February 25, 2018 Earthquake: S Highlands, Hela, Indonesia, Papua New Guinea

Tectonic Summary

The Feb 25, 2018, M7.5 earthquake occurred as the result of thrust faulting at shallow a depth. Preliminary focal mechanism solutions indicate slip occurred on either a moderately dipping fault striking west-northwest, or on a moderately dipping fault striking southeast. At the location of this earthquake, the Australia plate is converging with the Pacific plate, moving towards the east-northeast with respect to Pacific lithosphere at a velocity of approximately 107 mm/yr. Earthquakes in this geographical region are generally associated with the large-scale convergence of these two major plates, and with the complex interactions of several associated microplates, most notably the South Bismarck plate, the Solomon Sea microplate, and the Woodlark plate. The location, depth, and focal mechanism solution of this earthquake are consistent with it occurring as intraplate faulting within the crust of the Australia plate. Papua New Guinea experiences a high rate of seismic activity, with 23 other events of M6+ occurring within 250 km of the Feb 25, 2018 earthquake over the preceding century. The closest of these was a M6.2 earthquake in August 1993, about 17km to the north of today's earthquake. The largest was a M7.2 event in June 1986, 230 km to the north-northeast on or near the Australia: Pacific plate boundary in the region. With the exception of a M7.5 earthquake at intermediate depth in eastern Papua New Guinea in Feb 1963, all prior M7.5+ earthquakes in this region have been associated with the shallow subduction zone plate boundaries in northern New Guinea. The vast majority of moderate-to-large earthquakes in this region are not known to have caused significant damage or casualties, though few have been as large as today's earthquake.

More than 125 people killed, 500 injured, 17,000 displaced and many homes destroyed or damaged in Hela, Southern Highlands and Western Provinces. Some buildings damaged at the Hides Gas Conditioning Plant and part of the runway damaged at Komo Airport. The Porgera Gold Mine sustained damage to its gas and electricity infrastructure. Landslides, sinkholes and power outages occurred in the affected areas. Landslides blocked the Ok Tedi Mine access road and damaged parts of the highway between Tabubil and Kiunga in Western Province. Several buildings damaged in Kabupaten Boven Digoel, Indonesia.

Tari, Southern Highlands, Papua New Guinea (PNG) - CDI: 9; Mendi, Southern Highlands, PNG - CDI: 8; Ambunti, East Sepik, PNG - CDI: 8; Kundiawa, Simbu, PNG - CDI: 8; Wabag, Enga, PNG - CDI: 8

(above ref #13456)

Provincial authorities [Hela and Southern Highlands] say more than 300 villagers have been injured and properties destroyed [...] Komo Airport was believed to have suffered damages to half of runway. (ref #12037)

In Bosavi area, two villages reported buried in landslides(ref #12047)

devastation in [Tari] town of 10,000 was immense. Most buildings collapsed including schools and parts of hospital (ref #12049)

In the Southern Highlands Province 45 people died and 15,000 displaced with the worst affected areas being Mendi, Karins, Lai Valley, Kandep, Pangia and Nipa/Kutubu. In neighbouring Hela Province 80 were confirmed dead with 20,000 people displaced...16,000 of whom are from the Komo area, with Magarima, Tari, Koroba and Mt Bosavai areas also being affected (ref #12061)

killed 145 people, number is expected to rise (ref #12070)

damage to the building of a mosque, one post of Indonesian Armed Forces, an elementary school building, a district office, a damaged house in the border district of Mindiptanah, Kombut, Arimop. (ref #12046)

USD 290 million overall losses (ref #12634)

160 fatalities, 500 injured, 190 USD million economic losses (ref #13727)

Note: deaths may include fatalities from 28 Feb, 4 & 6 March earthquakes