An earthquake is a vibration or oscillation of the surface of the Earth caused by the elasticity or the isostatic adjustment of the rocks, beneath the surface of the Earth.
Earthquakes and volcanic eruptions are most frequent near tectonic plates. A tsunami is usually the result of an earthquake below or near the ocean floor.
Earthquakes:
- An earthquake is an abrupt shaking or trembling of the Earth, a natural event resulting from the release of energy that generates waves propagating in all directions.
- Energy Release Mechanism: Occurs along a fault, a sharp break in the crustal rocks.
- Rocks move in opposite directions along the fault, causing deformation.
- Eventually, the blocks slide past one another abruptly, releasing energy.
- This release of energy produces seismic waves that travel in all directions.
- Scientific Understanding: The study of seismic waves contributes to understanding the Earth’s interior.
- Seismology is the scientific study of earthquakes and related phenomena.
- Richter Scale: Developed in 1935 by Charles F. Richter, measures the magnitude of an earthquake on a logarithmic scale ranging from 0 to 10.
- Mercalli Scale: Measures the intensity of an earthquake in terms of visible damage, with a range of 1 to 12.
- Instrumentation: The instrument used to record earthquake waves is called a seismograph.
Intensity and Magnitude of an Earthquake:
| S.No. | Mercalli Intensity | Instrumental | Richter Magnitude |
| I | Feeble | Slight | <3.5 |
| II | Weak | Slight | <3.5 |
| III | Weak | Slight | 3.5-4.2 |
| IV | Moderate | – | 4.3 |
| V | Rather strong | – | 4.8 |
| VI | Strong | – | 4.9-5.4 |
| VII | Very strong | – | 5.5-6.1 |
| VIII | Destructive | – | 6.2-6.9 |
| IX | Ruinous | – | 6.9-7.0 |
| X | Disastrous | – | 7.0-7.3 |
| XI | Very disastrous | – | 7.4-8.1 |
| XII | Catastrophic | – | 8.1 |
Hypocentre and Epicentre:
- Hypocentre (Focus): The point where energy is released beneath the Earth’s surface.
- Epicentre: The point on the surface directly above or nearest to the focus.
Prediction of Earthquake:
- Animal Behavior: Animals can detect low-frequency sounds and vibrations, sensing impending earthquakes.
- Radon Gas: The discharge of radon gas from rock masses before an earthquake.
- Oil Wells: Fluctuations in oil flow from wells before earthquake occurrences.
- Temperature Change: Significant temperature rise or fall before earthquakes.
- Changes in Seismic Wave Velocity: Decrease in lead time between arrival of P and S waves before earthquakes.
Earthquake Waves:
Body Waves:
- P-Waves (Primary Waves): Short waves of high frequency.
- Move faster than S-waves, reaching the surface first.
- Longitudinal, traveling through gaseous, liquid, and solid materials.
- Vibrate parallel to the wave direction, causing stretching and squeezing of materials.
- S-Waves (Secondary Waves): Transverse waves, traveling only through solid materials.
- Contribute to understanding the Earth’s interior structure.
- S-waves create troughs and crests in the material, perpendicular to the wave direction in the vertical plane, arriving at the surface after P-waves.
Surface Waves:
- Surface waves, generated as body waves interact with surface rocks, move along the surface, being the last to appear on seismographs.
- These waves vibrate perpendicular to the direction of propagation, causing displacement of rocks and structural collapse, making them the most damaging waves.
- Two types of surface waves are Love Wave (L-wave) and Rayleigh Wave (R-wave).
Shadow Zone:
- Specific areas where earthquake waves are not reported are termed the ‘shadow zone.’
- Seismographs within 105° from the epicenter record both P and S-waves.
- Beyond 145°, seismographs record P-waves but not S-waves.
- The zone between 105° and 145° from the epicenter is identified as the shadow zone for both P and S-waves.
- The entire zone beyond 105° doesn’t receive S-waves, known as the shadow zone for S-waves.
- The shadow zone of S-waves is larger than that of P-waves, appearing as a band around the Earth between 105° and 145° from the epicenter.
- These are of long wavelength and low freq They travel slower than body waves
- Circum-Pacific includes areas (70% of earthquakes) with the most frequent occurrence E along the Pacific Ring of Fire.
- Mid-Continental belt (20% of earthquakes) includes the Mediterranean-Himalayan belt.
- Mid-Atlantic ridge (10% of earthquakes) includes the earthquakes of New Madrid, Charleston, Boston, etc.
Causes of Earthquakes:
- Fault Zones: Most shallow earthquakes result from the sudden release of stress along a fault rupture (crack) in the Earth’s crust.
