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Earthquakes

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Earthquakes

Postby Strider » Wed Dec 27, 2006 10:10 pm

I noticed there has been a lot of seismic activity lately. Any stories about earthquakes while hiking in the high country?

A few years ago, I was scrambling up Burro Creek from Mountain Home to Maggie Lakes when all the squirrels and birds started chattering. I could feel an earthquake rumbling up the canyon, and then stop abruptly at the top of the escarpment. All the boulders seem to jump as the canyon "caught" the earthquake. It was awesome.



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Postby giantbrookie » Thu Dec 28, 2006 10:18 am

Actually, the rate of seismicity is really no different than in the past--public consciousness of earthquake occurrence waxes and wanes depending (in part) on how events are reported by the media. Be that as it may, I haven't experienced any earthquakes while hiking, although I was in the White Mountains when the M6+ on the Hilton Creek fault (cuts across McGee Creek) went off in May 1980 (this is also sometimes referred to as the Mammoth Lakes earthquake sequence). I was camped with my senior geology class at the time and didn't feel a thing--given the distance and size of the earthquake, this is not surprising. We did take a look at the aftermath the next day and it was pretty impressive. All of the snowfields on the east side of Mt Baldwin and ridge between Baldwin and Morrison looked "dirty" meaning they were covered with rockfall. Some huge boulders had come rolling off of the mountains above 395, some of them coming to rest within 100 yards of the highway. The moraines of McGee Creek had a fresh fault scarp cutting across them (can still be seen) which could be followed northward until it crossed 395 where it formed a crack in the pavement (but the vertical component was fortunately negligible by the point, otherwise it would have meant major road repair). The softer sediment in Long Valley (ie upstream of Lake Crowley) had lots of cracks from lateral spreading, etc. We students took great delight in this one crack that had broken a cowpie in two--we called this out as a "faulted cow pie" even though we knew the crack wasn't really a fault.

I recall there were reports of some hikers being in Convict Canyon when that earthquake hit. It was apparently a terrifying experience, with rocks falling from both directions. Convict Canyon is very narrow with no room to take cover. I seem to recall that one hiker suffered a broken leg or arm as a result of being hit by rockfall. Only John Muir would have enjoyed an experience like that. Of course, his is the best Sierran earthquake account. Without ever having experienced an earthquake Muir had surmised that earthquakes were the main agents that formed the big talus piles beneath cliffs in the Sierra. He based this on the fact that the steady state rockfall rate was way too slow to account for the amount of talus and the fact that lichens growing on the rocks seemed to be of the same size (this latter observation was formulated into a quantitative technique more than a century after Muir made this observation). In any case he got to experience the 1872 earthquake in the Sierra, including a lot of rockfall that cut loose.
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
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Postby cgundersen » Fri Dec 29, 2006 4:44 pm

Hi Strider,
As giantbrookie noted, there are spots in the Sierras where one really does not want to be when a big one hits. Having said that, I discovered long ago that the best motivator for my wife, particularly when she is getting a bit anxious on a tricky ascent (or, descent) is to raise the specter of an earthquake. Although she has become desensitized to this ploy, it still evokes a bit of an activity surge (she's even returned the favor).

As for quake action, I've never experienced more than minor rumbles in 30+ years of wandering the Sierras. However, in the very canyon alluded to by giantbrookie, I experienced an amazing display of subterranean seismic activity: we were camped above McGee Lake and had been treated to a minor dinnertime rumble that triggered a series of echoing rockslides. In the process of settling down to sleep, we noticed that if one planted one's ear to the ground, there were deep resonant rumbles that seemed to be emanating from the bowels of terra firma. The best notes sounded as if they came from something akin to gigantic kettledrums that were muffled by layers of gauze. It was fascinating. My minds eye envisioned lava rearranging in cavernous chambers, but it was probably something appreciably more prosaic. Anyway, we were sufficiently curious that we camped at the same spot on the way out (about 10 days later). However the spellbinding noises had ceased, and on a more-recent pass through that area, we could not summons a repeat performance. My guess is that the best chance of an encore would be right after another quake. Since that area certainly has periods of seismic activity, I'm keeping it in mind!
Happy new year!
CG
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Postby giantbrookie » Fri Dec 29, 2006 5:53 pm

I've never experienced (or realized I was in) an earthquake in the Sierra in my 40+ years up there, but I have witnessed some stunning rock falls that didn't seem to be seismically triggered (although I could very easily be wrong). There was a big one on the face south of Lake Italy in 1986. First off all, it made a lot of noise. Second it was amazing sight in pitch darkness to see all those sparks from the boulders hitting each other.
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
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Postby gcj » Mon Jan 01, 2007 6:58 pm

Hi all,
In October, 1978 I was heading south on 395, when I began to see a lot of strange clouds rising above the mountains. When it was announced on the radio that there had just been a strong earthquake, I stopped and took this picture looking up Pine Creek Canyon:

