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Earthquake Magnitude and Energy Ratio Calculator

Magnitude-Energy Relationship: Taking moment magnitude (MW) as an example, when magnitude increases by 1.0, energy increases 31.6 times; when increased by 2.0, energy increases about 1000 times (31.6²)

Formula: E2/E1 = 10^(1.5 × ΔM), where ΔM is the magnitude difference

Energy Ratio

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Earthquake Magnitude Calculator Guide

Types of Earthquake Magnitude Units

Earthquake magnitude is a physical quantity that measures the energy released by an earthquake. Different magnitude units are suitable for different types and distances of earthquake observations. Common magnitude units include: ML (Local Magnitude), MS (Surface Wave Magnitude), MB (Body Wave Magnitude), MW (Moment Magnitude), etc. Understanding these units and their applicable ranges helps in scientifically comprehending earthquake energy and destructive power.

  • ML (Local Magnitude): The earliest proposed magnitude unit, also known as "Richter Scale". Mainly used for measuring local and small to medium earthquakes (generally within 600 kilometers).

    Formula: ML = log(A) + 2.56log(Δ) - 1.67

    Where: A is maximum seismic wave amplitude (mm), Δ is epicentral distance (km)

  • MS (Surface Wave Magnitude): Used for measuring distant earthquakes (epicentral distance > 2000 km), based on surface wave amplitude with a 20-second period.

    Formula: MS = log(A/T) + 1.66log(Δ) + 3.3

    Where: A is maximum ground displacement amplitude (μm), T is period (s), Δ is epicentral distance (degrees)

  • MB (Body Wave Magnitude): Mainly used for measuring deep-focus or distant earthquakes, based on body wave amplitude with a 1-second period.

    Formula: MB = log(A/T) + Q(Δ,h)

    Where: A is P-wave maximum amplitude (μm), T is period (s), Q is distance correction, Δ is epicentral distance, h is focal depth

  • MW (Moment Magnitude): Currently the most widely used and scientifically sound magnitude unit internationally. Based on physical parameters of the earthquake fault.

    Formula: MW = 2/3 × log(M0) - 6.07

  • Other Magnitude Units:

    mb_Lg: mb_Lg = log(A) + B(Δ)

    Md: Md = 2.0log(τ) + 0.0035Δ + 0.87

    Where: τ is signal duration (s), Δ is epicentral distance (km)

Unit Abbreviation Application Range Description
Local Magnitude ML Local, small to medium earthquakes Traditional Richter scale, suitable for local earthquakes
Surface Wave Magnitude MS Distant, large earthquakes 20-second surface waves, suitable for long-distance observation
Body Wave Magnitude MB Deep-focus, distant earthquakes 1-second body waves, suitable for deep earthquakes and nuclear explosions
Moment Magnitude MW All types of earthquakes Physical parameter calculation, international standard unit
Lg Wave Magnitude mb_Lg China and surrounding areas Suitable for small to medium earthquakes
Duration Magnitude Md Micro earthquakes Estimated through seismic wave duration

Note: Magnitude values from different units are usually similar, but may show significant differences in extreme earthquakes or special earthquake types. Conversion results are for reference only, as actual earthquake energy is affected by geological conditions, focal depth, and other factors.

Earthquake Magnitude

Earthquake magnitude is a measurement standard used to quantify the size of an earthquake, primarily reflecting the total energy released by the earthquake.

Magnitude Damage Description
1-2 Not felt by people, only detected by instruments
3 Slight indoor vibrations felt, hanging objects swing slightly
4 Noticeable indoor shaking, cars rock noticeably, hanging objects swing
5 Buildings shake, sleeping people wake up, some items may fall
6 Difficult to stand, buildings damaged, walls may crack
7 Severe damage to unprotected buildings, ground cracks appear, some buildings collapse
8 Most buildings severely damaged, terrain changes occur
9 Widespread building destruction, ground faults appear, railway tracks severely bent
10-12 Catastrophic destruction, landscape completely altered, rarely occurs

Earthquake Intensity

Earthquake intensity is an indicator showing the severity of earthquake effects, with different countries and regions using different intensity scale standards. Unlike magnitude, intensity varies by location for the same earthquake.

