4.5 Temblor a Familiar Wake-Up Call : Seismology: Early- morning aftershock near San Fernando is largest in two months. No major damage is reported.

Residents of Los Angeles and Ventura counties received a jarring but short-lived wake-up call Wednesday morning when the largest aftershock to the Northridge earthquake in two months rattled the Los Angeles Basin, but caused only minor damage.

While the 4.5-magnitude shaker was only powerful enough to break a few dishes and rattle some nerves, for many it provided a grim reminder of the destructive pre-dawn quake of Jan. 17.

“I was like ‘Here we go again,’ ” said Shawn Rucker, 24, of San Fernando. At his house, picture frames and plants fell to the floor and several glasses broke in his kitchen.

“It was like a train going through my house,” he said. “I expected it to go on like the Jan. 17 earthquake, then it just stopped.”

The 5:56 a.m. temblor, which shook for as long as 15 seconds in parts of the San Fernando Valley and Hollywood, was centered three miles northeast of San Fernando. It was felt throughout the basin and as far west as Camarillo in Ventura County. Caltech seismologists said it was even felt on Catalina Island.

Throughout the day, smaller aftershocks struck the same area.

“Probably the more emotional people were just starting to relax,” said Kate Hutton at Caltech. “This was a pretty good feeler. It’s the nature of nature, and we can’t do much about it.”

As jarring as the aftershock was, scientists say it was not only normal, it was overdue.

U.S. Geological Survey seismologist Lucile M. Jones said a computer analysis predicted we would likely get four aftershocks over magnitude 4 between March 20--the date of the last significant aftershock--and Wednesday’s temblor. Instead, there was only this one, and it was a relatively small one at that.

“This was a little less than would have been expected,” said Jones. “It is not very typical at all.”

Residents a few miles from the epicenter were particularly shaken. At the Tahitian Mobile Home Park in Sylmar, where 64 trailers burned after the Northridge quake, the jolt brought renewed fear.

“I was thinking that if it went on any longer, I would throw my body over my sons, and then it stopped,” said Susan Rezvani, 37, standing with her two boys, Neema, 12, and Naveed, 4, outside a friend’s trailer. “I thought about not letting them go to school today, but I ended up sending them.”

Otto Hofmann, 60, has lived in a motor home outside his Sylmar house since it was red-tagged after the Northridge quake. During Wednesday’s temblor, he said the rubber wheels on the trailer made it bounce up and down like a ball.

“I thought the epicenter was here,” said Hofmann. “Everybody started yelling and screaming, ‘My God, not again!’ ” Luckily, the only casualty in his makeshift home was a fax machine that fell from a shelf, Hofmann said.

In other areas, the damage was also minor. Cracks in the walls of homes not yet repaired from the January quake widened, chandeliers swung, dishes broke and frightened children hopped in bed with parents who couldn’t get back to sleep anyway.

There were no reported electrical, water or phone service disruptions and no freeway closures due to the aftershock, officials said.

Of the 8,000 aftershocks since the Jan. 17 quake, only about 400 could be felt by residents. Seven of the aftershocks were between magnitudes 5 and 6; approximately 40 were between 4 and 5. More than 300 were between 3 and 4.

The March 20 aftershock, which measured magnitude 5.3 and was centered near Panorama City, sparked two fires in the Valley but caused no injuries.

Times staff writer Kenneth Reich contributed to this story.

Shock After Shock Although the number of daily aftershocks from the Jan. 17 Northridge earthquake has dropped substantially, the earth continues to move. According to seismologists at Caltech and the U.S. Geological Survey in Pasadena, Wednesday’s early morning 4.5 shaker was the strongest since a magnitude 5.3 temblor on March 20.

“They come in spurts,” said USGS seismologist Thomas Heaton after last week’s 3.6 temblor. “Any random phenomena comes in clusters.”

Recent aftershocks include:

Date: 5-25 Magnitude: 2.8 Time: 2:41 p.m. Epicenter: 1 mile south-southwest of San Fernando

*Date: 5-25 Magnitude: 4.5 Time: 5:56 a.m. Epicenter: 3 miles east-northeast of San Fernando

*Date: 5-24 Magnitude: 3.1 Time: 1:56 p.m. Epicenter: 2 miles southwest of San Fernando

*Date: 5-22 Magnitude: 2.8 Time: 8:34 a.m. Epicenter: 1 mile north of Chatsworth

*Date: 5-18 Magnitude: 3.6 Time: 11:12 p.m. Epicenter: 2 miles north of San Fernando

*Date: 5-18 Magnitude: 2.8 Time: 8:02 p.m. Epicenter: 2 miles north of Canoga Park

*Date: 5-18 Magnitude: 3.0 Time: 11:54 a.m. Epicenter: 4 miles north-northwest of Northridge

*Date: 5-16 Magnitude: 3.7 Time: 1:40 a.m. Epicenter: 6 miles south-southwest of Valencia

*Date: 5-15 Magnitude: 2.9 Time: 10:45 a.m. Epicenter: 3 miles east of Northridge

*Date: 5-9 Magnitude: 3.2 Time: 4:45 p.m. Epicenter: 3 miles north-northwest of San Fernando

Sources: Caltech, U.S. Geological Survey; Research: DAVID BRADY/Los Angeles Times