Firstly, we are happy to hear that you are enjoying your Shake! It’s always a great reward for us when our users like the models we are developing.
Regarding the two traces that you have posted, a couple of notes to help you in the future:
- There is the need to take into account the time that the seismic waves will take to travel from the earthquake origin (in this case, Iceland) to your seismometer. Usually, from there to the UK waves can take between two and four minutes (approximately) to arrive and so, if an earthquake happened at 09:23 UTC, you will have to look for arrivals between 09:25 and 09:27, more or less.
An interesting example of wave propagation can be found on this page, focusing on the major event in Sumatra in 2004: Seismic Waves - 2004 Sumatra Quake & Tsunami
Continuing in the case of the first image, the big spike is most likely local noise, created by something that has maybe passed close to your house, or someone closing a door a bit hard nearby. Our instruments can detect this type of vibrations too.
On your second waveform image, I can see it happening many times during the day, with a similar spectrogram appearance (to view the spectrogram, click on the icon high on the right with the 9 dots assembled in a square, the fourth from the left). This too may be something local, that happens around every 15/30 minutes, more or less. It could be some kind of nearby heating equipment, machinery at work, or similar installations that turns on for a minute/two or so and then it shuts off again.
Keep exploring the waveforms, I’m sure you will find many more examples of different things that our Shake can detect, and correlating these to the real world can be very interesting sometimes!