terremoto

By Guy McCarthy

Everybody around here seems to have an answer to the question "Where were you at 11:42?"

Here's mine.

The image above, created in 2001 by NASA/Goddard Space Flight Center, shows a part of the earth's crust that started trembling at 11:42 a.m. July 29 2008.

Visible are the Los Angeles metro region, San Diego, north Baja, the Transverse Range, the San Andreas Fault, the Salton Sea and a bit of the Colorado River. In the most obvious urbanized area, west of Cajon Pass and San Bernardino, lie the Chino Hills - epicenter for the 5.4-magnitude temblor.

What it felt like as it rumbled for 15 to 30 seconds depended on where you were.

This week I'm working night shifts at Parker Center, the aging Los Angeles Police Department headquarters in downtown L.A. When the quake struck Tuesday morning, I was at home sound asleep on the second story of a nearly 100-year-old house in an orange grove east of San Bernardino.

The grove itself is situated on a bed of alluvium - loose sediment borne out of the fault-riven, fault-raised mountains of the Transverse Range that includes the San Gabriels, San Bernardinos and San Jacintos.

In other words, like most of urbanized Southern California, the ground under the grove house is not bedrock. It's layers of eroded sand, pebbles and stones.

So no matter how ho-hum the temblor felt to some California old-timers, that 5.4 jolt about 30 miles west of my place made the second floor where I was sleeping shimmy like a belly dancer on stilts.

More on this later. I have another night shift at Parker Center and need to get some rest.