Skip to comments.Moderate quakes shake Southern Calif.; no damage
Posted on 05/22/2010 1:25:21 PM PDT by Ernest_at_the_Beach
) 1 hour ago
SAN DIEGO A series of moderate earthquakes south of the California border on Saturday shook buildings in downtown San Diego but there were no reports of damage or injuries.
The U.S. Geological Survey says a magnitude-4.9 earthquake struck at 10:30 a.m. Saturday, centered in Baja California about 16 miles southwest of Calexico. A magnitude-4.8 earthquake struck about three minutes later, followed by a 3.6 quake at 10:59 a.m.
San Diego County Sheriff's Lt. Hank Turner says shaking was felt in downtown San Diego. Dispatchers received no calls reporting damage or injuries.
Saturday's earthquakes struck in the same area as the magnitude-7.2 quake that killed two people in Mexicali, Mexico, on April 4. The region has seen a surge in seismic activity since then.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
SAN DIEGO (AP) A series of moderate earthquakes south of the border shook buildings in downtown San Diego but there are no reports of damage or injuries.
The U.S. Geological Survey says a magnitude-5.3 earthquake struck at 10:30 a.m. Saturday, centered in Baja California about 16 miles southwest of Calexico. A magnitude-4.9 earthquake struck about three minutes later, followed by a 3.6 quake at 10:59 a.m.
(Excerpt) Read more at google.com ...
|MAP||3.9||2010/05/22 20:15:52||32.571||-115.759||3.8||25 km ( 16 mi) SSW of Seeley, CA|
|MAP||3.0||2010/05/22 19:57:38||32.577||-115.743||2.4||24 km ( 15 mi) SSW of Seeley, CA|
|MAP||3.0||2010/05/22 18:34:03||32.558||-115.730||3.3||25 km ( 16 mi) WSW of Calexico, CA|
|MAP||3.6||2010/05/22 17:59:45||32.583||-115.777||2.4||25 km ( 15 mi) SSW of Seeley, CA|
|MAP||4.8||2010/05/22 17:33:17||32.622||-115.802||0.0||22 km ( 13 mi) SSW of Seeley, CA|
|MAP||4.9||2010/05/22 17:30:57||32.593||-115.756||5.4||23 km ( 14 mi) SSW of Seeley, CA|
I felt nothing in RB.
BTW, still no oil on my beaches.
They shook the South40 estate pretty well.
Some thing is rocking and rolling south of the Salton Sea .
How close is the estate?
Good luck and stay alert.
The stress-triggering theory makes intuitive sense: large earthquakes cause stress release on the faults where they occur, but they also add and subtract stresses on the surrounding region. A seismic event, by changing the stresses around it, can make one quake less likely and another one more likely. Ross Stein, a U.S. Geological Survey scientist who is the main driver of this line of research, calls this interaction "earthquake conversations."
An example is the San Francisco Bay area, where the great earthquake of 1906 reduced stresses across the bay, causing a lull in moderate-sized quakes that lasted the rest of the 20th century. The opposite occurred in Turkey along the great North Anatolian fault. A large quake in 1939 sent stresses farther down the fault, triggering a 60-year series of quakes whose latest installment was the deadly Izmit earthquake of 1999. The stresses have risen in the crust near the city of Istanbul, and a quake there is now considered more likely.
Let's see how it works in southern California. A decade ago on the morning of 28 June 1992, the magnitude-7.4 Landers quake changed stresses over a wide region shown on the map below. Red is higher, purple is lower stress.
"Coulomb" stress changes in southern California after Landers earthquake. Pacific Ocean at lower left, Salton Sea at lower right. San Andreas fault zone runs northeast from Salton Sea; Pinto Mountain fault runs east-west in center. White dots are significant aftershocks. All images courtesy U.S. Geological Survey.
Three hours after this earthquake, the magnitude-6.5 Big Bear quake occurred where the stress rise was the greatest (the gray dots are aftershocks and other unrelated earthquakes):
In the nine years afterward, other earthquakes including the Hector Mine quake struck in different parts of the post-Landers stress pattern, but as of the end of 2001 little had changed in the part near Big Bear. If you were looking at this map below, where might you forecast the most likely quake in that part?
Now see where the February 22 event took place:
So this earthquake fits Stein's theory quite well. The only strike against it is that it's not a large quake and won't change the stresses around Big Bear much. But another quake this size happened in the same place on 26 October 1998, and a 5.1 quake occurred nearby in February 2001. A few more of these will start to add up.
Ross Stein's research group at the USGS has some great supporting information online. The stress images come from a fascinating animation there. You can also read a very lucid version of his thinking in the January 2003 Scientific American in the article "Earthquake Conversations."
And I was up close to the Hector Mine Quake....
It was a nice slow roller in Mission Bay.
East San Diego County, about 60 miles away.
Thanks for the clarification.
“Rancho Bernardo is in the northern hills of the city of San Diego, California.”
It’s on the I-15....
I see something I recognize, Big Bear.
I spent Christmas there four years ago, on the lake.
I have not problems with constipation since that quake.
We felt the 10:30 one....a little jolt that tipped over a small picture frame on the dresser.