- Earthquakes along thrust faults (convergent boundary) can have ruptures of approximately 1,000 km.
- Plate Tectonics: Slipping of land along faultlines at convergent and divergent boundaries causes earthquakes.
- Earthquakes associated with normal faults (divergent boundaries) generally have a magnitude less than [specific magnitude].
- Volcanic Activity: Volcanic activity can trigger earthquakes in volcanic regions.
- Earthquakes in these areas result from the release of elastic strain energy by both tectonic faults and the movements of magma in volcanoes.
- Exogenic Forces: Exogenic forces, such as weathering and erosion, can trigger landslides, potentially leading to the activation of weak faults and the sudden release of energy.
- Human-Induced Earthquakes: Human-induced earthquakes, often minor tremors, are caused by activities such as mining, large-scale petroleum extraction, artificial lakes (reservoirs), nuclear tests, and more.
Types of Earthquakes:
- Tectonic Earthquake: Most common, generated by sliding rocks along a fault plane.
- Volcanic Earthquake: A subset of tectonic earthquakes, confined to areas with active volcanoes.
- Collapse Earthquake: Occurs in mining areas when underground mine roofs collapse, causing minor tremors.
- Explosion Earthquake: Ground shaking due to explosions from chemical or nuclear devices.
- Reservoir-Induced Earthquake: Earthquakes occurring in areas near large reservoirs.
Effects of Earthquake:
- While earthquake activity lasts only a few seconds, the impact can be devastating, especially with a magnitude above 5 on the Richter scale.
- Ground Shaking: Varies from gentle in small earthquakes to violent in large ones.
- Ground Rupture: Earthquake movement breaking the Earth’s surface along a fault.
- Land and Mudslides: Caused by direct rupture and sustained shaking of unstable slopes.
- Floods from Dam and Levee Failures: Earthquake-induced ground shaking can lead to dam collapses.
- Soil Liquefaction: Sediment grains floating in groundwater, causing soil loss of solidity.
- Avalanches: Forces induced by earthquakes can trigger avalanches.
- Fires: Ground rupture and liquefaction can rupture gas and water mains, contributing to fires.
Earthquake in India
- Earthquake in India India, due to the presence of the active Himalayan fold mountains, is highly prone to earthquakes.
- The country is divided into four seismic zones (II, III, IV, and V) based on scientific inputs related to seismicity, historical earthquakes, and tectonic characteristics.
Seismic Activities and Disaster Management in India
- The most sensitive regions in India include the Himalayas, the region of North Bihar, Himachal Pradesh, Uttarakhand, the Rann of Kutch in Gujarat, and the Andaman and Nicobar Islands.
- Some of the devastating earthquakes have affected India. More than 58.6% of Indian Territory is vulnerable to earthquakes of moderate to very high intensity.
- Some of India’s most significant earthquakes include
- Cutch Earthquake (1819) which was 8.3 magnitude
- Bihar-Nepal Earthquake (1934) of 8.4 magnitude
- Koyna Earthquake (1967) of 6.5 magnitude
- Bhuj (2001) of 7.7 magnitude
- Seismic Zone Map of India
- Jammu and Kashmir (2005)
Stages of Disaster Management:
- The disaster-management cycle consists of five crucial stages, and when effectively implemented, it can significantly reduce the impact of catastrophic events.
Prevention:
- Proactive measures, such as identifying potential hazards and devising safeguards, are crucial in disaster prevention.
- Implementation of evacuation plans and strategic city planning to minimize flooding risks through structures like locks, dams, or channels.
Mitigation:
- Aims to minimize the loss of human life through both structural and non-structural measures.
- Structural changes in the physical characteristics of buildings or environments to mitigate disaster effects.
- Non-structural measures involve adopting or amending building codes to enhance safety in future constructions.
Preparedness:
- An ongoing process involving planning and training for individuals, communities, businesses, and organizations.
- Includes activities like fire drills, active shooter drills, and evacuation rehearsals.
Response:
- Actions taken after a disaster occurs, involve both short and long-term responses.
- Coordinated use of resources to restore personal and environmental safety, minimize additional property damage, and ensure effective recovery.
Recovery:
- Prioritizing the restoration of essential services like food, clean water, utilities, transportation, and healthcare.
- Gradual restoration of less-essential services, focusing on safer urban planning and minimizing damages.
National Centre for Seismology (NCS):
- The NCS, under the Ministry of Earth Sciences, is the nodal agency for earthquake monitoring in India.
- Maintains the National Seismological Network (NSN) with 115 observatories across the country.
