Yesterday’s magnitude 5.2 Southern California earthquake is a reminder to everyone that we must all be prepared. The quake happened around 1am on Friday, June 10, 2016 and was centered in a desert northeast of San Diego just northwest of Borrego Springs in San Diego County.
The quake was felt from San Diego to parts of Los Angeles as well as far as the Mexican border. It was followed by a series of aftershocks, more than 450, including a magnitude 3.5 earthquake at 4:14am. There were no reports of injuries or significant damage but residents were scared as objects in the house swayed and fell to the floor.
This earthquake occurred on the San Jacinto fault which is the most active in the region and is remarkably long as it stretches for 130 miles from Cajon Pass in San Bernardo County toward the Mexican border. There have been 19 magnitude 5.0 or larger quakes on the fault since 1937. The largest was a magnitude 6.6 in 1968 just south of Friday’s quake.
Seismologist Dr. Lucy Jones said that you can tell if a quake is going to be large based on how long it lasts. Basically, the longer the shake, the larger the quake.
For those who are wondering if an earthquake on the San Jacinto would trigger a bigger earthquake on the more famous San Andreas fault, Dr. Jones said:
“We have never seen a San Andreas earthquake triggered by a San Jacinto earthquake”
Even though we haven’t seen the San Jacinto trigger the San Andreas, geologist Julian C. Lozos discovered this past March that the San Andreas and the San Jacinto faults may have ruptured together about 200 years ago that created an earthquake that was felt from just north of LA to San Diego based on historical data.
Lozos said “If there’s a joint rupture it will create a larger earthquake, especially if it starts on the San Jacinto”
Jones mentioned “The mountains are here and they are growing. However we don’t know when in a human lifespan that large earthquake will happen”.
The USGS said that the San Andreas fault is due for a major earthquake on average every 150 years. It has been about 250 years since a major earthquake struck the region.
“We have twice the average recurrence time. This fault is storing a lot of energy for a big earthquake” Jones said.
People are becoming afraid of “The Big One” so it is changing our approach for earthquake preparedness. More people are preparing now whereas before people were more reactionary and only prepare after a major disaster.
Jones noted “It used to be that people had to experience something in order to think it can happen to them. But our global society is changing the way we see earthquakes. Think about the earthquake in Japan which triggered a tsunami. Or Nepal. Or New Zealand. Or Haiti. We’re able to see what’s happening to other countries.”
That’s why earthquake preparedness is so important. Just like the recent Cascadia Rising drill, we must all make sure we know what to do when a major earthquake strikes. Not only do you have to worry about an earthquake but if the quake is large enough you’ll have to deal with deadly tsunamis as well.