science

Japan Meteorological Agency magnitude scale

Japan Meteorological Agency magnitude scale is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Japan Meteorological Agency magnitude scale rather than just read about it. In short: The Japan Meteorological Agency magnitude scale (Japanese: 気象庁マグニチュード) is a seismic magnitude scale set by the Japan Meteorological Agency. Overview In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japan Meteorological Agency (JMA) calculates a magnitude labeled MJMA, MJMA, or MJ.

Key takeaways

Japan Meteorological Agency magnitude scale belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Japan Meteorological Agency magnitude scale to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Japan Meteorological Agency magnitude scale from memory before moving on to harder problems.

Reference excerpt

The Japan Meteorological Agency magnitude scale (Japanese: 気象庁マグニチュード) is a seismic magnitude scale set by the Japan Meteorological Agency.

Overview In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japan Meteorological Agency (JMA) calculates a magnitude labeled MJMA, MJMA, or MJ. (These should not be confused with moment magnitudes JMA calculates, which are labeled Mw(JMA) or M(JMA), nor with the Shindo intensity scale.) JMA magnitudes are based (as typical with local scales) on the maximum amplitude of the ground motion; they agree "rather well" with the seismic moment magnitude Mw in the range of 4.5 to 7.5, but underestimate larger magnitudes.

Notes

Sources Katsumata, A. (June 1996), "Comparison of magnitudes estimated by the Japan Meteorological Agency with moment magnitudes for intermediate and deep earthquakes.", Bulletin of the Seismological Society of America, 86 (3): 832–842, Bibcode:1996BuSSA..86..832K, doi:10.1785/BSSA0860030832, S2CID 130279928. Bormann, P.; Wendt, S.; Di Giacomo, D. (2013), "Chapter 3: Seismic Sources and Source Parameters", in Bormann (ed.), New Manual of Seismological Observatory Practice 2 (NMSOP-2), doi:10.2312/GFZ.NMSOP-2_ch3, archived from the original (PDF) on 2019-08-04, retrieved 2021-06-02. Bormann, P.; Saul, J. (2009), "Earthquake Magnitude" (PDF), Encyclopedia of Complexity and Applied Systems Science, vol. 3, pp. 2473–2496. Doi, K. (2010), "Operational Procedures of Contributing Agencies" (PDF), Bulletin of the International Seismological Centre, 47 (7–12): 25, ISSN 2309-236X, archived from the original (PDF) on 2022-01-20. Also available here (sections renumbered).

Worked examples

Example 1 — a first encounter with Japan Meteorological Agency magnitude scale

Start with the simplest possible case. Write down what Japan Meteorological Agency magnitude scale claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Japan Meteorological Agency magnitude scale before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Japan Meteorological Agency magnitude scale ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Japan Meteorological Agency magnitude scale

In research: Japan Meteorological Agency magnitude scale appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Japan Meteorological Agency magnitude scale in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Japan Meteorological Agency magnitude scale is common in secondary-school and first-year university syllabi. It links to neighbouring topics Japan Meteorological Agency, Seismic magnitude scales, Seismology stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Japan Meteorological Agency magnitude scale outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Japan Meteorological Agency magnitude scale in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Japan Meteorological Agency magnitude scale means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Japan Meteorological Agency magnitude scale out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Japan Meteorological Agency magnitude scale in simple terms?

The Japan Meteorological Agency magnitude scale (Japanese: 気象庁マグニチュード) is a seismic magnitude scale set by the Japan Meteorological Agency. Overview In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japan Meteorological Agency (JMA) calculates a magnitude labeled MJMA, MJMA, or M…

Why does Japan Meteorological Agency magnitude scale matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Japan Meteorological Agency magnitude scale?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Japan Meteorological Agency magnitude scale.