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English · हिन्दी · తెలుగు · தமிழ் · മലയാളം · मराठी · ಕನ್ನಡ

Earthquakes, tsunamis and volcanoes

मराठीत स्पष्टीकरण

Geomorphology: plates, earthquakes, volcanoes and landforms · Part 2 / 4 · Fact-checked on · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

How earthquakes are caused, classified and measured, their effects, tsunamis and India's warning centre, the world's earthquake belts and India's seismic zones, how volcanoes work, the types of volcano and lava, intrusive igneous landforms, and India's volcanoes and hot springs.

Each idea is explained first in Marathi (मराठी), ending with the English and Hindi exam terms, followed by the same point in exam English. UPSC Prelims is in English or Hindi, so understand it in Marathi and revise it in English.

पृथ्वीचा वरचा थर तुकड्यांत विभागलेला असून ते तुकडे अगदी हळू सरकतात. पण त्या हालचालीत साचलेला ताण एकदम बाहेर पडतो — ताणून ताणून सोडलेल्या स्प्रिंगसारखा. तो अचानक ताण सुटणे म्हणजे भूकंप; समुद्राखाली घडला तर कधी त्सुनामी; वितळलेला खडक वर आला तर ज्वालामुखी. हे कसे होतात, कुठे जास्त, कोणती भूरूपे तयार करतात — हे या भागात पाहू. (→ English: earthquake, tsunami, volcano · हिन्दी: भूकंप, सुनामी, ज्वालामुखी)

In exam EnglishThe first part showed that the lithosphere is broken into plates that pull apart, collide and grind past one another. The stress built up by that slow movement is released suddenly. This part deals with those sudden releases: earthquakes, the tsunamis some of them set off, and volcanoes, where molten rock escapes to the surface. It explains how earthquakes are caused and measured, why tsunamis grow as they reach the coast, where these hazards are concentrated in the world and in India, and which landforms volcanic activity builds.

एखादी काठी दोन्ही हातांनी वाकवत राहिलो तर एका क्षणी ती कट्‌कन मोडते आणि दोन्ही तुकडे मागे उडतात. विभंगाजवळचे खडकही तसेच: घर्षण धरून ठेवते, भूपट्टांची हालचाल वाकवत राहते, सहनशक्ती ओलांडली की ते घसरतात — तोच भूकंप. आत तुटायला सुरुवात होते ते भूकंपनाभी; त्याच्या अगदी वर जमिनीवरचा बिंदू अपिकेंद्र. तिथून भूकंप लहरी सगळीकडे पसरतात. (→ English: earthquake, focus, epicentre, seismic waves · हिन्दी: भूकंप, उद्गम केंद्र, अधिकेंद्र, भूकंपीय तरंगें)

In exam EnglishAn earthquake is the shaking of the ground caused by a sudden release of energy inside the Earth. Most earthquakes happen on faults, fractures along which blocks of rock shift. Friction locks the two sides together while plate movement keeps straining them, so the rocks bend and store energy like a drawn bow. When the strain exceeds the strength of the rock, the fault slips in seconds and the bent rocks spring back towards their unstrained shape. This explanation, called the elastic rebound theory, was put forward by H. F. Reid after the San Francisco earthquake of 1906. The point inside the Earth where the rupture begins is the focus or hypocentre; the point on the surface directly above it is the epicentre. From the focus, energy spreads out as seismic waves.

कारणानुसार भूकंपाचे अनेक प्रकार. भूपट्टांच्या हालचालीने विभंग घसरून होणारे सर्वाधिक आणि सर्वात शक्तिशाली. ज्वालामुखीखाली शिलारस हलला तर काही; गुहा किंवा खाणीचे छत कोसळले तर लहान धक्के; स्फोटांमुळे काही. मोठ्या जलाशयाचे वजन आणि खाली झिरपणारे पाणी आधीच ताणात असलेल्या विभंगाला घसरवू शकते — कोयना हे उदाहरण. खोलीनुसारही वर्गीकरण आहे; सर्वात खोल भूकंप फक्त अधोगमन होते तिथेच, कारण थंड कडक खडक इतक्या खोल तिथेच पोहोचतो. (→ English: tectonic earthquake, reservoir-induced earthquake, subduction · हिन्दी: विवर्तनिक भूकंप, जलाशय-प्रेरित भूकंप, अधोगमन)

