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Magnitude 6.7 (ELEVEN YEARS AGO TODAY) Northridge, CA 1994 Jan 17 12:30:55 UTC local time 4:30AM
USGS Earthquake Hazards ^ | 17 January 1994

Posted on 01/17/2005 3:45:05 AM PST by bd476

Earthquake Hazards Program: Northridge, California 1994 01 17

"The USGS Earthquake Hazards Program provides earthquake information for current and past earthquakes, hazards and preparedness information, and education resources for teachers and students."

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EQ Facts & Lists


Large Earthquakes in the United States

Northridge, California
1994 01 17 12:30:55 UTC (local time: 4:30 a.m.)
Magnitude 6.7

Northridge, California

Sixty people were killed, more than 7,000 injured, 20,000 homeless and more than 40,000 buildings damaged in Los Angeles, Ventura, Orange and San Bernardino Counties. Severe damage occurred in the San Fernando Valley: maximum intensities of (IX) were observed in and near Northridge and in Sherman Oaks.

Lesser, but still significant damage occurred at Fillmore, Glendale, Santa Clarita, Santa Monica, Simi Valley and in western and central Los Angeles.

Damage was also sustained to Anaheim Stadium. Collapsed overpasses closed sections of the Santa Monica Freeway, the Antelope Valley Freeway, the Simi Valley Freeway and the Golden State Freeway.

Fires caused additional damage in the San Fernando Valley and at Malibu and Venice. Preliminary estimates of damage are between 13 and 20 billion U.S. dollars. Felt throughout much of southern California and as far away as Turlock, California; Las Vegas, Nevada; Richfield, Utah and Ensenada, Mexico. The maximum recorded acceleration exceeded 1.0g at several sites in the area with the largest value of 1.8g recorded at Tarzana, about 7 km south of the epicenter.

A maximum uplift of about 15 cm occurred in the Santa Susana Mountains and many rockslides occurred in mountain areas, blocking some roads. Some ground cracks were observed at Granada Hills and in Potrero Canyon. Some liquefaction occurred at Simi Valley and in some other parts of the Los Angeles Basin.

1994 Northridge, California Earthquake

USGS Response to an Urban Earthquake Northridge '94

Northridge Earthquake Research Products


 

 



TOPICS: Extended News; Front Page News; News/Current Events; US: California
KEYWORDS: aftershocks; california; earthquakes; epicenters; faults; focus; foreshocks; geologists; geophysics; hazards; hypocenters; intensity; intensityscales; magnitudes; magnitudescales; mercalli; moment; northridge; plates; probability; quakesprobabilities; richter; seismic; seismicity; seismograms; seismographs; seismologists; seismology; subduction; tremors; unitedstates; waves; world
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To: commonguymd
Did you hear about the 6.8 quake on the 12th in the mid Atlantic?

Your door frame advice reminds me of a story I heard when I first moved to California:

There was a rather large quake which hit unexpectedly (somewhere) in the Midwest during an after work wine tasting party. One man yelled out "I'm from San Francisco, I'm going to stand under a door frame!"

Another man yelled "I'm from New York! Where do I stand?!"

41 posted on 01/17/2005 5:10:56 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476
There was a female student just getting out of her car when the walls fell on her. Very sad.

That was the '87 Whittier Narrows quake, and it was Cal State L.A. I lived in Whittier and was on my way to the same school for a morning class, and always parked in that same lot, which was in the back of the school. It gave me a really creepy feeling, death hitting so close to home.

42 posted on 01/17/2005 5:15:15 AM PST by truthkeeper (Yeah, I have a 1998 signup date. So?)
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To: Route101
Right, the Sylmar quake was not fun for those nearest the epicenter.

I have friends that live probably fairly close to where your family was located. I remember going up there to see if I could help clean up their house.

When those helicopters fly overhead, the least they could do is squawk through their loudspeakers what or who they are looking for and what, if anything they see.

43 posted on 01/17/2005 5:15:37 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476
What's really hard to imagine is that you returned to your job on the 22nd floor in a building on Olive St.

The building was safe - on springs. The swaying up there (I had a window office) was really different than the liquifaction on the west side.

We were closed for the MLK holiday but I recall our boss chewing us out for not coming in and checking that everything was ok. Coming in over a freeway that had overpasses down. Now HE was nuts ;-)

44 posted on 01/17/2005 5:17:51 AM PST by DaveMSmith (http://www.heavenlydoctrines.org)
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To: truthkeeper
It's always amazing to me how far away each earthquake can be felt.

Fortunately, I was not here during the 1971 quake. Everyone who was here, usually says the same thing - that it was far worse than the Northridge quake.

45 posted on 01/17/2005 5:18:28 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

Exactly...those choppers would criscross the area shining their high power lights all over the neighborhood all night long...freaky.