- Disseminates earthquake information to central and state disaster authorities promptly for timely mitigation measures.
Institutions and Guidelines for Earthquake Risk Minimization:
- The National Disaster Management Commission (NDMA) formulates short and long-term strategies to manage various disasters, including earthquakes.
- Adherence to guidelines from the Bureau of Indian Standards (BIS), Building Materials and Technology Promotion Council (BMTPC), and Housing and Urban Development Corporation (HUDCO).
- Guidelines are widely circulated among the public and administrative authorities to ensure the design and construction of earthquake-resistant structures in prone areas.
Tsunami
- The word, Themums is a Japanese term that stands for harbeer waves. A Bunami is a series of large waves usually noticed on a sea of ocean surfaces that can lead to a considerable amount of hons of life and property It is a sudden displacement of water that can take place in any waterbody if underlying causes are
Causes and Features of Tsunamis:
Tsunamis are triggered by various underlying factors, including:
- Earthquakes: Seismic activity, especially underwater, can induce tsunamis.
- Erupting Submarine Volcanoes: Volcanic activity beneath the ocean surface contributes to tsunami formation.
- Gas Bubble Eruptions: Sudden releases of gas bubbles in the sea can lead to tsunamis.
- Underwater Landslides: Violent movements from underwater landslides displace water and cause tsunamis.
- Interstellar Objects: Objects like asteroids or comets reaching Earth possess the potential to generate tsunamis.
- Nuclear Weapons: Detonation of nuclear weapons poses a threat to causing earthquakes and triggering tsunamis.
Features:
Tsunamis exhibit distinct characteristics:
- Location: Tsunamis can occur in any large body of water where underlying causes are present.
- Frequency: Tsunamis lack a specific timeframe and can happen unpredictably.
- Intensity: Tsunamis produce high waves, reaching heights of 10-100 feet.
- Speed: Traveling at speeds of 20-30 miles per hour, tsunamis can cover considerable distances.
- Wavelength: Tsunamis possess a high wavelength, ranging between 100 and 500 kilometers.
Tsunami Forecasting:
- Japan, situated in the Pacific Ring of Fire, employs advanced tsunami forecasting due to its vulnerability to earthquakes and tsunamis.
- About 90% of seismic activity worldwide occurs in the Pacific Ring of Fire, with numerous dormant and active volcanoes.
- The movement and collision of large plates in the Pacific Ring of Fire generate earthquakes, affecting Japan and resulting in numerous tsunamis.
- The 2011 Tohoku earthquake disrupted Japan’s economic and social life significantly.
- Deep-ocean Assessment and Reporting of Tsunamis (DART) systems, developed by the Pacific Marine Environmental Laboratory, play a critical role in real-time tsunami monitoring.
Tsunami Warning Systems
- Tsunami Warning Systems, including Decision Support Systems (DSS), assess tsunami threats early, supporting decision-makers in issuing timely warnings.
- INCOIS (Indian National Center for Ocean Information Services) serves as a crucial center for tsunami early warning in the Indian Ocean region, collaborating with various governmental bodies.
- The tsunameter, measuring water pressure at the sea floor, contributes to accurate tsunami monitoring and forecasting.
- The surface mooring employs a 2.5 m diameter with a displacement of 4000 kg. Its deployment is designed to maintain a precise watch circle, ensuring the buoy remains positioned within the cone of the acoustic transmission.
Volcanoes:
- Volcanism encompasses all phenomena related to the movement of molten material from the Earth’s interior to its surface. A volcano is an aperture in the Earth’s crust through which molten materials emerge, serving as the conduit for gases, ashes, and molten rock material to escape to the ground.
- Within the mantle, there exists a weaker zone known as the asthenosphere, from which molten rock material ascends to the surface. The material in the upper mantle, referred to as magma, transforms into lava upon reaching the crust or surfacing.
- Materials released to the ground include lava flows, pyroclastic debris, volcanic bombs, ash, dust, and various gases such as nitrogen compounds, sulphur compounds, and minor amounts of chlorine, hydrogen, and argon.
Topographic Features of Volcanoes:
- Magma exists in two forms—basaltic and granitic. Basaltic magma is fluid, while granitic magma is viscous.
- Once surfaced, magma, being lighter than adjoining rocks, moves upward, giving rise to specific topographic features.
- Intrusive features formed beneath the surface include:
- Lopoliths: Plate-shaped bodies mirroring the structure of the rocks they intrude.
- Batholiths: The largest intrusive bodies with elongated, oval, or isometric shapes, typically found in central parts of folded regions.
