Major quake could hit in 30 years -- or minutes

United States Geological Survey warns that Bay Area is more than 60 percent likely to be shaken by large earthquake by 2040

Two "micro-earthquakes" that hit south of Portola Valley in the past five days were too weak to merit updating the United States Geological Survey's (USGS) "probability" prediction for the Peninsula's getting hit by a major quake, a public information officer said Tuesday (Jan. 25).

A 1.7-magntitude earthquake hit the Kaiser Permanente quarry east of Portola Valley on Jan. 20 at 2:24 p.m. A weaker quake followed in a section of the San Andreas fault southeast of Portola Valley in the early hours on Jan. 24.

"They were too small to know" if a larger quake may hit, Public Information Officer Susan Garcia said.

The USGS's 2008 forecast for the Bay Area estimated a 63 percent likelihood that a major earthquake measuring at least 6.7 will shake the region within the next 30 years. For years, USGS scientists have cautioned that such a quake could hit anytime, even within 30 minutes.

The probability is highest for the Hayward-Rodgers Creek Fault system at nearly one in three and lower at the San Andreas Fault, responsible for the 1989 Loma Prieta earthquake, at around one in five.

"There's always the reminder that we do live in earthquake country -- be prepared," Garcia said.

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Like this comment
Posted by Panther
a resident of Midtown
on Jan 26, 2011 at 6:04 pm

Interesting. Well, 60% of the time, it works every time.

Like this comment
Posted by Garrin
a resident of South of Midtown
on Jan 26, 2011 at 6:12 pm

The Loma Prieta quake, in 1989, was a real local shaker, but it was not a disaster. The real question is, what the is the chance of a 7.5, or greater, quake in the next 30 years?

Like this comment
Posted by Resident
a resident of Another Palo Alto neighborhood
on Jan 26, 2011 at 6:42 pm

I have lived here for 20 years and they have been saying that all the time. Does that mean that they are really talking about 10 years, or is it a stretchable 30 years?

Like this comment
Posted by Charlie
a resident of Barron Park
on Jan 26, 2011 at 9:41 pm

IF I keep saying 30 years earthquake warning after every 20 years, I can't be wrong!

Like this comment
Posted by Ron
a resident of Another Palo Alto neighborhood
on Jan 26, 2011 at 10:17 pm

There is going to be an earthquake tomorrow in this area. Gee I will be 50% right

Like this comment
Posted by Why I Love Palo Alto
a resident of Palo Alto High School
on Jan 26, 2011 at 11:36 pm

Intellectual postings.

Like this comment
Posted by Resident
a resident of Another Palo Alto neighborhood
on Jan 27, 2011 at 7:58 am

Sure, some may scoff at this news and others may scoff at the responses here.

But really, is this news? We live amongst major fault. We get smaller earthquakes all the time. We know that at any time we may get a more moderate and even a big one. But we hear this and it means nothing more than seeing the terror alert at orange (which is about to be scrapped anyway).

Talk about the boy calling wolf.

Like this comment
Posted by Not-an-ostrich
a resident of Midtown
on Jan 27, 2011 at 10:50 am

An earthquake will happen in the Bay Area, but no one knows when or in what section. The USGS is only doing the best it can based on past experience both here and around the world.

Whether anyone chooses to prepare is certainly up to them. But it's easy and inexpensive to do so. Why anyone would not do some planning or preparation is beyond me. After all we know we will retire in 5 to 40 years and plan for that (most of us!!!).

Like this comment
Posted by Jon
a resident of Another Palo Alto neighborhood
on Jan 27, 2011 at 10:54 am

Actually the time to prepare for an earthquake is now. Also the Richter scale is not a perfect measure of the damage an earthquake can cause. If we have another one same "size" as Loma Prieta it might be rather worse

Like this comment
Posted by We-Are-All-Going-To-Die
a resident of Another Palo Alto neighborhood
on Jan 27, 2011 at 11:18 am

And let's not forget the massive flooding that is also going to destroy California --
Web Link

Digital News Report – California could be faced with a super storm that could produce up to 10 feet of rain, and that is why scientists, the Federal Emergency Management Agency (FEMA), the California Emergency Management Agency (Cal EMA), and the United States Geological Survey met last week in Sacramento to discuss the possibility of massive flooding that could cause a potential of $300 billion in damages.

The "emergency preparedness" business is no doubt a little slow at the moment, so never a bad time to rattle the drums a little. We also have to worry about volcanoes and asteroid impacts, which have been theorized as the source of mass extinction events.

Wow .. maybe we all should just go back to bed and wait 'till it's safe to come out and play again.

Like this comment
Posted by David Pepperdine
a resident of Another Palo Alto neighborhood
on Jan 27, 2011 at 11:34 am

Folks, this is serious and it's about you and your loved ones.
People in New Orleans used to joke in bars about Lake Ponchantrain but it's not funny any more. The Bay Area is a great place to live. As anyone who was here in 1989 can tell you, the Big One is really scary. Take a few minutes and:

a) Secure your heavy furniture
b) Prepare an emergency supplies kit (esp. water)
c) Make sure your house is bolted to the foundation

You'll be glad you did.

