The Riverwalk Blues Festival takes place November 7- 9 at Fort Lauderdale’s Bubier Park (Andrews Ave. and Las Olas Blvd.). Five stages of local and national performers will include Magic Slim and Roomful of Blues. Tickets are $5 and $7 in advance; $8 and $10 at the door. For info, call the Cool Blues Hot Line 954-761-5934. . . It’s time again for Lorain, Ohio’s annual Gospel Explosion November 8 at the Palace Civic c Center (Broadway & Sixth St.). Choirs nationwide will perform. Tickets cost $15. For info, call 216-288-0991… November 18 marks the birthday of abolitionist Sojourner Truth. The Black Americana Museum in Omaha, Nebraska (1240 S. 13 St.; 402-341-6908) celebrates her life with seminars, exhibitions and storytelling. Admission is $5 for adults; $3 for students and children… View Nigerian art at the Smithsonian’s National Muse of African Art (950 Independence Ave. SW, Washington, DC; 202-357-4814) in The Poetics of Line: Seven Artists of the Nsukka Group. The exhibit, 64 paintings, drawings, sculptures, and mixed- media, remains on display until April 26, 1998.