Quake activity along the San Andreas fault is picking up

Hey farmerman, do you know of any geology/scientific blogs or forums where the professionals observe and discuss the plate movement and quake activity? I'd be interested in monitoring one but have yet to find one accessible to the public.

http://www.latimes.com/news/la-me-quake9-2009jan09,0,1518580.story

From the Los Angeles Times
Small earthquake rattles Los Angeles area
By Monte Morin
Los Angeles Times Staff Writer

8:41 PM PST, January 8, 2009

A 4.5 magnitude earthquake centered about a mile south of San Bernardino jolted Southern California briefly at about 7:50 p.m. Thursday evening, according to the U.S. Geological Survey and the Southern California Earthquake Center.

The quake was felt in downtown Los Angeles, parts of the High Desert, San Pedro and and coastal and inland Orange County, but was not felt as far south as San Diego. There were no immediate reports of damage, according to authorities.

"We felt the jolt, whatever time it came in, but we haven't had any reports of damages yet," said Rancho Cucamonga fire Capt. Ty Harris, whose station was built more than 50 years ago. "Our building is fairly old, and cinder block, and it shook pretty good here," he said.

Closer to the origin of the quake, Cal State San Bernardino Professor Dale Sechrest said the shaking lasted roughly 15 seconds. "Nothing fell over, nothing fell off the shelves," he said.

"Wow, we heard rumbling noise before the shock waves hit our home in Ontario," one reader wrote on a San Bernardino Sun message board.

The shaking was lighter -- but still strong -- in Orange County. "We felt it here in Yorba Linda. Shook the house for about 5-6 seconds. Nothing much except rattling but clearly an earthquake," a reader said on The Times' quake report board.

The USGS originally believed the quake measured 5.0. But officials later downgraded it to 4.5.

Earthquake experts have long said San Bernardino is particularly vulnerable to a massive temblor -- the type many times stronger than Thursday's quake.

San Bernardino lies between two of the state's most active earthquake faults, the San Andreas and the San Jacinto. Moreover, much of the city was built above a huge underground water basin.

Experts say this loose soil could liquefy in the event of a massive quake, causing buildings to topple. As of 2005, about 100 unreinforced masonry buildings in the city lacked any form of retrofitting, according to city and state records.

Moderate quake strikes San Bernardino
The Associated Press
Posted: 01/08/2009 08:10:32 PM PST


SAN BERNARDINO, Calif."A moderate earthquake struck Thursday night in San Bernardino, with shaking felt from Los Angeles 55 miles to the west and south to Orange County. No immediate reports of damage or injuries were reported.
A preliminary reading by the U.S. Geological Survey shows a 4.5-magnitude quake struck at 7:49 p.m. about one mile south of San Bernardino, a city of about 200,000 people. The USGS initially reported it at 4.9, then 5.0.

San Bernardino County Fire Supervisor Tim Franke said there were no reports of damage.

"It was a little roll and big jolt, then a sonic boom kind of noise," Franke said.

San Bernardino police, Orange County and Los Angeles County sheriff's officials also said no damage or injuries were reported.

Bryan Gillott, a tattoo artist who works at Alla Prima Ink Lab in San Bernardino, said he felt the ground rolling under his feet for several seconds. Gillott said he tried to call his mother on his cell phone but the call didn't go through.

"I was on the computer," he said. "We all just got to a doorway and waited for it to be over."

Julie Zeoli, a librarian at the Yorba Linda Public Library in Orange County, said she felt shaking but didn't have any mess to clean up.

"We didn't even have any books fall," she said. "We only felt it for about a second."

The quake struck near the San Jacinto fault, which is part of the San Andreas Fault system, said seismologist Lucy Jones of the

U.S. Geological Survey.
The San Jacinto fault cuts through the fast-growing city of San Bernardino west of City Hall. The city has dozens of unreinforced mansonry buildings that are prone to damage during a big quake, Jones said.

The quake was the latest moderate temblor to hit the region in recent months. A 5.1 magnitude hit in early December, and in July a magnitude-5.4 quake centered in the hills east of Los Angeles was the strongest to rattle a populated area of Southern California since the 1994 Northridge disaster.

4.5 earthquake shakes San Bernardino and much of Southland
Jason Pesick, Staff Writer
Posted: 01/08/2009 09:14:29 PM PST


SAN BERNARDINO - A 4.5 earthquake centered near downtown shook much of the Southland on Thursday night.

