12 comments on “Lago Ilopango – an El Salvador Caldera (updated and reposted)

  1. Meanwhile in Peru: Ubinas volcano, which had produced phreatic eruptions during the last years, has now a magma body creeping up that causes some concern to the authorities. As there haven’t been any eruptions lately, the conduit seems to be bottled up. Volcanologists are now warning of a possibly strong eruption, where the lava could break out either from the crater or any place. They are quite concerned about possible flank eruptions. Yesterday a first (moderate) ashy explosion from the crater opened the game.

    Sentinel-2 image (Sentinel Hub EO Browser), 18.08.2019, false colour (urban); shows the measured thermal anomalies from a near-surface magma body


  2. And while everyone is waiting for a magmatic eruption from Ubinas, it’s actually Sabancaya that has revved up its seismic activity:


  3. Ilopango cannot be possibly responsible for the 536 sulfate signal but it is indeed the strongest candidate for the 541 signal.
    536 signal is only limited to Northern Hemisphere and cannot be attributed to a tropical eruption. Rather, 541 signal is distributed more evenly in both hemispheres.

    Recently, Kuwae caldera is ruled out to be the source of the 1453(Greenland)/1459(Antarctica) sulfate deposition based on glass composition from Antarctica ice-core, and the cooling and distribution of aerosol are likely only limited to Northern Hemisphere. The study has been submitted to Nature Geoscience: https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=4089&context=etd


    • Thanks for the additional information. We looked at Kuwae in 2015. Looks to me like we need more information to pin the first eruption on it.

      If the 536 AD signal was primarily northern Hemisphere, you quickly run out of locations for massive eruptions – Philippines, Indonesia, Central America and Mexico, Pacific Islands, Japan, Kamchatka, Iceland? Go too far north and you end up like we did with Baekdu / Paekdu – massive eruption with lots of ejecta that doesn’t travel far enough south to impact global temps. Interesting detective story, though. Cheers –



      • The Antarctica ice-cores do not record the 536 AD signal which appears only in the Greenland ice-cores. Tree-ring reconstruction of 536 AD cooling is also from northern Hemisphere.
        The source of 536 AD signal might not be a single massive eruption but multiple eruptions around the globe. Based on the glass compositions from that level, at least three distinct compositions (All belong to west coast of North America) of tephras were erupted during that year.
        Sigl et al (2015)


      • The coolings and sulfate signals in 1450s AD are elusive. In Antarctica, ice-cores record only one but it is an extremely powerful one with various timings from 1450-1460 AD in different cores. In Greenland, ice-cores record two separate strong sulfate depositions in 1453 AD and 1459 AD.
        It is hard correlate the Antarctica sulfate spike with either 1453 or 1459 AD recorded in Greenland, and whether the Antarctica spike is bipolar at all still remains to be a question.
        The highly variable magnitude and timing of the Antarctica sulfate peak favors rather a regional Antarctic eruption without hemispherical effect.
        In fact, climate reconstructions from the entire northern hemisphere only show significant drop in temperature in 1453 AD.
        The best inference we can make at this point is that there is a significant volcanic eruption in northern hemisphere in 1452 AD with cooling and aerosol largely limited to northern hemisphere. The sulfate spike in Antarctica is most likely due to a regional eruption and does not have global effects. The compositions of the tephras from the Antarctica sulfate layer does not match with those from Kuwae either, therefore excluding Kuwae as the source of sulfate. The 1450s sulfate signals are unlikely to be bipolar.
        As you have explored before, the inland eruptive deposits of Kuwae do not indicate a power subaerial eruption.


  4. The caption to the “San Salvador city from space” picture states that “Loma Caldera is at far left”. That is incorrect. It is Lake Coatepeque, a large crater lake in the east part of the Coatepeque Caldera. You can locate Loma Caldera with this link: https://goo.gl/maps/JU6k8WwNV5PTMQsU6.


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