October 16, 2023

Krakatoa. The loudest sound on earth

Krakatoa is one of the most famous volcanoes in the world. Its huge eruption in 1883 occured at a time when the telegraph was connecting the world, while the increasing popularity of daily newspapers meant news was becoming increasingly global. The horrors of the eruption became one of the first world events to be discussed at the breakfast table and in the pubs at night. 

It has been estimated that the explosion was equivalent to that of 13,000 nuclear bombs of the size that devastated Hiroshima. Scientists consider it to be the loudest sound ever heard on earth at an estimated 310 decibels. Loud enough to be heard on the island of Mauritius, 4,780 km (2970 miles) and in Perth in Western Australia, 3,100 km (1920 miles) away.

Just to give a little bit of context, a clap of thunder directly overhead produces around 120 decibels, and anything over 160 decibels will rupture an eardrum. Anyone living close to the island, within 20km, would have been permanently deafened.

Sadly that was not to be their biggest concern as the 37 metre (120 feet) Tsunami produced by the eruption wiped out all island and coastal life on the nearby shores of Java and Sumatra. The death toll was estimated at close to 40,000, but with no official records, or census at that time, the toll could have been much higher. For years afterwards skeletons were washing up on the east coast of Africa on beds of floating pumice stone.

Little remained of the original Krakatoa island, a few jagged peaks ot the original caldera and a few small islands. But in 1937 a small volcano emerged in the centre of the caldera. Named Anak Krakatoa (Son of Krakatoa) that has been growing at a rate of 7 to 9 metres (22 to 29 feet) a year since.

This new crater has been becoming increasingly active, particularly since 2018 when an eruption destroyed the eastern flank of the new caldera sending a tsunami that devastated the coastal villages in Sumatra and Java, particularly in Carita Beach and Anyer, where Seventeen, a local Indonesian rock band was playing on a stage on the beach. Several of the band were killed as part of 437 people who lost their lives to the second worst Tsunami of the twenty-first century.

The band Seventeen performing on Anyer Beach in 2018 as the Tsunami hits

The sheer size of the eruption is still very impressive today. When the lava and water combined the island disintegrated, turned into ash and pumice with what once was a large crater being now mostly hidden under the sea. 

Krakatoa remains a volcano with a danger that can not be underestimated or ignored. Not surprisingly for me, I still wanted to climb it. Some large explosions from the active crater in September 2023 meant the island was off limits for all visitors, but finding up-to-date news was near impossible when I visited Indonesia in October 2023. 

Seeing as the eruptions had moderated to plumes of white smoke and hot gases I was hopeful I could land. Krakatoa is located in the centre of the Sunda Sea separating Sumatra from the main Indonesian island of Java, approximately 55 km (34 miles) from land. I decided to head to Carita beach via train, bus and ojek (Indonesian motorbike taxi, with no helmet provided).

The warning that you are entering a "Disaster Prone Area"

Carita Beach was typical of many Indonesian beaches, beautiful but with little care of litter being placed in bins. The condominiums which faced the water were in a poor state, Many had been abandoned after the 2018 Tsunami had killed many occupants of the ground and first floor apartments. It felt strange staying in an apartment with a keyed door when the ones either side of mine were windowless and had boarded up doors. At least it was quiet. Probably not the ideal weekend beach getaway.

I was not here for the beach, and I spent the first day negotiating with middle men to try and get to Krakatoa. "Too far, much money" was the opening gambit of the few English speaking touts (admittedly it was over 50 km away) who then offered me their best price which was equivalent of a flight to Australia. 

The next day I walked to the small port at the southern edge of the beach. Thanks to Google Translate I was able to secure a reasonable price for a two engined boat to head over to Krakatoa the next day. I could have rented a single engine boat for a lot less, but even the Indonesian sailors thought that was too risky, which was good enough for me. 

I had read that there was a 5 km (3 mile) exclusion zone around the island, with the latest update being in September. Was this still active? The Captain shrugged his shoulders leaving me none the wiser. We agreed to meet at 6:30 AM the next morning. 

Anak Krakatoa with smoke pouring from the crater in front of a surviving part of the crater wall of the original Krakatoa

The speedboat had seen better days but had two working engines, the captain, an engineer and a lovely smiling local, Marto, who was an extra crew member/guide, although his guiding ability I was soon to discover was somewhat limited.

Marto had survived the 2018 Tsunami by chance. Reluctantly leaving his beachside home, which was destroyed, to attend a wedding of distant relatives inland. Luckily for him, he had run out of reasonable excuses not to go.

His knowledge of history prior to the 2018 eruption was very limited, nor did he have any recent updates on the crater activity. But he could lead and point out the path up the volcano, which, of course, was what I needed.

At least we should get there. We sped out from the bach with the engines on full throttle, bouncing into each oncoming wave. The Captain had tried to increase the agreed price as we left, an interesting tactic, by suggesting we were were going to have to pay fines to the police to get close to Krakatoa. 

