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6.8 earthquake hits Sikkim, many buildings

damagedCNN-IBN

New Delhi: An earthquake measuring 6.8 on the richter scale hit North India on Sunday andthe epicentre was 64 km from Gangtok in Sikkim at 6:10 pm, causing damages in the area.

Mild tremors were felt in Delhi and other parts of North India. Tremors were felt in Patna,

Uttar Pradesh and West Bengal also.

Reports said that tremors were felt for almost 30 seconds. People in most parts of North and

East India rushed out of their homes in panic.

Aftershocks measuring 6.1 and 5.3 on the richter scale were also felt around Sikkim 20

minutes after the earthquake.

Speaking to CNN-IBN, the DGP of Sikkim said that many buildings were damaged. He also

said that roads were blocked and people were stranded on roads. He said that the Sikkim

Chief Minister Pawan Chamling has called for an emergency meeting.

Arvind Kumar, Principal Resident Commissioner of Sikkim said that there was excessive

damage in the northern parts of Sikkim. He also said that the rescue operations had started in

the area.

The Chief Secretary of Sikkim Karma Gyatso said that there were reports suggesting that one

child succumbed to injuries after the earthquake.

There were intermittent power outages.

There were also reports of landslides following the earthquake in areas around Sikkim and

also Darjeeling.

The Prime Minister also spoke to the Sikkim Chief Minister and offered all help. The Prime

Minister also directed the Cabinet Secretary to call for an emergency meeting.

There were reports of damages from Bihar. Two buildings collapsed in Katihar in Bihar. The

NTPC power plant in Kahalgaon in Bihar has also been shut down because of the earthquake

following which North Bihar was under power crisis. One person reportedly died in Bihar ina stampede following the Earthquake.


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Chief Election Commissioner SY Qureshi who was staying in a hotel in Bhutan said that

there were minor cracks in the hotel.

RS Dattatreya, Director, Seismology in the Met Department said that there were possibility of

aftershocks only in the area around the epicentre.

This is the second earthquake felt in Delhi in the last 10 days.

Sikkim quake: Landslides and rain hamper rescue efforts

See photoGANGTOK/NEW DELHI: The death toll in the powerful Sundayearthquakehas increased

to 40 with 19 people being killed in Sikkim, five in West Bengal, two in Bihar, seven each in

NepalandTibeteven as rescue and relief operations were stepped up in the affected areas.

Over a hundred people have been injured in the 6.8 magnitude tremblor which has caused

extensive damage to buildings and roads in Sikkim and several other places.

The casualties have occurred mostly in the North District and in towns and villages like

Rangpo, Dikchu, Singtam and Chungthang located along the course of Teesta river, they said.

In Gangtok, power was restored this morning. Residents had spent the night outside their

houses fearing aftershocks. At least 20 aftershocks throughout the night had created panic in

the city. The road network and telecommunication system have been affected.

There are fears that several tourists may still be trapped in Gangtok and the surroundingareas. Gangtok is barely 54 km from the epicentre and several tourists may be spread across

the many tourist spots around the capital city.

Meanwhile, rain and landslides have hampered the massive rescue efforts of hundreds of

workers searching for survivors.

According to reports from Union home ministry, there are 16 landslides in a stretch of 10 km

in Sikkim. Reports say several important roads in the state have been washed away and the

main highway has been blocked.

Nearly 400 personnel of the National Disaster Response Force (NDRF) reached the Bagdograairport on Monday morning. The NDRF personnel will be airlifted to the epicentre of the

earthquake for the rescue operation. Five more rescue teams have also left Kolkata for

Gangtok.

The earthquake has also triggered off landslides, blocking off nearly all roads towards

Sikkim's capital Gangtok. Personnel of the Border Roads Organisation (BRO) are working on

a war footing to clear the blocked roads.

712 personnel of ITBP are already engaged in rescue and relief operations in Sikkim.

The Army has deployed a total of 72 columns including infantry troops and combat
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engineers, four Dhruv and five Cheetah helicopters.

IAF has deployed 2 C-130J 'Super Hercules' aircraft from Hindan airbase to Bagdogra,

carrying 9 tonne of relief material and 200 National Disaster Relief Force personnel. One IL-

76 plane hsa been sent from Agra to Bagdogra via Kolkata, carrying 8 tonne of relief material

and 110 passengers. Also, an AVRO from Palam, with a 20 member Medical Team, 2 AN-32medium lift aircraft from Agra, and 8 helicopters have been pressed into service for relief and

rescue operations.

