Hindu Kush

Deep under the ground, pieces of the Earth's outer shell push against each other.

This pushing makes the ground shake in earthquakes.

NASA explains that the Eurasian and Indo-Australian tectonic plates keep pushing against one another under this region. The constant pressure and grinding cause many earthquakes: on average about four major ones a year, of magnitude 5 or more.

The Hindu Kush joins the Pamir, the Karakoram and the Himalayas in one long system of mountains, which ESA says includes the highest places on Earth.

Earthquakes are common in the Hindu Kush because the Eurasian and Indo-Australian tectonic plates continue to push against one another; NASA reports an average of four major earthquakes (at least magnitude 5) a year from this constant pressure and grinding.

ESA places the range at the western end of the Hindu Kush-Himalaya system, which includes the highest elevations on Earth.

In winter, snow blankets the mountains.

Many major rivers flow from these mountains and their neighbors.

NASA says glaciers and heavy snowfall are ever-present in these mountains. In a 2006 satellite image, ESA showed winter snow covering the Hindu Kush and spreading down to the desert lowlands around it.

ESA says the whole Hindu Kush-Himalaya system holds more ice and snow than anywhere outside the polar regions. Many major rivers flow from it, and the system is estimated to supply water for 500 million people.

Glaciers and heavy snowfall are ever-present features of the range (NASA). ESA's Envisat image of January 2006 shows winter snow blanketing the Hindu Kush and the Pamir and reaching surrounding desert lowlands.

The Hindu Kush-Himalaya system makes up the greatest concentration of ice and snow outside the polar regions; many major rivers flow from it, and it is estimated to supply water for 500 million people (ESA). The Helmand River flows south from the Hindu Kush.

Many people live in the valleys between the mountains.

They bring water to their fields to grow crops.

NASA says the Hindu Kush is heavily populated. People water the valleys to grow crops, but farming is hard at such high altitudes and low temperatures.

High mountain passes cross the range, and NASA says they are still important routes for trade and travel. People here also live with earthquakes, which NASA says are common because of the plates pushing together under the mountains.

NASA describes the Hindu Kush as heavily populated; the valleys are heavily irrigated, but growing crops at such high altitudes and low temperatures is difficult.

The range's high-altitude passes remain important trade and travel routes (NASA). Residents also live with frequent earthquakes.

People can get sick high up on mountains, so go up slowly.

If your head hurts high up, tell a grown-up and go down.

The Hindu Kush averages 4,500 meters high. The US Centers for Disease Control and Prevention (CDC) says the body can adjust to thin air up to about 5,200 meters, but it needs time, and children get altitude sickness as easily as adults. Its main sign is a headache.

The CDC says to go up slowly and avoid going "too high too fast". Altitude sickness gets better quickly by going down 300 meters or more.

The CDC Yellow Book notes that the body can adjust to moderate hypoxia up to about 5,200 m but needs time, and children are as susceptible to altitude illness as adults; headache is the main symptom of acute mountain sickness.

Travelers should ascend gradually, avoiding going "too high too fast"; above 3,000 m, sleeping altitude should rise by no more than 500 m a day. Acute mountain sickness improves rapidly with a descent of 300 m or more.