June 28, 2012
Landers @ 20
Posted by Austin Elliott
My favorite earthquake photo ever: dextral offset of a desert road surrounded by Joshua trees, taken by geologist Kerry Sieh during a reconnaissance trip five hours after the 1992 Landers earthquake.
Today is another noteworthy anniversary. [Quakiversary, as I’ll start calling them if I’m not careful and don’t restrain my incessant compulsion to merge phrases through obnoxious portmanteau-ing of things.] It marks twenty years since California’s largest earthquake in the last six decades, an earthquake that once again transformed the way we understand fault rupture.
Twenty years ago, on June 28, 1992, Angelenos and others throughout the desert southwest were rolled from their slumber by a massive 5am shock from the Mojave. The M7.3 earthquake ripped erratically through small California desert towns just north of Joshua Tree National Park (then a National Monument). The rupture jumped from one fault to another, linking together fractures in the ground that experts had previously considered discontinuous, unconnected, and thus capable of producing only relatively smaller earthquakes.
Fresh fault rupture passes directly beneath/through a house in Landers, CA after the 1992 earthquake. This scene illustrates the value of setting structures back from active faults as outlined in California’s Alquist-Priolo Zoning Act.
The towns of Yucca Valley and Landers were hit exceptionally hard, with violent shaking and in many cases primary ground rupture ripping through homes and buildings. Other desert towns–Twentynine Palms, Palm Springs, Barstow, Victorville–and the San Bernardino mountains experienced a lengthy period of strong shaking. The vast but more distant populations of Los Angeles and Las Vegas were rocked strongly and slowly, undoubtedly recognizing that something serious was happening somewhere… else. This was not their earthquake.
USGS Community Internet Intensity Map for the June 28, 1992 M7.3 Landers earthquake
Aftershocks rumbled and rattled as people began their days in premature wakefulness, and as details of the disruption in the desert towns occupied the headline spot in the 8am news, a sudden sharper jolt tore outwards through Los Angeles.
Have a look at the event occurring in CNN’s national feed. Skip ahead to 3:00 for the full experience.
[youtube=http://www.youtube.com/watch?v=iQWbJX-HGuU]
The second earthquake, this one of magnitude 6.5, had been unleashed closer to L.A., rather far from the 5am mainshock and on a completely different fault system, centered near the resort town of Big Bear in the San Bernardino Mountains. Now aftershocks were emanating from the mountains above town and the giant tear out in the desert.
Basic map showing location and time of major earthquakes in the 1992 Landers sequence, and their aftershocks. Mapped June 28 fault ruptures are in yellow, other faults in black. The Los Angeles metropolitan area occupies the freeway-filled basin in the lower left.
Field teams from the USGS, Caltech, and other institutions around southern California mobilized immediately to investigate the damage and ground rupture from this earthquake, and thus is it one of the best recorded and documented earthquakes of recent decades. It was the first so have such extensive immediate field coverage.
To mark the current anniversary, the Desert Sun has a slideshow of pictures from the early 90s aftermath, along with some eyewitness reminiscence.
The Landers sequence is my favorite illustration of earthquake behavior because it covered all the basics: There were immediate foreshocks–all <M3–preceding the event by minutes, but a sequence of substantial quakes near the mainshock epicenter had occurred back in April. The aftershocks began immediately, and quickly delineated the extent of fault rupture. Then there’s the triggered earthquake and its own aftershocks. Much research has focused on the stress changes induced by the 7.3 mainshock and how they led to the 6.5 Big Bear quake that happened three hours later, outside of the strict aftershock zone.
We learned a lot about seismicity from this sequence of quakes, but its more lasting impact has been the recognition that nearby faults can link together and rupture in a single earthquake. The Landers earthquake broke open five separate, previously mapped faults, connecting them to each other through a network of unmapped structures that hadn’t been visible in the landscape prior. Since then many more earthquakes have occurred in this manor, including notably its Mojave successor the 1999 M7.1 Hector Mine earthquake, as well as the recent M7.2 El Mayor-Cucapah earthquake just south of the border.
Looking eastward down Linn Road on a 2010 visit to Landers, CA. The 1992 earthquake right-laterally offset the entire street grid several meters, so its effect is still quite visible today, 20 years later.