Shaken, not stirred,


Like this comment
Posted by Julius
a resident of Monroe Park
on Jan 27, 2011 at 11:57 am

We should trigger earthquakes deliberately using surplus nukes from the worldwide build-down. Thanks to GPS-based plate tracking, the stress build up can be estimated pretty well along the faults. The deep holes needed could also be used for geothermal energy extraction, hopefully paying for the project and more.

Like this comment
Posted by Nuke-'Em
a resident of Another Palo Alto neighborhood
on Jan 27, 2011 at 12:58 pm

> We should trigger earthquakes deliberately using surplus nukes

This has been suggested, from time-to-time. However, no one wants to take responsibility for the project, if it goes wrong.

Like this comment
Posted by Steve
a resident of Menlo Park
on Jan 27, 2011 at 2:52 pm

I work for USGS on the Earthquake program and have a couple things to contribute:
1. The M1.7 event near Permanente Quarry was not an earthquake - it was an explosion set off by the quarrying operations at the quarry. They happen frequently and are easy to recognize by the shallow depth (0 km in this case), the location, occurrence during working hours, etc. The seismograms from a blast are also distinct from those of an earthquake.
The USGS website shows the epicenter in either Google Maps or GoogleEarth so you can zoom right into the quarry to get an idea how good the location is: Web Link
2) The 63% probability of a damaging quake (M6.7 or larger) in the next 30 years in the Bay Area is based on an improving but still incomplete knowledge of faults and strain accumulation in the area. There's nothing special about the 30 year window - it was chosen because that's the length of the average home mortgage, which provides a comprehensible length of time that most people can relate to. If you want to read more about how the probability is determined, it's all on-line at Web Link
3) There have been only 4 historical earthquakes as large as M6.7 in the Bay Area. The first, in 1838, is believed to have occurred on the San Andreas, perhaps in the Portola Valley/Woodside area, though the evidence is limited to a recollection 40 years after the event by a citizen of San Jose who experienced it.
Next was the M6.8 earthquake in 1868 that ruptured the Hayward fault from Fremont to San Leandro. Damage from this quake was so great in San Francisco that they called it the Great San Francisco earthquake.
Of course that name was reassigned a few decades later to the truly "Great" M7.9 quake of 1906 that ruptured the San Andreas from San Juan Bautista to Cape Mendocino.
Fourth and most recent is the M6.9 Loma Prieta quake that killed 63 and produced about $6 Billion in damage. The take-away lesson from Loma Prieta was that it was be "best" earthquake we could hope for in that it was remote from most populated parts of the Bay Area, having occurred beneath the lightly populated Santa Cruz mountains. The next "big one" is almost certain to occur much closer to the more populated and developed areas. For example, think of how many homes, businesses, highways, etc. are built directly over the Hayward fault. A recurrence of the 1868 earthquake will be much more devastating than Loma Prieta for that simple fact.
4) Finally, all this is summarized in a USGS published brochure available in some Home Depots and OSH outlets. It covers the science but also the questions of why people need to be prepared and what they need to do to get ready, whether the quake happens tomorrow or 30 years from now. It's also on-line at Web Link

Like this comment
Posted by JeffO
a resident of another community
on Jan 27, 2011 at 3:58 pm

Seems like some fact checking could have been done by the author of this article.

1 - the quarry where the "earthquake" took place is technically "east" of Portola Valley, kind of in the same sense one could say LA is "east" of Reno. It would have been far more accurate to say the quarry is west of Cupertino.

2 - it wasn't an earthquake (as Steve the USGS guy stated), and the magnitude was 1.2, not 1.7.

3 - the "Kaiser Permanente Quarry" hasn't been that for YEARS! It became the Hansen Quarry in 1999, and then in 2007 became the Lehigh Southwest Cement Company, Permanente Plant.

Like this comment
Posted by Steve
a resident of Menlo Park
on Jan 27, 2011 at 4:22 pm

JeffO -
Looks like another blast today at 1:20pm. This is the M1.2 I think you're referring to. The earlier blast (on Tuesday I think) was a legitimate M1.7 but it looks to have been removed from the web page, probably because the timers confirmed it as an explosion and removed it from the map. Verified explosions are removed to avoid confusion - people expect an earthquake map to have only earthquakes, though seismic networks don't discriminate between tectonic sources and man-made sources.
Thanks for the info on the quarry - it was implanted in my memory as Kaiser Permanente Quarry many years ago and I'm going to have trouble adjusting to the new name. How about Permanente Quarry, since they obviously still quarry limestone to make the cement?

Like this comment
Posted by JeffO
a resident of another community
on Jan 27, 2011 at 4:55 pm


Just to be clear, my comments/criticism was directed to the author of the article, not you. I appreciate your additional info, and it was from your link that I saw the 1.2 magnitude "quake", which I now see was the one that happened today.

The current quarry owner does have a web page - Web Link - and they refer to the cement plant as the Permanente Plant.

If you ever want to visit, just go to Portola Valley and head "east" :-).

Sorry, but further commenting on this topic has been closed.

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