I was not totally clear on why there would be fines, although I was beginning to guess the 5 km (3 mile) exclusion zone was still in force and that a bribe/fine might be needed. Rather than pay upfront I agreed that if the police boarded us I would pay whatever fines were issued. In the event we saw no other human close to the Krakatoa crater, although that situation is different on weekends, which is probably when the police hit paydirt.

Out in the Sunda Sea we passed fishing boats but then there was nothing but ocean as we sped westwards. About 90 minutes into the journey the distant peak of part of the old Krakatoa caldera became visible on the horizon. 

We slowed down as we passed the heavily forested remains of the original volcanic island and entered the sunken caldera. The new island of Anak Krakatao in the middle looked devoid of life, made predominantly of ash and lava no vegetation had been able to take hold as yet. 

I jumped off the boat and waded to shore to start the climb up to the crater. A sign gave a somewhat understated warning that this was a 'Disaster Prone Area' but did not actually say 'No Entry'. No one else was around though as we began walking upwards in the stifling heat.

Smoke rises from Anak Krakatoa in the middle of the larger Krakatoa caldera

A strong smell of sulphur was present from when we had approached the island and this only got more overpowering the higher we went. The path was littered with lava bombs from when the activity was greater and this area was more downwind. We had already checked the wind direction before climbing, just for added safety. There were also lots of gullies cut out of the ash by rain, which would make good shelter should they be needed.

The climb was nor particularly difficult, with only a very few steep sections, although the ground was at times slippery where the ash was not compacted. The biggest issue, apart from the sulphur smell was the intense humidity and heat. Although it was only 10:00 AM the temperature was approaching 35 C (95 F) and it felt as if I was walking through an oven.

The plume of smoke and gases was rising about 100 metres (330 feet) into the sky with no visible lava or rocks being propelled out of the crater. Krakatoa is one of the more dangerous types of volcano, not just because of its historical activity, but due to its nature to erupt pyroclastic flows, deadly superheated clouds of ash and gas that, as Vesuvius showed with Pompeii, kill every living thing in its path. 

Anak Krakatoa is defined as a Surtseyan eruptive volcano, named after the Icelandic island off the South coast of Iceland, a particularly violent and explosive type. Growing from the bottom of the ocean they eventually collapse and disappear back under the sea without continual eruptions, due to the actions of the sea. Krakatoa's many eruptions seem to preclude this, unlike the original island of Surtsey which is becoming smaller every day.

A massive gap on the eastern side of the rim was all that was left of the original rim, The collapsed eastern rim of the crater, which caused the deadly 2018 Tsunami was clearly visible. The island lost two thirds of its size during the collapse and where the rim had been was now just beds of ash cut through with rain channels.. The majority of the land on this side of the island was now buried under the sea.

The collapsed eastern side of the crater. Now just ash and lava 

As the island continues to grow another collapse is seen as inevitable, scientists believe that the western side, where I was standing, will next crash into the sea creating another deadly Tsunami. This newly formed island lacks a strong submarine plateau to give it the stability to support the newly formed mainly ash based land above, while the continual destructive actions of the sea combine with the constant tremors and vibration from eruptions to weaken the rim. 

It may happen tomorrow or in twenty years, but it will happen. With only 55 km (34 miles) from the volcano to the nearest land it is estimated that it would take less than 30 minutes for the resulting Tsunami to reach the coast.

Even if effective early warning systems were in place this would not give enough time to evacuate. Neither Western Java or Southern Sumatra would be the place to build your dream beach home close to the water.

Anak Krakatoa in the middle of the caldera

Far Flung Tips

* Krakatoa can be reached by boat from either Sumatra or Java. The Sumatra route from Lampung will probably involve an overnight stay at Sabesis Island and will take longer. The costs are roughly the same.

* To reach Krakatoa from Java either hire a 3 hour to Carita Beach or Anyer Beach for approx US$60 through the Gojek app (a must have in Indonesia). Note that getting a car in the opposite direction is very hard. Or catch the regular commuter train from Jakarta Tanahabang station to Rangkasbitung for avery cheap US$1, which gets you two thirds of the way there. Then either proceed by Gojek car all the way (US$20) or a quick motorbike journey to Pandeglang Bus terminal to get the regular bus to Labuhan and then a final motorbike ride to your beach destination. Slightly longer, lots of fun depending on luggage, and at a cost of US$3.

* English speaking touts will approach you on the beaches asking for exorbitant amounts of money for a boat to the volcano. Go to the port and negotiate directly in Bahasa using Google Translate to cut out the middle man. It is a long way and requires a lot of fuel so you will not be able to bargain down that much.

* Check the weather. I was stuck in Carita Beach for two days because of high winds. It is not worth travelling in this weather, although the Captain may still want to take you there to make money. You will add more risk and suffer an uncomfortable long journey.

* Go for a 2 engine boat. More expensive than a one engine boat but again a lot less risk. You are out in the ocean with few to no other boats around.

* Exclusion zones dependant on volcanic activity and/or Police patrols may prevent you landing. The views will still be spectacular if you just sail around the volcano.

Anak Krakatoa erupting lava in September 2023

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