The well studied rupture from this earthquake is still evident out in the desert as subtle, rain-softened scarps stretching northward from Joshua Tree NP. The entire town of Landers was literally rent in two, with the eastern half sliding meters southward and the western half lurching to the north. The grid of streets still shows this spectacular offset. The whole area is worth a visit if you’re doing some fault-finding tourism, and especially if you love the Mojave.
Yours Truly perched next to the 1992 rupture scarp of the Emerson Fault near Galway Lake Road, site of the maximum slip. The photo is from 2007, 15 years after the quake, and the scarp has deteriorated since then, but will remain a conspicuous step in the landscape for millennia.
I was about 150 miles away from the epicenter when the Landers quake struck and I’m sad to say I slept thru it. My field assistant felt it and once we heard radio reports of where it was and what had happened we took a day off to go find the fault trace. It took us most of a day to find the good ground offsets, but I got a couple of great slide photos of offset features (most of which are packed away right now, or I’d scan and share them). I remember particularly the right laterally offset chalk parking space lines in the dirt lot behind a small Baptist(?) church in Landers. The best offsets though were out in the desert along the Emerson Fault, if I recall correctly. We got there fairly late in the day and nearly got ourselves lost in the desert when the sun set. It was an unforgettable experience. Thanks for the reminder of its anniversary.
That sounds like a phenomenal experience: instant fault-finding adventure. We geomorphologists always want more of those. My PhD advisor’s Landers experience is pretty legendary. Maybe I should get him to tell it–I’ve always suggested he write a little essay about this–but the gist is that he was camping with friends in the San Bernardino Mountains. Lots of heavy shaking, out in nature with only the rocks and trees to jostle. The most notable thing he reports (other than the terror of not knowing where the quake hit and whether L.A. had just been wrecked) is the difference in sound between the more distant Landers quake/aftershocks and the much closer Big Bear quake/aftershocks, which occurred directly underfoot. The close ones made loud audible roars, while the distant ones were silent and bouncy. Frequency-dependent attenuation at work!
I was in Anaheim during this earthquake. I was 12 and my family was on a Southern California vacation. We were staying on the second floor of a motel and sleeping when the earthquake woke us up. The motion was VERY rolly. It definitely felt like you were out in the ocean riding big ocean swells. Nothing scary, you were just going along for the ride. After it was over, we went outside and everybody was out in the parking lot. Then we turned on the TV and watched the breaking news coverage. Interestingly, we didn’t feel the Big Bear quake. I don’t know where we were at the time, maybe driving around.
That’s quite a way to be introduced to SoCal! I suspect most people in quake-prone areas have some sense of the difference in urgency (maybe it’s just intuitive) between “sharp, jolting” quakes and “rolling” ones. SoCal has had enough geographic scattering of quakes that I think people recognize the rolling motion means you’re feeling a big quake that’s really hitting somewhere else, as opposed to the sharp, high frequency jolt of a nearby temblor.
I am always fascinated by that period you mention, after an earthquake, when news and new information are slowly trickling in and everyone is realizing the location and scope of what happened. It makes a remarkably different perspective from our more common historical view of earthquakes as well constrained events whose effects we talk about factually. In the immediate aftermath there’s so much confusion and ongoing surprise as people reel from what happened.
It’s also interesting how situationally dependent perception of earthquakes is. If you’re driving, or even running outside, it can be so easy to miss them–even sizable ones, obviously.
My grandmother took my cousin to California that summer and they spent it in San Diego, where one of my aunts was stationed at the time. It was his first plane ride and she promised him that there wouldn’t be an earthquake (he was terrified of them, and we really don’t have them in Pennsylvania.) Needless to say…the Earth had other ideas!
I, of course, was jealous beyond words.
(The Big Bear quake was captured on live international television via CNN, but I’ve yet to find any footage of it.)
It’d be great to see (or hear) any media coverage of the quakes from that morning. The only footage I know of is from the Big Bear Solar Observatory, where four astronomers/technicians were checking on damage from the earlier quake and recorded their escape as the nearby 6.5 rocked them. I can’t find it anywhere on the net, but I have it in an old VHS documentary about earthquakes.
