Blair Brown, Stephen Spinella, Fionnula Flanagan and Valerie Mahaffey are among thesps taking part in this weekend’s Pacific Playwrights Festival at South Coast Repertory in Orange County.

Four new plays will have semi-staged readings at SCR, starting Friday at 1 p.m. in the Julianne Argyros Theater with Lucinda Coxon’s “Vesuvius.” David Emmes directs Simon Billig, David Paul Francis, Anna Gunn, Jennifer Hinds and Kevin Sifuentes.

That’s followed Friday at 3:30 by Sarah Ruhl’s award-winning “The Clean House” on the Segerstrom Stage. Bill Rauch directs Ivonne Coll, Francois Giroday, Joan MacIntosh, Zilah Mendoza and Mary Lou Rosato.

Saturday at 10:30 a.m. in the Segerstrom, Bartlett Sher directs “Singing Forest” by Craig Lucas. Cast includes Robin Bartlett, George Coe, Flanagan, Kristen Flanders, Nathanael Johnson, Matt Letscher, Lorenzo Pisoni, Spinella and John Vickery.

Richard Greenberg’s latest, “Safe as Houses,” is directed by Ethan McSweeny Sunday at 11 a.m. in the Segerstrom. Cast includes Nathan Baesel, Brown, Robert Foxworth, Mary Joy, Mahaffey and Adam Scott.

New plays join fully staged productions of Amy Freed’s “Safe in Hell” in the Segerstrom and Noah Haidle’s “Mr. Marmalade” in the Argyros. Both are world preems; “Safe in Hell” was read in the 2003 Pacific Playwrights Festival.

For more information call (714) 708-5555 or visit www.scr.org.