In exam EnglishEarthquakes are grouped by cause. Tectonic earthquakes, from slip on faults as plates move, are the most common and most powerful. Volcanic earthquakes accompany the movement of magma beneath a volcano. Collapse earthquakes are small tremors from caving-in mines or caves. Explosion earthquakes are caused by human blasts, including underground nuclear tests. Reservoir-induced earthquakes occur when the weight of water in a large reservoir, and the water seeping into faults below it, trigger slip on faults that were already stressed; the Koyna earthquake of 1967 in Maharashtra is the example most often cited. By depth of focus they are shallow (less than about 70 km), intermediate (about 70 to 300 km) and deep (about 300 to 700 km). Deep-focus earthquakes occur only at subduction zones, where cold, brittle plates sink to such depths.

दोन मापे वेगळी. परिमाण म्हणजे उगमस्थानी सुटलेली ऊर्जा — एका भूकंपाचे एकच. एखादा बल्ब किती वॅटचा हे एकच, पण जवळ उभ्या माणसाला प्रकाश जास्त, दूरच्याला कमी — तीच तीव्रता. रिश्टर मापनात एक अंक वाढला की हालचाल दहापट, ऊर्जा सुमारे 32 पट. तीव्रता मर्कली मापन I ते XII मध्ये मोजते; अपिकेंद्रापासून अंतर वाढेल तशी ती कमी होते. (→ English: magnitude, intensity, Richter scale, epicentre · हिन्दी: परिमाण, तीव्रता, रिक्टर पैमाना, अधिकेंद्र)

In exam EnglishEarthquakes are recorded by seismographs and described in two ways. Magnitude measures the energy released at the source, so one earthquake has one magnitude. The Richter scale, devised by Charles Richter in 1935, is logarithmic: each step of one whole number means about ten times the ground motion on a seismogram and roughly 32 times the energy. For large earthquakes the moment magnitude scale, based on the size of the fault slip, is now preferred. Intensity describes the effects at a particular place, judged by what people felt and how buildings fared; the Modified Mercalli scale grades it in twelve levels written in Roman numerals from I to XII. One earthquake therefore has a single magnitude but many intensities, which fall with distance from the epicentre. In India the National Center for Seismology (Ministry of Earth Sciences) monitors earthquakes.

भूकंपाने होणारे नुकसान त्याच्या आकारावरच नव्हे, तर त्या जागेवरही अवलंबून असते. पाण्याने भिजलेली वाळूची जमीन हादरली की, तांदळाचा डबा हलवल्यावर वर ठेवलेली वस्तू आत रुतते तशी, इमारती कलतात आणि खचतात — याला द्रवीकरण म्हणतात. उतारावर भूस्खलन, तुटलेल्या गॅस वाहिन्यांमुळे आगी. बहुतेक मृत्यू इमारती कोसळल्यानेच; म्हणून सारख्या परिमाणाच्या दोन भूकंपांचे नुकसान खूप वेगळे असू शकते. (→ English: earthquake, liquefaction · हिन्दी: भूकंप, द्रवीकरण)

In exam EnglishThe damage an earthquake does depends as much on local conditions as on its size. Ground shaking is the main hazard, and it is felt most strongly where the focus is shallow and the epicentre is close. Where faults break the surface, roads, pipelines and rail lines can be offset. In loose, water-soaked sand and silt, shaking can make the ground lose its strength and behave like a thick liquid, a process called liquefaction, so that buildings tilt or sink even when they do not collapse. On steep slopes shaking sets off landslides, and broken gas lines can start fires. Because collapsing buildings cause most deaths, two earthquakes of the same magnitude can have very different tolls depending on soil, building quality and preparedness.

