5 comments on “What are the tectonics behind Rinjani?

  1. Thank you agimarc for working your way through this tectonically tricky corner of the world! I read that there are still new papers coming out suggesting different interpretions of the “jumbled tectonic mess”. But that’s mostly about the niceties, the overall picture seems not too hard to understand once you go into it.

    Looking at the last graphic – unfortunately I can’t read the legend, it seems the coloured bands are rock formations of the different geologic times – strange how they converge in eastern Kalimantan, as if that island is a completely dead area (tectonically speaking), or as if it had been a pole everything else rotated around.


  2. Howdy Granyia –

    Apologies for the final graphic. The bands are what are called magmatic arcs dating since the Cretaceous (70 My ago). Can’t see the legend either, but age of the bands are generally older the farther north and west you get. I included it because it kind of showed me how the volcanism of the region has grown / moved over the last 70 My or so.

    I thought the sharp corner in the most recent magmatic arc (black dots are volcanoes on the second / red arc) may be related to whatever is going on in Sulawesi, which you touched upon with your Colo post some months ago. What makes that sort of corner in what was previously a smooth line of subduction? Cheers –


  3. Update for Rinjani today: 11 – 16 Nov. 2015 – The eruption has been going on but with less intensity, and flight conditions are back to normal. Lava flows down the NE and NW of the cone. – It is estimated that a buildup of 4.5 million m^3 (0.0045 km^3) of pyroclastic material has accumulated in this eruption. Temperature of the lake water has risen fom 21°C (June 2015) to 38°C. – With the increased volume of erupted material in Lake Segara Anak water level has risen 1 m (!), causing an over/outflow of more than double the usual rate. There is an imminent danger of flooding along the river Kokok Putih, especially in heavy rain conditions.

    Info Siaga: Mount Marapi in western Java has had an ash eruption Saturday night (14 Nov.), but the ~500 climbers up there for the weekend were not affected. Volcano Marapi (not to be confused with infamous Mt. Merapi in E Java) has been on alert level 2 since 08/2011 but was quiet lately.

    Volcan Colima in Mexico did a brilliant show at dawn this morning:


  4. Pingback: New activity at Bromo / Tengger Caldera, Indonesia | VOLCANO HOTSPOT

  5. Pingback: Gunung Semeru, East Java, Indonesia |

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