Monthly Archives: January 2010

Berkeley Hills Landslide 2010

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Last week’s third and final storm was a doozy, setting all-time record low pressure in a number of cities. Here in the Bay Area we got 3 to 8 inches of rain, and wind gusts of over 80 mph.

Powerful Thunderstorms Drench Berkeley and North Bay

All along the coast, 20 foot waves pounded the shore:

Storm Surf – Jan 2010

causing significant beach erosion:

Beach erosion – Great Highway, San Francisco – Lea Suzuki – Chronicle

And as I mentioned in my last post on the storms, the first of the three storms even produced a tornado (and some waterspouts) in Southern California. (see Berkeley Hills-El Nino Storms Hit Hard)

And of course, snow in the Sierras was measured in feet—8 to 10 feet in some spots!

Sierra Summit Had 10 feet of Snow! – Ken Clark

After the mid-week second storm, I wanted to hike into the Berkeley Hills to see the effects of the storm on the canyons. But because it was so muddy, instead of taking a fire trail, I took one of my favorite paved roads up into the Hills, Panoramic Way:

I usually walk south on Piedmont, past the Memorial Stadium:

And then take a left up Bancroft, just past the International House:

When Bancroft dead-ends, I walk up the Bancroft Steps and then cross over to Panoramic Way, which winds up into the Hills:

Panoramic Way – Google Map View

As soon as I got up into the upper, less-developed parts of Panoramic Way, I saw lots of rocks on the road and erosion like this:

Typical Panoramic Way Storm Erosion

Typical Panoramic Way Storm Erosion – Closeup

But I was really shocked when I came around a bend of on the upper part of Panoramic Way and found this:

Panoramic Way Landslide

A landslide!  Not a huge one, but still, impressive to see first-hand. Over a hundred feet of the steep upper slope adjoining the road had given way:

Source Area – Where the Slope Gave Way

And flowed down Panoramic Way for quite a distance:

Depositional Area on Panoramic Way

I was struck by how intact the top layer was; the whole section had been slipped down the slope pretty much in one piece, carrying along most of the shrubs intact.  Although small in scale, this little landslide had all three of the basic  elements of any landslide:

Of course, this landslide on Panoramic Way in the Berkeley Hills was a small one compared to the huge landslides California is famous for.  In the hills and on the cliffs all along the California Coast, heavy rains and steep, unstable land create a deadly combination that leads to highly destructive and often lethal landslides and debris flows. One of the worst in recent memory was the La Conchita landslide in 2005, which killed 10 people.

2005 La Conchita Landslide – John Lehmkuhl

In Southern California, this vulnerability is only made worse after wild fires, fanned by the infamous Santa Ana winds, denude the hills of vegetation.   Without vegetation to slow it down and trap it,  water runs off too quickly, causing flash floods and debris flows filled with huge rocks and tons of sand and gravel. Sometimes truly enormous boulders are set loose:

300 Ton Topanga Canyon Boulder – 2005 Landslide – (AP Photo)

You don’t have to have barren hills to be at risk for a landslide. Doing research for this article, I came across this amazing image of a landslide in England.  Known as the Holbeck Landslide, it occurred south of Scarborough in North Yorkshire:

Holbeck Hall Landslide – England 1993 – British Geological Survey

Fortunately, this particular landslide didn’t happen in a moment.  It took place over a two-day period, so people were able to evacuate when the first signs of movement became evident.  The scale of the movement of land is hard to fathom, until you know that the the cliffs in the depositional area are over 180 feet high! Geologist estimate over a million tons of loose glacial till (sediment) flowed down to the sea shore.

Looking at the Holbeck Hall image, I have to admit that the little landslide on Panoramic Way seems pretty insignificant! (Although I wouldn’t have wanted to be in its way when it broke loose!) Still, the soil physics involved are very similar.  All you need for a landslide is instability—relatively loose soil and rock, a steep-enough slope, and some sort of triggering mechanism, such as too much rain, an earthquake, or erosion of the base of a slope of land.  As this USGS diagram shows, there are all kinds of landslides:

Kinds of Landslides – USGS

The bottom line is that at some point, the friction and cohesion that hold the soil on a slope are simply overcome by gravity, and the soil and rock take off down hill, acting more like a liquid than “solid” land. In California, the majority of landslides caused by rainstorms, though earthquakes and tremors are a not-too-distant second.

Because of the unique geology and weather of California, landslides and debris flows are always going to be a part of the California experience, just like earthquakes, wildfires, Santa Ana winds, and El Niño events.  Because Californian love their hills and the vistas they offer, hill dwellers are always going to be in harm’s way.

Claremont Canyon Hills – Beautiful Vistas and Risk

We can do what we can to be safe, but as nature writer John McPhee makes so clear in The Control of Nature, even our best efforts may be inadequate.   In the last section of his outstanding book, he shows how  residents of the San Gabriel Mountains in Southern California have had little success in preventing debris flows from destroying their houses in spite of spending millions on creating man-made diversion pits and dams.

Landslide & Debris Flow Scars in the San Gabriel Mountains – USGS

From the standpoint of geology, landslides, mudslide, and debris flows are simply the more spectacular forms of the ceaseless erosion that shapes our beautiful planet, wearing down mountains and creating the sedimentary rock and soil so much of life depends upon.  Walking in the Berkeley Hills, you can see evidence of this  ceaseless erosion of wind and rain up-close and personal.

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National Geographic has a fantastic video on YouTube about landslides.  The opening scene of a landslide in Portland, Oregon is simply amazing.  Watch as a fellow in a truck outruns a landslide coming down the street, sweeping away cars and everything in its path!