- Sills: Thin sheet-like intrusions of highly fluid basaltic magma inserted between bedding planes, separating layers of sedimentary rocks.
- Laccoliths: Huge masses of igneous rocks bent upward to form a dome with a level base fed by a pipe-like tube from below the surface.
- Dykes: Formed when magma infiltrates fractures in surrounding rock, cooling vertically and cutting across bedding planes.
- When volcanic features manifest on the Earth’s surface, they are termed extrusive features and include the following:
- Flood Basalts: Resulting from fissure eruptions with minimal explosive activity due to the low viscosity of basaltic lava, as seen in the Deccan Trap.
- Shield Volcanoes: Enormous basaltic domes formed through continuous outpouring of highly fluid basaltic lava, exemplified by Mt. Mauna Kea and Mauna Loa in Hawaii.
- Ash or Cinder Cone: Emanates from central-type eruptions with a prevalence of pyroclastic materials, as observed in Paricutin, Mexico.
- Shield Type: These volcanoes vary in size, with noteworthy examples like Mauna Loa, whose total height from the sea floor base is 4,170 m above mean sea level, surpassing Mt. Everest’s elevation of 8,850 m by a total of 9,000 m.
- Composite or Strata Cone: The tallest volcanic cones, characterized by thorough stratification of pyroclastic and lava, constructed through alternating layers of lava and fragmental flows, as seen in Pinatubo (Philippines) and Fuji (Japan).
- Parasitic Cone: Formed in the proximity of the main cone, drawing resources from the primary structure.
- Crater: A pit situated at the summit of a volcanic vent.
- Caldera: A large, more or less circular depression with a diameter several times that of a crater.
- Hot Springs When groundwater encounters magma and is heated beyond 36°C, it emerges as hot springs, found in locations such as Ladakh, Manali, volcanic regions of Iceland, and Yellowstone National Park.
- Geyser: A specialized hot spring, like the Old Faithful geyser in the USA, ejects steam and superheated water at regular intervals, faithfully erupting every 66 minutes.
- Fumaroles: Characterized by continuous jet-like emission of hot water from a vent.
- Central Eruption or Explosive Type: In this type, magma forcefully emerges through a small vent, spreading to distant locations, as seen in Hawaiian, Strombolian, Pelean, Vesuvius, etc.
- Fissure Eruption: Large quantities of lava quietly flow from fissures, spreading over surrounding areas and forming features like the Deccan Plateau.
Causes of Volcanism:
- Plate Tectonics: Occurs at converging lithospheric plates, where one overrides the other, forcing it down into the mantle.
- Ocean Floor Spreading: Active volcanism along the oceanic ridge system, where plates move apart, and magma wells up from the mantle.
- Weak Earth Surface: High-pressure magma and gases escape through weak zones in the Earth’s surface.
- Faults: Extreme pressure along fault lines may lead to eruptions when earthquakes expose fault zones.
- Magma Crystallization: Decreasing temperatures cause old magma to crystallize, sinking to the chamber’s bottom and forcing fresh liquid magma upward.
- Decrease in External Pressure: A decrease in external pressure can trigger eruptions by increasing pressure inside the magma chamber.
- Plate Movement: Volcanism may occur due to plate movement over a ‘hot spot,’ allowing magma to penetrate the surface, as seen in the Hawaiian Islands.
Parts of Volcanoes:
- Magma Chamber: Large underground pool of molten rock under pressure.
- Volcanic Vent: Weak point in the Earth’s crust allowing hot magma to reach the surface.
- Volcanic Cone: Formed by layers of igneous rocks from previous eruptions, with each lava flow adding a new layer.
- Volcanic Crater: Depression or hollow from which eruptions expel magmatic material.
Types of Volcanoes:
- Based on Periodicity of Eruption:
- Active Volcanoes, Dormant Volcanoes, Extinct Volcanoes.
- Based on Explosiveness:
- Quiet Fissure Volcanoes, Central Explosive Volcanoes.
- Based on Geographic Location:
- Divergent Plate Boundary Volcanoes, Convergent Plate Boundary Volcanoes, Intraplate Volcanoes.
- Based on Acidity and Alkalinity:
- Pelean Type, Strombolian Type, Vulcanian Type, Vesuvian or Plinian Type, Hawaiian Type.
Based on Periodicity of Eruption:
Active Volcanoes:
- Considered active when showing signs of unrest, such as unusual earthquake activity, indicating an imminent eruption.
- Defined by the Smithsonian Global Volcanism Programme as having erupted in the last 10,000 years.