West Bengal chief minister Mamata Banerjee has left Kolkata for Darjeeling to hold a

meeting with the administration at Kurseong at 3pm. Banerjee will be assessing the situation

after the meeting in Kurseong with the top brass of the administration. She is likely to visit

some worst hit areas in Darjeeling district and give necessary instructions for the rebuilding

work.

Mamata Banerjee has announced compensation worth Rs 2 lakh to the family of the

deceased. The West Bengal chief minister has postponed her election campaign inBhawanipore to September 22, where she was supposed to hold a rally on Tuesday. Banerjee

is looking to get elected from Bhawanipore assembly constituency in the assembly

byelection.

Meanwhile, the quake was felt all the way to Delhi as well as inBangladesh, shaking

buildings. At least 10 people were injured and some buildings suffered minor damage.

Chinese state-run news agency Xinhua reported that at least seven persons have been killed

and 22 others injured in Tibet in the quake which has caused landslides and has disrupted

traffic, power and water supplies as well as telecommunication in Yadong County, an area 40

km away from Sikkim.

Three people were killed at Lainchaur inKathmandu, two in Sunsari district, and one each in

Dhankuta and Sankhuwasabha districts in eastern Nepal, according to home ministry sources

in the Nepalese capital.

4.2 magnitude earthquake in the New Delhi,

IndiaUpdate 09/09/2011

\Earthquake overview : After a long 30 minutes of receiving I Have Felt It reports from

concerned New Delhi people we could finally report that a magnitude 4.3 earthquake struck

close to New Delhi.

Keep this page open or return regularly as we will be back with more details when they

become available

Update 09/0907:39 UTC : One woman was injured after falling and fracturing her

hand in Delhi. Minor damage like broken plaster and cracks in walls, occurred in some

parts of area.In 2007, a magnitude 4.7 earthquake occurred in the Delhi region causing minor damage.
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The strongest recent historical earthquakes in the Delhi region include the M 6.0 Khurja-

Bulandshahr earthquake on 10 October 1956, the M 6.0 Gurgaon earthquake on 27 August

1960 and the M 5.6 Moradabad earthquake on 15 August 1966.

Historically, the 15 July 1720 earthquake in the Delhi region caused the greatest damage

in the city causing many deaths and widespread damage including knocking down large parts

of the city wall in Old Delhi from Kabuli Gate to Lal Darwaza.

Update 08/0908:03 UTC : More I Have Felt It reports

Update 08/09

07:31 UTC : The map at right is showing the earthquake risk areas in Northern India.

The Haryana area, New Delhi and the Sonipat epicenter are located in a low to medium

risk area. The colors and scale at the right side are showing the "Peak Ground Acceleration

(m/s) with a 10% probability of exceeedance in 50 years. The areas to the north have far

more risks on damaging and even catastrophic earthquakes as we have seen many times

in the past.

Update 08/0907:16 UTC : The Fire Department in Delhi said that they have not received

any call for help. There are NO reports of even minor damage. At Earthquake-Report.com,

we can confirm that earthquakes with magnitude 4 to 4.5 are very rarely generating damage.

At the most cracks in walls and loose items falling on the ground.

Update 08/0907:10 UTC :The tremors were felt across North India, including Kashmir

and Uttarakhand.

Update 21:49 UTC : There are still NO reports of damage or injuries so far. Although we

are not really expecting major damage from the shaking (the shaking lasted only about 10seconds), we would not be surprised to see houses and buildings with cracks, shattered


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tiles, etc when daylight arrives in this very populated area with a lot of badlyconstructed brick houses.. So far however, no signs of any minor damage.

Update 21:48 UTC : Delhi is among thirty important cities in India that fall into high

risk seismic zone while Srinagar is among places at very high risk of earthquakes, the

government said.

