These cards all show the same image, looking west on 18th St. at Valencia on 4/18/1906 (earthquake day). The building at left (SW corner 18th/Valencia) was a three story building, pancaked to two stories by the quake. The fire destroyed these buildings on the following afternoon (4/19/1906). The Valencia St. Hotel is half a block south on Valencia; my Valencia St. Hotel page has much more information about the hotel.
Left: Unknown publisher, postmarked Los Angeles 4/26/1906 (eight days after the quake). This card is slightly smaller than normal and badly printed in b+w, like many cards printed immediately after the earthquake. Next: A.H., dated 7/05/1906, postmarked 7/06/1906 (from VA, not from CA). Next: Newman, O., Los Angeles. Right: American News 93411.
Steve's SF postcard pages: