Miata: Buzzing Sound from Engine Bay?

Hello!

I have a 2004 Mazdaspeed Miata, and after a long trip I noticed a loud buzzing sound coming from under the driver's side of the engine compartment. It buzzes when the engine is running, and also buzzes for about 1 second when I turn the key from "off" to "run" (in other words, before I start the engine, I can hear it during the time I assume the fuel pump is charging the engine with fuel for startup).

Is this the electric fuel pump? The buzzing is electrical-sounding and is similar to the sound a streetlight makes, or the sound a speaker makes when it's busted.

Thanks for any tips on where to start looking!