त्सुनामी म्हणजे समुद्रातील मोठे पाणी अचानक ढकलले गेल्याने उठणाऱ्या लांब लाटांची मालिका — बहुधा समुद्राखालच्या भूकंपामुळे. तळ्यात मोठा दगड टाकला की वर्तुळे उठतात तसे. खोल समुद्रात विमानाच्या वेगाने जाते, पण उंची कमी, जहाजांनाही कळत नाही. किनाऱ्याजवळ खोली कमी झाली की वेग कमी होतो, लाटा एकवटतात आणि उंची एकदम वाढते. आधी समुद्र मागे हटणे हा निसर्गाचा इशारा. याचा भरती-ओहोटीशी संबंध नाही. (→ English: tsunami · हिन्दी: सुनामी)

In exam EnglishA tsunami is a series of long sea waves caused by a sudden displacement of a large volume of water. Most are set off by undersea earthquakes at subduction zones that suddenly lift or drop the sea floor; undersea landslides and eruptions can also cause them. The word is Japanese for 'harbour wave'; tsunamis have nothing to do with tides. In the deep ocean a tsunami travels at the speed of a jet aircraft, about 800 km an hour, yet it is often less than a metre high and passes ships unnoticed, because its wavelength can be hundreds of kilometres. In shallow water near the coast it slows, the waves crowd together and their height rises sharply; often the sea first draws back, a natural warning. The tsunami of 26 December 2004, set off by a magnitude 9.1 earthquake off northern Sumatra, killed over two lakh people around the Indian Ocean, including in Tamil Nadu and the Andaman and Nicobar Islands. The Indian Tsunami Early Warning Centre at INCOIS, Hyderabad, set up after it, began work in 2007.

भूकंप कुठेही विखुरलेले नसतात; ते भूपट्टांच्या कडांवरच येतात — फाटलेले कापड शिवणीपाशीच पुन्हा पुन्हा फाटते तसे. पॅसिफिकभोवतीच्या 'अग्निकंकणात' सर्वात मोठे भूकंप जास्त. खंड एकमेकांवर आदळतात ती आल्प्स-हिमालय पट्टी दुसरी. मध्य महासागरीय रांगेवर वारंवार, पण उथळ आणि मध्यम भूकंप. भारताचे II ते V असे चार विभाग केले आहेत; V सर्वात धोकादायक. (→ English: Ring of Fire, mid-ocean ridge, seismic zones · हिन्दी: अग्नि वलय, मध्य महासागरीय कटक, भूकंपीय क्षेत्र)

In exam EnglishEarthquakes trace the edges of plates. The Circum-Pacific belt, often called the Ring of Fire, follows the trenches and subduction zones around the Pacific Ocean and it has the large majority of the world's biggest earthquakes. The Alpine-Himalayan belt runs from the Mediterranean through Turkey and Iran to the Himalaya and Myanmar, where continents are colliding. A third belt follows the mid-ocean ridges, with frequent but shallow, moderate earthquakes. In India, the Bureau of Indian Standards' earthquake design code, IS 1893 (Part 1): 2016, divides the country into four seismic zones, II to V, with Zone V the most hazardous. Zone V covers the whole of the North-East, parts of Jammu and Kashmir, Himachal Pradesh and Uttarakhand, the Rann of Kutch in Gujarat, parts of north Bihar and the Andaman and Nicobar Islands, while Delhi lies in Zone IV. A revised code issued in 2025 that added a Zone VI for the Himalayan arc was withdrawn in March 2026, so the four-zone map remains in force.

ज्वालामुखी म्हणजे भूकवचातील एक छिद्र — त्यातून शिलारस, वायू, खडकांचे तुकडे बाहेर येतात; त्याभोवती साचलेल्या डोंगरालाही तेच नाव. आत असताना शिलारस, बाहेर आल्यावर लाव्हा. कुकरच्या शिट्टीच्या छिद्रासारखे मुख, वर वाटीसारखे विवर. फार मोठ्या उद्रेकाने खालचा कक्ष रिकामा झाला की माथा खचून रुंद खळगा — काल्डेरा. जागृत, निद्रिस्त, मृत असे तीन प्रकार. बहुतेक अधोगमन होते तिथे, सागरी रांगांवर, तप्त स्थानांवर. (→ English: volcano, magma, lava, crater, caldera, subduction · हिन्दी: ज्वालामुखी, मैग्मा, लावा, क्रेटर, काल्डेरा, अधोगमन)

In exam EnglishA volcano is an opening in the crust through which magma, gases and fragments of rock reach the surface, and also the landform built up around that opening. Magma that reaches the surface is called lava; solid fragments, from ash to volcanic bombs, are pyroclastic material. Material escapes through a vent, often at the bottom of a bowl-shaped crater at the summit. When a very large eruption empties the magma chamber below, the summit can collapse to form a much wider depression called a caldera, often later filled by a lake. Volcanoes are commonly described as active (erupting now or in recent history), dormant (quiet but able to erupt again) or extinct (not expected to erupt again). They occur mainly at subduction zones, where melting above the sinking plate feeds chains of explosive volcanoes; along mid-ocean ridges, where plates pull apart; and over hotspots far from plate edges, such as Hawaii.

