SANTA CRUZ COUNTY FIRE CREWS HAVE BEEN CALLED ON TO HELP FIREFIGHTERS IN THE CENTRAL VALLEY.    EARLY THIS MORNING (TUES) A STRIKE TEAM MADE UP OF TWO DOZEN CREWS HEADED OUT TO FIGHT THE JUNCTION FIRE.  THE           1,200 ACRE BLAZE IN MADERA COUNTY HAS DESTROYED 8 STRUCTURES AND THREATENS 500.     THE CREWS COULD BE IN THE CENTRAL VALLEY FOR UP TO TWO WEEKS.