Fault East Of (SF) Bay Area 'Locked And Loaded'

The Guardian (UK) ^ | 3-25-2006 | Scott Lindlaw

[blam]

Fault East of Bay Area 'Locked and Loaded'

Saturday March 25, 2006 7:31 PM

By SCOTT LINDLAW

Associated Press Writer

HAYWARD, Calif. (AP) - New cracks appear in Elke DeMuynck's ceiling every few weeks, zigzagging across her living room, creeping toward the fireplace, veering down the wall. Month after month, year after year, she patches, paints and waits.

``It definitely lets you know your house is constantly shifting,'' DeMuynck said. So do the gate outside that swings uselessly 2 inches from its latch, the strange bulges in the street and the geology students who make pilgrimages to her cul-de-sac.

DeMuynck could throw her paint brush from her front stoop and hit the Hayward Fault, which geologists consider the most dangerous in the San Francisco Bay Area, if not the nation. Like others who live here, she gets by on a blend of denial, hope and humor.

It's the geologists, emergency planners and historians who seem to do most of the worrying, even in this year of heightened earthquake awareness for the 100th anniversary of San Francisco's Great Quake of April 18, 1906.

Several faults lurk beneath this region, including the San Andreas Fault on the west side of the Bay area, but geologists say the parallel Hayward on the Bay's east side is the most likely to snap next.

``It is locked and loaded and ready to fire at any time,'' said U.S. Geological Survey seismologist Tom Brocher.

The Hayward Fault runs through one of the country's most densely populated areas; experts say 2 million people live close enough to be strongly shaken by a big quake.

It slices the earth's crust along a 50-mile swath of suburbia east of San Francisco, from exclusive hilltop manors overlooking the bay to Hayward's humble flatlands...

[fremont_steve]

Does a quarter-mile from the Hayward count as "in the area?" Oddly, I found out just last week exactly where the fault runs. It's at the bottom of the hill I live on.

Let's just say that I keep my quake insurance up-to-date - though it has a $50K deductible!

[A message]

I'm thinking Boise, Boise, Idaho. I never hear of nor'easters or hurricanes or tornados and earthquakes hitting Boise.

But I'm sure that could change too when the Yellowstone super volcano erupts.

Or a dam breaks.

The nation's dam-safety program, for example, was created after the poorly designed Teton Dam in Idaho broke in 1976, killing 11 people and costing millions of dollars in damage.

[Robert A Cook PE]

34 years in the Midwest and I had never seen a tornado or the start of one. Lots of sirens yes but not the real thing.

And yet 21 years here in GA, and I've already had 6 tornadoes touch down (go over under, around and through) the immediate 5 miles radius of my house and business; and four hurricanes go rumbling overhead on their way north from the Gulf.

[Fatuncle]

Come here to Arizona. Not much doom and gloom here, except for the heat.

Good heavens! You're still posting in English?

[A message]

Oddly, I found out just last week exactly where the fault runs. It's at the bottom of the hill I live on.

Ruh roh

I can look out my front window and see this side of the hill that borders Lake Chabot. There's that pesky fault about 2 par 5's and 3 par 4's from where I live.

I figured the Good Lord had me move out here just to keep the place stable. Nobody worry while I'm here. When I leave I'll let you know because that is the time to start worrying.

[A message]

Note to self: Do not move near Robert A. Cook, PE. :-)

[Robert A Cook PE]

A quake damages the REGION around it's epicenter, which is USALLYunderneath the fault.

But ...... (dramatic pause)

The fault itself is almost always sloped underground, so the "fault" itself can't be considered a small "line" in the ground. The ground's surface will move, and make "break" into visible movement lines, but the shaking from an earthquake affects the whole region. Damage then, follows from the shaking and movement of the earth.

BUT ALSO .... (another dramatic pause) the earth's changing ground types and rocks types bend and focus the waves as they travel. So an area NEAR the epicenter 5-8 miles) might also get very little movement, while a region 14-15 miles away gets a focused and much greater movement. In a different direction, an area also 7 miles away gets a tremendous amount of movement and an area 14 miles away gets almost no movement.

So, further from the epicenter, USUALLY the lower the shaking and movement and the duration of the movement. Lower the magnitude of the quake, less the shaking and movement.

The Haywood fault is so close that you are in extreme likely of getting a major, very damaging reaction, from anything more than a 6.0. Even a 5.0 from an epicenter close to you will almost certainly crack and break things.

[sit-rep]

I would recommend expansion joints to solve her problem. Put a couple of these in, and instead of every year repairing the cracks, simply reset the expansion joint every 5... Simple solution to a major problem.

[dersepp]

While in the National Guard, I had access to reports that would stupefy the average person as to what is coming with quakes in the East Bay. For example:

Although on the other side of the bay, 8,000 casualties per square block in Chinatown are anticipated.

The only place I have ever seen this information in the mainstream media would be the fifth and ten year anniversary programs done by KRON TV.

[Robert A Cook PE]

I appreciate the update. Hadn't been tracking the funding and grants.

But, how much of the "defocusing" (away from the probably-not-immediate-future large earthquake in LA) is due to group-think and politically correct/let's get research money by looking at populated areas earthquakes?

[Old Professer]

We got knocked out of bed in 1994 in the so-called Northridge quake; we lived on Leadwell just a bit over a mile from the epicenter.

I think they concluded that the particular fault that shot everything upward by -1.5G was not one that had been mapped and determined to be of concern.

We ended up leaving Ca. when my wife was offered a transfer and she still can't stand sudden noises or movement.

[RightWhale]

We get all those effects here, too. Permafrost. Slow motion ocean.

[Robert A Cook PE]

http://www.mcs.csuhayward.edu/~shirschf/tour-4.html

When I lived in Vallejo, GA (south of Napa, near the old Mare Island Naval Shipyard), I walked the San Andreus fault as it cross from SFO out across the bay, then appears back inland north of the Golden Gate. Sobering, very sobering.

Nearer to you, these photo's of how curbs move slowly due to the Haywood fault are actually the safest way to relax the pressure and stress.

100 small quakes of 1/4 inch each will give a gradual movement at 2-3 inches per year that will cut buildings and dams and curbs and streets in half, but not catastrophically as in a major quake that moves the earth 6 or 10 feet in one jerk.

That one big jerk will flatten the region.

[ChildOfThe60s]

What is dumb as regards NOLA is they are going to rebuild below sea level. And whine like hell if/when it happens again.

[Lester Moore]

God speed and good luck.

[Nam Vet]

Yeah, but they obviously don't need our military to bail them out.

Can you imagine if the military went in there to help out after an earthquake? The freaks wouldn't know whether to cr*p or go blind.

Nam Vet

[dfwgator]

Oh I'm sure they'll be thankful for the help, then immediately turn around and go back to spitting on them afterwards.

[noblejones]

>>
. . . it has a $50K deductible!
<<

When a 9.0 finally hits, you'll feel pretty good about a measly 50k. Too bad everyone can't be responsible like you.

[BenLurkin]

I haven't seen one of their forecasts born out yet with a a MMI VI event so I couldn't say what their predictor would model. Generally speaking it appears that the more the activity the more likely the model will predict a near term event.

[BenLurkin]

See also : http://pasadena.wr.usgs.gov/step/