- Examples include Kilauea in Hawaii, Mount Etna, and Mount Stromboli in Italy, the latter erupting consistently for the past 2000 years.
Dormant Volcanoes:
- Refers to volcanoes capable of erupting, likely to do so in the future, but haven’t erupted for an extended period.
- Examples include Mount Kilimanjaro in Tanzania (Africa) and Mount Fuji in Japan.
Extinct Volcanoes:
- Describes volcanoes cut off from their magma supply and not expected to erupt again.
- Examples include Mount Thielsen in Oregon (USA) and Mount Slemish in Northern Ireland.
Based on Explosiveness:
Quiet Fissure Volcanoes:
- Emit large volumes of lava along a fissure or fracture.
- Low-viscosity lavas allow gases to escape readily.
- Examples include the Deccan Plateau and Mount Kilauea in Hawaii.
Central Explosive Volcanoes:
- Explosive eruptions result from gas buildup under highly viscous magma deep within the volcano.
- Violent eruptions spew lava, ash, and volcanic materials into the air.
- Examples include Krakatau and Tambora in Indonesia, and Mount Rainier, and Mount St Helens in Washington State (USA).
Based on Geographic Location:
Divergent Plate Boundary Volcanoes:
- Occur at constructive plate boundaries where plates move away from each other.
- The Earth’s crust pulls apart, creating pathways for magma to reach the surface.
- Examples include Iceland on the Mid-Atlantic Ridge.
Convergent Plate Boundary Volcanoes:
- Form at destructive or convergent plate boundaries where plates move towards each other.
- Subduction processes create different types of volcanoes, such as island-arc volcanoes in ocean-ocean subduction and Andean-type volcanoes in ocean-continent subduction.
- A third setting, continent-continent, results in mountain-forming processes like the Alps and the Himalayas.
Intraplate Volcanic Phenomena
- Intraplate volcanic activities occur within tectonic plates and are unrelated to plate convergence or divergence. Regions with active volcanoes on the surface of tectonic plates are commonly known as hotspots.
- Intraplate volcanoes primarily form when mantle plumes reach the Earth’s surface and spread in a mushroom-like shape.
- These plume heads typically have a diameter of about 500-1000 km. Examples of intraplate volcanoes include the Hawaiian and Emperor Seamount chains.
Classification Based on Acidity and Alkalinity
Pelean Type
- Pelean eruptions involve explosive outbursts generating pyroclastic flows—dense mixtures of hot volcanic fragments and gas, as described in the Lava, Gas, and Other Hazards section. Named after the destructive 1902 eruption of Mount Pelée in Martinique.
Vulcanian Type
- The Vulcanian type, named after Vulcano Island near Stromboli, entails moderate explosions of gas laden with volcanic ash. This creates dark, turbulent eruption clouds that rapidly ascend and expand in convoluted shapes.
Strombolian Type
- Strombolian eruptions involve moderate bursts of expanding gases ejecting clots of incandescent lava in cyclical or nearly continuous small eruptions. Stromboli volcano off the northeast coast of Italy is known as the lighthouse of the Mediterranean due to its small, frequent outbursts.
Hawaiian Type
- The Hawaiian type is akin to the Icelandic variety. Fluid lava flows from a volcano’s summit and radial fissures to form shield volcanoes with large and gentle slopes.
Vesuvian or Plinian Type
- The Plinian type is an intensely violent volcanic eruption exemplified by the Mount Vesuvius outburst. In this eruption, gases from gas-rich magma generate enormous, nearly continuous jetting blasts that core out the magma conduit and rip it apart.
Distribution of Volcanic Belts
Volcanic belts are unevenly distributed worldwide, with three prominent volcanic belts:
Circum-Pacific Belt
- The Circum-Pacific region, known as the Pacific Ring of Fire, has the highest concentration of active volcanoes. The volcanic belt and earthquake belt closely overlap along the Pacific Ring of Fire, extending across the Kamchatka Peninsula, the Islands of Japan, the Philippines, New Guinea, New Zealand, and the Solomon Islands. It also passes through Antarctica and the western coasts of North and South America.
Ring of Fire
- The path along the rim of the Pacific Ocean characterized by active volcanoes and earthquakes is called the Ring of Fire, also known as the Circum-Pacific Belt or Circum-Pacific Seismic Belt.
- It spans 40,000 km and runs through 15 countries, including the USA, Indonesia, Mexico, Japan, Canada, Guatemala, Russia, Chile, Peru, and the Philippines.
