Nepal struck by huge earthquake

JamesMike said:

The death toll tops 1,400 and is expected to rise. Text my friends there to check on them, crossing my fingers.

http://www.cnn.com/2015/04/25/asia/nepal-earthquake-7-5-magnitude/index.html

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USGS said:

The April 25, 2015 M 7.8 Nepal earthquake occurred as the result of thrust faulting on or near the main frontal thrust between the subducting India plate and the overriding Eurasia plate to the north. At the location of this earthquake, approximately 80 km to the northwest of the Nepalese capital of Kathmandu, the India plate is converging with Eurasia at a rate of 45 mm/yr towards the north-northeast, driving the uplift of the Himalayan mountain range. The preliminary location, size and focal mechanism of the April 25 earthquake are consistent with its occurrence on the main subduction thrust interface between the India and Eurasia plates.
Although a major plate boundary with a history of large-to-great sized earthquakes, large earthquakes on the Himalayan thrust are rare in the documented historical era. Just four events of M6 or larger have occurred within 250 km of the April 25, 2015 earthquake over the past century. One, a M 6.9 earthquake in August 1988, 240 km to the southeast of the April 25 event, caused close to 1500 fatalities. The largest, an M 8.0 event known as the 1934 Nepal-Bihar earthquake, occurred in a similar location to the 1988 event. It severely damaged Kathmandu, and is thought to have caused around 10,600 fatalities.

In the coming week, the USGS expects 3-14 M≥5 aftershocks of the magnitude 7.8 Nepal earthquake. Additionally, the USGS estimates that there is a 54% chance of a M≥6 aftershock, and a 7% chance of a M≥7 aftershock during this one-week period. After this, in the following month and then the following year, USGS expects several M≥5 aftershocks, with a significant chance of M≥6 aftershock (greater than 50%). The potential for an aftershock larger than the mainshock remains, but is small (1-2% in each time period).
Felt earthquakes (i.e., those with M≥ 3 or 4) will be common over the next weeks to months. Based on general earthquake statistics, the expected number of M≥ 3 or 4 aftershocks can be estimated by multiplying the expected number of M>=5 aftershocks by 100 or 10, respectively. The expected location of the aftershocks will be in the zone of current activity and at its edges. Currently aftershocks are occurring in a zone extending approximately 200 km away from the mainshock epicenter.

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eko91 said:

This is horrible! 7.8 earthquake?? Imagine the aftershocks... I wonder how long this earthquake lasted for.... I really do hope that the families / friends are able to find each other in this chaos. Cause I'm sure the students were at school and some parents were prob outside working!

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Geologists Warned That Huge Quake Could Strike The Himalayas
April 28, 2015 5:15 AM ET

STEVE INSKEEP, HOST:

Next we have the underlying cause of a disaster.

RENEE MONTAGNE, HOST:

It's a look at plate tectonics, the movements of the Earth's crust that caused last weekend's earthquake in Nepal.

INSKEEP: We learn in school that the crust of the earth is divided into huge plates that drift apart or collide. The immense Himalayas were made by an especially dramatic collision.

KERRY SIEH: Basically India is now sliding beneath the Himalaya and beneath Tibet.

MONTAGNE: Kerry Sieh is director of the Earth Observatory of Singapore. He explained how this all got started. India used to be an island. Then, about 50 million years ago, it crashed into the rest of Asia.

SIEH: That collision produced the Himalayas. It's produced big earthquake faults in Tibet and in eastern China.

INSKEEP: A sudden movement along those faults is what we call an earthquake, like the one last weekend, as well as others that killed tens of thousands of people in Pakistan and China a few years ago. Another earthquake in Nepal back in 1934 was even bigger than the latest disaster.

MONTAGNE: All according to Sieh because one of those two tectonic plates is still slipping under the other.

SIEH: It has frictional resistance like two pieces of sandpaper against each other. But after you push enough, it finally decides, I can't stand this anymore, and it suddenly slips.

MONTAGNE: And, he says, this quake could point to others ahead.

SIEH: We're concerned that the areas to the east and to the west of this and also further south are ready to break.

INSKEEP: The problem of course is knowing when. As Sieh puts it, it could be tomorrow; it could also be 100 years from now.

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JamesMike said:

The USA has provided two helicopters, four Ospreys and 100 Marines to add Nepal.

http://www.bbc.com/news/world-asia-32572533

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Scepticalscribe said:

Apparently, today, a second powerful earthquake - of magnitude 7.3 (compared with the earthquake of three weeks ago, in western Nepal, which was 7.8) has struck eastern Nepal.

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bradl said:

And that was the aftershock..

BL.

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JamesMike said:

A U.S. Marine helicopter assisting in providing aid to Nepal is missing. Hopefully they were able to land safely.

http://www.msn.com/en-us/news/world...ng-in-nepal-earthquake-aid-mission/ar-BBjGjx8

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mrkramer said:

From what I've seen this was a separate earthquake. You don't get that big of an aftershock this long after.

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USGS said:

The May 12, 2015 M 7.3 Nepal earthquake (SE of Zham, China) occurred as the result of thrust faulting on or near the decollément associated with the Main Himalayan Thrust, which defines the interface between the underthrusting India plate and the overriding Eurasia plate to the north. At the location of this earthquake, approximately 80 km to the east-northeast of the Nepalese capital of Kathmandu, the India plate is converging with Eurasia at a rate of 45 mm/yr towards the north-northeast – a fraction of which (~18 mm/yr) is driving the uplift of the Himalayan mountain range. The May 12, 2015 event is the largest aftershock to date of the M 7.8 April 25, 2015 Nepal earthquake – known as the Gorkha earthquake - which was located 150 km to the west, and which ruptured much of the decollément between these two earthquakes.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Events of the size of the May 12, 2015 earthquake are typically about 55x30 km in size (length x width). The April 25, 2015 M 7.8 mainshock had approximate dimensions of ~120x80 km, directed from its hypocenter eastwards, and towards Kathmandu. The May 12, 2015 earthquake is located just beyond the eastern end of that rupture.

The boundary region of the India and Eurasia plates has a history of large and great earthquakes. Prior to April 25, four events of M6 or larger had occurred within 250 km of this area over the past century. One, a M 6.9 earthquake in August 1988, 140 km to the south-southeast of the May 12 event, caused close to 1500 fatalities. The largest, an M 8.0 event known as the 1934 Nepal-Bihar earthquake, ruptured a large section of the fault to the south of this May 2015 event, and east of the April 2015 mainshock, in a similar location to the 1988 earthquake. It severely damaged Kathmandu, and is thought to have caused around 10,600 fatalities. Prior to the 20th century, a large earthquake in 1833 is thought to have ruptured a similar area as the April 25, 2015 event. To date, there have been close to 100 M3+ aftershocks of the Gorkha earthquake. In the first two hours after the May 12 event, six further aftershocks have occurred, to the southwest-to-southeast of that earthquake.

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