Image

This was taken about 30 or so minutes after the quake. The wisps of haze in the sky are actually clouds of dust. I could be mistaken, but I think that this was the M5.8 that defined the end of a relatively long quiet period of seismic activity in this region and which began the series of events that culminated in the 1980 Mammoth quake. I had been on my way to climb N. Palisade via South Lake, Bishop Pass, etc., but I experience at least two after-shocks in the vicinity of Long Lake that convinced me that it was not a good time to be on high steep crumbly mountains! :paranoid:

On Memorial Day weekend, 1980, I had planned a trip up Convict Creek, but the big earthquake a week(?) or so earlier put an end to those plans. I went instead up McGee Creek. I don't think this was one of my better decisions. The NFS had crews up there using explosives to clear parts of the trail. At one point I had to wait about 20 minutes while they set off a series of charges. In camp that night I felt one very strong after-shock that made me feel very insecure about the canyon wall rising above my tent. :eek:

1980 had been a heavy snow year. When I continued up the trail the next morning, I saw that the snow in the cirques and basins above was very dirty with earthquake debris. By the time I'd reached the narrow canyon above Little McGee Lake, the warm sun had softened the snow enough so that rocks and boulders were almost constantly rolling down the canyon walls. I found a safe vantage point to watch the show for a while and then hiked all the way back to the trail-head and drove home. It seemed too dangerous to be up there while there was still so much instability.
Last edited by gcj on Mon Jan 01, 2007 9:14 pm, edited 1 time in total.
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Postby markskor » Mon Jan 01, 2007 8:27 pm

Not really an earthquake per se, but in YNP a few years back, I was just coming down from LYV, right before that big rock let go above the apron of the Glacier Point massive. They estimated that the rock was 40 - 50 feet across...uber huge...and the resultant crash from the 3000 ft. fall, even from miles away, sounded like a howitzer exploding...echoing throughout the canyons. Upon getting to the vicinity of the Muir trailhead, there was a thick cloud of pink/gray dust cloud hovering about 200 feet high, tops of trees were sheared off/ splintered like a giant weed-eater had just come through, and parts of the paved section of trail were missing...completely blown off. We had to pull out bandanas in order to breathe without choking, and there was easily a foot of fine silt along the trail itself.

Another time, we were coming down the trail from Nevada Falls, just a day or so after an earthquake. That section of trail near the base of the falls resembled more like a giant talus field than a stepped trail...10-foot rocks scattered all over the path. It made you feel quite puny...inadequate in comparison.
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Postby tomcat_rc » Mon Jan 01, 2007 9:08 pm

Back in about 1984 - I was fishing in Bishop at the pleasant valley reservoir. back in those days - we would drive across open desert and then descend down the rocks to fish on the opposite side from the access road. I was on my way out - about half way up the side in the boulder section when an earhtquake shook everything around. suddenly I felt very small for my surroundings and "pucker factor" took on a hole(no pun intended) meaning. rocks were tumbing down all around - but thankfully nothing at or around me let loose. I would guess it was about a mid 5's level.
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Postby giantbrookie » Tue Jan 02, 2007 9:59 am

gcj wrote:Hi all,
In October, 1978 I was heading south on 395, when I began to see a lot of strange clouds rising above the mountains. When it was announced on the radio that there had just been a strong earthquake, I stopped and took this picture looking up Pine Creek Canyon:

On Memorial Day weekend, 1980, I had planned a trip up Convict Creek, but the big earthquake a week(?) or so earlier put an end to those plans. I went instead up McGee Creek. I don't think this was one of my better decisions. The NFS had crews up there using explosives to clear parts of the trail. At one point I had to wait about 20 minutes while they set off a series of charges. In camp that night I felt one very strong after-shock that made me feel very insecure about the canyon wall rising above my tent. :eek:


Great photo! Great account by Tomcat of his earthquake experience, too!
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
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Talus

Postby DoyleWDonehoo » Tue Jan 02, 2007 4:54 pm

One of John Muir's first observations was that most all of the talus of the Sierra was made at the same time, and his guess for the reason was earthquakes. Later it was proved to him when he was in Yosemite Valley when a big quake hit and he saw a talus slope form by an avalanche not far from his cabin.
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"A Noble Earthquake, a noble earthquake"

Postby gdurkee » Thu Jan 11, 2007 8:46 pm

Some great stories here -- excellent photo too.

In 19 ought and 70 something (74??) I was the ranger in Little Yosemite Valley. We had a canvas tent set up on cut lodgepole with a dirt floor. A couple of us were inside the tent and heard what sounded like a freight train coming up the valley. Native San Franciscan that I am, I knew it was an earthquake and immediately rushed to the "door frame" of the tent as the most structurally safe place. After about 1/2 a second, I realized that was pretty dumb. Still, instinct and training.... .

I think that was the same earthquake a climber was on Half Dome and watched the huge flake he was on shake back and forth away from the face. He was anchored into the crack and his protection dropped down farther. The flake, fortunately, held.

George
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