A MASSIVE 8.1 EARTHQUAKE ROCKS PAKISTAN - 26 October 2015

A MASSIVE EARTHQUAKE ROCKS PAKISTAN MEASURING 8.1 ON THE RICHTER SCALE

HITS REGION WITH EPICENTRE IN AFGHANISTAN — 60KM FROM CHITRAL - 26th OCTOBER 2015

The earthquake reportedly caused widespread panic across the region with people saying that it caused major alarm. Many of them took to social media and uploaded the moment when the quake hit. Residents in several Pakistani cities in the country’s north said that they could feel the buildings that they were in sway.

The earthquake struck almost exactly six months after Nepal suffered its worst quake on record, on April 25. Including the toll from a major aftershock in May, 9,000 people lost their lives and 900,000 homes were damaged or destroyed.

MASSIVE 8.1 EARTHQUAKE ROCKS PAKISTAN  

MASSIVE 8.1 EARTHQUAKE ROCKS PAKISTAN 

MASSIVE 8.1 EARTHQUAKE ROCKS PAKISTAN 

8.1 EARTHQUAKE ROCKS PAKISTAN 

8.1 EARTHQUAKE ROCKS PAKISTAN 

EARTHQUAKE ROCKS PAKISTAN 

Epicenter

According to the US Geological Survey, an earthquake with magnitude  7.5 occurred at 2.09pm (PST) on Oct 26, 2015. It said the quake was 212.5 km deep and centred 82 km southeast of Feyzabad in a remote area of Afghanistan in the HinduKush mountain range.

The Pakistan Metrological Department said the magnitude of the quake was 8.1.

USGeological Survey 

has issued a detailed report and some of the excerpts are as follows

“On the north-western side of the Tibetan Plateau, beneath the Pamir-Hindu Kush Mountains of northern Afghanistan, earthquakes occur at depths as great as 200 km as a result of remnant lithospheric subduction. The curved arc of deep earthquakes found in the Hindu Kush Pamir region indicates the presence of a lithospheric body at depth, thought to be remnants of a subducting slab. Cross-sections through the Hindu Kush region suggest a near vertical northerly-dipping subducting slab, whereas cross-sections through the nearby Pamir region to the east indicate a much shallower dipping, southerly subducting slab. Some models suggest the presence of two subduction zones; with the Indian plate being subducted beneath the Hindu Kush region and the Eurasian plate being subducted beneath the Pamir region. However, other models suggest that just one of the two plates is being subducted and that the slab has become contorted and overturned in places.

Shallow crustal earthquakes also occur in this region near the Main Pamir Thrust and other active Quaternary faults. The Main Pamir Thrust, north of the Pamir Mountains, is an active shortening structure. The northern portion of the Main Pamir Thrust produces many shallow earthquakes, whereas its western and eastern borders display a combination of thrust and strike-slip mechanisms. On the 18 February 1911, the M7.4 Sarez earthquake ruptured in the Central Pamir Mountains, killing numerous people and triggering a landside, which blocked the Murghab River.”

What caused the quake?

US Geological Survey says in its report that earthquake near the Hindu Kush region of Afghanistan occurred as the result of reverse faulting at intermediate depths, approximately 210 km below the Hindu Kush Range in northeastern Afghanistan.

Reverse faulting is a geologic fault in which the hanging wall moves upward elative to the footwall. Reverse faults occur where two blocks of rock areforced together by compression.

Focal mechanisms indicate rupture occurred on either a near-vertical reverse fault or a shallowly dipping trust fault. At the latitude of the earthquake, the India subcontinent moves northward and collides with Eurasia at a velocity of about 37 mm/yr.

Active faults and their resultant earthquakes in northern Pakistan and adjacent parts of India and Afghanistan are the direct result of the convergence between the India and Eurasia plates. This collision is causes uplift that produces the highest mountain peaks in the world including the Himalayan, the Karakoram, the Pamir and the Hindu Kush ranges.

“Earthquakes such as this event, with focal depths between 70 and 300 km, are commonly termed “intermediate-depth” earthquakes. Intermediate-depth earthquakes represent deformation within subducted lithosphere rather than at the shallow plate interfaces between subducting and overriding tectonic plates. They typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth earthquakes may be felt at great distance from their epicenters. “Deep-focus” earthquakes, those with focal depths greater than 300 km, also occur beneath northeastern part of Afghanistan. Earthquakes have been reliably located to depths of just over 300 km in this region.”

Army chief orders relief measures