Here’s the report of the observatory experience, for guidance if anyone wants to continue trying to track the video down:
http://solarnews.nso.edu/1992/12_92.html#2
Here are some great YouTube videos of media coverage that morning. You’ll see some of the famous SoCal seismologists (Lucy Jones, Tom Heaton, etc.) but looking much younger!
http://www.youtube.com/watch?v=LWms7nZZKh8
http://www.youtube.com/watch?v=iQWbJX-HGuU
http://www.youtube.com/watch?v=o4ucxltysUU
http://www.youtube.com/watch?v=P54bZFB5kIE
http://www.youtube.com/watch?v=VgYutThPmxk
oh, I forgot part of the story. My cousin’s mother was watching CNN at the time of the Big Bear quake, having been informed that there was an earthquake that morning, and completely melted down.
I don’t think either of them will ever go to California ever again.
Fascinating stuff. Keep up the good work.
[…] Excellent write-up from Trembling Earth blog marking 20 years since M7.3 Landers earthquake http://tremblingearth.wordpress.com/2012/06/28/landers-20/ […]
Remember this earthquake I was taking a summer bible class in Glendora when the Big Bear earthquake hit and it rocked the building I remember seeing the outside post sitting on Citrus Ave swaying the door was open and the door slam shut right after the earthquake.
I was living in Lucerne Valley at the time of the Big Bear quake. I remember being terrified because we couldn’t get out of the house. Things were shifting so badly the back door wouldn’t open and the front door was blocked by a china hutch that had fallen over. We spent the entire day sitting outside at our picnic bench listening to the radio broadcasts and watching the telephone poles sway with each aftershock. I was 16. Twenty years later I can recall with great detail everything from the terror of being woken up by an earthquake to the fascination of watching the telephone poles sway and the asphalt road ripple.
If I may resurrect a year old post…
I was living in Hesperia, CA when the Landers quake hit. I was out of state, but I returned shortly after the quake. In the following fall, I was taking a college class on the geology of California, and a friend from the class and I went to Joshua Tree National Monument (now National Park) to drive the geology tour road, allegedly for extra credit. Neither my friend nor I needed it, but it was a good excuse to go.
On the way back home, I asked my friend if he wanted to drop by my great-grandma’s house, as we’d be passing right by there. He said sure, and after meeting my relative and a wild desert tortoise ambling through her yard, we elected to climb the “mountain” behind her house.
From up there, we were looking nearly in line with Reche Road, one of the major east-west through streets in Landers. The asphalt was gray, with the obvious exception of a short bit that was dark black– obviously new. The new pavement had a rather pronounced offset to the right (quite obvious from the perspective of the low “mountain” we were on).
Excitedly, I pointed it out to my friend, and we of course knew what we were seeing. He was as thrilled as I was. We climbed down the mountain and drove to the section of new road we’d seen.
In piles on both sides of the road still lay the discarded asphalt from the patched section. The line of telephone poles to the immediate north of the road was obviously offset, and while the actual surface fault trace was no longer visible as a fissure as in the photo in this post, its location could easily be estimated… a large metal building in someone’s yard (just to the north of the offset pavement) was twisted on whatever means of ground anchorage it used, and just to the north of that, the posts that held up part of the roof that shaded their patio were bent at about a 45 degree angle, with the fault slip apparently having taken place between the house and the supports for the overhanging roof, which of course was now sagging toward the ground.
We jumped in my truck and saw similar offsets in fences (some repaired, some not; the ones that were not often had the wire or chain link material under a bit of tension with the posts on either side of the fault trace sometimes at odd angles.
Linn Road, which is to the north of Reche Road, had a new black patch just as Reche Road did. Most of the roads in the area are dirt roads, and it is more difficult to see the offsets on dirt roads. Fence lines, though, made the fault trace easy to follow.
All in all, it had been quite a geology day… on the way to the park that morning, I realized that a mass of rock I had seen passing by that way before was in fact the Blackhawk slide we’d read about in our texts and discussed, and we made a short side trip to check that out as well.
