There are actually two main departure procedures that most of those European flights depart on. One is called the "LOOP" departure which was described by Ward86IND. Aircraft depart LAX
on a westbound heading and have to cross back over the Los Angeles VOR (on the airfield) at or above 10,000 feet. They have to start the turn back to the Los Angeles VOR at 15 nautical miles.
A lot of the heavies are unable to comply with this climb restriction, largely in part due to their weight. In their case, the "SEBBY" departure is assigned. This procedure has the aircraft fly westbound 15 miles offshore, then turn back direct to the Seal Beach VOR (located near Long Beach) to cross it above 10,000 feet.
The only flights that depart northbound are Asian flights, trans-pacific flights, and other northwest US destinations. All of the other departures off LAX
fly westbound for XX number of miles before they make a southbound turn to go east or northeast.