I want so much to be able to return to the mountain kingdom of Nepal and help them in their hour of need. To see all those wonderful people again would be so great. That may seem a strange thing to say. But I know for a fact that even in the midst of tragedy they remain an optimistic and warm people. Right now I’m missing them and praying for their safety. I wanted to post some pictures of Nepal that I’ve never shared, and also go into some background on how and why this happened.
THE GEOLOGIC STORY
You may have heard that Mt. Everest is getting taller, and we just saw dramatic and horrific evidence of that fact. India collided with south Asia some 55 million years ago, and the mighty Himalayas began then. But that slow motion and awesome event continues today, as huge slabs of the earth’s crust continue to be shoved beneath the Tibetan Plateau. The zone where they come together, along the 2400 km. (1500 mile) long Himalayan mountain front is complex. But north-directed subduction, or underthrusting, is the dominant process.
The earth’s most recent and currently most dramatic tectonic collision has resulted in shortening of northern India and southern Nepal, bringing Delhi and Lhasa closer together. This in turn causes the crust to greatly thicken (mostly in the downward direction). In other words, most of the long mountain range lies beneath sea level. Like a giant iceberg, active mountain ranges have roots that are hundreds of times more voluminous than their visible parts. The north-south shortening doesn’t just create crustal thickening; it also causes the region to widen in an east-west direction via a series of large strike-slip faults (like the San Andreas).
Deep beneath the Himalaya, collision takes the form of a slow, hot, plastic deformation. There are no sudden jerking motions. But in shallower regions, where the rocks are cooler and brittle, this is impossible. Instead, the stress builds up until it’s finally released with a sudden rapid slide along a plane of weakness (or fault).
It is at those times that we on the surface of this planet are reminded that ours is a dynamic planet. These events, which can vary from a gentle rocking that lasts only seconds and which you only notice if you are in a quiet place to violent minutes-long shaking that can bring down buildings and even whole mountainsides, are called earthquakes.
The earthquake of April 25th was centered about 80 km. (50 miles) NW of Kathmandu, It was magnitude 7.8 on the Richter scale. It was located about 15 km. (9+ miles) deep. That is fairly shallow for a quake of this size. Combined with the dense population and low quality of construction in most of the region, this made for a major disaster. Considering what is going on here, the coming together of two of Earth’s greatest tectonic plates, historic earthquakes are relatively few. The last one to affect the same area was in 1988 and killed 1500. The 1934 Bihar earthquake killed some 10,600 and severely damaged Kathmandu.
Most of the people here, with the resources to live from day to day and not much more, have been deeply affected by this disaster. The current count is over 4000 and still rising. Many people live far from roads, so the final tally could take weeks or even months. Undoubtedly many of the deaths will turn out to be caused by major landslides. In any mountainous region, a big quake leads to landslides of epic size. Snow avalanches also occurred in the alpine regions, including one caught on video that roared down the south side of Everest and hit base camp.
So much misery can be brought by earthquakes. They strike without warning of course, and this makes them truly terrifying. I have been in a few small ones, and get a visceral thrill out of it. I get the same feeling witnessing a volcanic eruption. That’s partly because I’m a geologist and know about the connection between a living breathing planet and life. But I’m sure my reaction would be one of pure terror if and when I’m caught in a truly big event. Once, in 1999, I flew out of Istanbul less than 24 hours before a major quake hit that city, killing 17,000.
Please give if you can to the legitimate aid organizations helping in Nepal. And in any case, please keep those beautiful souls in your thoughts and prayers. I’ve never seen a harder working people. I’m sure they will recover, but big aftershocks continue as I’m writing this.
Friends of mine are camped outside in pouring rain, afraid to return to their homes. So right now I’m hoping and praying the aftershocks are many and small, not fewer and large. Namaste to all Nepalis and all those who have connections to the country.