Elaine Meinel Supkis
I used to live in Berkeley. This last three days, the Hayward Fault has shaken several times, each time in the exact same spot, same depth and same intensity. This could be a signal the fault is going to blow. This segment of the complex California geology has not had any adjustments except very small ones, since 1889. This makes it one of the most dangerous faults in the state because it also runs right through the center of several major cities and cuts across lots of modern landfill.
&hearts There has been yet another one today besides this one last night.
(12-22) 23:12 PST Berkeley, Calif. (AP) --A small earthquake struck the San Francisco Bay area Friday night, but there were no immediate reports of injury or damage.
The quake, which struck at 10:49 p.m., had a preliminary magnitude of 3.7 and was centered about 2 miles east of Berkeley, just across the bay from San Francisco, according to the U.S. Geological Survey.
I once lived less than 150 feet away from the Hayward Fault. We used to joke about it. Our commune had a number of students in it and I lived in the kitchen and pantry...you see, there was little room for everyone so we lived everywhere including closets. I didn't have to pay any real rent, just electricty but I cooked food. So one day, I was flipping eggs over easy when the pan shot sideways. The eggs landed on the stove. I was standing on one leg because of an injured right foot so I thought the swaying was myself trying to stand up. Then I noticed everything creaking and groaning like an old man with arthritis trying to rise from his chair.
I thought, 'Oh no, it might be the Hayward earthquake!' and I tried to leave the kitchen only the door was now jammed shut! So two of the guys ran over and knocked it open with their shoulders and we all ran outside and stood next to the big Gandalf statue in the backyard. It was a minor earthquake. But what if a 7 or worse, 8 mag quake hits?
&hearts Just two days ago, there was the first of this series of earthquakes.
By Richard BrennemanRaked by a legal broadside, the University of California beat a temporary retreat Wednesday, agreeing to halt development at Memorial Stadium pending a hearing in Alameda County Superior Court.
The move grants a short reprieve to the grove of oaks and other threatened trees west of the stadium where four protesters are camped out in the branches in protest over the impending loss of the last remaining grove of coastal live oaks in the Berkeley plains.*snip*
At 7:12 p.m. the Hayward Fault fired off the first of a pair sharp jolts, followed at 12:55 a.m. by a second, smaller shock—both with epicenters less than 1.2 miles southeast of the stadium.
The first single, sharp jolt hit 3.7 on the 10-point Richter scale. The second rated a feebler 2.2.
The first temblor, felt as far away as Las Vegas, Nev.—659 miles southeast—and Eugene, Ore., 689 miles to the north—was more than 1,000 times weaker than the Hayward Fault shocker that U.S. Geological Survey seismologists say has a one in five chance of happening in the next two decades.
I remember that grove! We loved the trees there. I really loved them, myself. The carpet of soft needles, the red bark of the trees was also soft. Birds filled the upper stories of the trees, the birdsong rang out every dawn and dusk. It was the most magical part of Berkeley. I used to play the cello there.
From day one, back in the sixties, the University wanted to chop them down and put up various things in their place, very Sarumanish, we thought. So we fought them. Now I own my own forest and I get to chop down trees but the forest remains and grows.
The football stadium is dead center on the dangerous mega-big Hayward fault! The building is old and poorly designed. The chances of it collapsing in a major quake is around 100%. The solution? Build a bigger thing there!
Unfortunately for the builder's plans, if the fault jerks north the degree other great quakes have done in the past in California, it will most likely jump around 12-25 feet in less than 90 seconds. This is very fast. Buildings ripped in two will be ripped in two no matter how well built! This is why mapping and understanding these faults is literally life and death! Building across them is suicide.
&hearts Click here for the official government maps of this region.
A spring just north at the terminus point of the Hayward Fault is also having smaller quakes, almost a dozen 2 mag or less trembling, a very faint shaking. But in a very significant spot. There is absolutely no way to tell if the shaking this week is heralding a bigger event. What we do know is, more than 100 years has passed since the last major quake in this zone and each day, one is more and more likely. It will happen, we just can't say when.
&hearts Click here to see a photographic map of the region. The dividing line of the major faultline and all the attendent secondary fault lines are easy to see. Of course, the human habitations are all built right on top of the nastiest of the fault lines.
&hearts Click here for a photo tour of the Hayward fault line.
Click on image to enlarge
Even with only very tiny quakes like the one I described, the sidewalks in my old neighborhood have shifted significantly even since the last curb repairs were done not too many years ago. Note also how this dangerous fault line goes straight through the building the sidewalk borders.
The Hayward fault runs through some of the most densely populated regions of the San Francisco Bay Area, and has a high probability of failing with a magnitude 7+ earthquake within the next 30 years. Hence, the identification of regions where high amplitude ground motions are expected is important for seismic hazard assessment. We present preliminary results of 3D simulated ground motions in the San Francisco Bay Area due to scenario earthquakes of Magnitude 7.1 along the Hayward fault (north and south segments combined). We consider 3 rupture scenarios: 1) south to north propagating; 2) north to south propagating; and 3) bilateral. These simulations were performed with E3D, a finite-difference seismic wave propagation code developed at Lawrence Livermore National Laboratory, and implemented on the Lab's massively parallel high performance computers. The simulations utilize a geologic model developed at the University of California at Berkeley.
