This blog entry is written by Major Langer of The Law Offices of Larry H. Parker’s sister law firm, Perona, Langer, Beck, Serbin.
As the senior partner of the law firm of Perona, Langer, Beck, Serbin I have had the unique experience over the course of my forty-five year career as an attorney to have handled many large landslide cases, including the Blue Bird Canyon Landslide, The Flying Triangle Rolling Hills Landslide, and the Abalone Cove Landslide. In the process of investigating these cases before going to trial I have received a practical education on earth movement from the geologists, hydrologists and other geotechnical engineers who worked as experts for our clients.
The first lesson I learned is that there are no simple landslides. Lesson number two was that Palos Verdes has a complex, dynamic geological history that includes several episodes of violent uplifting that shattered the bedding planes, active hot springs in near shore areas including Malaga Cove and White’s Point, and volcanic activity complete with ancient lava flows that can be seen today. In fact it’s a layer of ancient volcanic ash (bentonite) that contributed to both the Flying Triangle/Portuguese Bend/Abalone Cove and Trump landslides.
This is why three weeks ago a friend of mine who lives in San Pedro asked if I would take a look at the Paseo Del Mar/White’s Point Landslide. I had actually not heard anything about it until that time, so we spent several hours walking the roadway and the area up slope of the old underground Nike base.
As we hiked my friend was pointing out numerous cracks in the ground well past the roadway and trending up slope, at least seventy-five to a hundred yards north of the roadway. Oddly, someone had filled many of these with sand, perhaps in an attempt to get some sort of gross measurement to determine if they were caused by active earth movement or just normal cracking as part of the natural wet/dry cycle. From what I saw, if that’s the case, then in my opinion there is cause for concern. Some of the cracks had deepened, swallowing up the new sand filling.
My friend walked the same area subsequent to our visit and sent me photographs of additional cracks that he observed since then. Some were perhaps as much as five inches in width and two feet or more deep.
Of course, I do not know whether or not these cracks relate to earth movement or seasonal earth shrinkage which is prevalent in the area. My own personal opinion, based on observation, experience and the size and rapid appearance of the feature makes me think that there’s a mixture of both, but the ones that caught our eye are wide, long and deep, certainly suspect, and worthy of additional investigation. I have not seen any comments from County or City engineers concerning these up-slope features as of this time.
What I saw was somewhat reminiscent of the features in the Flying Triangle area of Rolling Hills when cracks caused by land sliding would propagate, and then when the winter rains came, these cracks would be conduits for enormous quantities of water to percolate into the movement. It’s this layer, known as bentonite clay, when wet, lubricates the slide and accelerates the earth movement. I believe it’s possible we may be seeing another slow-motion slide in progress.
I have no specific knowledge of the underlying bedding in the White’s Point slide area but it occurs to me that the arc of the current known active slide referred to in the news reports, should it continue to move towards the ocean, with the potential of failure, would create a lack of support and could remove whatever support there would be for up slope areas which could further potentially remove lateral and subjacent support in the areas to the north, east and west. To what extent, if any, again remains unknown. Again, this would depend, amongst other things, on the bedding in those neighborhoods adjacent to the active slide whose features are currently unknown.
As far as the general geology of the area, it is fairly well known that south facing slopes on the Palos Verdes Peninsula have adverse beddings and are affected by the constant erosion of the cliffs caused by the ocean tides. The areas of highest erosion are at the center of each of the numerous coves. The areas of least erosion are at the points of the coves where the lava has upwelled and remains exposed. The hard lava rock doesn’t erode as quickly as the soft sedimentary rock and acts as a natural erosion barrier.
Again, the bluff at White’s Point slide is quite steep, is roughly in the center of a cove, and could easily be affected by wave erosion as well.
Regrettably, Palos Verdes is now known as home of the largest active urban landslide in the world. Palos Verdes is about as active as it gets and high resolution bathymetric sonar maps even show evidence of underwater landslides along the steep cliffs about a mile or so offshore.
The Portuguese bend landslide was determined to have been caused by the construction of Crenshaw Boulevard and the loading of the head of the ancient slide area during that construction process. That slide has continued to move since the 1950s and has created a large graben (geologist’s term for a depressed area between two parallel faults). The central part of the Portuguese Bend landslide during winter rains collects water from much of the Portuguese Bend area.
When I represented homeowners in the Abalone Cove Slide, my experts felt that to some extent water from that Portuguese Bend slide may have found its way to the Abalone Cove area adjacent to the Portuguese Bend Slide. Additionally, with respect to the Flying Triangle, we argued that the removal of support from the Flying Triangle was probably a factor in the continuous movement of the Flying Triangle Landslide.
Since that time, (as part of our settlement with various governmental entities) numerous constructive steps have been taken to minimize the effects of water intrusion from all stability of that particular landslide mass.
The most recent landslide of note occurred in 1999 shortly after Donald Trump purchased what was then called Ocean Trails Golf Course. The 18th hole slid into the ocean and the surrounding holes became so unstable that until it was stabilized it was jokingly referred to as “The World’s Only 15 hole Moving Golf Course.”
Again we see water intrusion (a leaking water hazard liner) as playing a role in the Trump landslide. The geologists even have a pet name for this sort of movement: Deep Creep.
We understand, that slide has been stabilized by Trump’s installation of a massive and expensive retaining wall after digging out and removing the bedding plane containing the bentonite clay layer.
Hopefully the White’s Point mass will stabilize on its own but it appears to me that unless positive efforts are taken by responsible governmental entities who own the property, water mains and storm drains involved, the future stability of this existing landslide complex and adjacent potential complexes is uncertain.
It does not bode well that the EIR filed by Marymount College discovered that the 16,000 year-old South Shores Landslide, about a mile and a half north of White’s Point Given the history of landslides along the Palos Verdes coastline in the San Pedro area (notably back as far as 1929 with what became to be known as the Sunken City Landslide) and continuing today, in my opinion it is irresponsible that the water mains and storm drains along our coast are not inspected now and monitored regularly from now on if not already monitored and inspected by the appropriate governing authorities. The hazard is well known, the history is well documented.
The photographs taken by my San Pedro friend and my own photographs of what appears to be cracks in the ground and corroded water pipes are available. Should anyone wish to receive copies of these photographs you can contact me at major.langer at gmail dot com.