There seems to have been minor harmonic tremor in Katla volcano this evening. This harmonic tremor seems to have started after a ML0.7 earthquake with the depth of ~3.7 km did happen inside the Katla volcano caldera. Last harmonic tremor spike did take place on the 24th of August according to the tremor plot on Icelandic Met Office web page.
Here is the harmonic tremor that I see on the tremor plot. It is the second spike. But the first spike is actually a earthquakes that did happen earlier today. Copyright of this image belongs to Icelandic Met Office.
On other SIL stations around Katla volcano the signal is not so clear. But this is really a small event and unlikely a pre-eruption event. But it is hard to know it for sure, as Katla volcano has done this before and there was no eruption following this type of events. All that can be done now is to wait and see what happens next. It is also important to notice that Icelandic Met Office has not confirmed this harmonic tremor spike yet.