Karen Brown, a dispatcher with the U.S. Forest Service working at Tippecanoe Avenue and Mill Street, said she hadn't heard of any damage.

"It felt like the building was picked up, dropped and shook," she said.

The quake struck at 7:49 p.m. and could be felt as far away as San Diego, according to the U.S. Geological Survey.

The July 29 Chino Hills quake that broke water lines, shattered windows, knocked food off grocery-store shelves and knocked out power measured 5.4 by comparison.
There were also a number of small aftershocks in the hour following the quake, including a 3.3 earthquake in San Bernardino at 8:47 p.m.

Public-safety agencies said there were few reports of immediate damage.

"We do not have any calls for service, anyone reporting damage to property or injuries to any person," said sheriff's spokeswoman Jodi Miller.

County and San Bernardino city fire officials also said there were no reports of injuries or damage.

Loma Linda fire officials said a woman they thought was about 90 years old fell out of bed while reading the newspaper and landed on her leg, breaking it. She also had a bloody nose and lip.

The earthquake was powerful enough to knock over small objects sitting on tables in Los Angeles.

It appeared to be centered near the San Bernardino Police Department's headquarters.

"It was actually underneath our E Street gate," said Lt. Gwendolyn Waters.

More curious quake activity. We've had 5 quakes over 2.5 today all in the same spot. The last 4 have been in the last 90 minutes starting at 2.8 and increasing to 3.9. Including the ones under 2.5 there have been 18 quakes in that spot today.

It is all centered near Tres Pinos near the same locality as the Loma Prieta quake in '89.

For comparison, there were only 2 quakes in that same area yesterday (19th), each less than 2.0. And there was only 1 quake in that area on the 18th and 17th.

I dont like news about quake swarms. They can be messengers. It appears that theres no focus of energy in these last ones.

Reading along, as a former Californio...

We're still moving. 12 more at Tres Pinos today so far, the largest of which was 3. 4. At least the magnitudes have stopped increasing.

There was a total of 32 of them on the 20th, so hopefully that was the worst of it for now.

I see that the swarms are continuing into 1/23. I do get concerned when quake swarms coalesce around tidal maxima.
Anybody know when the full or dark moon is?

Dark moon is the 26th, Full moon is Feb. 10th.

Hmmm, a coupla geos at Menlo have been plotting quake intesnity and occurence v moon phases (moon phases parallel major and minor tidal variation)

http://www.adn.com/news/alaska/story/666212.html

USGS has it as a 6.1 quake.

We're heading out of the full moon phase today and the swarm of small quakes continues in the areas of Tres Pines, Cloverdale and the Geysers areas though not quite as frequently as a month ago. Most have been under 3.0 but a few have been above.

You could be out of the woods for another few earth tide cycles. These cycles dont necessarily mean that a big one is imminent, just that conditions seem to be favorable. I was worried because of the mess of swarms of quakes at not a single focus, that usually means that some larger tectonics is going on along the entire western cordillera all the way to Alaska.

Having a bunch of quakes at lower intensities does release some of the stresses so thats good.

FM: I'm trying to grasp what this means....so with the greater intensity with the Alaskan activity, doesn't that indicate an Alaskan area quake ?

One thing about earthquakes is the simple fact that nobody is able to predict the when. We just know it'll come in the future - like other natural disasters.

prediction is better than it once was but hardly someting to plan your life around -- though if you're on a fault line..you have no choice, as you have to.

No you don't have to even then. Albuquerque, especially the south end area called the "South Valley" sits on a ancient fault that sooner or later will cut loose though it has not done so for many hundreds if not thousands of years. According to the resident experts, it could generate a quake in excess of 8.0.

Not being a particularly active seismicly active area, we would be completely unprepared for that and our infrastructure and buildings were not constructed with earthquakes in mind so the damage would be massive if not total.

But do we go around fretting about that? No. Probably very few people even know the situation exists and the those of us who do figure the odds are in our favor that it won't happen in our lifetime. So we don't worry about it.

We live near the shadow of two catastrophic volcanoes that could reawaken any time too, and we don't spend any time worrying about that either.

If we were getting a lot of little shakers and other warning signs though, I'm sure we would be educated and a bit more cautious really quickly.