Has anyone noticed "the slide" area of the mountain lately?

[backincali]

Today I was driving home and I happened to notice that the slide area on the mountain (that area with no trees where there was a land slide many many years ago) seems to have slid some more? I noticed there was alot of dirt that came down more and you can see cracks in it where the water came down it during the last rainstorm. Did anyone else notice that? Has it been there awhile and I just havent noticed it? Kind of worries me a little bit after some of the other mud slide stories we have seen on the news. Does anyone ever go up there and check that area out to make sure its stable? Just curious.

[RobertW]

[ForestGal]

[tiltronix]

The slide in the 1940s was started by an earth shake.  It could happen again!

[Nolena]

[RobertW]

[cpineshadows]

It's not a matter of it could happen again, it will happen again.   What type of preventive measures can be applied to this area.  Is there any Federal or State departments that are responsible or can help us control this problem?  What areas would most be involved if a slide happens.

[RobertW]

[KWBoy]

im waiting to see if they are going to build a house on that hill that they are grading by the 138 between the 2 and phelan. And if they put a house up there how long it will take till it slides 

[Wrightwood]

Click here for the 1976 - 100 year debris or mud flow map of Wrightwood (950k)

[cpineshadows]

Excellent information! Thank you.  That explains why I had to purchase flood insurance and all the rocks in my yard.

[Wrightwood]

The map is one of the many scientific reports made of mud flow and debris movement in the Wrightwood area. Myself and a few others have been searching and compiling numerous reports for the past year and one of these days I'll build a web page to make all of them available.

[Nolena]

That explains why I had to purchase flood insurance and all the rocks in my yard.

I got the rocks in my yard for free! 

[raddog]

So what this map basically tells me is that if this mud flow were to happen like it is on the map.  Pinon Mesa where my house is located at will be completely surrounded by mud and debris.  I don't know what's worse being stuck in the mud flow or being stuck on top of it.

[pining away]

Can anyone tell me more about the landslide dangers posed by the Heath Slide? I understand that there is a heckuva of a lot of loose earth dangling just above Wrightwood that could go in a bad earthquake or exceptionally bad spring melt, but it's hard to get much more information than that. I am particularly interested to know which parts of Wrightwood are under the gun.

I searched for a topic on this and didn't find one, but maybe someone can point me in the right direction if I missed it.

[RobertW]

Extensive geological studies were done in the mid 70s on this very issue.  I have in possesion maps from the State of California Department of Water Resources.  They conducted a Wrightwood Debris and Mud Flow Investigation for Areas of Potential Damage From 100-Year Debris or Mud Flows, dated 1976.  (Thanks "Wrightwood")

The Map shows the potential areas of Wrightwood that will be impacted from Slides coming down Heath, Sheep and Acorn Canyons.

The Heath Canyon Slide would have the biggest impact on Wrightwood.  According to this study a significant slide coming down Heath Canyon would affect Wrightwood from about Twin Lakes and Walnut St. on the West to Heath Creek Dr. on the East and all the way down to the Hwy.

Areas closest to the Heath Creek channel along with Oak St. and a path directly down the middle between Walnut St. and Oak St. would have a High Potential for damage, while the other areas between the above mentioned boundaries would have Moderate Potential for Damage.

I also remember reports that many geologists feel that the mountain between the Heath and Sheep Canyon slides could easily slip as there is a fissure between the two slides.  Of course such an event would be catastrophic.  Mind you, I remember hearing that decades ago, but haven't been able to have that report substantiated.

[KW]

Umm, I'm afraid to ask, but where would the Acorn slide go? I'm just two blocks from Acorn....

[RobertW]

Umm, I'm afraid to ask, but where would the Acorn slide go? I'm just two blocks from Acorn....

I'm closer to Acorn than you!  Being your neighbor, that was the first thing I checked out when receiving the maps.

Acorn Canyon would have two flows.  We are both safe from both of them.  One flow would be very close to your place but a little closer towards Pine St.  That flow would stick pretty close to Pine St.  If you've ever noticed the cabin on the corner of Pine and Robin with the bridge, My grandfather built that cabin and the bridge was there because of the Acorn Canyon Flow.  That bridge used to be 6 feet high but has filled in over the decades.  You can still see how the flow would come down between some of the cabins close to Pine, then pop out at Pine right below Robin.  My mother can remember Pine being a rushing river of mud when she was a girl.

The other, more significant flow coming out of Acorn Canyon would come right down Acorn and spred to the West to Wright's "bog" and angle out down View Ave.

The strip between Acorn and Pine is pretty much high and dry according to the map.

[pining away]

Thanks, Robert. That helps a lot. Sounds like I'm right on the edge of one of the threatened areas.

Any chance you could scan in that map for all to see?

[RobertW]

Thanks, Robert. That helps a lot. Sounds like I'm right on the edge of one of the threatened areas.

Any chance you could scan in that map for all to see?

The maps are very large, 3ft by 2ft.  I received them from "Wrightwood".  You can be sure that the Disaster Preparedness Team has been thouroughly over these maps.

In the Wrightwood History Forum you can see pictures of the last two significant Slide events in the 40s and 60s.  My mother remembers both of them.  I remember very vividly the 69 event.  We have pictures of us standing on top of cabins that were buried to the roof in mud.

I'll be honest with you, I don't know why the Heath Slide didn't come down two springs ago.  Even now there are serious fissures all across the plateau near the top and you can see where large parts of the slide have slid some 10 feet.

The slide comes down every year, as can be attested to by the road being closed at the grates each winter during storms.  As long as it comes down slowly the channel is designed to control it.  The problem will come if it has a heavy snow pack and we get a quick thaw in the spring.  That is what triggered the last to significant slide events. It could also come down if we have torrential rain for a significant period of time, or we have a big earthquake.