The narrative which follows is taken in part from the field journal for my 1989 field season. I will refer to a few events which occurred in the 1990 field season as well. These events took place mostly in the Shumigan Islands near the tip of the Alaska Peninsula while I was employed as a precious metals exploration geologist with Battle Mountain Gold Corporation. One of the earthquakes I shall refer to occurred in 1990 in the central Aleutians while I was prospecting Unalaska and Umnak Islands for Battle Mountain Gold Corporation.
Although, how I came to be in this location is a story in itself, I will reserve that for a future time. On Sunday, June 4, 1989, I found myself part of a hand picked team of geologists walking beneath the 200' to 500' high beach cliffs of Popof Island, as Bill Ellis, the head of our field operations, gave us an exhaustive introduction to the geology we would soon be prospecting for gold. Our helicopter was flying the long semicircle around the Gulf of Alaska from Seattle and would not arrive for another week, so we had lots of time for sightseeing. We were in a spectacular place of high snow capped peaks, and deep and impossibly violent ocean passages cutting into, or through, the islands.
Bill impressed us all when he rolled over one of the beach cobbles and picked up several small gold nuggets lying glittering in the all too rare sunlight. He told us not to get too excited because the beach placer was already owned, and the owner wanted to sell it to us for $3,000,000! We did have the owner's permission to collect as much gold as we wanted in our "free" time. Since we worked 30 days on and 1 day off, we would not be getting rich at the placer.
I did not know it yet, but I was about to start one of the most physically demanding experiences of my life. That is saying a lot, considering I had previously had a remarkable experience while spending 30 days at sea skippering a 36 foot yacht between the Grenadine Islands and Florida. During this period we fought through hurricane Alice, while suffering little sleep and almost no food. I lost over 30 pounds in that short time period! Little did I know that similar physical hardships were just around the corner. The big difference, however, was that we had unlimited food of the highest quality. Even with the wonderful dining I would soon trim down by more than twenty pounds.
Being the only civil engineer/geologist, I was soon assigned the job of designing and flagging a three mile access road to the top of our first prospect, "Propolof." With one evening of design and layout time behind me, I found myself 100 yards ahead of a D-8 Cat, Brunton compass in one hand and flagging in the other, laying out the horribly steep and winding road up the mountain. This road led to the top of a high peak where a strange crater-like formation lay hidden. I managed to stay just ahead of the dozer and finished the road layout by early evening. I stopped at the top for a rest and to gaze upon the fantastic beauty of the ocean and islands stretching off into the distance. I also looked closely at the strange crater lying just below me.
The "crater," as we all called it, was about half a mile wide. It had numerous small lakes in the bottom, and showed patches of brightly colored hydrothermally altered rock in places. What was stranger still were a series of sub parallel lines cutting across the crater. Some of the lines joined neighboring lines, forming an intricate pattern in the tundra. I probably would not have even noticed most of them except that the sun was low, and the oblique lighting showed them up quite distinctly. Less than a week later a similar lighting situation would give me the clues that would soon allow me to unlock the mystery of the "crater." I did notice that several of the lines were deeply cut into the tundra, much as if a plow had cut one single giant furrow across the crater. In places there were big blocks of tundra standing on edge as much as three feet above the surrounding surface along the furrow, which was three to four feet deep in places!
I found the view of the tortured tundra strangely disquieting. Looking at the crater I got a cold chill down my neck, and my hair wanted to stand on end. I passed it off as a side effect of being all alone, looking at the fantastic view, and starting to chill due to the 40-50 mph winds cutting across the peak. It was apparent that the good weather was about to end, as I watched the islands disappear in the rapidly forming fog and clouds. I would soon get to know that weather pattern very well as the unending storms lashed our little tent camp. I would also almost forget what sunlight was as the only four sunny days of the season passed into memory. I didn't know it yet, but my next field season the following year would be much better, with a full 6 days of sun shine!
A week later our helicopter arrived. The craft was a beauty, an Alawette A-Star. It could carry four in the back seat, and a cramped three in the front. Everyone was pretty excited as it settled on the pad for the first time. Our camp mascot "Diamond," a beautiful golden Lab, quickly adopted the aircraft as his own. The helicopter could not take off without Diamond on board, lying at the pilot's feet.
The next morning Bill assembled all members of the camp, exploration geologists, camp based rock sample testing and logging geologists, cooks, and camp manager, to organize an all day helicopter tour of the islands and the sites we would be working. Since the crew was too big to all go on one trip, we employed a leap frog process, with the exploration crew going first, and the rest of the crew following on the next trip. It was just after sunrise when I climbed on board for my first ride in the A-Star. We lifted off in a buzz of excited chatter between the members of the exploration crew.
