News

Two Sunday quakes were 'relatively shallow'

Temblors originated in Monte Vista fault zone, with epicenters in Los Altos

The two Sunday earthquakes that jolted parts of the Midpeninsula and were centered in Los Altos occurred at a depth considered "relatively shallow" in the Bay Area -- 3.5 km (2.1 miles), a seismologist from the U.S. Geological Survey (USGS) reported Monday morning.

The first quake, a 3.1 magnitude at 9:28 a.m., emanated under Briarwood Court, which is northeast of the Rancho Shopping Center. It was accompanied by two aftershocks of magnitude 2.0 less than 0.2 miles away, near Covington Road and Riverside Drive, seismologist Steve Walter stated in an e-mail.

A map of seismic activity also showed a smaller shock hit Sunday just east of Interstate 280, where the fault plane surfaces, near Dawnridge Drive.

Sunday's second quake -- a 2.4 magnitude -- occurred at 6:38 p.m. with an epicenter along Altos Oaks Drive, less than 0.3 miles from the morning quake.

Due to their depth, the quakes were determined to have originated in the Monte Vista fault zone, Walter said.

"The Monte Vista fault zone is part of the larger Foothills Thrust fault system that bounds the southwest margin of urban Santa Clara Valley," Walter wrote in an e-mail, quoting a paper by Vicky Langenheim and others.

A seismic map shows the plane of the Monte Vista fault zone surfaces along 280 and branches into forks on both the east and west sides of the highway. It reportedly runs through the Foothill College campus.

Although residents were startled by the earthquake, there was little if any damage.

Kathy Hobson, a resident on Briarwood, said described the morning temblor as "a loud bang."

"My dog came and looked at me and said what's going on? The lights were swinging, but nothing fell off anything," she said.

Another resident on the street, who did not want to be named, said it "sounded like a freight train" when the quake hit.

"It shocked me out of my chair," she said.

Click here for a map containing local fault lines.

Bay City News contributed to this report.

— Palo Alto Weekly staff

Comments

 +   Like this comment
Posted by nothing in midtown
a resident of Midtown
on Dec 19, 2010 at 9:51 am

I didn't feel anything.


 +   Like this comment
Posted by Palo Verde Resident
a resident of Palo Verde
on Dec 19, 2010 at 9:52 am

Didn't feel it!


 +   Like this comment
Posted by Palo Verde Resident
a resident of Palo Verde
on Dec 19, 2010 at 9:54 am

Didn't feel it! But, who has lost power?


 +   Like this comment
Posted by Rose
a resident of Charleston Meadows
on Dec 19, 2010 at 9:54 am

I felt it--a mild rocking back and forth. I guess that it's time to double check my emergency water supplies. :)


 +   Like this comment
Posted by Downtown condo
a resident of University South
on Dec 19, 2010 at 9:58 am

Felt it. It was a subtle but noticeable shake. I looked at the clock and it was 9:28.


 +   Like this comment
Posted by Em
a resident of Mountain View
on Dec 19, 2010 at 10:14 am

Woke us up this morning! Exactly at 9:28. Felt like someone slammed the front door and the house vibrated for a second. Went to look up if there had been an earthquake because we couldn't really tell.


 +   Like this comment
Posted by MC
a resident of Mountain View
on Dec 19, 2010 at 10:21 am

Felt it. I moved into a doorway for fear of a larger quake immediately after. Probably good to have these small quakes to release the pressure along the fault though.


 +   Like this comment
Posted by Seacliffee
a resident of another community
on Dec 19, 2010 at 10:27 am

Noticed at Seacliff State Park, Aptos (Santa Cruz Co)- Thought it was a big Gust of wind when my RV rattled!


 +   Like this comment
Posted by FeltitinLosAltos
a resident of Los Altos
on Dec 19, 2010 at 10:31 am

Does that map show the exact epicenter? It looks like it hit right by Andronicos on Foothill Xwy. Wonder if anything fell off of the shelves.


 +   Like this comment
Posted by LA gardener
a resident of Los Altos
on Dec 19, 2010 at 10:49 am

I live near the epicenter and it felt a lot bigger than 3.1. Several big shakes and rumbles.


 +   Like this comment
Posted by NicoleinPA
a resident of Palo Alto Hills
on Dec 19, 2010 at 10:58 am

I felt it, it woke me up. It felt like a jolt then a slight short rumble. It did not last long and it was mild. I also thought it might have been the wind.


