Vysoká Hill.

Report SPELEOLOGY, GEOPHYSICS 2021

Vysoká is a hill near Havlíčkův Brod. Crystals of a number of metals can be found in the fields, it is a polymetallic deposit. In ancient times, hot igneous rock penetrated into the subsoil at a depth of several hundred meters, which “boiled” the rocks above it. The metals in the overburden crack brought hot solutions under high pressure. As the temperature dropped, the metals crystallized, and erosion carried away some of the upper layers, bringing the veins closer to the surface.

We measured here with a prototype of a new transmitter that does not use antenna pulse transmission. It was the first test sometime in the spring of 2021, and after passing about 50 m, the record began to be skipped. We burned the insulating pads under the transmitter. However, we measured this interesting radargram, which probably showed the interface of two rocks or some deep crack.

One black and white radargram on the right with a wave recording. And the same radargram with a color scale – it is more detailed.

We returned to the same place in November 2021 and measured longer profiles, this time with the transmitter in the final version. Isolines in inverse colors are used here. View up to 200 m, the crack between 12-18 m is still there.

Radargram up to 1 km with a slightly different color scale. At a distance of 16 m, an anomaly resonates at a depth of about 250 m. The resonances have very little attenuation, it looks like an air cavity. The half-period is 200 ns and it would be around 30 m in the air. That’s a nice hole and will there be crystals? At a distance of 8 m there is at a depth of 300 m about another cavity and also resonates.

Below is a radargram measured about 30 m next to it. The cavity at 260 m is also there at a distance of 222 m, so the profiles are not far from each other and it is therefore the same cavity.

Below is a radargram with data recording to a depth of 3 km. From 1 km down there is nothing interesting going on there, it is possible that there is only compact rock. The wave record in the right part of the image is from where the cross cursor is. The reflected signal is still above the noise level and creates meaningful contours, at least in places.

Another demonstration of a new type of filtering with the Spirio SW from December 2021. The same crack 30 m further. The isolines were nice, but they didn’t tell us anything about the rock structure. It wasn’t until the wave gradient filter detected it.

And we can also make a detail of the purple area at a depth of about 200 m.