Hot spots from the July 18 eruption in Kermadec volcanic arc

 

 

A new submarine eruption occured in the Kermadec volcanic arc producing large amounts of pumice. The pumice rafts were visible on satellite images during the following weeks. The submarine volcano at the source of these pumice rafts is usually difficult to locate precisely. In the case of the current eruption, MODIS satellite was very useful in detecting hot spots when the eruption was underway. This is the first reported volcanic activity from this remote location.

 

hotandspot1

This MODIS satellite image is a night scene collected on July 18, 2012 at 10H50Z (MODIS band 22: 3.959µm). This is the only image so far showing a thermal hot spot related to the recent submarine eruption and is the best evidence for eruption location. A cold eruptive plume is drifting towards the NW from the hot spots.

 

 

hot_spot2

Closer view of the hot spots from the 10H50Z MODIS Terra image. Hot spot location is Lat: 31°7' S, Long: 179°12'W. SST4 temperatures are around 22-23°C for the hot pixels with an average sea temperature around 17-18°C. Pixel size = 1km.

 

 

 

The images below are day scenes of the same area collected a few hours later. They are showing the first appearance of pumice rafting visible in the middle of the clouds as a small brown area with bluish water associated. Hot spots are not detected because solar radiance is reducing the thermal contrast. This solar radiance explains also the apparent thermal anomaly of the eruptive plume (Fred Prata, personal comm.) making the detection so easy.

dayscene1

MODIS "true" color image from http://rapidfire.sci.gsfc.nasa.gov/realtime/ , July 18 at 21H50Z

 

dayscene 2

 

dayscene3

Brightness temperature image from MODIS band 20 (3.75µm). 18 July 2012 at 21H50Z

 

 

 

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