5:15 am, my ride is here. To break up the monotony of the
trip I have booked a ride to Rabaul caldera and its ring-fracture volcanoes. My
driver is completely crazy, and he barrels down the narrow street at 100 km/hr,
as if we were in a competition. My two fellow explorers are two young American
men that seem oblivious to the dangers of the road and have their noses stuck
into their cell phones.
Rabaul is at the very end of the beautiful bay formed by the
collapse of the roof of a shallow magma chamber, a caldera (I am calling it a
caldera although I have not identified a large tuff or ignimbrite to justify
this designation). The bay is closed on the seaside by three active ring-fracture
volcanoes. Kokopó is on the land end of the mouth of the bay, outside of the
caldera rim. Rabaul was the main city of the region until it was destroyed by
the 1994 twin eruption of Tavurvur and Vulcan. It is not that close to either
of the volcanoes, but the wind was blowing the wrong way, and tephra started
accumulating on the roofs of the buildings. A few of the owners took proactive
measures and started sweeping the tephra off the roofs, and their buildings
survived; most others fled in panic, the tephra accumulated, and the roofs
collapsed under its weight. A good 70% of the city was destroyed this way, and
most of it has reverted to jungle. There has been some reconstruction, and
Rabaul still works as a container port (in a very reduced scale) and as
anchorage for Chinese and Philippino fishing boats that sell tuna to PNG.
We blasted past the town and eventually made it to the
cluster of three volcanoes that most of us foreign geologists associate to
ring-fracture volcanism along the north edge of the Rabaul caldera. From
largest (and oldest) to smaller (and youngest): Kombiu, Takumau (aka
Turangunan), and Tavurvur. The fourth ring-fracture volcano is across the bay
and is called … Vulcan. Notable eruptions happened in 1937, 1979, 1994, and most
recently in 2014. In 1937 there was a twin eruption of Kombiu and Vulcan, and
in 1994 there was a twin eruption of Tavurvur and Vulcan (twin eruptions,
within hours of each other, are very rare as far as I recall). The most recent
one, in 2014, only involved Tavurvur, which is the one we were going to climb.
The climb was rough, because the eruption landed huge blocks
of jagged basaltic andesite all over the flanks of the volcano, so the slope is
steep and unstable. The basaltic andesite is almost aphyric, vesiculated, and
in rare instances formed thin rinds of glass on typical bread-crust bombs. One
thing that I had not seen before was a field of landing craters on one of the
plains at the foot of the volcano. The plain was being covered with pumiceous
tephra 1 to 2 cm in diameter, when the volcano started hurling enormous blobs
of magma (car-size blobs) that landed like mortar bombs and created craters, in
the middle of which the blob spread itself like a big cow patty (if cows were
the size of buses and could fly …). Sometimes the patty cracked to form a
jigsaw puzzle of small blocks, which the locals collect to form small piles on
the edge of the bay, which are bought by the fishing boats for ballast, for
PNGK 50 per pile. Finally, some of the giant blobs landed at a low angle, and
after carving their craters bounced out of them! It is a beautiful example of
what physical volcanologists do in their spare time.
My guide was a local kid, Edward, who, upon discovering I
was a geologist, immediately answered that he too wanted to become a geologist
and study volcanoes and rocks. Of course I was not going to let this
opportunity for some mentoring go to waste, so I gave him my standard talk
about geology as a science and geology as an applied engineering discipline. I
told him that in PNG they needed good geologists to continue the mineral, oil,
and gas exploration, for geothermal development, to manage their water
resources, and to work together with civil engineers. He was quite enthusiastic
at the many prospects, and told me he wanted to go to Australia to study. He is
still in high school, so I told him to work hard on his math, physics,
chemistry, and English. All this time we were climbing and laughing, and I kept
telling him about the rocks and the landforms. Once we came down he stopped for
a second and told me with admiration: “This is the first time I speak with a
white person, and it happened to be a geologist!” Since the kid was about 18
years old I take his comment as meaning the first time he has had a meaningful
conversation with a white man. I was honored.
Huffing and puffing I made it to the top, and right in front
of my eyes I could see The Gates of Hell. The crater, which previous to the
2014 eruption had been a mere bowl filled with “sand”, was now a jagged inferno
where big fumaroles of steam and H2S escaped with a hiss and a
rotten egg smell. Big patches were coated with yellow elemental sulfur, and the
rocks had been oxidized to blood red.
My adventure partners had brought a drone, which they used
to film the steaming crater from every possible angle and elevation. I think
they got the basic footage for the next B movie of Dwayne “The Rock” Johnson,
and then some.
We were back in town by 9:30 am, which was a bit
disappointing. For the PNGK 315 I paid for the tour (worth every penny just for
the experience of seeing the crater and its fumaroles), I was hoping we would
spend most of the day out there. I am afraid of getting bored here at the
hostel. I have now planned on taking a PMV to Rabaul, and spending one of my
empty days just walking around and saying hello to the people. Kokopó and
Rabaul are completely safe, and people are not pushing any merchandise or
services upon you.
Prior to midday I went down to the beach, and had the
opportunity to regret how much trash was strewn on the beach and floating in
the water. I promise I will stop bickering about not getting a free plastic bag
at the shop, but I suspect that what is truly needed here are properly built
and operated sanitary landfills. Trash is dumped in any convenient swell, and
is not compacted or buried, so of course it disperses as litter. For the sake
of cleaner oceans, next time there is a beach cleanup in California please
invite me to come along and help.
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