Manam Island Volcano Revisited

Posted in Dangerous, Mixed Nuts on January 6th, 2009 by MadDog
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We in Madang are very interested in volcanoes. That’s because there are several very grumpy ones near enough to us that they could cause, at the very least, extreme inconvenience. In the worst case, we could be flattened by the active, sometimes noisy volcano on Kar Kar Island, which I can see clearly out my front door each morning:

You can see the volcano on the other side of nearby Kerosene Island.

Another volcano on the north coast which could dump a lot of ash on Madang if the wind were in the right direction is Manam Island. For your entertainment, I shamelessly ripped the text and satellite images that follow from a NASA web site:

Papua New Guinea’s Manam Volcano sits in the southwest segment of the Pacific Ring of Fire where the Pacific Plate sinks beneath the Indo-Australian Plate. One of the region’s most active volcanoes, Manam forms a tiny 10-kilometer wide island that rises from the Bismarck Sea 13 kilometres off the shore of Papua New Guinea. The volcano has erupted frequently since its first recorded incident in 1616.

An eruption began on 24 October 2004 with an explosion that forced thousands of villagers on Manam Island out of their homes. A large ash plume spread north-westward from the island, located at bottom right. The thermally active areas detected by MODIS are outlined in red:

Manam ash plume and weird clouds

Interestingly, the winds higher up in the atmosphere appear to have been blowing in the opposite direction at the time this image was captured. Streamers of clouds stretch from the coast north-eastward over the ash plume and farther out to sea. In the afternoon sunlight, the thicker clouds cast shadows down onto the ash plume. North of the cloud streamers, the tail of the ash plume is being rippled by the wind into rows of evenly spaced, nearly parallel waves.

It was still erupting on 15 November 2004, when the Moderate Resolution Imaging Spectroradiometer (MODIS) flew overhead on NASA’s Terra satellite. In this true-colour image, dark ash rises from the volcano and is drifting southwest over Papua New Guinea:

Ash plume of Manam Island eruption in 2004

The Manam Volcano has an interesting structure. Its 1,870-meter summit is bare and carved by four large avalanche valleys that radiate from the summit down the flanks. These valleys are spaced roughly 90 degrees apart around the cone-shaped mountain, and lava and pyroclastic debris flows have funnelled through these valleys and reached the coast in past eruptions. The volcano has two summit craters, and both are active.

A few months ago Kar Kar Island was venting in at least one place. We could see it clearly from Madang. Last Saturday, we were out at Pig Island and Richard Jones got this shot through a polarizing filter:

Stratified smoke or ash above Kar Kar Island

You can clearly see highly stratified layers of something. We have no way of know what’s presently causing this. In the past, we could connect it to either eruptions of nearby volcanos (or Kar Kar itself), or to big bush fires nearby. I don’t know if they still burn off the sugarcane in the Ramu Valley. If they were doing so, it could cause the same effect.

I’ll leave you with a sunset photo that I shot near Manam Island a few years ago:

Manam Island at sunset

As in many places in the world where natural hazards lurk close by, here there is abundant natural beauty also.

Paradise with a bit of hell around the edges.

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