Mid-Continental Belt
- Formed through the convergence of the Eurasian plate and the northward-moving African plate, this belt encompasses volcanoes along the Alpine mountain chain, the Mediterranean Sea, and the fault zone of Eastern Africa, including Stromboli, Vesuvius, Etna, Kilimanjaro, and others.
Mid-Atlantic Belt
- Located along divergent plate boundaries, the Mid-Atlantic Ridge is a volcanic mountain range rising from the Atlantic abyssal plain, extending from the Arctic to the Antarctic.
- Volcanoes in this belt exhibit fissure eruption types, such as those found in Iceland, the Canary Islands, Cape Verde, the Azores, and more.
Positive Effects of Volcanism
- Volcanic activity shapes new landforms like islands, plateaus, and volcanic mountains, as seen in the creation of the Deccan Plateau and Mount Vesuvius. The fertile volcanic ash and dust benefit agricultural lands.
- Volcanoes bring metallic ores to the surface, contributing to mineral resources. For instance, South Africa’s Kimberlite rock, a source of diamonds, originated from the pipe of an ancient volcano.
Relationship between Earthquakes and Volcanoes
- The connection between earthquakes and volcanoes is explained by the Theory of Plate Tectonics.
- During volcanic activity, when magma breaks through inner layers and reaches the surface, earthquakes occur due to the breaking of layers.
- Not all earthquake-affected areas experience mandatory volcanic activity, as subduction of plates may not occur deep enough for the plate to melt and transform into magma. Volcanic activity is primarily associated with convergent and divergent plate movements, excluding continent-continent collisions, while earthquakes occur at all plate boundaries.
Terminology Related to Volcanoes
- Magma/Lava The molten rock beneath the Earth’s surface is termed magma, while the erupted molten liquid is called lava.
- Lava is also referred to as liquid magma. Magmas with high silica content exhibit greater degrees of polymerization and higher viscosities than those with low-silica contents.
- Volcanic Bomb A pyroclastic rock formed when a volcano ejects viscous fragments of lava during an eruption. Volcanic bombs, often brown or red, weather to a yellow-brown color, and their final shape is influenced by the initial size, viscosity, and flight velocity of the lava bomb. They cool and solidify after leaving the volcano.
- Lapilli Gravel-sized particles ejected from a volcano, found either in molten or solid states, with diameters ranging from 2 to 64 mm (0.08 to 2.52 inches).
- Pumice A very light and porous volcanic rock formed during explosive eruptions. Pumice floats on water due to its low density resulting from air bubbles inside.
- Dust/Ash Fine rock particles that can be carried by the wind.
| Volcano | Features | Location |
| Mount Koh-i-Sultan | – | Pakistan |
| Ojos del Salado | – | Argentina/Chile |
| Llullaillaco | – | Argentina/Chile |
| Nevado Sajama | – | Bolivia |
| Chimborazo | – | Ecuador |
| Cotopaxi | – | Ecuador |
| Kilimanjaro | One of the five volcanoes in the form of Island of Hawaii | Tanzania |
| Cayambe | Second highest in Ecuador | Ecuador |
| Mount Elbrus | Highest volcano in Eurasia, the highest peak in Russia | Russia |
| Pico de Orizaba | Highest volcano in North America, the highest peak in Mexico | Mexico |
| Mount Damavand | Second highest volcano in Asia, the highest peak in Iran | Iran |
| Popocatepetl | – | Mexico |
| Iztaccihuatl | – | Mexico |
| Mount Kenya | Second highest volcano in Africa, the highest mountain in Kenya | Kenya |
| Mount Damavand | Dominant stratovolcano and highest peak of Iran | Iran |
| Mount Kazbek | Highest volcano in Georgia | Georgia |
| Mount Bona | Highest volcano in the United States | Alaska |
| Klyuchevskaya Sopka | Highest active in Eurasia, the highest mountain in Siberia | The Kamchatka Peninsula; Russia |
| Mount Karisimbi | Highest mountain in Rwanda | Rwanda/Democratic Republic of Congo |
| Mount Rainier | – | Washington |
| Mount Giluwe | Highest volcano in Australasia and Pacific islands | Papua New Guinea |
| Volcan Tajumulco | Highest mountain in Central America | Guatemala |
| Mauna Kea | Highest volcano in the contiguous United States | Hawaii, USA |