Fantastic story. The right-lateral offset of the whole street grid of the town of Landers (as you describe, and shown in my second-to-last photo) is a worthwhile pilgrimage for any curious geologists visiting Joshua Tree. It’s literally just 10 minutes north of Yucca Valley on Old Woman Springs Rd. (Hwy 247).
I just found the dilapidated old black and white photo I took from atop the “mountain” that day. I was also in a photography class at that time; otherwise, I would have been shooting in color. It’s definitely tattered and faded, but the patched section and the offset is still visible. Send me an email if you’d like to see it!
Ah yes, I’d love to see it. I suppose you can’t attach/link to it in the comments. Feel free to e-mail me. A working address is listed on my personal webpage, linked from the sidebar here –>
I was living in Corona at the time. Woke up in terror. It was the strongest shaking I’d felt since 1971 Sylmar quake (lived in Burbank back then.) The water in our pool sloshed so much it was still hitting the patio doors five minutes after the quake. Then a few hours later the Big Bear quake rolled through. There was too much going on to miss- landslides even. Got rolling with a 15 year old son who is also a geology nerd and arrived in Landers about 11am. We drove as far as we could down Reche Rd. before the road was blocked to traffic, found a spot to leave the car and took off on foot. There was no scarp visible from the offset on the road, only blocks of asphalt. Headed in the general direction of where it should have been and weren’t disappointed. One resident pointed us to that infamous white house on the knoll that was destroyed as it rested astride the fault. We sat on a 3-4 foot scarp about 500 feet away and felt a couple small aftershocks. Have photos of it and the house at that point- approximately Golden Slipper and Karol Rd maybe? Given encouragement will hunt them down. Walked as far as we could along the scarp northward as it disappeared and reappeared in the terrain. A shaken resident whose mobile home had been shaken off it’s foundation told us that “Jesus is coming”. Seeing Landers on that day was one of those once in a lifetime events, better than seeing Yosemite Valley for the first time- almost painfully beautiful.
Just as an aside, because we were in Landers my 15 year old HAD to see where the ufologist George Van Tassel had built his “Integratron” at Giant Rock. Before his passing in 1978 George claimed to have hosted visitors from outer space at the Integratron, and received cosmic revelations he called “Solgonda”. It was a big white dome and in 1992 it while it looked neglected, his “electrostatic dirod” was still there. Van Tassel put Landers on the map long before the earthquake, hee-hee.
Thanks for the great article. I live in Oregon now and waiting for Mt Hood to go off. 🙂
Haha, great anecdote, and I love that final touch with the glorious Mojave residents. I’d love to see the photos if you can scrounge them up.
I was 9 when the Lander/Big Bear quakes happened. I was living in Yucca Valley are remember the devastation quite vividly. My neighbor lost his house, we lost our bowling alley, K-Mart, movie theater, and more. We didn’t have water for over a week, power for a couple days and food was rationed by the national guard. it was a crazy experience, especially for a child. But at least earthquakes don’t bother me anymore. I actually find them exciting and fascinating these days. While everyone’s running for for cover I’m all smiles!
I was right on the epicenter when this quake hit. Right off of Richie Road. I grew up in California and have been thru dozens of quakes. Most don’t scare me as you just ride them out. However! This one was the worst I’ve even been in. Unbelievable. If this magnatude would have hit San Diego or LA there would have been loss of life and terrible property damage. After the quake finally stopped, which seemed like forever. We got our flashlights and could see all the damage and mess. Then every few minutes it seemed like we had after shocks. Needless to say your nerves were slightly rattled after a few hours of this. I will never forget it. I felt like I was on a drum and someone was beating it!
My husband and I were living in Victorville, CA at the time of the Sylmar quake. We were there from Louisiana as he was in the air force. We lived upstairs in an older building and the whole thing was shaking and trembling! We were awakened to this early morning event, wondering “what is this!” Pendant lights swayed, objects fell from shelves, and water and fish sloshed out of the aquarium! We were terrified! We had been through many hurricanes in our lives in LA but never anything like this!