लाव्हा कसा आहे यावरच ज्वालामुखीचा आकार ठरतो. पातळ लाव्हा — ताकासारखा — दूर वाहतो आणि रुंद, कमी उताराचा घुमट बनवतो: ढाल ज्वालामुखी. घट्ट लाव्हा — घट्ट दह्यासारखा — वायू आत अडकवतो, दाब वाढून स्फोट होतो; लाव्हा आणि राख यांच्या थरांनी उंच, तीव्र उताराचा शंकू: मिश्र ज्वालामुखी. एकाच छिद्राभोवती पडलेल्या तुकड्यांनी लहान सिंडर शंकू. लांब भेगांतून पातळ लाव्हा थरांनी पसरला की पठार — दख्खनचे पठार (दख्खन ट्रॅप) असेच. (→ English: lava, shield volcano, composite volcano, flood basalt · हिन्दी: लावा, शील्ड ज्वालामुखी, मिश्रित ज्वालामुखी, बाढ़ बेसाल्ट)

In exam EnglishThe shape of a volcano and the violence of its eruptions depend largely on the kind of lava. Basaltic lava is low in silica, very hot and runny, so gas escapes easily and the lava flows far before it cools. Repeated quiet outpourings of it build shield volcanoes, broad domes with gentle slopes such as Mauna Loa on Hawaii. Lava rich in silica is thick and sticky; it traps gas until the pressure is released in an explosion. Composite volcanoes, also called stratovolcanoes, are built of alternating layers of such lava and ash into tall, steep cones, as at Mount Fuji in Japan and Vesuvius in Italy, and they are typical of subduction zones. Cinder cones are small, steep hills of loose fragments thrown out around a single vent; Parícutin in Mexico appeared in 1943. Very fluid basalt pouring from long fissures, sheet after sheet, builds a flood basalt plateau; the Deccan Traps of peninsular India are a prime example.
Types of volcano compared
TypeLava and eruptionShapeExample
ShieldFluid basalt; quiet outpouringsBroad dome, gentle slopesMauna Loa (Hawaii)
Composite (strato)Viscous, silica-rich lava and ash; explosiveTall, steep cone of layersFuji (Japan); Vesuvius (Italy)
Cinder coneLoose fragments from one ventSmall, steep hillParícutin (Mexico, 1943)
CalderaSummit collapse after a huge eruptionWide basin, often a lakeCrater Lake (USA); Toba (Sumatra)
Flood basaltVery fluid basalt from long fissuresVast stepped plateauDeccan Traps (India)

सगळा शिलारस वर येत नाही; मोठा भाग आतच थंड होऊन अग्निजन्य खडक बनतो, वरचे खडक झिजल्यावरच दिसतो. बॅथोलिथ खूप मोठा गोळा, पर्वतांच्या गाभ्यासारखा. लॅकोलिथ खाली सपाट, वर घुमटासारखा — वरचे थर फोडासारखे वर ढकलतो. लोपोलिथ बशीसारखा मध्ये खचलेला. फॅकोलिथ घड्यांच्या माथ्यावर किंवा खोलगट भागात भिंगाच्या आकाराचा. पुस्तकाच्या पानांमध्ये कागद ठेवावा तसा थरांमध्ये आडवा पसरला तर सिल; थरांना उभा छेदत गेला तर डाइक. (→ English: magma, igneous rocks, batholith, laccolith, sill, dyke · हिन्दी: मैग्मा, आग्नेय शैल, बैथोलिथ, लैकोलिथ, सिल, डाइक)