 +   Like this comment
Posted by Me neither
a resident of Palo Verde
on Dec 19, 2010 at 11:08 am

I did not feel it neither, but my dog did, she cried as she was in pain, and got nervous. I thought it was the wind.


 +   Like this comment
Posted by Barely felt
a resident of Charleston Meadows
on Dec 19, 2010 at 11:28 am

So in conjunction with the minor earthquake there was last year, does this mean we can start to expect a lot more from the Monta Vista fault?


 +   Like this comment
Posted by Resident
a resident of Los Altos Hills
on Dec 19, 2010 at 11:52 am

We felt it...whole house rattled...we live near 280-Page Mill...


 +   Like this comment
Posted by Casper48
a resident of Mountain View
on Dec 19, 2010 at 12:12 pm

I live in a first floor condo in the PA/LA/MV triangle, and I felt it. There were two loud bangs -- I thought my neighbors had slammed their doors really hard -- until the shaking. This was the first time in my life I ran underneath a door jamb. According to USGS, it was felt as far as Boulder Creek and parts of Santa Cruz. Is Monta Vista a spur of San Andreas??


 +   Like this comment
Posted by saleha
a resident of Old Palo Alto
on Dec 19, 2010 at 1:05 pm

First it sounded like someone slammed a door hard and then there was a sharp jolt...like somebody really heavy fell upstairs...I didn't feel any shaking though.


 +   Like this comment
Posted by Just like it is
a resident of Greenmeadow
on Dec 19, 2010 at 4:19 pm

Made me choke on my oatmeal, after the dog barked and scared me! Yee Haw!!!!


 +   Like this comment
Posted by nothing in midtown
a resident of Midtown
on Dec 19, 2010 at 7:14 pm

Didn't feel either one in midtown.


 +   Like this comment
Posted by the watcher
a resident of another community
on Dec 19, 2010 at 11:30 pm

A friend of mine lives near the Nob Hill/Marshalls Mall on Grant Rd.
She says the 9:30am earthquake's jolt was felt in two short successions. The first jolt was heavier in that her dwelling actually shook. The duration of the EQ was less than 5 seconds. She reported no damage was done.


 +   Like this comment
Posted by Mr. Big
a resident of Embarcadero Oaks/Leland
on Dec 20, 2010 at 1:12 am

Definite felt the first one and it's the closest epicenter of a quake I felt in memory.

I was on the second floor then heard a crack then the rumbling of the earth. I figured it was a low 3 at the time, I'm pretty good at guessing the Richter ratings since I've lived here my whole life.


 +   Like this comment
Posted by Shake'n'Bake
a resident of Menlo Park
on Dec 20, 2010 at 9:44 am

Where I live, we have three or four earthquakes most evenings. That is, right along the Caltrain corridor, when the freights go by. It's about 3.0 on the Richter scale.


 +   Like this comment
Posted by Alan
a resident of Charleston Meadows
on Dec 20, 2010 at 10:21 am

According to the USGS web-site that area has had 6 small earthquakes in the past 48 hours. Only the two largest are reported here. Another 2.4 was deeper and an other three 1.x earthquakes happened also.


 +   Like this comment
Posted by Palo Alto native
a resident of Charleston Meadows
on Dec 20, 2010 at 10:40 am

Didn't feel either of those yesterday.


 +   Like this comment
Posted by Dr. W
a resident of Stanford
on Dec 20, 2010 at 11:03 am

My husband felt it! He thought it was the wind blowing the house.


 +   Like this comment
Posted by Berrocal
a resident of Los Altos Hills
on Dec 20, 2010 at 10:03 pm

I live about 100 yards from a mapped fault called the Berrocal fault. On the fault map linked-to in this article, look for Palo Alto Foothills Park. You'll see a black line running through it. That's the Berrocal and a geologist once told me it is capable of a 7.0 quake. He said if that ever happened, my property (south of the fault) would gain about a foot in elevation. Yippee!


 +   Like this comment
Posted by What earthquakes?
a resident of Another Palo Alto neighborhood
on Dec 21, 2010 at 1:35 pm

Earthquakes? Those were tiny and I felt nothing... Of course, I haven't felt too many earthquakes since the Loma Prieta earthquake in 1989. Now that was an earthquake.


 +   Like this comment
Posted by yabadoo
a resident of Los Altos
on Dec 21, 2010 at 2:38 pm

Kathy Hobson reportedly claims that her dog "came out and looked at me and said what's going on"? according to this Weekly story. Yikes! Once dogs start talking, I'm preparing for the big one.


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