| Mount Sidley | Highest volcano in Antarctica | Antarctica |
| Mount Cameroon | Highest mountain in Cameroon | Cameroon |
| Mount Aragats | Highest mountain in Armenia | Armenia |
| Mount Kerinci | Highest volcano in Indonesia, the highest mountain in Sumatra | Sumatra, Indonesia |
| Mount Fuji | Highest mountain in Japan | Chubu Region, Honshu |
| Mount Etna | Active, Highest volcano in Western Europe; the highest peak in Italy | Sicily |
| Haleakala | The highest peak of Maui | Hawaii, United States |
| Mount Agung | Highest mountain in Bali | Bali, Indonesia |
| Pico Basile | The highest mountain in Equatorial Guinea | Bioko, Equatorial Guinea |
| Mount Popa | – | Myanmar |
| Mount Apo | Highest mountain in the Philippines | Mindanao |
Prelims facts
- Intensity of earthquake is measured on which scale? -Mercalli scale (IAS (Pre) 2001
- During an earthquake, which type of waves are generated? P-S-L waves (APSC (Pre) 2013
- The amount of ground displacement in earthquake is called Stip (Manipur PSC (Pre) 2016)
- The North-Western region of the Indian subcontinent is susceptible to earthquake activity because of -Plate tectonic activity (UPPSC (Mains) 2015)
- The cause of earthquakes in the region from the Himalayas to the Arakan yoma is Collision of Eurasian plate and Indian plate (APSC (Pre) 2017
- Central America and Pacific Plate [BPSC (Pre) 2018]
- Cocos plate lies between
- The scale use for measuring the intensity of the earthquake is – Richter Scale (WBCS (Pre) 2020
- The word ‘tsunami’ is related to which language? -Japanese (UPPSC (Pre) 2015]
- What is the origin of tsunami? -Earthquake originating under the sea [JPSC (Pre) 2015
- What can be considered as a primary warning for an Impending tsunami? Rapid diversion of water from the coast (UPPSC (Pre) 2006).
- Where is the tsunami warning centre located in India? Hyderabad (UPPSC (Mains) 2012)
- Which type of Earthquake wave cannot travel through liquid? Secondary wave I(MPSC (Pre) 2016
- The molten material found inside the Earth is called -Magna (UKPSC (Pre) 2008
- The most abundant gas emitted from volcanoes is Water vapour [IPSC (Pre) 2003)
- Volcanic eruptions do not occur in which sea? Baltic Sea (IAS (Pre) 2001
- Cotopaxi, Etna and Fujiyama are type of which volcanoes? Active volcanoes (UPPSC (Mains) 2007
- What is the name of most active volcano? Kilauea (UPPSC (Pre) 2009
- In which belt, the volcanic eruption is maximum? Circum Pacific [UPPSC (Pre) 2000
- Where is Mauna Loa an active volcano, located at ? -Hawaii (UPPSC (Pre) 2005)
- The highest peak in Africa Mount Kilimanjaro is a Volcano (BPSC (Pre) 2000)
- Which volcano is called ‘The lighthouse of Mediterranean sea’? Stromboli (MPPSC (Pre) 2017
- 80% of the world’s active volcanoes exist in which belts? -Mid-continental belt and Circum Pacific belt (BPSC (Pre) 2004)
- Where is the volcanic mountain Mount St Helena is located? -United States of America [IAS (Pre) 2005]
UPSC NCERT Practice Questions
1. Which type of earthquakes occur in mining activities?
(a) Tectonic earthquakes
(b) Volcanic earthquakes
(c) Collapse earthquakes
(d) Explosive earthquakes
2. The Magnitude of earthquake is measured on the
(a) Barometer
(b) Anemometer
(c) Kelvin meter
(d) Richter scale
(d) rotation of the Earth
3. Tsunamis are originated
(a) sea waves
(b) earthquake
(c) hurricane
(d) rotation of the Earth
4. Which one of the following has the largest number of active volcanoes?
(a) Alaska
(b) Aleutian Island
(c) Hawaii Island
(d) Iceland
5. Which is the most active volcano in indonesia?
(a) Mount Yasur
(b) Mount Erebus
(c) Mount Merapi
(d) Mount Kilimanjaro
6. What is an earthquake fissure?
(a) The parts of plate boundaries which is prone to Increased tsunamis
(b) Sections of the plate boundaries which repeatedly contracted in the near past.
(c) Sections of the plate boundaries which have not contracted in the near past.
(d) Those plate boundaries which record no volcanic activity
7. Which of the following statements is not correct regrading the primary waves of earthquakes? UPPSC (Pre) 2019
(a) These are like sound waves
(b) They can only move through solids.
(c) They can move through gaseous, liquid and solid materials.
(d) They move fast and are first to reach the surface.
