LOS ALAMITOS, Calif. - The ground was shaking in Los Alamitos, but it wasn't an earthquake.
It was earthquake testing.
Seismologists are bringing heavy equipment to several Southern California locations this week to help gather geologic data that will allow scientists to better understand the fault lines and help people prepare for a big quake.
A team from consulting firm LA Seismic worked in Los Alamitos, using a truck that sends acoustic energy 15,000 feet into the ground, to gather valuable information that bounces back.
The data will be provided to the U.S. Geological Survey and CalTech in hopes of preparing for an earthquake, especially in urban areas.
"Information is bounced back to each one of the 6,000 sensors that the USGS will use to identify fault lines," said Tracey Farmer with LA Seismic.
Local residents were notified in advance that the testing would occur.
Some people who were in the area at the time said the vibrations felt almost like an earthquake.
"We were standing at the sidewalk, we felt the ground going kind of like an earthquake, going back and forth," said Edward Manukian, who works at a nearby auto shop.
The survey is set to continue in Seal Beach and Long Beach through the end of the week.