Jakarta, CNBC Indonesia \u2013 The Centre for Volcanology and Geological\nHazard Mitigation (PVMBG) under the Geology Agency of the Ministry of\nEnergy and Mineral Resources has officially announced that, after\nlasting approximately 25 hours, the continuous eruption episode of Mount\nAnak Krakatau that began on 4 September 2026 at 23.07 WIB ended on 6\nSeptember 2026 at 00.04 WIB.<\/p>\n
Following this, activity returned to Strombian eruptions, which are\ncharacteristic of Mount Anak Krakatau\u2019s current behaviour. This was\naccording to a report released by PVMBG on Monday morning, 7 September\n2026. It was emphasised that intensive visual and instrumental\nmonitoring continues, and that the status and recommendations will be\nre-evaluated promptly should there be any significant change in\nactivity.<\/p>\n
This eruption of Mount Anak Krakatau drew attention because volcanic\nash spread to various parts of West Java and also to Jakarta.<\/p>\n
Moreover, this volcanic activity was also linked to a loud booming\nsound that startled residents of Bandung Raya and its surroundings in\nthe early hours of Saturday (5 September 2026). However, the\nMeteorology, Climatology and Geophysics Agency (BMKG) later stated that\nit was unlikely the sound was transmitted from the eruption of Mount\nAnak Krakatau. According to the BMKG, the wind blowing from east to west\nat the time of the event reduced the likelihood of the eruption\u2019s sound\nwaves propagating towards Bandung Raya, so the source of the boom is\nstrongly suspected to be something else that still requires in-depth\nstudy.<\/p>\n
Could it trigger a Sunda Strait megathrust?<\/p>\n
What about tectonic earthquakes? Could the eruption of Mount Anak\nKrakatau, located in the waters of the Sunda Strait between Java and\nSumatra, trigger one? Indonesia does have a megathrust zone segment in\nthe Sunda Strait.<\/p>\n
The Sunda Strait megathrust segment has drawn attention because it is\ncited as one of the segments that has long failed to release its energy,\nraising fears that it could unleash its energy at any time and trigger a\nmegathrust earthquake.<\/p>\n
Daryono of the Indonesian Disaster Experts Association (IABI)\nexplained that tectonic earthquakes are shaking caused by the shifting\nor rupture of rock layers in the Earth\u2019s crust due to the movement of\ntectonic plates. Volcanic earthquakes, on the other hand, occur due to\nthe movement of magma or the release of gas within the body of a\nvolcano.<\/p>\n
\u201cRegarding the relationship between the two, volcanic earthquakes\nfundamentally do not possess enough energy to trigger a tectonic\nearthquake because the pressure they exert is only local in scope,\u201d he\ntold CNBC Indonesia on Monday (7 September 2026).<\/p>\n
\u201cConversely, a large-scale tectonic earthquake is very capable of\ntriggering a volcanic eruption, provided the volcano is already in an\nactive state and its magma chamber is full, so that the shaking can\nbreak through the magma plug or trigger a release of gas,\u201d Daryono\nadded.<\/p>\n
He also explained that, geographically, Mount Anak Krakatau sits in\nthe Sunda Strait, an area close to the transition zone between the\nSumatra Subduction zone and the Java Megathrust.<\/p>\n
\u201cMount Anak Krakatau\u2019s position is indeed within a vulnerable zone\ninfluenced by that regional tectonic setting. Therefore, if a powerful\ntremor from a tectonic earthquake in the Sunda Strait megathrust zone\noccurs, it could potentially set the magma in motion and accelerate an\neruption of Mount Anak Krakatau if the volcano is active,\u201d Daryono\nexplained.<\/p>\n
\u201cHowever, this triggering relationship works in one direction only.\nThus, volcanic activity at Mount Anak Krakatau cannot trigger the\ncollapse or occurrence of a major tectonic earthquake in the Sunda\nStrait Megathrust Zone,\u201d Daryono stressed.<\/p>\n
He said the same theory applies to the seismic conditions of other\nvolcanoes on the Indonesian mainland.<\/p>\n
Update on Mount Anak Krakatau<\/p>\n
PVMBG explained that, based on monitoring, during the period of 6\u20137\nSeptember 2026, Strombian eruptions were observed with black eruption\ncolumns reaching a maximum height of 300 metres above the summit.\nInstrumentally, 3 eruption earthquakes, 9 blowing earthquakes, 93\nlow-frequency earthquakes, 98 hybrid\/multiphase earthquakes, and other\nvolcanic seismic events were recorded.<\/p>\n
The energy of the volcanic activity, based on RSAM values, rose on 5\nSeptember 2026 before declining again on 6 September 2026. Deformation\ndata have not yet shown any significant change indicating a rapid\nincrease in pressure.<\/p>\n
\u201cThe end of the continuous eruption and the temporary return to a\nStrombian eruption pattern are interpreted, for now, as the end of one\ncontinuous eruption episode. However, volcanic activity dynamics remain\nhigh, and the possibility of another eruption in the near future still\nexists,\u201d PVMBG stated.<\/p>\n
\u201cThe main potential hazards are incandescent rock ejections, heavy\nashfall, pyroclastic clouds, and lava flows should a continuous eruption\noccur again,\u201d the PVMBG report stated.<\/p>\n
It was stressed that the activity level of Mount Anak Krakatau\ncurrently remains at Level III (Alert).<\/p>\n
\u201cMembers of the public, tourists, and maritime operators are not\npermitted to enter within a 3-kilometre radius of the centre of\nactivity.\u201d<\/p>\n
\u201cResidents of coastal areas of Banten and Lampung are urged to remain\ncalm. The current eruptive activity is not triggering a tsunami, so\npeople can carry on their activities as usual whilst continuing to\nfollow official information and the directions of regional governments,\u201d\nPVMBG emphasised.<\/p>\n
The eruption of Mount Anak Krakatau does not trigger eruptions of\nother volcanoes<\/p>\n
Meanwhile, Daryono stressed that eruptions of volcanoes occurring\nclose together in time are a spatial and temporal coincidence.<\/p>\n
\u201cThis is because Indonesia lies within an active plate subduction\nsystem with dozens of active volcanoes at Alert or Waspada status,\u201d he\nexplained.<\/p>\n
\u201cWhen several volcanoes happen to reach the threshold of gas and\nmagma saturation at nearly the same time, they erupt independently\nwithout directly triggering one another,\u201d he added.<\/p>\n
Geologically, he explained, there is no direct magma channel\nconnecting Mount Anak Krakatau with other volcanoes.<\/p>\n
\u201cEach volcano has its own magma chamber, conduit, and pressure\nsystem, separate from one another within the Earth\u2019s crust. Each of\nthese volcanoes has its own independent gas supply dynamics,\u201d Daryono\nexplained.<\/p>\n
\u201cA simultaneous increase in activity is a statistical coincidence of\nlocal dynamics at each volcano, such as the accumulation of internal gas\npressure or magma crystallisation in each system, so an eruption at one\nvolcano does not transfer pressure or ignite an eruption at another,\u201d\nDaryono said.<\/p>", "url": "https:\/\/jawawa.id\/newsitem\/mount-anak-krakatau-eruption-could-it-trigger-a-megathrust-alert-an-expert-explains-1788762151", "image": "" }, "sponsor": "Okusi Associates", "sponsor_url": "https:\/\/okusiassociates.com" }