In exam EnglishMuch magma never reaches the surface but hardens underground into intrusive igneous rocks, seen only after erosion strips away the rocks above. A batholith is a huge mass, often of granite, that solidified deep in the crust and may form the core of a mountain range. A laccolith is a dome-shaped body with a flat floor, fed from below by a pipe, which pushes the overlying layers up into a blister. A lopolith is the reverse, a saucer-shaped body that sags downward in the middle. A phacolith is a lens-shaped mass lying along the crest of an upfold or the bottom of a downfold in folded rocks. Where magma squeezes between layers and spreads out as a flat horizontal sheet, it forms a sill; where it fills a crack that cuts across the layers, usually close to vertical, it forms a dyke. Sills, laccoliths, lopoliths and phacoliths follow the layering of the host rock, while dykes and batholiths cut across it.
Intrusive igneous bodies
BodyShapeRelation to rock layers
BatholithHuge, deep mass, often graniteCuts across
LaccolithDome with a flat floor, fed from belowFollows layers
LopolithSaucer sagging in the middleFollows layers
PhacolithLens at the crest or trough of a foldFollows layers
SillFlat horizontal sheetFollows layers
DykeWall-like sheet, near verticalCuts across

आपल्या देशात ज्वालामुखी फार कमी; महत्त्वाचे दोन्ही अंदमान समुद्रात, भारतीय भूपट्ट खाली जातो त्या कमानीवर आहेत. बॅरन बेट हा देशातील एकमेव जागृत ज्वालामुखी — खूप काळ शांत राहून 1991 मध्ये पुन्हा जागा झाला. उत्तरेकडचा नारकोंडम निद्रिस्त. आतल्या उष्णतेने भूजल तापून वर आले की गरम पाण्याचा झरा — मणिकरणसारखा. मधूनमधून पाणी आणि वाफ कारंज्यासारखी उडवणारा तो गायझर; लाव्हाशिवाय वाफ आणि वायू सोडणारे छिद्र फ्युमरोल. (→ English: volcano, Barren Island, hot spring, geyser · हिन्दी: ज्वालामुखी, बैरन द्वीप, गर्म जल स्रोत, गीज़र)

In exam EnglishIndia's two notable volcanoes lie in the Andaman Sea, on the arc where the Indian Plate sinks beneath the plate carrying the Andaman Islands. Barren Island, north-east of Port Blair, is India's only active volcano. Its first recorded eruption was in 1787; after a long quiet period it became active again in 1991 and has erupted several times since. Narcondam, a small island farther north, is a volcano that the Geological Survey of India classifies as dormant. Elsewhere, hot springs, where groundwater warmed by hot rock rises naturally, show heat near the surface, as at Manikaran in Himachal Pradesh and in the Puga valley of Ladakh. A geyser is a hot spring that throws up jets of water and steam from time to time, and a fumarole is a vent that gives off steam and volcanic gases without lava.

भूकंप, त्सुनामी, ज्वालामुखी — एकाच कुटुंबातले तीन भाऊ जणू, तिघांचा बाप भूपट्ट विवर्तनिकी. भूपट्टांचा ताण विभंगांवर सुटला की भूकंप; तो समुद्राखाली घडला तर त्सुनामी; भूपट्ट खाली जातात, दूर सरकतात तिथे खडक वितळून वर आला की ज्वालामुखी. म्हणूनच दोघांचे नकाशे त्याच रेषांवर; आपल्या देशात हिमालय, ईशान्य भारत, अंदमान बेटे जास्त धोक्यात आहेत. पुढचा भाग जमीन हळूहळू झिजवणाऱ्या बाहेरच्या बलांबद्दल. (→ English: plate tectonics · हिन्दी: प्लेट विवर्तनिकी)

In exam EnglishEarthquakes, tsunamis and volcanoes are three faces of the same restless system described by plate tectonics. Stress built up by moving plates is released as earthquakes along faults; when that happens under the sea at a subduction zone, the displaced water can travel across an ocean as a tsunami; and where plates sink, pull apart or pass over hotspots, rock melts and rises as magma. That is why maps of earthquakes and volcanoes trace the same lines, and why the Himalaya, the North-East and the Andaman and Nicobar Islands are India's most hazardous regions. The next part turns from these sudden internal forces to the slow external ones, weathering, mass movement and running water, that wear the land down.

Exam traps

Recap

Practice questions

Q1. The point on the Earth's surface directly above the place where an earthquake rupture begins is called the

  1. focus
  2. epicentre
  3. shadow zone
  4. hypocentre
Show answer

Answer: B. epicentre

(b) is correct: the epicentre lies on the surface directly above the focus. (a) and (d) are wrong because the focus, also called the hypocentre, is the point inside the Earth where rupture begins. (c) is wrong because a shadow zone is a belt on the surface where certain seismic waves are not recorded.

