Updated

A Northern California county escaped with what appears to be just minor damage from a powerful weekend earthquake, and residents and officials say their quake readiness played a role.

Damage from Saturday's offshore 6.5 magnitude quake was widespread in Humboldt County but so far minor as agencies continue their assessments — cracks in walls and floors, temporary power outages, shattered windows, toppled store shelves, broken dishes and home appliances and fixtures, some bent railings on bridges.

SLIDESHOW: 6.5 Magnitude Quake Rocks California

"We're very, very fortunate that it's not worse, but there is a lot of damage," U.S. Congressman Mike Thompson of California said in a press conference Sunday in the county's main town, Eureka.

A preliminary estimate of damage in Eureka came to $12.5 million, said the city's fire chief, Eric Smith. No countywide assessment was available.

There were no serious injuries. More than two dozen people sustained cuts and bruises mainly from shattering glass and an elderly woman broke her hip.

"I think we can attribute some of this to being prepared," said Phil Smith-Hanes, Humboldt County spokesman. "Folks in this area are used to living in earthquake country."

Agencies and residents say they were earthquake-ready with plans in place and an awareness of safety measures such as not hanging heavy things on walls. That helped avert destruction and panic, and sped along the recovery, officials said.

The quake's location — centered in the Pacific Ocean about 22 miles west of Ferndale and away from urban areas — also helped the region escape relatively unscathed what could have been a major disaster. A quake of similar size — 6.7 magnitude — killed 72 people and caused $25 billion in damage in 1994 in the Los Angeles area.

An earthquake analyst with the U.S. Geological Survey said that while earthquakes cannot be predicted, a series will generally start with the largest tremor, then taper off in size and frequency. A magnitude-4.2 aftershock struck the region late Sunday night, the latest of many to hit the area since the quake.

"Almost always we see this pattern where they taper off," said Don Blakeman, with the USGS. This quake happened at the intersection of three plates — the Pacific, the North American and the Gorda.

Power outages were widespread, affecting about 36,000 customers initially, but a quick response restored electricity to all by early Sunday, said Janna Morris, a spokeswoman for Pacific Gas & Electric Co.

A hazardous materials team responded to the Eureka campus of College of the Redwoods to a report of spilled chemicals in a lab. Smith, the fire chief, told the Eureka Times-Standard Sunday evening that just one chemical spilled and the cleanup went smoothly.

Click here for more from the USGS.