Update 20:42 UTC : We have a crazy situation in India where a lot of press is still

mentioning a cruel 6.6 magnitude value. 6.6 was a value which circulated shortly after the

earthquake occurred. Even the Times of India (and we) were taking over this value (although

we did not believe it as seismological agencies did not confirm it quickly enough)

EARTHQUAKE

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release

of energy in theEarth'scrustthat createsseismic waves. The seismicity or seismic activity

of an area refers to the frequency, type and size of earthquakes experienced over a period of

time. Earthquakes are measured using observations fromseismometers. Themoment

magnitudeis the most common scale on which earthquakes larger than approximately 5 are

reported for the entire globe. The more numerous earthquakes smaller than magnitude 5

reported by national seismological observatories are measured mostly on the local magnitude

scale, also referred to as theRichterscale. These two scales are numerically similar over their

range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible and

magnitude 7 and over potentially cause serious damage over large areas, depending on theirdepth. The largest earthquakes in historic times have been of magnitude slightly over 9,

although there is no limit to the possible magnitude. The most recent large earthquake of

magnitude 9.0 or larger was a9.0 magnitude earthquake in Japan in 2011(as of March 2011),

and it was the largest Japanese earthquake since records began. Intensity of shaking is

measured on the modifiedMercalli scale. The shallower an earthquake, the more damage to

structures it causes, all else being equal.[1]

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes

displacement of the ground. When theepicenterof a large earthquake is located offshore, the

seabed may be displaced sufficiently to cause atsunami. Earthquakes can also trigger

landslides, and occasionally volcanic activity.
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In its most general sense, the word earthquake is used to describe any

seismic eventwhether natural or caused by humans that generates

seismic waves. Earthquakes are caused mostly by rupture of geological

faults, but also by other events such as volcanic activity, landslides, mine

blasts, andnuclear tests. An earthquake's point of initial rupture is calleditsfocusorhypocenter. Theepicenteris the point at ground level directly

above the hypocenter.

Effects of earthquakes

1755 copper engraving depictingLisbonin ruins and in flames after the1755 Lisbon earthquake,

which killed an estimated 60,000 people. Atsunamioverwhelms the ships in the harbor.

The effects of earthquakes include, but are not limited to, the following:

Shaking and ground rupture

Shaking and ground rupture are the main effects created by earthquakes, principally resulting

in more or less severe damage to buildings and other rigid structures. The severity of the local

effects depends on the complex combination of the earthquakemagnitude, the distance from

theepicenter, and the local geological and geomorphological conditions, which may amplify

or reducewave propagation.[44]

The ground-shaking is measured byground acceleration.

Specific local geological, geomorphological, and geostructural features can induce high

levels of shaking on the ground surface even from low-intensity earthquakes. This effect iscalled site or local amplification. It is principally due to the transfer of theseismicmotion

from hard deep soils to soft superficial soils and to effects of seismic energy focalization

owing to typical geometrical setting of the deposits.

Ground rupture is a visible breaking and displacement of the Earth's surface along the trace of

the fault, which may be of the order of several metres in the case of major earthquakes.

Ground rupture is a major risk for large engineering structures such asdams, bridges and

nuclear power stationsand requires careful mapping of existing faults to identify any likely to

break the ground surface within the life of the structure.[45]

Landslides and avalanchesMain article:Landslide
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Earthquakes, along with severe storms, volcanic activity, coastal wave attack, and wildfires,

can produce slope instability leading to landslides, a major geological hazard. Landslide

danger may persist while emergency personnel are attempting rescue.[46]

Fires

Fires of the1906 San Francisco earthquake

Earthquakes can causefiresby damagingelectrical poweror gas lines. In the event of water

mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a

fire once it has started. For example, more deaths in the1906 San Francisco earthquakewere

caused by fire than by the earthquake itself.[47]

Soil liquefaction

Main article:Soil liquefaction

Soil liquefaction occurs when, because of the shaking, water-saturatedgranularmaterial

(such as sand) temporarily loses its strength and transforms from asolidto aliquid. Soil

liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the

liquefied deposits. This can be a devastating effect of earthquakes. For example, in the1964

Alaska earthquake, soil liquefaction caused many buildings to sink into the ground,

eventually collapsing upon themselves.[48]

Tsunami

Main article:Tsunami

The tsunami of the2004 Indian Ocean earthquake
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Tsunamis are long-wavelength, long-period sea waves produced by the sudden or abrupt

movement of large volumes of water. In the open ocean the distance between wave crests can

surpass 100 kilometers (62 miles), and the wave periods can vary from five minutes to one

hour. Such tsunamis travel 600-800 kilometers per hour (373497 miles per hour), depending

on water depth. Large waves produced by an earthquake or a submarine landslide can

overrun nearby coastal areas in a matter of minutes. Tsunamis can also travel thousands ofkilometers across open ocean and wreak destruction on far shores hours after the earthquake

that generated them.[49]