8. Which of the following are active volcanoes? UPPSC (Main) 2017
1. Aconcagua
2. Cotopaxi
3. Etna
4. Fujiyama
Select the correct answer by using the codes given below. Select
(a) 1 and 2
(b) 3 and 4
(c) 1, 2 and 3
(d) 2, 3 and 4
9. Match List I with List II and select the correct answer by using the codes given below the lists. BPSC (Pre) 1994, UPPSC (Pre) 2010
List 1 (Volcano Types)
A. Etna
B. Vesuvius
C. Erebus
D. Cotopaxi
List II (Locations)
1. Ross island
2. Ecuador
3. Italy
4. Sicily
Codes
(a) 1234
(b) 4312
(c) 342 1
(d) 4 3 2 1
10. Match List I and List II and select the correct answer by using the codes given below the lists.
| List I (Volcanoes) | List II (Countries) |
| A. Mount Kinabalu | 1. Argentina |
| B. Elburz | 2. Malaysia |
| C. Aconcagua | 3. Tanzania |
| D. Kilimanjaro | 4. Iran |
Codes
(a) 1423
(b) 3 214
(c)2 4 3 1
(d) 2 4 13
11. 80% of the world’s active volcanoes exist in which of the following belts? BPSC (Pre) 2004
1. Atlantic ocean belt
2. Mid-continental
3. Circum pacific belt
4. Indian ocean belt
Codes
(a) 2 and 3
(b) 1 and 2
(c) 3 and 4
(d) 1 and 3
12. Read the following statements related to Earthquake shadow zone’ and choose the correct option. CGPSC (Pre) 2020
Statement ( 1) The shadow zone of one earthquake is totally different from the shadow zone of another earthquake.
Statement (2) Seismometers record both ‘P’ and ‘S’ waves at any distance out of 105° from earthquake’s epicentre.
Codes
(a) Both the statements 1 and 2 are true.
(b) Statement 1 is true, but statement 2 is false.
(c) Statement 1 is false, but statement 2 is true.
(d) Both the statements 1 and 2 are false.
13. Consider the following statements about earthquakes. IAS (Pre) 2001
1. Intensity of earthquake is measured on Mercalli scale.
2. Earthquake’s magnitude is the measurement of energy released.
3. Magnitude of earthquake depends directly upon amplitude of an earthquake waves.
4. Every integer on Richter scale shows a 100 times increase in energy released.
Which of the statements given above are correct?
(a) 1, 2 and 3
(b) 2, 3 and 4
(c) 1 and 4
(d) 1 and 3
14. The ideal time for occurence of Tsunami is
1. during the Neap tide.
2. only in the evening.
3. any time of the day or night.
4. only in the summer months.
Select the correct answer from the codes given below.
(a) 1 and 2
(b) 2 and 3
(c) Only 3r
(d) All of these
Know Right Answer
1 (c)
2 (d)
3 (b)
4 (b)
5 ( c)
6 (c)
7 (B)
8 (d)
9 (b)
10 (d)
11 (a)
12 (b)
13 ( a)
14 (c)
Frequently Asked Questions (FAQs)
Q1: What are the main causes of earthquakes and tsunamis?
A1: Earthquakes are primarily caused by the movement of tectonic plates beneath the Earth’s surface. The Earth’s lithosphere is divided into several large and small plates that constantly interact. When these plates grind against each other, pull apart, or collide, it can result in seismic activity, leading to earthquakes. Tsunamis, on the other hand, are often triggered by underwater earthquakes. The sudden vertical movement of the ocean floor displaces water, generating powerful ocean waves.
Q2: How do volcanoes form, and what are the different types of volcanic eruptions?
A2: Volcanoes form when magma (molten rock) from the Earth’s mantle erupts through the Earth’s crust. This can happen at convergent boundaries, where tectonic plates collide, or at divergent boundaries, where plates move apart. The magma may reach the surface as lava, leading to the formation of a volcano. There are various types of volcanic eruptions, including explosive eruptions where ash and volcanic rocks are forcefully expelled, and effusive eruptions where lava flows more steadily. The explosiveness depends on factors such as magma viscosity and gas content.
Q3: How do earthquakes and volcanic activity contribute to shaping the Earth’s surface?
A3: Both earthquakes and volcanic activity play crucial roles in shaping the Earth’s surface. Earthquakes can create or modify landforms through processes like faulting and folding. Mountain ranges, valleys, and other geological features often result from tectonic plate movements. Volcanic activity, on the other hand, adds new material to the Earth’s surface. Lava solidifies to form volcanic rocks, and volcanic ash enriches soil. Over time, repeated volcanic eruptions contribute to the formation of volcanic landforms, such as calderas, cones, and plateaus, influencing the overall topography of the Earth.
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