It was my birthday Oct. 1, 1987. The marching band was on the football field practicing a halftime show. At 7:42 a.m., a 5.9 magnitude quake lasting four to five seconds rippled under us. The Earth, rather than the spectators in the stands, was doing the wave, from the flute section through the drum line. It was fascinating to see the peaks and troughs of wave movement along the yard lines and it was cool to get a “birthday quake” that morning.
Earthquakes appear in mythology of ancient cultures.
In China, a giant dragon shook the Earth when annoyed. The Greeks told of a great bull bellowing in the tunnels below the palace in Crete. The Romans believed Atlas was shifting the Earth from shoulder to shoulder and in Japan, it was a giant catfish who carried the world on its back. The Russians attributed the movement to the God’s dog scratching fleas.
Modern science offers us more insight. Our 4.5-billion-year-old planet has been shaped by continual natural forces. Valleys, mountains, lakes and shorelines formed from slipping, sliding, shifting, sinking, floating, compressing, tilting and deforming as the Earth’s rocky crust moves over the magma mantle.
Coastal California is a dynamic place at the boundary where the dense Pacific oceanic plate meets the North American continental plate. The 800-mile San Andreas fault line has been active for 28 million years, shifting the western side north at an average of 2 inches per year.
Reminders are in the landscape and treasured places. The towering boulder outcrops at Pinnacles and Joshua Tree National Parks are matching rocks that have traveled half the length of the state. Bodega Head and Montara Mountain were once the southern Sierra Nevada. This year on a spring wildflower visit to the Carrizo Plain National Monument we observed a creek bed channel which had shifted 30-feet along the fault line.
While we can hope the movement continues slowly and gradually, rock does get locked together and when it slips, the release of energy results in the big quakes. History tells us this is the norm. Change in nature is inevitable.
Floods. Mudslides. Fires. Earthquakes. Tsunamis. Earth’s constantly changing nature is important to understand and respect so we may prepare, react and problem-solve when necessary. Update emergency kits and procedures to keep families and friends safe. And keep up the conversation about the natural phenomena of our dramatic, dynamic and ever-changing planet.
Deborah McArthur is an environmental and outdoor educator. Contact her at debz.mcarthur@gmail.com.
