Last week, this happened near Semeru volcano on Java in Indonesia:
Semeru has been quite active lately, so there was much loose ash lying around.
I’m not sure where the heavy rains came from, as the rainy season ends in April or May, and the tropical cyclone season, AFAIK, hasn’t begun yet.
The closest I’ve been able to come is a mention in online English-language news reports of atmospheric disturbances over the East Java Sea.
In any event, on July 3 Indonesian meteorologists at BMKG issued a warning for severe weather and heavy rains in the area from July 4 on, and that forecast verified with a vengeance.
The rain pounded Semeru and its thick layers of recent volcanic products so hard that you can see a before-and-after appearance in satellite images:
membandingkan citra satelit puncak semeru pada tanggal 04/07/2023 (sebelum banjir bandang) dengan citra satelit tanggal 09/07/2023 (pasca banjir bandang). dari citra tersebut nampak banyak meterial yang terbawa banjir bandang pada tanggal 07/07/2023. pic.twitter.com/Mztt7tLbWV
— INFOMITIGASI™ (@infomitigasi) July 10, 2023
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There were landslides, too. All in all, The Jakarta Post reports three dead.
The lahars reportedly took out six bridges, and hundreds of people were forced out of their homes.
By the time I began to realize the scale of what had happened, Indonesians were already in recovery mode.
Giat Banser Tanggap Bencana, BPBD, ASN Lumajang dan TNI-POLRI dalam penanganan dampak guguran lahar dingin dari puncak Gunung Api Semeru Kab Lumajang, Jatim yg merusak persawahan, ladang 3 hektar, 50 Rumah warga, dan 1 Masjid.#BanserTanggapBencana pic.twitter.com/7TgQAvKk7c
— Ahmad Taufiq (@addtaufiq) July 11, 2023
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Many other areas suffered from the flooding rains, but I want to focus on the lahars not just because of the volcano connection but also because many of them looked like floodwater.
They aren’t.
Locals call this more watery type of mudflow a banjir lahar. It still carries a lot of powdered rock and packs even more of a wallop than ordinary floods do.
This is good to mention because these are not limited to Indonesia. Watery lahars –banjirs, if you will — are part of the hazard at any volcano near water (including ice, snow, crater lakes, etc., as well as rainfall).
Featured image: ANTARA FOTO/Irfan Sumanjaya – detikFinance.
Sources:
As linked above, plus:
- “Indonesia – Severe Weather in Bali Triggers Deadly Flooding and Landslides” — Floodlist
- “Bridges crumble as intense rains, volcanic activity triggers lahar that swallows parts of Indonesia”*** — Fox Weather
- “Three dead, hundreds displaced in East Javan landslides” — Jakarta Post
- “3 dead, hundreds displaced after landslide hits East Java, Indonesia” — Victoria Advocate
- Voight, B.; Constantine, E. K.; Siswowidjoyo, S.; and Torley, R. 2000. Historical eruptions of Merapi volcano, central Java, Indonesia, 1768–1998. Journal of Volcanology and Geothermal Research, 100(1-4): 69-138. (Re: banjirs)
***A little lagniappe:
It’s great that Fox Weather covered the story, but it’s going to take more than rain to swallow parts of Indonesia. 😉
https://youtu.be/FsXc3FcWi3g&rel=0
Flight To Wonder 