Q2. Consider the following statements:
1. On the Richter scale, an increase of one whole number means about ten times greater ground motion.
2. The intensity of an earthquake on the Modified Mercalli scale is the same at every place where it is felt.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct: the Richter scale is logarithmic, and one step means about ten times the ground motion (and roughly 32 times the energy). Statement 2 is wrong: intensity describes local effects and falls with distance from the epicentre; it is magnitude that is one value per earthquake. So (b) and (c) accept a wrong statement, and (d) rejects a correct one.

Q3. The Koyna earthquake of 1967 in Maharashtra is most often cited as an example of which kind of earthquake?

  1. Volcanic earthquake
  2. Collapse earthquake
  3. Reservoir-induced earthquake
  4. Deep-focus earthquake
Show answer

Answer: C. Reservoir-induced earthquake

(c) is correct: Koyna is the standard example of an earthquake triggered by the filling of a large reservoir. (a) is wrong because there is no active volcano in that region. (b) is wrong because collapse earthquakes are small tremors from the caving in of mines or caves. (d) is wrong because deep-focus earthquakes occur only in subduction zones, hundreds of kilometres down, and peninsular India has none.

Q4. Consider the following statements about tsunamis:
1. In the deep ocean a tsunami moves very fast but is usually low in height.
2. The Indian Tsunami Early Warning Centre is located at INCOIS, Hyderabad.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: C. Both 1 and 2

Both statements are correct. In deep water a tsunami travels at about 800 km an hour but is often less than a metre high; it grows tall only in shallow water near the coast. The warning centre, set up after the 2004 tsunami, works at INCOIS, Hyderabad, and began in 2007. So (a), (b) and (d) each reject at least one correct statement.

Q5. Consider the following statements about India's seismic zoning under IS 1893 (Part 1): 2016:
1. The country is divided into four seismic zones numbered II to V.
2. Delhi lies in Zone V.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct: the code has four zones, II to V, with no Zone I. Statement 2 is wrong: Delhi lies in Zone IV; Zone V includes the North-East, the Rann of Kutch and the Andaman and Nicobar Islands among other areas. So (b) and (c) accept a wrong statement, and (d) rejects a correct one.

Q6. Match List I (type of volcano) with List II (example):
List I
A. Shield volcano
B. Composite volcano
C. Cinder cone
D. Flood basalt
List II
1. Deccan Traps
2. Parícutin
3. Mauna Loa
4. Mount Fuji
Select the correct answer using the code given below:

  1. A-3, B-4, C-2, D-1
  2. A-4, B-3, C-2, D-1
  3. A-3, B-4, C-1, D-2
  4. A-1, B-4, C-2, D-3
Show answer

Answer: A. A-3, B-4, C-2, D-1

(a) is correct: Mauna Loa is a broad shield of fluid basalt, Fuji a steep composite cone, Parícutin a cinder cone that grew in 1943, and the Deccan Traps a flood basalt plateau. (b) swaps the shield and composite examples. (c) swaps Parícutin and the Deccan Traps. (d) calls the Deccan Traps a shield volcano and Mauna Loa a flood basalt.

Q7. An intrusive body of igneous rock that cuts across the layers of the surrounding rock, usually in a nearly vertical position, is called a

  1. sill
  2. laccolith
  3. dyke
  4. lopolith
Show answer

Answer: C. dyke

(c) is correct: a dyke fills a crack that cuts across the layers. (a) is wrong because a sill is a horizontal sheet lying parallel to the layers. (b) is wrong because a laccolith is a dome that pushes the layers up while following them. (d) is wrong because a lopolith is a saucer-shaped body that also follows the layers.

Q8. Consider the following statements:
1. Barren Island is the only active volcano in India.
2. Narcondam Island lies in the Arabian Sea.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct: Barren Island, which became active again in 1991, is India's only active volcano. Statement 2 is wrong: Narcondam, a dormant volcano, lies in the Andaman Sea north of Barren Island, on the same subduction arc. So (b) and (c) accept a wrong statement, and (d) rejects a correct one.

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