I have different JavaScript function associated with each option tag to toggle layers on/off in an OpenLayers map. It works fine Opera, Firefox and IE9, but not in Chrome and Safari. I read that I could use onchange on the select tag, but since I'm new to JavaScript, I don't really how it would call four different functions?

<select size=1 name=usgsfeed id=usgsfeed>

<option value=usgs_hour onclick=display_usgs_hour();>Past hour, all earthquakes</option>

<option value=usgs_day onclick=display_usgs_day(); SELECTED>Past day, magnitude > 1</option>

<option value=usgs_week onclick=display_usgs_week();>Past week, magnitude > 2.5</option>

<option value=usgs_month onclick=display_usgs_month();>Past month, magnitude > 2.5</option>

<option value=none onclick=display_none();>None</option>

</select>