YUCCA VALLEY — Longtime residents have a milestone by which they gauge time. Events can be described as pre or post earthquake.
Before the Landers Earthquake of June 28, 1992, few people outside the Morongo Basin knew this area existed. Afterward, the world knew.
At 7.3 magnitude, it is the largest quake in the continental United States in 40 years and the fifth largest in California’s history.
To provide a 20 years perspective, the Hi-Desert Nature Museum and Morongo Basin Historical Society co-sponsored a program, cheekily dubbed “Shift Happens,” Wednesday, June 13, in the community center.
Dr. Sally McGill, a geology professor at Cal State San Bernardino, explained to the audience of about 65 people in layperson’s terms what happened.
The quake was preceded by a foreshock two months earlier in Joshua Tree National Monument. McGill explained the “warmup” quake changed the stress in surrounding crusts, forcing it to readjust.
In the same way the Joshua Tree quake triggered the Landers quake, the 7.3 main event also set off a quake in Big Bear a few hours later. In turn, the events here changed stress levels along the San Andreas Fault.
The Landers Earthquake traveled more than 50 miles along multiple fault lines northeast toward Barstow. Beginning at 4:57 a.m., tectonic plates shifted along the faults for 24 seconds and shock waves continued to shake the ground for several more seconds afterward.
The quake caused one death when a stone chimney collapsed on a 3 1/2-year-old boy who was here with his parents from Massachusetts for a Yucca Valley High School class reunion.
The earth shifted up to 18 feet laterally and up to three feet vertically.
“It was a complicated rupture,” McGill said as she projected images of the contorted roads and desert floor. Dirt roads and trails provided the geo-investigators with reference lines to measure the shifts.
Geologists swarmed here to study the effects of the seismic activity. McGill remained in the area for three weeks.
“It was such an exciting experience for all of us,” the professor professed.
Following McGill’s talk, David Stewart, who works at a survival supply store in Palm Springs, provided tips about preparing for a quake by stockpiling supplies and forming neighborhood support networks.
Stewart advocated maintaining a one-month supply of food and water because a major earthquake will disrupt transportation and supply lines.
“Buy an extra propane tank for the outdoor grill,” Stewart advised, for cooking and boiling water for purification.
The program included a video presentation of television news footage shot soon after the quake, capturing the raw emotion of the disaster. The fear in people’s voices and their dazed expressions depict a mix of terror and wonderment at surviving the tremendous event.
What would have been humorous if not for its tragedy was one earnest interviewee who exclaimed emphatically to the TV reporter, “I’m selling everything I own and leaving this state!”
Under the direction of Mara Cantelo, the Red Cross served 65,000 meals in 31 days following the quake. The food was prepared at Yucca Mesa Elementary School and delivered to the emergency shelter in the La Contenta Middle School gym.
Volunteers with off-road vehicles were able to bypass torn-up roads to deliver meals.
“It was pretty interesting,” Cantelo said after Wednesday’s lecture. “Everybody pulled together.”