La Palma Eruptions viewed with MICRODEM

A few years ago we spent spring break in the Canary Islands.  We were going to go to La Palma, but instead if Santa Cruz de la Palma, we wound up at Las Palmas to Gran Canaria.  We would up having a great time, but I don't have any pre-eruption pictures to go with the recent activity.

Figure 1 shows the Sentinel-2 image from 26 August 2021, before the resumption of volcanic activity.  This is false color; the red is really near infrared (NIR) which is not the standard thermal imagery, but just light we cannot see and which vegetation reflects strongly.  This has 10 m pixels.
Figure 2 shows the Landsat 8 image from September 26, showing the same color scheme but with pan sharpening to achieve 15 m pixels. There is ash trailing to the NE, and a lava flow going down the hill to west, with smoke or steam rising.  The lava flow itself is a thin red line, which is NIR energy which will be a mixture of reflected sunlight and heat emitted by the lava witch might be at 800 C.  The saturated white on the right side of the image are clouds.


Figure 3 shows the thermal infrared band 10 from Landsat 8.  The two lava flows seen here are the hottest things in the scene and they saturate the sensor which is not designed to record such temperatures.  The darkest are the clouds on the east part of the scene.  Sentinel-2 does not have a thermal band, so it cannot create this display.


Figure 4 shows the Sentinel-2 image from October 15.  The NIR shows the heat from the active lava flow.

Comments

Post a Comment

Popular posts from this blog

Connect the data points or not?

Image
  This graph shows 6 terrain parameters, which are only very indirectly related, plotted against the FUV (fraction of unexplained variance, 1-r squared).  It shows one test DEM (satellite radar derived) versus a reference DTM (lidar derived).  Low value is best, so ELEV (elevation) agrees very closely, whereas TPI does not. Because they are not related, some of my colleagues prefer the version on the bottom. I prefer the one on top because: With the lines, it is clear that the urban category is the best (largest FUV).  With the points, it is much less obvious. Despite the attempt to use both colors and different symbols, it is very hard to see all the values when they are close (say with RUFF, roughness).  With the lines, that is clear. Where lines cross, the relative rankings change and it's clear (say shrubs, between HILL, hillshade, and SLOPE). It might not be clear that all the categories are in fact present for the ELEV. As long at the graph is explained, I...
Read more

3D view of La Palma

Image
  This shows the Sentinel-2 image overlaid on the Copernicus DEM. The ash clouds and clouds are plastered on the terrain, since the program has no information of their altitudes and only has the DEM.
Read more