Ordinarily, subduction earthquakes under magnitude 7.5 on the Richter scale do not cause

tsunamis, although some instances of this have been recorded. Most destructive tsunamis are

caused by earthquakes of magnitude 7.5 or more.[49]

Floods

Main article:Flood

A flood is an overflow of any amount of water that reaches land.[50]Floods occur usuallywhen the volume of water within a body of water, such as a river or lake, exceeds the total

capacity of the formation, and as a result some of the water flows or sits outside of the normal

perimeter of the body. However, floods may be secondary effects of earthquakes, if dams are

damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods.[51]

The terrain below theSarez LakeinTajikistanis in danger of catastrophic flood if the

landslide damformed by the earthquake, known as theUsoi Dam, were to fail during a future

earthquake. Impact projections suggest the flood could affect roughly 5 million people.[52]

Human impacts

Damaged infrastructure, one week after the2007 Peru earthquake

An earthquake may cause injury and loss of life, road and bridge damage, generalpropertydamage(which may or may not be covered byearthquake insurance), and collapse or
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destabilization (potentially leading to future collapse) of buildings. The aftermath may bring

disease, lack of basic necessities, and higher insurance premiums.

Major earthquakes

One of the most devastating earthquakes in recorded history occurred on 23 January 1556 in

theShaanxiprovince, China, killing more than 830,000 people (see1556 Shaanxi

earthquake).[53]

Most of the population in the area at the time lived inyaodongs, artificial

caves in loess cliffs, many of which collapsed during the catastrophe with great loss of life.

The1976 Tangshan earthquake, with death toll estimated to be between 240,000 to 655,000,

is believed to be the largest earthquake of the 20th century by death toll.[54]

The largest earthquake that has been measured on a seismograph reached 9.5 magnitude,

occurring on 22 May 1960.[28][29]

Its epicenter was near Caete, Chile. The energy released

was approximately twice that of the next most powerful earthquake, theGood Friday

Earthquake, which was centered inPrince William Sound, Alaska.[55][56]The ten largestrecorded earthquakes have all beenmegathrust earthquakes; however, of these ten, only the

2004 Indian Ocean earthquakeis simultaneously one of the deadliest earthquakes in history.

Earthquakes that caused the greatest loss of life, while powerful, were deadly because of their

proximity to either heavily populated areas or the ocean, where earthquakes often create

tsunamisthat can devastate communities thousands of kilometers away. Regions most at risk

for great loss of life include those where earthquakes are relatively rare but powerful, and

poor regions with lax, unenforced, or nonexistent seismic building codes.

PredictionMain article:Earthquake prediction

Many different methods have been developed for predicting the time and place in which

earthquakes will occur. Despite considerable research efforts byseismologists, scientifically

reproducible predictions cannot yet be made to a specific day or month.[57]

However, for

well-understood faults the probability that a segment may rupture during the next few

decades can be estimated.[58]

Earthquake warning systemshave been developed that can provide regional notification of an

earthquake in progress, but before the ground surface has begun to move, potentially

allowing people within the system's range to seek shelter before the earthquake's impact isfelt.

Preparedness

The objective ofearthquake engineeringis to foresee the impact of earthquakes on buildings

and other structures and to design such structures to minimize the risk of damage. Existing

structures can be modified byseismic retrofittingto improve their resistance to earthquakes.

Earthquake insurancecan provide building owners with financial protection against losses

resulting from earthquakes.
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Emergency managementstrategies can be employed by a government or organization to

mitigate risks and prepare for consequences.

Historical views

An image from a 1557 book

From the lifetime of the Greek philosopherAnaxagorasin the 5th century BCE to the 14th

century CE, earthquakes were usually attributed to "air (vapors) in the cavities of the

Earth."[59]

Thalesof Miletus, who lived from 625547 (BCE) was the only documented

person who believed that earthquakes were caused by tension between the earth and water.[59]

Other theories existed, including the Greek philosopher Anaxamines' (585526 BCE) beliefs

that short incline episodes of dryness and wetness caused seismic activity. The Greekphilosopher Democritus (460371 BCE) blamed water in general for earthquakes.

[59]Pliny

the Eldercalled earthquakes "underground thunderstorms.

Size and frequency of occurrence

It is estimated that around 500,000 earthquakes occur each year, detectable with currentinstrumentation. About 100,000 of these can be felt.

