Wednesday, November 30, 2011
Readers Respond To The Underdog For Kids Column About the Paseo del Mar Landslide from a Geologist to a Researcher
Keep it Natural
There is really only one way to keep a place "natural", undisturbed, etc... Stay out of it. This is not a jest. It really has been proved repeatedly in ecological research. Even the Jane Goodall's upset the balance. So, nature has made it harder for folks to get to this area, and now it will be a little more protected. Like most every change in the universe, there are benefits as well as drawbacks.
Wow, Diana....what a beautiful article...and amazing pictures! I never realized that so many of us have a special bond with that tree. My dear friend Al Carr, who has since passed away, used to call it the "pineapple palm" because of its chubby base and shape of the fronds. He and I would take walks along Paseo and turn around at the "pineapple palm"- such fond memories. You are right, Diana, when you say that the landslide is breaking hearts- it truly is!
Thank you, Diana, for capturing the mood of what so many of us are feeling. I have forwarded your article to my friends who used to live in San Pedro. I so appreciate your writing, Diana!
Area Landslide Histories
Provided By Mike Bennett
1929 Six-Acres of Point Fermin Park began to slide into the ocean, today known as Sunken City.
It should be noted that while Sunken City began in 1929, it continued to slip until 1934/1935. All but two homes were pulled towards Shepard Street and saved. *
1933 A Japanese constructed a seaside resort centered on a sulphur spring bathhouse at Royal Palms, closed due an earthquake, which sealed off the sulphur springs.
I include this occurrence due to the area being between two of Southern California Earthquake faults and wonder (no proof) what became of the water from the hot springs, as the geological phenomena of the area is called a "Slump."
1956 Portuguese Bend slide began destabilizing 260 - 300 acres of hillside on the Palos Verdes Peninsula.
1969/1970 A 300-foot-long crevice opened up at edge of the slide area in Sunken City. Along the “Palisades” portion of Paseo del Mar, due to heavy storms eroding the cliffs and poor storm run-off, one home was lost as were a series of guesthouses.
(This is how/reason we have "Zero-lot-lines" on the ocean side of Paseo, due to houses being pulled toward the street and away from the cliffs and I have one of the massive storm drains). *
More cracks appeared a few streets away (East of our current slide area), from an Active/Historic landslide area (as Sunken City is also labeled).
It should also be noted there is also the South Shores Landslide Area (Dormant), just beyond the Western Border of South Shores. All of these are illustrated on the California Geological Survey: “Landslide Inventory Map of the Palos Verdes Peninsula.” (Wayne D. Haydon).
1999 A landslide at Trump’s Ocean Trails Golf Course sent 16 acres into the ocean.
2009 A portion of the cliff beneath Paseo del Mar, less than a quarter of a mile from the current landslide, eroded. The cliff was bridged & repaired from underneath the street.
No one to date has noted that a large portion of this repair was lost in the current slide, as can be seen in recent photos. It should also be mentioned that a comparison of Google Earth Maps, for the Nature Preserve, show moment in the South-Eastern portion of the Preserve and has been identified as unstable in a number of geological surveys of the area.
2010 Another large chunk of Sunken City dropped 100 feet into the surf.
As presented by Pipkin & Ploessel, (1972) in their paper: “Coastal Landslides of Southern California;” “Between Abalone Cove and Cabrillo Beach …53% of the shoreline has undergone some form of land sliding, and the remainder has experienced rock falls.”
A Geologist’s Point of View
In every generation in San Pedro there will be land movement. The first big one most people remember is Sunken City. Another example, though much more directly connected to human influences, was the sinkhole on Western Avenue at Summerland. And how about the 18th hole at Trump National Golf Course? The current landslide is not much different.
As a professional geologist, I'm a bit taken aback by people's reaction to the current landslide, also known as "Paseo No More." There seems to be an out pouring of emotion. "Let's save the tree." Realistically, that's not going to happen. The time for doing that was before the sinkhole turned into the landslide, and even then, tree removal would have been risky. For all we know, it was that tree's roots that kept the land so stable for so long. Taking away the tree could have then been seen as the cause of the landslide, whether or not that actually was the case.
Is the loss of this strip of land heartbreaking? Is this a major tragedy? As much as I am saddened by the loss of a favorite strip of earth to walk, my personal reaction has not been one of absolute loss as much as some other people. I am awed by the forces of nature. I am in wonder that a sinkhole could change so dramatically with just the right rainfall, and I anticipate that with the next few rainstorms, the geometry of this area will continue to change.
The study of geology tells us that cliff erosion happens. Landslides happen.
The geology of San Pedro is not that different from that of Palos Verdes Hill. Old landslides line the coast. Buried clay deposits in the ground are resting at just the right angle for a landslide to occur should there be enough moisture to make the surface slick enough to fail.
The real question that I see at hand is what about the nature preserve? How long will the nature preserve remain here? When--and not if--Paseo del Mar is rerouted in the area, it will need to cut through the preserve. How much of the nature preserve will remain afterwards? The street will not be placed at the newly formed cliff's edge. There will be a setback. The question is how far will the setback go and how much of a bend will be needed to reconnect one part of the street to the other. Not easy questions.
Moreover, there will be debate about leaving the concrete bunkers in place. Did the old infrastructure accumulate and leak water to the subsurface? Would a new road be placed too close to these old structures? Because of these questions, the federal government--which placed the military structures in this location--will need to be involved in the construction of the new road.
And when all of the new road-building studies are done, how much of the nature preserve will remain? Somehow, in the face of these questions, the fate of the lone palm tree pales. How about the future of all the brush and critters in the preserve. Is that little bit of nature in San Pedro doomed?