Langila is one of the more active volcanoes in Papua New Guinea (PNG) and spent a while on the Smithsonian Global Volcano Program (GVP) list of currently active volcanoes in 2018.
It is a nested group of craters, the youngest two still active that were formed by continuing volcanic activity on the western end of New Britain. Activity that initially built a pair of stratovolcanoes a half million years ago progressed to a group of volcanic cones in the saddle between the two volcanoes and finally into the nested set of craters on the flank of Talawe, one of the original stratovolcanoes.
The practice of naming an active satellite eruptive center as a totally different volcano is not uncommon. Santiguito’s relationship to Santa Maria is one such example. Multiple named peaks on Nevados de Chillan is another. https://volcanohotspot.wordpress.com/2016/05/09/continuing-eruptions-at-santiaguito-guatemala/
The area surrounding the volcano is sparsely populated, with nearly 12,000 within 30 km and 46,000 within 100 km.
The region is densely forested with rainforest (or jungle depending on your worldview). It was also home to tribes of indigenous peoples some of whom practiced cannibalism around the time the western world discovered New Britain. This made early exploration somewhat more exciting than it would otherwise have been.
Webcams for Langila can be found here: http://webcams.volcanodiscovery.com/Langila
Link is courtesy Volcano Discovery blog.
The Darwin VAAC can be found here: http://www.bom.gov.au/info/vaac/
NASA Earth Observatory images can be found here. Do a search on Langila to find the most recent images. https://earthobservatory.nasa.gov/?eocn=topnav&eoci=home
New Britain, PNG
New Britain is a crescent-shaped volcanic island north and east of the island of New Guinea. It is 520 km along its crescent-shaped long side, perhaps 146 km wide, with an area of 36,500 km2. It hosts a population of nearly 514,000. Indigenous population of New Britain is in the vicinity of 190,000.
The island is divided into two provinces, with the eastern being the most developed. The largest cities in each province are Rabaul / Kokopo in the east and Kimbe in the west.
Rabaul is situated in the Rabaul caldera, with a pair of active volcanoes Tavurvur and Vulcan. Tavurvur buried Rabaul in a 1994 eruption, triggering a provincial capital move to neighboring Kokopo. The area is also tectonically active with numerous large quakes in the M 6 – 7 range, some as large as M 8, creating a continuing tsunami problem. Rabaul was hit with a 4 m tsunami in 1971.
Tavurvur was filmed in August 29, 2014 with a spectacular detonation and shock wave. It continues to be a most dangerous volcano. This video is an example of the sort of volcanic activity on New Britain. While located on the other end of the island, the explosion along with the associated shock wave is too good to pass up.
The island was held by Germany for perhaps 30 years around the turn of the 20th Century. It was held by Japan during WWII. Since the end of WWII, it has been part of Papua New Guinea.
Forests are being clear cut to provide land for oil palm plantations. Tourism is also an economic engine of the local economy as is mining.
Volcanoes in New Britain are located in several primary groups mostly along the northern shore of the main island. There are numerous active offshore island volcanoes to the north of the main island. Ritter Island is offshore the western end of the main island. Langila is located on the western end of the main island. Dakataua, Bola, Garua Harbor and the Garbuna Group are located along the Willaumez Peninsula center north of the main Island. Two other groups centered about Witori – Pago and Likuranga along the northern shore between the peninsula and the western tip of the main island. The Rabaul Caldera and active vents Tavurvur and Vulcan are on the north eastern tip of the main island. There are several volcanic islands offshore to the north and east of the main island. There are at least three calderas recently active at Witori, Dakataua and Rabaul which produced extensive pyroclastic flows and tephras.
Pago, Ulawan, Lolobau, Langila, Manam, Bam, Tavurvur and Vulcan all have erupted since the start of the 20th Century.
The line of active volcanoes stretches to the west just offshore the northern edge of the island of New Guinea. These active volcanoes include Long Island, Karkar, Manam and Bam.
The western tip of New Britain is generally referred to as the Cape Gloucester area. There are a pair of ancestral stratovolcanoes, Talawe and Tangi, both of which are over 1,500 m high separated by 13 km. A newer cluster of volcanic centers named the Aimaga Volcanic Complex built on the saddle between the two stratovolcanoes. Langila is the most recently active group of four volcanic centers on the eastern flank of Talwae, meaning that volcanic activity in the complex has generally moved east over time. The four centers are named Munlulu Crater, No.1, No.2, and No. 3 (newest dating from 1960), which is the currently Active crater. There are also satellite cones north and NE of Talwae which appear to be relatively recent.