The next five minutes proved to be the most important I would experience during my two seasons in the Aleutians. I had a window seat, and my intense interest in the islands kept me glued to the window. Everyone else was too preoccupied in their conversation to really look closely at the ground below us. In the oblique early morning light I could distinctly see a network of sub parallel lines cutting across the islands, very similar to those I had seen a week earlier in the crater. They became invisible when the Sun rose higher and the light became more direct. At this point neither instance made a great impression on me, but the lines were now filed away in my mind ready for events yet to come.
We had a wonderful day, covering many miles and many islands. The helicopter had to make frequent refueling trips back to camp while we explored the various locations. We landed on mountain tops, tundra, beaches, and even made our first "single skid" landing, a technique that would soon be one of our most common landing methods in rough terrain. During this first flight we even passed closely over a large herd of wild buffalo, or bison, that were left behind from a failed ranch on Popof Island. The buffalo had taken over the island and were living happily there by the hundreds. Two weeks later I would have a very close encounter with a huge bull buffalo. (In the image, the bump to the right of the big rock is the buffalo being chased away by the helicopter.) It still gives me chills when I think about it. Only the fast action of our pilot, Jim, averted catastrophe for me. He would prove equally reliable later in the season when we started working close to the giant brown bears of the Alaska Peninsula.
Our view of the southern Alaska Peninsula to the west was dominated by Pavlof volcano. When the weather was clear it was a spectacular sight. The weather closed in for an extended period, and when it broke for a few hours we could see that the volcano had been in eruption. All the snow was covered with black ash. It erupted several more times during the summer, but we never got to see it happen. It was always in the clouds during the eruptive events. Later, toward the end of the season, we would be working right near the base of the smoking giant.
On Tuesday, July 18, I made the most significant geologic observation of my career. I had to lay out sample lines up and over the top of Propolof prospect. It required surveying down through the crater area. I had a young college student, Dennis, along as my helper when I sat down on a hill within the crater for lunch. As we sat there talking I kept studying the strange pattern of sub parallel lines crossing the crater floor. The more I looked, the more certain I was that I was looking at an incredible series of fault lines. It was a classic imbricate fault structure! The more I looked the more excited I became. Several of the lines, as I mentioned earlier, were very deeply cut. In fact they were ragged trenches with the tundra ripped up into large blocks that were tilted up on edge at various angles. As I realized what I was looking at my hair began to stand on end once more. Later I walked down into one of the trenches, and it was waist deep and three to four feet wide. It cut down into the "crater," across the bottom, and back up and out the other side. These were freshly torn open fault lines, the cause of recent earthquakes. The fact that both sides were the same elevation indicated it was a strike slip fault. What I needed to know was if it was a left or right lateral strike slip fault, meaning, when I looked at the other side of the fault, had it moved to the right or left? The subsequent erosion of the ripped up blocks of tundra prevented me from determining the fault motion by the orientation of the blocks with any degree of certainty, and I needed to be absolutely correct.
The reason this was important is because the gold deposit on Propolof was truncated. It stopped abruptly. Knowing the motion of the faults might tell me where the other part of the deposit had gone. All of this came to me in a rush as we explored the crater. The parallel lines I had seen from the helicopter during that first flight, the lines cutting through the crater, all fit the picture. In my mind's eye I was now seeing the island made up of a large collection of faults and fault slices. I would later be able to determine that the faults were spaced at the incredibly small spacing of only 50-150 feet in many places!
We spent the afternoon studying the crater which overlooked Red Cove, and luck was with me. On one side the crater was open where a fault cut across it, forming a cliff which dropped into a deep valley below. I was able to climb down the cliff, and the "slickensides" left on the hard basalt cliff face due to the fault movement told the story. There were tension cracks, drag cracks, that told me the fault was a right lateral strike slip fault. That means that if you stand with one foot on each side of the fault, the block on your right side would be moving toward you during an earthquake. By this time I was boiling over with excitement.
The reason for my excitement was that this was the third year of a five year project. The crater, and its ore deposit, had been discovered some time earlier. The problem was that the ore body stopped suddenly, and no one knew where it went or why it stopped. A large number of very high powered geologists had worked on the problem without sucess. It was only that early morning flight that had made the difference for me. I now had the key to unlock the secret of the crater.
I told Dennis to say nothing about the discovery. I spent the remaining few hours field mapping the biggest faults. As I worked, it all became very clear what was going on. The crater was a huge fault sag and not a crater at all. The chemical alteration of the rocks was due to hydrothermal fluids coming up the faults, this was a classic process of mineralization on a large scale.