And 8.2 quake would simply flatten virtually everything in this zone. Note how the ripples of forces slam into either or both the northern bay and south in San Jose and due to landfill and other geological realities, amplifies the motion which also will boomerang backwards. The landfill at the lower end of the San Francisco Bay is very unstable. The last earthquake today was felt all the way to Reno, Nevada! This means the entire area is very tense. The Pacific Plate has shifted significantly since the Great Boxing Day Quake. We are well within the five year timeframe for after effect-style earthquakes.
I know the housing in the Bay Area real well. Much of it is not made to survive a great quake. The Great San Francisco Quake actually zipped alongside much of the city, it was the fires that destroyed the place so badly. The Hayward fault runs up the center of the great population centers and worse, the studies done by the Livermore people shows the possibility of the Great Quake in the future to ripple across the entire Bay and affect even Eastern San Francisco which is where most of the landfilled communities are, too!
The last truly major earthquake in the region was the 1906 San Francisco Earthquake which occurred on the San Andreas fault. Many seismologists believe that the 1906 earthquake reduced the stress on many faults in the Bay Area including the Hayward fault, creating an "earthquake shadow". Since the 1906 San Andreas event there have been no moderately strong earthquakes on the Hayward fault as were seen before that earthquake. It also appears likely that this quiet period in the earthquake shadow is ending, as projected by the rate of plate motion and the stress state of other faults in the region.
People are amazingly trusting. I drove exactly once on the McArthur double decker highway. I was practically yelling with anger when I saw how it was built and told everyone, we were to avoid it at all costs. I didn't care how slow the traffic was. I didn't like the Oakland Bay bridge much, either. Well, both collapsed partially or wholly in the World Series Earthquake!
Another side effect of Great Quakes is subsidence: namely, the shore areas collapsing to lower levels. Since a lot of this is already landfill, such an event will also cause tsunami-type problems for people living in the subsiding areas.
Not to be ignored! When Portugal had the 1755 Lisbon earthquake, most of the city perished because it collapsed into the sea or was overrun by the ocean which then receded. Draconian measures were used to rebuild the city and the country lost its ability to continue as a great empire.
If one lives in an earthquake zone this dangerous, one must take measures: store water in plastic containers on the floor in a safe place, not on shelves! Preprepared dry foods that require no cooking, dried fruits in airtight bags, all bookcases, etc, bolted to the walls (a good idea anywhere, actually, in my opinion), quake-proof the house properly and rehearse instructions for what to do and where to go if there is a Great Quake.
For the likelyhood of staying 'home' might be impossible. I do hope the schools now have the equivalent of fire drills whereby the teachers rehearse how they will deal with their students in such an emergency. Since they are the controlling adults. But most people prefer to imagine it won't happen now, to themselves. This discomfort isn't wise. Just like out here, we have many rules concerning blizzards so our children won't get lost or stranded, for example, ditto for this.
In New Jersey, they had no blizzard rules and when one hit, my son's school decided to send the children home in buses which got stranded in the storm. I was able to trace the bus route on foot, dragging a sled and blankets. Another mother with a 4WD one ton truck saved everyone. I helped her and several stayed at my house because they couldn't go any further. But after that, you can bet, the school district developed blizzard plans.
Hi Elaine,
Great article, and very pertinent for me.
We're about a mile from that epicenter, on a nice big rock, just a little bit down the hill.
First time we were talking in the living room, and felt like the truck hit our place; in about a second we were in the door jam.
Second time was also in the living room entertaining some friends. Freaked everyone out (they're a couple miles from us and felt the other one too). It was so quick no one moved.
The one this morning we slept through.
The cats have been useless as early warning systems.
We have loads of extra food and water - however, being in an urban area, if anything bad should happen, our best bet is to get out to the valley to my wife's grandfather's place - a small town, population 500, ~40 miles outside Modesto. The highly populated areas in the East Bay aren't going to be fun if there's ever an interruption of essential services.
I am hoping this gave the fault some breathing room and it will settle down now, but you never know... Isn't it pretty well known now that there's usually a cluster of small quakes (like the 3.5+ ones we've just had) before a large one.
Posted by: Rodney Reid | December 24, 2006 at 03:26 AM
WOW! Thanks for the information! I used to live right of Telegraph Avenue which should be renamed 'Hayward Rift Blvd'.
Previous to this, the earthquakes like the one you described happened in isolation. Once every other year, if that. Three in a row plus two smaller ones in one week isn't a good sign.
Modesto: the problem is getting there since the main highways in California, because it was 'easy', run on fault lines! This is crazy, of course, but California is la-la land.
Buy 5mile radius two-way radios. They are very useful, I have them, of course. Cell phones can fail if the buildings they are on or the towers fail. Also, too many calls jams up the services.
And water: always, one needs potable water and in fairly large quantities.
About animals and earthquakes: ant colonies that have tunnels are what one should watch, My California granddad told me, 'If you suddenly see lots of ants marching away from their homes, we will have either an earthquake or thunderstorm.'
In 'Barefoot Gen', the Japanese anime about the bombing of Hiroshima, the doomed little boy tells his daddy, 'Look, papa! All the ants are running away! Why?' and a minute later, the bomb hits.
Posted by: Elaine Meinel Supkis | December 25, 2006 at 01:00 PM