I was i Yucca Valley that morning.My house was on a hill I could see all the way to 29 palms.There is no way to explain the violent forces of that quake but I will try.the ground slid back and forth maybe 20 feet.Everything in the kitchen was in the living room.including the fridge.I fled the house for fear of collapse it was cinder block.huge rocks rolling down the hill forced me back in.
later I tried to get in my pick up for safety but it was bouncing so hi it was impossible.I could see transformers exploding and fires all across the valley.I finally got in the truck between aftershocks and rode out the morning.later I discovered my rear shocks on my 1 ton duelly had both tore thru the frame rails.
Not mentioned here is the non stop after shocks lasting a month.weeks later a car was thrown off the auto lift at a muffler shop .A week after the quake at the store on the pickle isle all glassware exploded of the shelf and broke.the most amazing thing was the liquefaction that I witnessed many times after the shock.seeing the desert turn to ocean cant be described.once it liquified during a bright moon in was amazing.the small plane airport had many planes destroyed and upside down.
when the quake started you could here it.heavy sharp rumbling then a violent explosion of energy.I helped 3 friends drag there refrigerator back into the house.I delivered water for weeks to people with my small tank and truck.they would have me fill every vessel they had including there bath tubs.the nation guard was 1st on the scene.the police were maybe keeping people out I only saw one in the first 3 days.Every one slept outside for weeks.
My well was ruined,house unsafe.no work to be found and the ground would not stop moving for months I moved to Alaska.
I now live near Talkeetna Alaska and we just had a 6.1?quake and it brought back these memories so I have shared them here.
I have spare water,food,gas,medicine.my spare generator has a spare generator.LOL
I met a pioneer here the other day and he at length shared his Good Friday quake experience with me and what we went threw in Landers was nothing.
when the tips of 80 foot birch trees are slapping the ground for 20 minutes that is a quake.
I LIVED THERE
[…] Other interesting stuff: 1. The earthquake hit at 4:57 am on June 28, 1992 2. We felt the 7.3 earthquake hit, we felt it 130 miles away 3. When we turned on the television, they were saying that they didn’t know where the epicenter was, but they were sure it was in Joshua Tree 4. At about 5:10 am I made a Prediction: I said “I will predict that the epicenter will be in Landers, at the corner of Aberdeen and Old Woman’s Springs Road. Everyone will now know where Landers is.” 5. If you looked down Reche Road from Old Woman Springs Road, you would see where the road moved sideways about 18 inches 6. At the same place, if you took a picture of the telephone poles, you would be able to see the movement, where the telephone poles are in a perfect straight line, then immediately go 18 inches sideways, and then go perfectly straight again (I have a nice picture of that). 7. We had a ton of aftershocks. I could feel one and say “4.1”, and be correct 8. We went out in our dune buggy a couple of days later. There are a lot of free standing boulders sitting on top of the sand in that location. We saw that the boulders had moved around in a circle, and that there was a round impression in the sand under each rock. 9. After 6 months, we had a presentation given by an older gentleman from the USGS at a Yucca Valley Water Board Meeting. He said that an earthquake usually has both sides moving, so an 18 inch movement would be 9 inches of movement from each side. But the Landers earthquake had one side move 18 inches, while the other side remained stationary. This means that the land boundaries in Landers are wrong now, and are off by 18 inches, depending on which side of the quake your land is on. Some of your land moved 18 inches onto the other guy’s land (check your fence line). He also said that the epicenter was 18 feet from the intersection of Aberdeen and Old Woman Springs Road, so I was off in my prediction by 18 feet (10 minutes after the earthquake occurred)!! Here are some good Pictures: https://blogs.agu.org/tremblingearth/2012/06/28/landers-20/ […]
[…] hasn’t seen primary tectonic surface rupture beneath residential structures since the 1992 Landers earthquake, and its occurrence is notable at a time when Alquist-Priolo fault setback zones have emerged as a […]
My wife and I were married the day before in Victorville and stayed in a hotel in Silverlakes next to Helendale. Our families were sleeping at home and my wife’s family from North Dakota was staying in our second story apartment in Apple Valley. Needless to say my wife’s family have not been back since! It was quite an experience this earthquake and gave our marriage a big shock forward. Her family even made Tshirts and hats blaming it all on us “The Earth Moved June 28, 1992” Thanks for this blog post!