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Tuturvur Volcanic Eruption, Rabaul, PNG

These photographs (below) were taken from the base of Turvurvur Volcano at Rabaul, Papua New Guinea in 2004.

I was lucky that the volcano, which previously had been dormant (not inactive), decided to erupt as I was exploring around the flanks of the volcano! There was an almightily BOOM followed by rocks falling around me; the BANG was loud enough to hurt your ears. Some of the rocks landed in the water around me with a HISS as they were quenched. In fintsite, I was probably lucky not to have been struck by a falling piece of andesite.

Turvurvur Volcano is subduction style volcanism and produces an unusual magma composition due to the presence of a very large subterranean magma chamber located beneath Simpson Harbour. This causes changes in the type of volcanism produced. Depending upon the magma composition (silica and water content) eruptions can be either effusive or explosive, or a combination of both styles over a period of time. The series of eruptions I observed continued over a period of days and are known as strombolian eruptions. These eruptions are usually short, sharp and frequent, and indicate a changing magma phase beneath the volcano.

Subduction style volcanism can produce phreatic explosions which can include pyroclastic flows. Phreatic explosions are caused when water mixes with thick silica rich magma causing rapid cooling and release of gas. The end result of this mix is a massive explosion in which large volumes of gas, ash and rock are propelled kilometres into the atmosphere. Once the upward velocity ceases, the material falls back to earth and can flow at very fast speeds to areas of lower topography. The effects of such explosions and ash flows are catastrophic.

This eruption was the beginning of a new volcanic phase for the Rabaul region. Turvurvur Volcano has since erupted on a relatively frequent cycle.

To a person trained as a geologist with an intense interest in geology and natural sciences, witnessing the awsome power of mother nature at such close quarters was a mind numbing, yet very humbling experience.

Click here to read more about the eruption phases from this volcano is Rabaul.

Click here to download the Volcanology Short Course

The photographs were taken with a Canon point & shoot digital camera.

 

First eruption

This was the first eruption. The BANG was loud enough to hurt your ears and small "volcanic bombs" landed near by simmering in the cool sand and water. The eruption was preceded by the sulphur springs in the foreground (and seen in successive photographs below) increasing in intensity

Main eruption

Note the large splashes near the base of the volcano. These were caused by very large (size of a bus) rocks that were propelled upwards only to fall with shallow steep trajectories as the energy from the volcano was expended We were lucky in that we had two cameras at different locations when the "BIG BANG" commenced

Eruption cloud as a backdrop to old Rabaul Old Rabaul was completely destroyed in the 1994 eruption. This building was the airport freight terminal beside the main Rabaul runway; the airport now totally inoperable and is covered in ash and an andesite flow

National in a canoe seemingly ignores the eruption as if it was a daily event. This was about number five eruption event in a sixty minute time envelope

Multiple eruption phase

A strombo volcanic eruption is classified as several eruptions over a period of time. Note the large volume of ash and dust in the atmosphere from previous eruptions. This is number four eruption in a 30 minute time envelope

Ash cloud

A closer image of an ash cloud showing the different layers within. The vertical layers are loosing velocity and are falling to earth whilst the billowing layers are still being propelled skyward. Airline pilots fear volcanic dust as it causes jet engines to fail!

Spring activity increases

Immediately before the eruption the springs went "crazy" and hot water and steam was propelled along with sulphur dioxide gas one meter into the air. The bubbling of the springs was followed by as exceptionally loud BANG as the cone began erupting. Steaming sulphur springs in a lull between eruptions

Cone development

Each successive eruption assist to build up the stratovolacano. Turvurvur extrudes both felsic (high silica) and mafic (low silica) type magma. The later gives the stratovolcano structure in combination with tephra (ash) fallout

Main eruption

The ash plume looses upward velocity and momentum and is captured by prevailing winds (moving to ward the left in this photo). Note the cumulous nimbus clouds in the background. Taken from Simpson Harbour. Also note the small dust plumes settling to the surface after the main eruption. The eruption was so intense that any dust or unconsolidated material surrounding the volcanic cone became airborne immediately. The sulphur springs can be seen in the foreground

Country rock expelled

Another eruption propels ash, andesite and country rock skyward. Note the ash in the atmosphere from several earlier eruption events

This photograph was taken from the end of what was, in 1994, the main runway at the airport. This runway was also used by the Imperial Japanese Airforce during World War Two

Ash cloud development

Ash cloud In this photo you can see the middle section of the ash cloud still being propelled upwards by the initial eruption whilst ash nearer the edges of the plume, loosing upward momentum, begin to mushroom outwards before falling back to earth

Volcanic ash cloud

This is what the airline pilots do not want to fly into. Fine ash eventually dissipates into the atmosphere and aircraft radar cannot decipher the ash in the air. This results in injection into jet engines which causes the engines to shut down until the ash clears. The ash comprises silica which also damages internal engine components and etches aircraft windscreens and paint

After several eruption phases the atmosphere was chocked with volcanic dust and the sky was barely visible

Eruption plume rockets skyward

This photograph was taken from the balcony of the motel I was staying at "old Rabaul". Volcanic ash was ingested into the motel's air conditioners causing them, to become inoperable

 

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