Quake Viewership Mixed Among Affiliates : Television: KNBC took an early morning lead but KABC and KCBS won in the afternoon and prime-time hours.

Although KNBC-TV Channel 4 drew what is believed to be an unprecedented share of the TV audience in the first 15 minutes following Monday’s earthquake, longtime news leader KABC-TV Channel 7 was the highest-watched station for most of the day, according to figures released by the A. C. Nielsen Co.

KNBC, which says it was first to report on the earthquake with Joe Rico’s dispatch from its newsroom 2 minutes after the 4:31 a.m. temblor, drew a 27.5 rating and 88% of the total television audience in its initial quarter-hour of coverage. With each local rating point being equivalent to 50,064 households, it means about 1,776,700 households were tuned in.

KNBC continued to draw the biggest audience between 4:30-7:45 a.m. At 8 a.m., KNBC and KABC-TV tied with a 14.6 rating.

From noon-8 p.m., KABC was dominant, winning the first two hours and all of 3:15-8 p.m.

Among stations covering the earthquake in prime time, KCBS-TV Channel 2 won 8-9 p.m., before KABC regained the lead, attracting the most viewers between 9 p.m. and midnight.

But KCOP-TV Channel 13, the only station with prime-time entertainment programming, was the overall ratings leader without any quake coverage between 8-10 p.m., broadcasting episodes of “Baywatch” and “Star Trek: The Next Generation.”

As is the case with catastrophic news events, viewership jumped dramatically over Monday’s normal levels. From 4:30-4:45 a.m., the percentage of Southland households with TV sets jumped from 3.8 to 31.1, an increase of 718%.

Prime-time viewership level was 61.9%, down from the 67% during the first day of coverage of the October wildfires; the 71% for April 30, 1992, the first full day of the civil unrest in Los Angeles and the 64.9% during for the previous Monday’s regular programming.