[28][29]Minor earthquakes occur nearly

constantly around the world in places likeCaliforniaandAlaskain the U.S., as well as in

Guatemala,Chile,Peru,Indonesia,Iran,Pakistan, theAzoresinPortugal,Turkey,New

Zealand,Greece,Italy, andJapan, but earthquakes can occur almost anywhere, includingNew York City,London, andAustralia.

[30]Larger earthquakes occur less frequently, the

relationship beingexponential; for example, roughly ten times as many earthquakes larger

than magnitude 4 occur in a particular time period than earthquakes larger than magnitude 5.

In the (low seismicity) United Kingdom, for example, it has been calculated that the average

recurrences are: an earthquake of 3.74.6 every year, an earthquake of 4.75.5 every

10 years, and an earthquake of 5.6 or larger every 100 years.[31]

This is an example of the

Gutenberg-Richter law.
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TheMessina earthquakeand tsunami took as many as 200,000 lives on December 28, 1908 inSicily

andCalabria.[32]

The number of seismic stations has increased from about 350 in 1931 to many thousands

today. As a result, many more earthquakes are reported than in the past, but this is because of

the vast improvement in instrumentation, rather than an increase in the number ofearthquakes. TheUnited States Geological Surveyestimates that, since 1900, there have been

an average of 18 major earthquakes (magnitude 7.07.9) and one great earthquake

(magnitude 8.0 or greater) per year, and that this average has been relatively stable.[33]

In

recent years, the number of major earthquakes per year has decreased, though this is probably

a statistical fluctuation rather than a systematic trend. More detailed statistics on the size and

frequency of earthquakes is available from theUnited States Geological Survey(USGS).[34]

Alternatively, some scientists suggest that the recent increase in major earthquakes could be

explained by a cyclical pattern of periods of intense tectonic activity, interspersed with longer

periods of low-intensity. However, accurate recordings of earthquakes only began in the early

1900s, so it is too early to categorically state that this is the case.[35]

Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000 km

long, horseshoe-shaped zone called the circum-Pacific seismic belt, known as thePacific

Ring of Fire, which for the most part bounds thePacific Plate.[36][37]

Massive earthquakes

tend to occur along other plate boundaries, too, such as along theHimalayan Mountains.[38]

With the rapid growth ofmega-citiessuch asMexico City,TokyoandTehran, in areas of

highseismic risk, some seismologists are warning that a single quake may claim the lives of

up to 3 million people.[39]

Measuring and locating earthquakesEarthquakes can be recorded by seismometers up to great distances, becauseseismic waves

travel through the wholeEarth's interior. The absolute magnitude of a quake is

conventionally reported by numbers on theMoment magnitude scale(formerly Richter scale,

magnitude 7 causing serious damage over large areas), whereas the felt magnitude is reported

using the modifiedMercalli intensity scale(intensity IIXII).

Every tremor produces different types of seismic waves, which travel through rock with

different velocities:

LongitudinalP-waves(shock- or pressure waves) TransverseS-waves(both body waves)
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Surface waves(RayleighandLovewaves)Propagation velocityof the seismic waves ranges from approx. 3 km/s up to 13 km/s,

depending on thedensityandelasticityof the medium. In the Earth's interior the shock- or P

waves travel much faster than the S waves (approx. relation 1.7 : 1). The differences intravel

timefrom theepicentreto the observatory are a measure of the distance and can be used toimage both sources of quakes and structures within the Earth. Also the depth of the

hypocentercan be computed roughly.

In solid rock P-waves travel at about 6 to 7 km per second; the velocity increases within the

deep mantle to ~13 km/s. The velocity of S-waves ranges from 23 km/s in light sediments

and 45 km/s in the Earth's crust up to 7 km/s in the deep mantle. As a consequence, the first

waves of a distant earth quake arrive at an observatory via the Earth's mantle.

Rule of thumb: On the average, the kilometer distance to the earthquake is the number of

seconds between the P and S wave times 8.[43]

Slight deviations are caused by

inhomogeneities of subsurface structure. By such analyses of seismograms the Earth's corewas located in 1913 byBeno Gutenberg.

Earthquakes are not only categorized by their magnitude but also by the place where they

occur. The world is divided into 754Flinn-Engdahl regions(F-E regions), which are based on

political and geographical boundaries as well as seismic activity. More active zones are

divided into smaller F-E regions whereas less active zones belong to larger F-E regions.
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