46 posted on 01/17/2005 5:21:23 AM PST by Route101
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To: commonguymd
Magnitude 6.8 - CENTRAL MID-ATLANTIC RIDGE
2005 January 12 08:40:03 UTC
Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver

A strong earthquake occurred at 08:40:03 (UTC) on Wednesday, January 12, 2005. The magnitude 6.8 event has been located near the CENTRAL MID-ATLANTIC RIDGE. (This event has been reviewed by a seismologist.)



Magnitude 6.8

Date-Time Wednesday, January 12, 2005 at 08:40:03 (UTC) = Coordinated Universal Time
Wednesday, January 12, 2005 at 7:40:03 AM = local time at epicenter
Time of Earthquake in other Time Zones

Location 0.838°S, 21.209°W
Depth 10 km (6.2 miles) set by location program
Region CENTRAL MID-ATLANTIC RIDGE
Distances
1095 km (680 miles) NW of Ascension Island
1290 km (800 miles) ENE of Fernando de Noronha, Pernambuco, Brazil
1710 km (1060 miles) ENE of Recife, Pernambuco, Brazil
3360 km (2090 miles) ENE of BRASILIA, Distrito Federal, Brazil

Location Uncertainty horizontal +/- 10 km (6.2 miles); depth fixed by location program
Parameters Nst=121, Nph=121, Dmin=>999 km, Rmss=1.15 sec, Gp= 86°,
M-type=teleseismic moment magnitude (Mw), Version=Q
Magnitude 6.8
47 posted on 01/17/2005 5:31:10 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

Yes....Any quake I have been in ...I measure by the Sylmar Quake...Honest to God it has helped me cope with all the rest of them....


48 posted on 01/17/2005 5:31:45 AM PST by Route101
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To: truthkeeper

Very tragic. I remember seeing her photo on the news, very sad. It sounds as if it was a close call for you.


49 posted on 01/17/2005 5:32:40 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: DaveMSmith
Yep, your boss probably was a few floors short of the top floor.

The exit off one of the freeways on my road to work collapsed, but my boss wanted everyone there pronto - and then requested everyone stay until the next day.

People were walking around in shock.

I remember that our street was completely blocked at both ends but I don't recall what it was blocking us in. It could have been the light poles which came down. Some parked cars were also displaced into the middle of the street - that was interesting.

There was a three story building on my block which was reduced to about a level and a half if you include that the top floor had pushed the first floor into the parking garage 1/2 way. Yet LA Fire Dept. couldn't get down our street to rescue anyone because the street was blocked.

They finally parked a street away and walked over to the crushed building. Fortunately the owners were out of state on vacation.

50 posted on 01/17/2005 5:41:44 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: commonguymd
... Stand near the door jam when possible ...

THIS GUY DISAGREES WITH THAT

BUT THE AMERICAN RED CROSS DISAGREES WITH HIM

51 posted on 01/17/2005 6:02:27 AM PST by FReepaholic (Proud FReeper since 1998. Proud monthly donor.)
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To: bd476


The Northridge Meadows Apartments is shown in this Feb. 16, 1994, file photo after a 6.7-magnitude earthquake centered in the Northridge section of Los Angeles struck Jan. 17, 1994. Of the dozens of people killed by the quake throughout Los Angeles, the most deaths in any one place, 16, came at the complex near the quake's epicenter. What remained of the apartments were razed and replaced with a new residential complex. (AP Photo/Nick Ut)



Rescue workers walk past the Northridge Meadows Apartments that collapsed during the earthquake in Los Angeles in this Jan. 17, 1994, file photo. Ten years later, it's hard to imagine that so many parts of Southern California lay in ruins on Jan. 17, 1994, thousands of its buildings smashed, millions of its people shaken both emotionally and physically, 72 of them killed. The remains of apartment building at the epicenter of the quake was torn-down and replaced with a new residential complex. (AP Photo/Eric Draper, File)
52 posted on 01/17/2005 6:04:42 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

53 posted on 01/17/2005 6:12:19 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

I'll never forget it. My sister called me from where she used to live in Sherman Oaks and said "We're having an earthquake and it's a really scary one this time!" and then the line went dead.

I was able to tell everyone in the newsroom minutes before the alert came across the wires, but man, was I nervous and upset until I heard from her again. They had damage but nothing major or irreplaceable and no one was injured. She said their cat had been acting strangely for about two days so he must've known it was coming.

She described that first day as something like a scene from 'an end-of-the-world movie', with people coming outside in the eery light, all confused and...well, shaken.


54 posted on 01/17/2005 6:18:15 AM PST by arasina (So there.)
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To: bd476
2002 News Releases

Northridge Quake Activity Has Apparently Subsided, Says NASA September 30, 2002

       The Northridge fault surprised residents of greater Los Angeles with a magnitude 6.7 earthquake on January 17, 1994, killing 60, injuring more than 7,000 and causing more than $20 billion in damage. Now, it has surprised scientists again.