Chinese Seismic Intensity Scale (CSIS)

Intensity Level Human Perception Object Response Building Response Ground Effects
Degree I Detectable by instruments, almost imperceptible to people Very few people at rest may feel it No effect No change
Degree II Few people at rest can feel it Hanging objects swing slightly No effect No change
Degree III Many people indoors can feel it, some wake up Hanging objects swing noticeably, dishes rattle Slight vibration No significant change
Degree IV Most people feel it clearly, people wake up at night Dishes clash, windows rattle Doors and windows shake, walls make noise Slight ground cracks in some areas
Degree V Difficult to walk, people panic Objects fall over, liquids spill Wall cracks appear, few buildings slightly damaged Small ground fissures appear
Degree VI Standing difficult, strong panic Many items collapse, heavy objects move Common buildings crack, some severely damaged Significant ground fissures appear
Degree VII Extremely difficult to stand, cannot walk Most items thrown, large equipment damaged Most buildings damaged, some collapse Widespread ground fissures, sand and water eruption
Degree VIII People cannot stand, thrown out Fixed objects thrown, trees break Many buildings severely damaged, most collapse Severe ground cracks, faults appear
Degree IX People thrown, cannot control movement Large machinery thrown, concrete poles break Widespread building collapse, underground pipes break Numerous ground fissures, landscape changes
Degree X People completely unable to stand Large structures thrown or collapse Most buildings destroyed or collapse Major ground deformation, large faults appear
Degree XI People completely lose control All objects thrown Almost all buildings collapse Ground completely destroyed, landscape changes
Degree XII Massive casualties All objects destroyed or thrown All above-ground buildings completely destroyed Landscape completely altered, terrain reshaped

Modified Mercalli Intensity Scale (MMI)

Intensity Description Effects and Damage
I Instrumental Only detectable by instruments, not felt by people
II Very Light Felt by very few people in upper floors, hanging objects may sway slightly
III Light Noticeable indoors, similar to a truck passing, parked cars rock slightly
IV Moderate Felt both indoors and outdoors, dishes rattle, windows vibrate, parked cars rock noticeably
V Rather Strong Most people feel it distinctly, unstable objects topple, sleeping people wake up
VI Strong Felt by everyone, heavy furniture moves, wall cracks appear, chimneys damaged
VII Very Strong Difficult to stand, buildings damaged, cars hard to control, groundwater levels change
VIII Destructive Driving difficult, ordinary buildings severely damaged, tall chimneys fall, landslides occur
IX Ruinous Buildings collapse completely, underground pipes break, ground cracks, rails bend
X Disastrous Most buildings destroyed, bridges collapse, dams severely damaged, rails severely bent
XI Very Disastrous Almost all buildings collapse, severe ground deformation, all underground utilities destroyed
XII Catastrophic Total destruction, landscape totally altered, objects thrown into the air

Japan Meteorological Agency (JMA) Seismic Intensity Scale

Intensity Human Perception and Response Indoor/Outdoor Conditions
0 Imperceptible to people Only detectable by seismometers
1 Felt by some people in quiet indoor conditions Slight swaying of hanging objects
2 Most people feel it, some wake up Lamps sway noticeably, dishes rattle
3 Everyone feels it strongly, some people are frightened Dishes clatter, hanging objects swing violently
4 Most people are frightened and want to escape Unstable items topple, furniture may move
5 Lower Most people find it difficult to move Furniture moves significantly, items fall from walls
5 Upper Standing impossible, must crawl to move Furniture topples, doors cannot be opened
6 Lower Cannot stand or crawl Most furniture moves, walls crack
6 Upper Thrown to ground, cannot move Buildings may collapse, ground cracks appear
7 Thrown through the air, completely immobilized Buildings collapse, terrain changes

European Macroseismic Scale (EMS)

Intensity Level Human Perception Building Effects Environmental Effects
I Not felt No effect No change
II Felt by very few people No effect No change
III Felt by many people indoors Slight damage No change
IV Felt by most people Moderate damage Slight ground cracks in some areas
V Difficult to walk Severe damage Small ground fissures appear
VI Difficult to stand Buildings damaged, walls may crack Significant ground cracks appear
VII Cannot walk Most buildings damaged, some collapse Widespread ground cracks, sand and water eruption
VIII People thrown to ground Many buildings severely damaged, most collapse Severe ground cracks, faults appear
IX People violently thrown, cannot control movement Widespread building collapse, underground pipes break Numerous ground fissures, landscape changes
X People completely unable to stand Most buildings destroyed or collapse Major ground deformation, large faults appear
XI People completely lose control Almost all buildings collapse Ground completely destroyed, terrain changes
XII Massive casualties All buildings completely destroyed Landscape completely altered, terrain reshaped

Major Earthquakes in Recent Years

Date Location Magnitude Fatalities Notes
February 6, 2023 Turkey-Syria M7.8 Over 50,000 One of the most severe earthquakes in modern history
March 11, 2011 Northeast Japan M9.0 15,899 Triggered Fukushima nuclear disaster
May 12, 2008 Wenchuan, Sichuan, China M8.0 69,227 Most destructive earthquake since the founding of PRC
December 26, 2004 Sumatra, Indonesia M9.1 ~230,000 Triggered Indian Ocean tsunami
January 12, 2010 Port-au-Prince, Haiti M7.0 ~316,000 Caused massive casualties