This happened to me a few days ago on the dirt road leading to my summer house in Sweden. My son (age 3.5) was sitting on my shoulders and had ample time to pay attention to the details of the surrounding landscape, whereas I kept a steady gaze at the forest up front while concentrating on walking. As usual, he saw many interesting details along the road, like little pebbles or items resembling bugs or even frogs. All of a sudden, he cried out:
Son: Look, what is that?
Father: Hmm. What is this?... Wow... These are like small volcanoes, like mud volcanoes. I have seen then on many occasions during field trips!
I let him down and we got down on our knees for studying the phenomena. Layers and layers of mud flows originating from central vent made these miniature volcanoes. The biggest had a diameter of about 40 centimeters. Spectacular. I took out my camera and started photographing while urging my son to not mess with them using sticks or pebbles. We got more excited.
They look very similar the mud volcanoes of Azerbaijan, just smaller.
Father: Can you stand over there, so I can take a picture?
Son: Yes, but why are these here?
Father: It’s the melting of the ice in the ground, the last remnant of winter.
Son: (pokes around) not bad, now I have seen mud volcanoes!
So, that must have been the trigger for the volcanoes. I know that a big truck used this road the other day, thus loading the ground and creating overpressure. The first mud volcanoes in Sweden! I got more excited, counted the vents (more than 60), thought about excavating the whole thing, making a cross section, statistics, taking samples… I even saw a gas bubble in one of the vents. And the nicest thing of all: all the volcanoes were associated with linear fractures in the road. It’s like volcanoes growing in a rift zone.
Son: Mud volcanoes!
Time was up. We walked the 30 meters to our house and had lunch.