After the chopper picked us up and returned us to camp I had a hard time containing my excitement. I didn't want to release it yet however, because I wanted a little more time to get the majority of the area geologically mapped. Unfortunately Dennis couldn't restrain himself and he made a comment to Bill, our camp boss. Bill came right to me and took me aside asking me to explain what I had discovered. I told him what I had observed, and that I had determined it was a right lateral imbricate fault system of giant proportions. He said not to talk about it, and asked me to fly up the next day and completely map the crater. He was keeping it quiet because each geologist had been given certain areas of responsibility to geologically map, and this area was not mine. It had been mapped by two senior level geologists who had not mapped a single fault there. When I brought this new information to light there was going to be raw feelings in camp.
There was another event that had occurred that same day that I was not yet aware of. Bill had met with a woman geologist in Sand Point that morning. She was concluding a 10 year study of the tectonics of the Shumigan islands. She had told Bill that the islands were cut by an imbricate series of right lateral faults! When I said the same thing, Bill became as excited as I was, but didn't let on to me. He instantly realized the significance of this information.
Once a week we would stay in camp for a geology "round table meeting" to discuss the weeks findings. On Friday, July 21, we met during one of the typical Aleutian storms. With the wind hitting 80+ mph, and the rain coming down in torrents, we tried to discuss our work. The first thing on the agenda was the crater on Propolof. Bill asked me to relate what I had found. I had not even finished before the two geologists whose area I was discussing violently disagreed with me. After all, they were full time year round geologists, not a summer contract geologist like me. After several hours of very heated discussion and argument, Bill settled the issue by announcing that he was having a geophysical exploration company send in two men with their "magic black boxes" to do a study of the crater area. Using low frequency resonance, and magnetic detection equipment, the issue would soon be resolved by their findings. I had a lot riding on what they found.
For the next two weeks, while the geophysicists did their work in the crater, the tension in camp was so thick you could have cut it with a knife. Finally the day was at hand. We all met in the office tent for our round table meeting, along with two new members from the geophysics company. I was asked to lay out my geologic field map of the crater area. Then the "geowizzes," as they are commonly called, were asked to present their findings. At this point my heart was beating like a trip hammer.
As their report was presented, their field map was almost an exact duplicate of mine! My faults exactly matched their's in the crater. They had a few additional faults, "structures," outside the crater where the surface evidence did not allow me to detect them. I had carried the day, but the anger that it created was to persist the rest of the season. We never were able to find the missing slice of the ore deposit. We were able, however, to determine that the faulting had displaced the ore body many miles northward. We searched the islands to the north, but finally gave up, concluding that it had either been concealed below the surface of the ground or was presently beneath the sea between the islands. Because of that missing slice, the ore deposit was not large enough to be economic to mine.
I was to run into the ripped tundra in other locations a number of times that first season, and again a thousand miles farther out in the Aleutian chain during my second season. In each case it was from a very recent earthquake, probably in the last 5 years or less. I experienced many earthquakes there, including two of substantial size. During one of them in Dutch Harbor I was awakened at 2:00 AM, and sent racing up a nearby hill side by the local fire department with my gear under my arm. They went racing through Dutch Harbor with their siren screaming, telling everyone to head for high ground due to a tidal wave, "tsunami," warning. I took this warning very seriously, having almost lost my life in the huge tsunami that hit Okinawa in 1962 from the great Chile earthquake. I was chagrined to observe that many of the sailors in Dutch Harbor headed up the hill sides with a case of beer under each arm! I guess they had their priorities too. One of the most spectacular indications of the very active tectonics I saw in the Aleutians was a bay on the Alaska Peninsula with 20-30 stranded beaches, one above the other. Each beach represented a great earthquake and a sudden uplift of the land of 20-30 feet!
We now have some amazing information regarding the tsunamis in the Aleutians and Gulf of Alaska. In the Aleutians, evidence has been found of a wave reaching a height in excess of 3000 feet! Also, in SE Alaska, in Lituya Bay in 1954, an earthquake occurred that created a giant wave which swept down the bay, clearing all soil and timber off the hill sides to an elevation in excess of 1700 feet! There were a number of fishing boats in the bay at the time. One of the boats survived after being carried over a peninsula covered with forest, and being deposited in the sea. The husband and wife team abandoned their sinking craft and climbed into a small dingy and lived to tell the tale. The local Indians had long told stories of great waves in the bay, but no one believed them until this happened. Now we know that great waves are a regular occurrence in Lituya Bay, caused by earthquakes on the Fairweather Fault which cuts through the upper bay.
I hope you enjoyed this narrative. I also hope that you can get to the Aleutians someday to see the amazing landscape of these spactacular islands. If you go, take your rain gear, gum boots, and if you plan to camp in the islands near the Alaska Peninsula, bring a BIG gun. We observed 22 big brownies in 15 minutes from our helicopter in that area!
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