Friday, February 21, 2014

The Big One(s)

Uh oh. Things may well be worse than I hope.
Though it is one of the most densely populated regions of California, Hollywood offers an unusual opportunity to recognize and walk along an active fault. The area was urbanized in the 1920s, before the widespread use of mechanized earth-moving equipment, so much of the original topography is still intact, even subtle features such as alignments of low hills and shallow troughs that record the trace of recent earthquakes. In essence, the network of winding streets and the placement at odd angles of apartment buildings and commercial enterprises, as well as the occasional abrupt slope across one of the sprawling lawns in Hollywood and nearby Beverly Hills, are subtle evidence of an original jumbled ground surface. And by finding the appropriate steep incline, one can follow the Hollywood Fault.

Begin at the corner of Hollywood and Vine and look north along Vine Street beyond the 13-storied cylindrical tower that houses Capitol Records. Just beyond Capitol Records, just before Vine Street reaches the Hollywood Freeway, the roadway ramps up a steep hill. The hill is there because the ground was pushed up by repeated earthquakes. Along the base of the hill is the Hollywood Fault.

From that point, the fault can be followed west along the base of the same hill, running parallel to and maintaining a distance of a few blocks north of Hollywood Boulevard. It runs along the base of the low hill where the Magic Castle, a private club of magicians and the home of the Academy of Magical Arts, is located. Farther west, the fault runs directly beneath the house where the Nelson family lived and where the opening scene of their famous 1960s sitcom—the series was called “The Adventures of Ozzie and Harriet”—was filmed.

Continuing west, close to where Hollywood Boulevard ends, the fault angles to the southwest and crosses just south of the busy intersection of Sunset and La Cienega Boulevards. This is a neighborhood of fine restaurants and fashionable boutiques. On the north side of Sunset Boulevard one can find, after considerable searching through the urban construction, an occasional outcrop of hard granite. This is the rock that comprises the Santa Monica Mountains to the north; high up the mountainside is the famous hollywood sign. South of Sunset Boulevard, there are no rocky outcrops; instead, one stands on a deep layer, several hundred feet thick, of loose sediments that washed out of the canyons of the Santa Monica Mountains and that fill the Hollywood Basin. It is this discontinuity—granite outcrops north of Sunset Boulevard and deep sedimentary fill to the south—that, here, defines the Hollywood Fault.

The western end of the fault lies somewhere near the grounds of the Beverly Hills Hotel, just north of the intersection of Sunset Boulevard and Rodeo Drive. From there, if one walks a mile or so south along Rodeo Drive to Santa Monica Boulevard, then turns right and continues to Wilshire Boulevard, one will now be standing at the eastern end of another fault—the Santa Monica Fault—which continues to the ocean’s edge and beyond.

Now return to where the Hollywood Fault crosses under Vine Street and head east. From here, the fault runs close to Franklin Avenue, then along Los Feliz Boulevard. At the east end of the Santa Monica Mountains—that is, at the southeast corner of Griffith Park, home of the Los Angeles Zoo and Griffith Observatory—the fault disappears under the floodplain of the Los Angeles River. What lies on the other side?

There is another fault—the Raymond Fault—which is, perhaps, a continuation of the Hollywood Fault and which runs eastward through southern Glendale and across the San Gabriel Valley, through South Pasadena to the foot of the San Gabriel Mountains. Kinks in the Raymond fault are responsible for the low hill where the luxurious Langham Hotel—formerly Ritz-Carlton—is perched and for the shallow depression that is Lacy Park. The Raymond Fault is also responsible for the low hills on the north side of the Santa Anita Racetrack, visible from the grandstand.

What do the Santa Monica, Hollywood, and Raymond Faults have in common? Besides lying along what seems to be a continuous line, all three ruptured about 10,000 years ago and again about 1,000 years ago.

Unfortunately, paleoseismologists have not yet determined whether the earthquakes along the Santa Monica, Hollywood, and Raymond Faults occurred as a single colossal event or as a series of relatively quick earthquakes, happening over years to centuries, the latter being an earthquake storm. (Unfortunately, the techniques used in paleoseismology are not yet sufficiently refined to distinguish, in this case, between years and centuries.) But there is a curious coincidence: All three faults did rupture at about the same time; then, after a period of several thousand years, all three ruptured again, lending further credence to Richter’s statement: “When you get a lot of earthquakes, you get a lot of earthquakes.”

Moreover, other nearby faults have a similar history.
If this sort of thing ended Bronze Age civilization (It's in the rest of the item, do you expect me to pull the whole thing out you lazy damn bastards?) what will it do to savage & uncivilized Calif.?

2 comments:

Weird Dave said...

Not big enough.

mikey said...

Yeah.

The problem with earthquakes is that they knock down a buncha buildings and kill a buncha peeps and then it's over and they all just come in with the bulldozers and start over.

As civilization destroyers go, earthquakes and hurricanes suck. Give me asteroids and volcanoes every time...