of the 400 residents of the village, 320 were unaccounted for in the aftermath.[24] Two people were killed and three others were left missing in Kuluguma, where 1,388 of the 1,735 houses were damaged.[25] In Abaria, the tsunami caused two charter boats to collide.[26]
On Boisa Island, all 2,420 houses were destroyed, and 515 deaths occurred;[27] most of the deaths were from the earthquake itself, as most of the island's villagers fled to higher ground in time and avoided the tsunami.[28]
In Bogia, 2,130 buildings were damaged and many people were left missing by the earthquake and tsunami.[29] Buildings were also damaged in Angoram[30] and Karkar.[31] The earthquake left all of Angoram, Sumkar, Bogia and Karkar districts without power, with 1.93 million households affected by blackouts.[32] Panic was also widespread in the cities of Madang and Wewak.[33]