Landslide

Page 1 Page 2

I was comfortable at the University of Tehran studying geology. I had meandered into this discipline randomly. My family enjoyed hiking in the nearby Alborz Mountains. My father had always been excited by unusual rock formations and pointed out the many layers of earth which had been compressed into colorful strips of rock on the face of the slopes. He encouraged me to start a rock collection. Although I was a lukewarm outdoorsman, I was attracted to the science by the sheer order of it. Every type of rock could be named and categorized. Natural forces slowly changed the stones. Just by looking at layers of rock, we could go back in time. A calmer time, I thought, with no humans mucking about, creating chaos. Eventually, I supposed, I would veer off into petrology, work for an oil company and live a comfortable life. God curses those whose highest ambition is comfort.

~~~

In 1979 I was writing a dissertation on landslides. Landslides were everything that my life was not: dramatic, unpredictable, shocking. I think I was getting a little bored with my field. Studying landslides felt a little daring to me, perhaps even taboo. I knew that my advisor was pained that I had not followed his suggestions of topics. My father had become exasperated with the amount of time I had spent doing research before I even began to write. Why didn’t I study something that would interest the oil companies and eventually lead to a decent salary? he asked. I had no answer for him. I had belatedly developed a passion and decided to follow it.

During that time, small trickles of dissent began to appear at the university, rolling pebbles signaling the beginning of a larger change. Lecturers began to argue about politics. Study groups degenerated into discussions of theology and power. Soon demonstrations appeared. These demonstrations were annoying to many of us at the university, but they were only an inconvenience, really. Groups of protestors dressed in traditional robes. A few stones thrown at women students without scarves. Fists shaken.

I shrugged it off. I was immersed in my studies. A pattern of slides in the Alborz Mountains just beyond the city had begun to appear in my data. Landslides had occurred historically in these mountains, at unpredictable intervals. The slides would occur, a few buildings would be damaged, some people would be killed or injured. If it was a devastating landslide in a village, there would be little hope of recovering the bodies. Of course, people always dug the earth for days looking for loved ones. Most often, nothing could be done. Generally, the authorities would declare the mounds of earth to be mass graveyards. Relatives would scatter flowers and tears and mourn. After a period of time, the villages would be rebuilt, and new growth would cover the scar of the landslide on the mountainside. The new growth was a symbol of recovery and rebirth, according to the holy men. Still, the tendency for these mountains to slump again was quite high, due to the unstable elements which made up the various layers of soil, going quite deep into the strata of the mountains.

One day as I arrived on the campus, I heard whistles and shouts as I stepped off the bus. More protests, I sighed inwardly. I was running late for my scheduled lecture to my undergraduate students. I walked hurriedly, puffing a little as I went uphill, and tried to cut between buildings, hoping to avoid whatever group of people was gathering. Instead, I heard sirens approaching and found my way blocked by wooden barricades. Some of my colleagues and a few of the younger students were gathered in the alleyway, waiting for a chance to pass to the other side of the campus. We eyed each other uneasily. We shrugged our shoulders and shuffled our feet impatiently. Suddenly, we saw a large mass of people moving down the hill in near silence. Old men, with long beards and glasses, followed by women in long, dark traditional dress, their hair covered by hijabs. I had only seen this garb on very old women, shuffling slowly by the side of the streets near the market. This group was different. Although the women were fully covered, I could tell that most of them were young. They strode confidently and moved gracefully, yet somehow deferentially. The few female faces that were unveiled looked proud, almost haughty. In the distance I could hear shouts and chants, but in front of me those sounds were muted by the silence of the parade passing before me. It took many minutes to go by.

When I reached my lab, I realized that it was too late to give my lecture. It was annoying, but it couldn’t be helped. These protestors were really becoming quite disruptive. I was starting to feel somewhat alarmed but decided that I needed to calm down and focus on my work. What did all this upheaval have to do with me? I was not political. I took some deep breaths and tried to shift my mind back to my dissertation. I decided to focus on the reasons landslides occur. Water, of course, is always an important trigger of landslides. Springs and rivers that escape out of their channels can be one cause of a landslide. Spring melts of snowfall, especially when they are sudden, can be an important factor, especially in very high mountain areas, such as the Himalayas. But most often, landslides are precipitated by rain. Large amounts of rain. Rain that lasts for a long time, slowly drenching the layers of soil and rock. Occasionally, rain that dumps a huge quantity of water over a short period of time can also cause the same type of damage. In either case, the rain penetrates the mountain and burrows through and under it. Cracks often appear; and sometimes gaps open, showing all the layers hidden underneath.

~~~

Days later, I finally delivered my lecture. Attendance had been rather light, but I felt satisfied that I had passed on many basics of rock and soil types and how they interacted during a landslide. I hoped the students felt my enthusiasm for geology, and even imagined that some would choose to further pursue the discipline. The questioning period had been brief, but there was an upcoming holiday, and I assumed that the students were looking forward to the festivities and to a little relaxation. I strolled back to my office slowly, thinking about an upcoming conference on sedimentology. I packed up my briefcase and, at the last minute, threw in my optimistic timeline for my dissertation, although I doubted that I would even glance at it over the holiday weekend.

I decided to eat at a restaurant before I went home to my apartment, assuring myself that when I got home, I would have an uninterrupted evening in which to review the role of liquefaction in deep-seated landslides, a complicated segment of my thesis. I sniffed the aroma of lamb turning on a skewer and realized that I was actually quite hungry. The streets seemed strangely empty, and a few chairs had been overturned at the outside cafes. In the distance, I heard a low rumbling sound. Odd, I thought. It sounded like a landslide.

~~~

When water has thoroughly saturated the upper layers of a mountain slope, small pebbles and loose sand begin to slide downwards, sometimes causing a faint smoky layer of dust to rise. Cracks will begin to appear in the upper areas of the slope. If enough water has seeped through to penetrate down to the glacial till, the layer of clay mixed with silt, small chunks of land will give way and slide down and leave a mark called a scarp. These types of shallow landslides are quite common. Highway workers have to scrape off the mess, and sometimes houses and outlying buildings are affected. Once in a while, an unfortunate person may lose his or her life. But, if the rain or ground water has seeped deep into the underlying layers and penetrated far into the face of the mountain, something bigger and more ominous occurs. This is a process called liquefaction. Sometimes this occurs during earthquakes: the land and the water mix quickly and destabilize the foundations under buildings, causing a multiplying factor of shaking, which can quickly cause the buildings to collapse. Less well known, liquefaction occurs in deep landslides. Large amounts of liquid mix all the layers of pebbles, fine soil and the layers of clay and silt, also known as glacial till. The resulting product is a liquefied mass of mud that begins pouring off the mountain at an unbelievable rate of velocity. It destroys and engulfs everything in its path and leaves a quagmire of destruction and ruin in its wake. Rivers change their course; buildings are engulfed; forests are tossed down the mountain like matchsticks; and everything is permanently changed. Modern geologists believe that perhaps they can come to learn the clues that signal imminent collapse and that one day they might be able to devise a system to warn people to evacuate, but no one believes that they can prevent such slides, nor even influence their flow. They are just too big and mighty: a grand and terrible force of nature.

Page 1 Page 2

Pages: 1 2