A week or so ago there was this big volcano eruption in Tonga that created Tsunamis and such. Terrible stuff.

I knew that big events like this can create pressure waves in the air that can travel across the globe. I just recently installed an air pressure sensor, a BME280 to my radio network. I had my doubts if such a cheap sensor could actually detect such faint changes in air pressure. Well, it's more sensitive than i thought

Let's take a look at the relevant data:

                                                   Air pressure BME   
+                                                  
                                                                      
+                                                  
       990 +----------------------------------------------------------
+--------------------------------------+           
           |        +        +       +  **    +        +        +     
+   +        +       +        +        |           
     989.8 |-+                          **                            
+                                    +-|           
           |                            ***                           
+                                      |           
           |                            * *                           
+                                      |           
     989.6 |-+                         ** *                           
+                                    +-|           
           |                           *  ******                      
+                                      |           
     989.4 |-+                        *     *  *                      
+                                    +-|           
           |                         **        **                     
+                                      |           
           |                         *          *        *            
+                                      |           
     989.2 |-+                      **          *       ****          
+                                    +-|           
 hPa       |                       **           *      **  *          
+                                      |           
       989 |-+                   ***            *     **   **         
+ ****                               +-|           
           |                  ****              **    *     *      ***
+**   **                               |           
           |* *      *********                   *   **     **   *** *
+*     **                              |           
     988.8 |************                         *   *       *   *    
+        **      *******             +-|           
           |                                     **  *        ***     
+         **   ******  **********      |           
     988.6 |-+                                    * *         ***     
+          *****                **   +-|           
           |                                      ***                 
+                                ***   |           
           |                                      **                  
+                                  **  |           
     988.4 |-+                                                        
+                                    **|           
           |        +        +       +        +        +        +     
+   +        +       +        +        |           
     988.2 +----------------------------------------------------------
+--------------------------------------+           
         15.01    15.01    15.01   15.01    15.01    15.01    15.01   
+ 15.01    15.01   15.01    15.01    15.01         
         18:00    18:30    19:00   19:30    20:00    20:30    21:00   
+ 21:30    22:00   22:30    23:00    23:30         
                                                      Logtime UTC

[download]

This corresponds quite well with data released by my government. So, it turns out you can use a cheap sensor from Ebay to detect volcano eruptions (or above ground nuclear tests). Fascinating!

With a network of these sensors over a larger geographic area, it should be possible to triangulate the (approximate) location of an event like that.

perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'

In reply to Plotting a volcano eruption halfway across the globe by cavac

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