Because of the earthquake activity in the Los Angeles Metropolitan area, buildings and other public structures had been equipped with accelerometers, and both the mainshock and the primary aftershock provided additional data for seismologists to analyze and compare with other Southern California events.

Beginning with the 1983 Coalinga earthquake, a blind thrust event in the central coast ranges of California, a change in perspective was brought about regarding these types of (concealed) faults.

Communication systems and local media were temporarily impaired and power was cut, leaving numerous early morning workers stranded in disabled elevators.

Los Angeles County+USC Medical Center took many of the injured, whose injuries were summarized by an emergency room spokesman as very bad to minor, and three people died as a direct result.

Other typical failures included more than 1,000 gas leaks, with many resulting in fire, ceramic elements on high-voltage substation equipment breaking and phone systems becoming overwhelmed.

The vertical accelerations were considered relatively high and early analysis (pre-digitalization) indicated that the mainshock was complex, with a double train of P-waves arriving with a 1.4–1.8 second interval.

[12] The National Strong-Motion Instrumentation Network (NSMIN) (a cooperative effort including the United States Geological Survey and other organizations) also monitored a set of 52 strong motion stations in the Los Angeles area.

Most of the stations successfully captured the event, and the closest unit to the mainshock, a rock site at Garvey Reservoir, recorded a peak horizontal acceleration of 0.47 g. A 12-story steel frame building in Alhambra was outfitted with accelerographs in the basement, at mid-level, and the top of the structure.

[4] A magnitude 5.2 event occurred three days later on October 4, causing additional damage in Alhambra, Pico Rivera, Los Angeles, and Whittier.

The shock's effects were assessed at VII (Very strong) on the Mercalli intensity scale with damaged chimneys, broken windows, and the collapse of two bell towers at the San Gabriel Civic Auditorium.

On February 11 of the following year, another small aftershock again damaged chimneys, broke windows, cracked drywall, and some homes' foundations in Pico Rivera, Pasadena, and Whittier.

[13] In order to gather funds to help the rebuilding effort, the city of Whittier approved the establishment of a 521 acres (2.11 km2) earthquake recovery redevelopment area.