National Geographic Landslide Video

In this next amazing video, caught on camera by a Japanese research team, you can watch a whole mountainside slide across a road with the forest riding along intact!  Amazing!

Heyelan Japan Landslide

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Berkeley Hills-El Niño Storms Hit Hard

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All my East Coast friends that used to live in the San Francisco Bay Area have told me how much they envy the weather out here—especially when the windchill is say, 20 below zero and snow and ice are everywhere! But they always warn, “True, the weather there is mostly wonderful, but wait until the winter rains come!

Well, they came, and I have to say, I’m impressed! The storms that march in from the North Pacific are indeed amazing, powerful storms, with huge amounts of water and energy.

As a weather buff, I knew this was coming, and in fact, have been looking forward to it. (See “Escape from New England-a weather nut’s confession“)

It’s El Niño Time!

We are in the middle of what’s called a “moderate” El Niño event (technically, the phenomenon is called the El Niño-Southern Oscillation ). The bottom line is ocean temperatures in the Pacific have changed dramatically, shifting global air masses, and allowing far more of the amazing storms that form in the Aleutian Low and in the Northern Pacific to strike all along the California coast.

(I’m going to do an in-depth discussion on El Niño in a later post, but if you’re interested, in the “weather nut’s confession” post, I explain the basic mechanism of storm genesis in this area, and the Aleutian Low is one of the very big players.)

Here Comes the Rain! ( And we need it!)

For now, suffice it to say that the rails are greased for all that moisture and energy that are often blocked off by semi-permanent high pressure to head our way the rest of this winter. And head our way they have! Today marks the passage of the third, and most powerful storm, in string of storms that have pounded both Northern and Southern California with flooding rain, snow, high winds, and even an apparent tornado in the Long Beach area Tuesday afternoon! (See “Rare Mesocyclone/Tornado Hits Southern California” at AccuWeather Ken Clark’s terrific Western US Weather Blog.)

Storm Surf in Pacifica – Paul Sakuma/AP

Petaluma Flooding – Brant Ward – The Chronicle

These last three low pressure systems have caused considerable damage with twenty-foot surf, winds over 80 mph, and flash floods.  Some areas have gotten over 6 inches of rain. Mudslides and debris flows have been a special problem in southern California, as they often are:

Even so, the development of this El Niño is not all bad. For one thing, the surfers at Mavericks, near Half Moon Bay, love the enormous swells that come with these powerful storms:

Storm Surf at Mavericks

But most of all, it’s bringing much-needed rain and snow to California and to the drought-parched Southwest. (The problem in El Niño winters is getting too much rain too fast.)

Here in the Bay Area and the Sierras, the heavy rain and snow are very good news. Due to a drought over the last three years, statewide reservoirs are still just at 74 percent of average to date, so all of this rain is a big boost.

The good news is that the Sierra snowpack, where the bulk of California’s water supply comes from, is now at 96 percent of normal, and will only pile higher with each new storm this winter.

Heavy Sierra Nevada Snows

The prognostication is that this very wet pattern will continue until spring, and if you look out in the north Pacific, you can see the next set of impressive storms are already forming and heading our way:

Pacific Storms Lining Up – The Weather Channel

Storm Scenes on UCB Campus and in the Berkeley Hills

Here in Berkeley, we got several inches of rain and wind gusts over 50 mph. Powerful thunderstorms embedded in the low pressure system actually produced hail, a rarity in this area. I wanted to take  pictures in the Berkeley Hills as each storm system passed through, but I would have needed an underwater camera!  In between storms, I did get some cool storm images. (All the images below are “clickable” for larger versions.)

During a break in the rain, I went out to see how the storm had affected the Berkeley campus.  The newly repaired and renovated Campanile had weathered the storm just fine:

and the campus was  a sea of umbrellas as students scurried to classes:

I did see a fair amount of tree damage from the high winds of the thunderstorms.  The Eucalyptus seemed fine, but I saw a fair amount of lost limbs with the red woods:

The north divide of Strawberry Creek runs in front of the Life Sciences building.  The debris line on the grass shows how high the creek got during the some of the torrential downpours:

Leaving the campus, I headed up Centennial Drive into Strawberry Canyon itself.   The Creek was really full, and even hours after the last heavy downpour, water was pouring into it from its tributaries:

On the hike up into the Canyon, I was once again struck by how beautiful the lichen and moss on the trees look, especially after a rain:

About half-way up the lower Strawberry Canyon  fire trail,  a thunderstorm cell moved through the canyon, and I got totally soaked:

But, I loved it.  Hiking in the rain, or in a storm, in the Berkeley Hills is one of my favorite things to do.  The rain makes everything so clean and  beautiful, and the smells and sounds are so intense.

As I got higher up the fire trail, I crossed over to Claremont Canyon.  Looking out at Oakland, I could see two strong thunderstorms moving through:

Looking north toward El Cerrito, I could see another powerful storm in the northern part of San Francisco Bay:

At this particular moment, San Francisco was in-between thunderstorm cells and catching a small break in the clouds (that line of lights on the right side of the picture, by the way, is University Avenue in Berkeley)

Soon, it was getting pretty dark, so I headed down from the fire trail onto Panoramic Way:

As the darkness closed in, I got one more photo of San Francisco and the Bay:

As the lights of Bay cities came alive, I thought to myself how blessed I am to live in Berkeley and in the Bay Area.  The storms of winter and  El Niño are all just part of the wonder of one of the most beautiful places in the world.

(In my next post, I’m going to show a large mudslide I discovered yesterday in the Berkeley Hills on Panoramic Way and discuss the mechanics of mudslides and debris flows.  Stay tuned!)