The United States Geological Survey reported that a magnitude 6 earthquake struck eastern Afghanistan on Sunday near Pakistan’s border just before midnight local time. Following were several aftershocks.
2,500 people were hurt and at least 800 were killed. Seismologists believe that the earthquake’s epicenter was at a depth of about 8 kilometers (5 miles), which makes it more intense and destructive, especially for fragile homes and communities.
In this visual explanation, we explain why earthquakes occur at shallow depths more frequently than deep ones, even when their magnitude is the same.
What causes earthquakes to occur?
Simply put, the Earth shakes, which causes an earthquake.
The Earth’s surface is made up of kilometers of hard rock, which are then encircled by a series of moving plates known as tectonic plates, which are positioned on a sea of hot, liquid rock that rolls as it cools, causing the plates to move. On the surface of these plates, earthquakes and volcanoes occur.
Plates are technically always moving, but they typically stay locked together until something breaks under them, allowing them to slide along well-known fault lines, which can extend for miles.
Energy erupts into the surrounding rock when the plate moves and suddenly the pressure releases.
How are earthquakes calculated?
Seismographs, which used to be wiggling needles that recorded the shaking of the ground, are now only digital, according to scientists.
This data is distributed over a global scale, as well as local and regional networks, and is largely open-source and connected automatically. Systems can accurately map the location, duration, and size of an earthquake by combining at least three measurements.
The most widely used scale measures earthquakes’ overall magnitude, with each unit increasing ten times its strength, as opposed to the various methods.
Depth is another crucial factor, as shallower earthquakes typically cause more damage than shallower ones.
Why do shallow earthquakes cause more damage?
Even if two earthquakes of the same magnitude are similar in magnitude, how much damage is done and how strong the effects are on the ground are affected by both earthquakes’ depths. Because of the shorter distances they travel before reaching people and buildings, shallower quakes are typically much more destructive.
As the energy travels through the rock’s layers in deeper earthquakes, it dissipates a lot. In densely populated areas, shallow ones, in contrast, release their energy closer to the ground, causing more shaking and harm.
There are typically three measurements used to classify earthquake depth: shallow focus (0-70 km or 0-43 miles), intermediate focus (70-300 km or 43-186 miles), and deep focus (300-700 km or 186-435 miles).
Where do earthquakes most frequently occur in Afghanistan?
The Hindu Kush mountain range is a hotspot for both shallow and deep earthquakes because Afghanistan is one of the most seismically active regions on Earth. Due to the tectonic collision between the Indian Plate and the Eurasian Plate, this region is very active.
In addition to forcing some of the lithosphere to steeply sink into the mantle, this enormous pressure also causes crust to crumple and fracture, according to the Hindu Kush. In consequence, there are frequent earthquakes that can reach 200 kilometers (124 miles) deep in the Pamir-Hindu Kush region of northern Afghanistan, a rare sight on earth.
In contrast, earthquakes typically strike closer to the surface where they cause the most damage, along the Sulaiman Range (western Pakistan and southeast Afghanistan) and near the Main Pamir Thrust.
The location of some of Afghanistan’s most deadly earthquakes since 1991 can be seen in the graphic below.
