Deep Afghan Quake: A Familiar Rumble in a Seismically Active Zone
JURM, Afghanistan — Wednesday’s magnitude 5.5 earthquake southwest of Jurm was a deep one. The U.S. Geological Survey pegged its depth at 216.694 kilometers. That matters.
Deep quakes behave differently than shallow ones. They spread their energy across a wider area.
The shaking at any one spot is less intense. This is not a new story for this part of Afghanistan. The USGS data shows the region has seen at least 232 earthquakes of magnitude 5.0 or greater within about 300 kilometers over the past two decades.
That is more than one a month. Most are forgettable.
Some are not. The strongest recent example was a magnitude 7.5 earthquake in 2015. That was a monster.
It killed hundreds across Afghanistan and Pakistan. It was also a deep quake — about 212 kilometers down, according to USGS records. The depth did not prevent widespread destruction.
Collapsed buildings and landslides killed people. The shaking was felt as far away as Delhi.
Wednesday’s quake was far smaller. A 5.5 is moderate. The depth of this event likely reduced the risk of serious damage near the epicenter.
Seismologists say deep earthquakes release their energy over a broader zone. That limits the intensity of shaking at any single point.
The encouraging part for residents is that deep quakes typically cause less surface damage than a shallow tremor of similar size. But depth is not a guarantee of safety. The 2015 quake was deep and still deadly.
The difference was magnitude. A 7.5 releases about 900 times more energy than a 5.5. That energy can overcome depth.
A deep 5.5 is a different beast than a deep 7.5. There is also the aftershock risk.
The USGS cautions that aftershocks are common following an earthquake of this size. They may continue for days or weeks. People in the affected area are generally advised to be prepared for further shaking.
Early findings suggest the depth of this event may have helped contain damage, but patients in the region should remain alert. The USGS detected the event through its real-time global seismic monitoring network.
No tsunami warning was issued. At least one person has reported feeling the earthquake so far. That number is likely to grow as reports come in from a wider area.
This region of Afghanistan is seismically active because of the collision of the Indian and Eurasian tectonic plates. That collision built the Himalayas. It also produces frequent earthquakes.
The 2015 quake was not an outlier. It was a reminder of the scale of energy stored in the crust here.
Wednesday’s quake was not that. It was a moderate event at a depth that probably spared the surface the worst. But the history of the region says the next big one is a matter of time, not chance.
The 2015 quake showed what a deep earthquake can do when it is big enough. Wednesday’s quake showed what a deep earthquake looks like when it is not.
If you feel shaking, drop, cover, and hold on. For those with concerns about structural safety or ongoing health needs, talk to your doctor or local emergency services. The USGS continues to monitor the region for any additional activity.
