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Environment & Science

State geologist finds Hollywood project would sit on top of quake fault




A woman takes a photo of the new Hollywood earthquake fault map released by the California Geological Survey Wednesday.
A woman takes a photo of the new Hollywood earthquake fault map released by the California Geological Survey Wednesday.
Mary Plummer/KPCC

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Where is the line between growth and safety? Apparently, right on top of a fault. California’s state geologist has concluded that there is an active fault line underneath the location of a planned Hollywood skyscraper project. This new conclusion is set to create a figurative earthquake at City Hall over how to approach the nearly $1 billion endeavor, particularly as private contractors had previously concluded that the location did not lie on top of an active fault.

See a map of the area below. 

Related: Active fault under site of proposed Hollywood skyscrapers, state says

The plans included building 35- and 39-story buildings, which would have created up to a million square feet to house stores, restaurants, offices, and apartments. While City Council voted 13-0 last year to approve the Millenium Project, some councilmembers are concerned as safety issues mount.

At the end of the day, one relatively obscure Department could determine the fate of the project: the Los Angeles Department of Building and Safety. LADBS has many options in front of it, including approving the project, banning it, forcing additional studies, and replanning. But before any of that happens, those behind the Millenium Project must submit their own geological surveys, which they have not done.

With the context of California’s earthquake history in mind, what is the best way to promote economic growth in areas that may be susceptible to geologic damage? Should the city approve the project? If so, should there be any caveats?

Guests:

John Parrish, Chief of the California Geological Survey and California State Geologist since 2005

Mike Reader, CEO of Group Delta Consultant and geotechnical engineer. The firm consults with several developers, including the Millennium Project in Hollywood

INTERVIEW HIGHLIGHTS 

 

How did you make the determination that the fault was under one of the buildings?

For the past year we’ve been gathering geological information from historical and academic papers and so forth and there was a lot of information being provided by researchers and consultants and we put all that information together and came out with a preliminary map earlier this year and following up on that with additional data and discussions we have just issued our final map for the area, which adjusts the original fault lines but placed the fault lines through the Millennium project area. There is one line that goes through the project area.

What is the best way to describe the line that goes through that area?

The Hollywood fault is composed of a number of parallel and subparallel fractures and traces. And this is one of the traces of the Hollywood fault zone.

And the concern is that could rupture?

Yes. The Alquist Priolo Act prescribes that we map these zones so that these structures will not be placed across them because of the fear of surface rupture and the destruction of the foundation of the building and that destroys its structural integrity then to withstand earthquake shaking.

What about the recency of activity on the fault? What is the threshold of saying there's a threat or not from a particular fault?

The state mining and geology board considers a fault active if it's moved in the last about 11,000 or 12,000 years. We know from various sites along this particular trace that it moved about 9,000 years ago so that caught our attention as being active. And we've recently gotten some other information from consulting firms and so forth that shows the fault in this area may have been active as late as 4,000 to 4,500 years ago.

That’s a risk number. The hazard is there regardless of the age of the fault. The risk of that hazard being activated is highest when it's been active within the last 11,000 or 12,000 years.

Guest: Mike Reader

What did your investigation of the site show?

Our findings are that there are no active faults at the Millenium site as far down to the bottom of the Holocene (last 10,000 years) as Dr. Parrish described for the age determination. 

So you're seeing different things or seeing the same things and interpreting it differently?

With the map the state's required to put out a fault evaluation report … and they described they believed there's a fault there based on borings, primarily the four or five borings done by a previous studier and they’ve used that to reach the conclusion to draw the segment through the Millenium property. Our data shows that even though there might be a deeper structure, it's demonstrably pre-Holocene and we find unbroken sediments in the Holocene period throughout Hollywood. So there may be a fault there, it's definitely not active in our opinion.

Dr. Parrish, what is your response to Mr. Reader's conclusions?

We used a lot of the information on here and we believe, using some of that same information that Mr. Reader is talking about, we do have an active fault on the south end of the trench that was dug.

We also have information from across the street where we have surface expression and to the west where we have other bore holes done by other agencies and so forth that there is a connection between the dots here that would put that active fault through the south part of the Millenium project area.

Is your determination the final word here or is there an appeals process? What comes next for the developers if they disagree with your conclusion?

We are through with the project now. We have placed our zone that says it's mandatory investigation if one is going to build in the area. So from here on it is up to the city planning commission, the people who issue the permits and the developer to discuss the information that is here and make a decision as to whether they need to alter the footprint design of the building to step away from the projected trace there or they can issue a permit on the area.