Eruptions are primarily explosive with effusive eruptions and lava flows. Recent volcanic activity has covered over 200 km2 with volcanic debris. Volcanic activity from Tangi is thought to have ended 650,000 – 700,000 years ago. The three main complexes – Tangi, Talawe and Aimaga are arranged along a roughly N – S line. The two stratovolcanoes are thought to have emerged from the sea, building the western end of the larger island.
Talwae is a well eroded volcano with crater remains perhaps 2.5 km long. There are satellite cones on its flanks. Its activity stopped after that of Tangi. It is surrounded by relatively fresh lava flows, bedded ash, and pyroclastic deposits.
Langila is composite basalt / pico-basalt / andesite / basaltic andesite volcano in New Britain, PNG. Of its four coalesced cones, Munlulu is the oldest and highest, topping out at 1,200 m. It is covered with vegetation, indicating no eruptions in historic times and has a crater 500 m in diameter. No. 1 crater is roughly rectangular measuring 460 x 380 m. Most recent activity from No.1 crater was confined to the western section of it. It is recently extinct but has active fumaroles. No.2 crater has been recently active.
Eruptions from active No. 3 crater are typically explosive, frequent, though not particularly large (so far). There are extensive lava fields around the volcano complex, created in a series of eruptions starting in 1960. It is roughly circular at 150 m in diameter. Emissions of water vapor and SO2 are almost continuous. It has produced lava flows and tephras.
While Langila is the most prominent set of satellite flank vents on Talawe there are other flank vents on the north and east flanks of the larger volcano. They are covered with vegetation, meaning it has been an extended period of time since they were last active.
There are numerous lava flows with flow fronts, levees, blocky surface structures stretch north from Langila craters. They are thought to be recent in origin. Newly erupted lava flows were observed in 1883.
Typical eruptions out of this volcano are in the VEI 2 range.
The current eruption cycle began on 17 – 18 May, with ash plumes observed via satellite on that day and 21 – 22 May. The plumes topped out at 2.1- 2.4 km.
There were 19 explosions the first half of 2017 that usually produced plumes reaching 1.8 – 2.4 km. One in mid-May reached 4.6 km. They were identified via MODIS thermal imagery. The most intense thermal anomalies were observed mid-April – early May 2017. There were occasional anomalies observed Aug – Dec 2016.
There was a six-month long series of eruptions Sept 2009 – Feb 2010. It was followed by a short series of eruptions in Dec 2012.
Several shorter eruption were observed in 2006, 2005, 2004 and 2002. There was a 27-year long series of eruptions 1973 – 2000. Eruptions are recorded as far back as 1878.
VEI3 eruptions were recorded in 1973 and 1954.
Clearly this volcano is not quiet for long.
A 1989 paper by Mori, et all discussed combinations of low frequency earthquakes and high frequency air waves recorded during explosions near or at the summit. Continuous tremor has been recorded lasting hours at t atime. It is divided into harmonic and non-harmonic tremor. Harmonic tremor is interpreted as related to a gas-filled cavity above the magma body within the volcano.
At its most basic, New Britain is a subduction-driven region. There are numerous microplates jostling between the ongoing collision between the Indo – Australian and Pacific Plates. New Britain resides on the South Bismarck Plate. To the north, is the North Bismarck Plate, which moves generally to the west. The north boundary of the North Bismarck Plate is generally subduction driven with the Caroline and Pacific Plates subducting under it.
The western portion of the north boundary of the South Bismarck Plate is generally moving in a strike – slip fashion (similar to the motion along the San Andreas Fault system). The eastern portion is a series of spreading centers.
The southern boundary of the South Bismarck Plate is subduction, with the Solomon Sea Plate / Woodlark Plate subducting under it. It is this subduction that drives volcanic activity in New Britain. There is some dispute about the extent of the Woodlake Plate. Some depictions of it show its northern portion (currently rifting) as the Solomon Sea Plate.
Crust under Langila is over 25 km thick.
The areas is tectonically complex, with recent formation and movement of subduction zones, rifts, spreading centers. Due to the forces of large plate impact (Indo – Australian and Pacific), activity along the boundary of microplates defining the impact zone have changed significantly in a very short period of geologic time.
As with any tectonically complex volcanic region, this region is also subject to large earthquakes in the M 7 – 8 range.
Langila is the most recent manifestation of volcanic activity on the western end of New Britain. This activity has been going on for over a half million years. There appears to be a decent magma supply due to ongoing subduction, so activity should continue, though whether that activity manifests itself at the current Langila crater complex is something else entirely. While I would expect the precise location of active vents to change over time, I would not expect it to cease any time soon.