The platform is set to automatically use the timezone of the event location. However, if the event is online, the organiser must choose which timezone to use (normally where the person running the event is based).

From an event attendee's view, if the event starts at 10.30am in San Francisco, but they have registered from their laptop in London, the event iCal will show in their calendar as 6.30 pm (the UK is 8 hours ahead of Pacific Time in USA).

Here is an example:

This is an online event starting at 10.30am PST.

I'm based in the UK and can see that the event start time on the website is showing as PST (Pacific Standard Time = GMT -8 hours). I register to attend and my confirmation email with iCal looks like this:

So the iCal shows in my local time and will go into my calendar using my time or there would be a real danger that I'd log into the event at 10.30am GMT and wonder why it hadn't started!