       "Recent measurements indicate the Northridge fault has slowed to a crawl," said Dr. Andrea Donnellan, a geophysicist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Following a quake, Earth's crust readjusts to changing forces. We expected the Northridge region to re-adjust for at least another 20 years, but it looks as though that readjustment is largely done."

       So what put the brakes on? Donnellan says evidence points to the physical state of rocks deep in the region's crust. The Northridge quake began in the lower crust, which unlike Earth's brittle upper crust is usually "gooey." "But with Northridge," says Donnellan, "measurements of the speed seismic waves travel through the region indicate the lower crust is actually cold and hard -- like frozen molasses. This cold crust apparently brought Northridge to the conclusion of its earthquake cycle much sooner than expected, or perhaps is causing the region to adjust so slowly that we can't detect it. In contrast, the lower crust in places such as Landers in the Mojave Desert -- site of a 1992 magnitude 7.6 quake-is 260 to 538 degrees Celsius (500 to 1,000 degrees Fahrenheit) warmer, so quake responses in such regions can be measured for a longer time."

       Donnellan cautioned that this information doesn't mean there still couldn't be aftershocks, or that neighboring faults couldn't rupture. "It's an interacting system," she said. "A quake on one fault may turn on or turn off a quake on another. While an earthquake is not likely to happen directly on the fault that broke in 1994, we don't know the status of Northridge's neighboring faults -- where they are in the cycle of building up stress, releasing the stress through a quake, and then building up stress again. There are indications neighboring faults were affected, and it's possible one of them may break, but we don't know when. Understanding the way those faults were affected will take time."

       In the study, presented recently to the Seismology Society of America, Donnellan and colleague Dr. Gregory Lyzenga, a JPL geophysicist and professor at Harvey Mudd College, Claremont, Calif., analyzed data from global positioning system (GPS) receivers arrayed throughout Southern California and radar images taken before and after the Northridge quake.

       When the quake struck, Donnellan and other scientists had been monitoring the area with GPS for eight years. Each receiver continuously measures its location, detecting surface changes as small as 3 millimeters (a tenth of an inch) horizontally and 7 millimeters (a third of an inch) vertically.

       Measurements show that during the 1994 quake, the fault slipped two to three meters (6.5 to 9.8 feet), starting about 18 kilometers (11 miles) deep in Earth's crust and rupturing up to about 5 kilometers (3 miles) below the surface. In the 18 months following the quake, it moved an additional 30 centimeters (about one foot), raising the nearby Granada Hills about 12 centimeters (about 5 inches).

       "Ninety percent of the movement after the initial earthquake was a quiet sliding motion, or aseismic," said Donnellan. "Only 10 percent was seismic -- the shaking motion a seismometer measures. That's why new tools like GPS and advanced radar are so important. We're just now seeing how Earth behaves with geodetic measurement -- we're able to observe these quiet processes and get insight into the whole system."

      

In response to the Northridge disaster, NASA led a collaboration of agencies to develop and install the Southern California Integrated GPS Network, which now includes more than 250 stations in 14 California counties and Mexico. The network allows scientists to monitor movements of Earth's plates. "We can now see how faults interact and look at whole fault systems, not just individual ones," said Donnellan.

       But while GPS receivers are measuring continually, they're not measuring everywhere. For the most complete map of every change a quake makes on the surface, scientists turn to satellite interferometric synthetic aperture radar.

By combining detailed radar images taken before and after a quake, they can pinpoint surface changes caused by the initial quake and track its aftermath. "You would need a GPS receiver every 20 meters (about 66 feet) to get the same information," said JPL geologist Dr. Gilles Peltzer, a specialist in interpreting radar data. Radar images of Northridge from the European Space Agency's European Remote Sensing Satellite-1 taken two months before the quake, combined with others from December 1995, help fill in the Northridge picture. Those results confirmed the GPS results, indicating the Northridge fault continued to slip after the event. They also shed light on the extent of the region subject to deformation as a result of the quake.

       Donnellan said increased use of space-based technologies will lead to better computer models and should, in the next 10 to 20 years, give scientists much clearer insights into how earthquakes behave and where and when they may occur.

       The two are now studying other California faults -- Oak Ridge, Sierra Madre, and San Cayetano -- developing computer models to see how stress is transferred between them.

       JPL is a division of the California Institute of Technology in Pasadena.

JPL News Release - Northridge Quake Activity Has Apparently Subsided, Says NASA



55 posted on 01/17/2005 6:29:09 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

Spose I better put my swimming trunks on - just in case.


56 posted on 01/17/2005 6:39:56 AM PST by commonguymd (My impatience is far more advanced than any known technology.)
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To: bd476

57 posted on 01/17/2005 6:46:51 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

58 posted on 01/17/2005 6:50:38 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

59 posted on 01/17/2005 6:53:50 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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To: bd476

60 posted on 01/17/2005 7:09:08 AM PST by bd476 (God Bless those in harm's way and bring peace to those who have lost loved ones today.)
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