What´s the difference between による, により and によって?

Question

I don't understand when you use it and what the difference is between each other. For example, when you say: > 火事によって多くの森林が焼けてしまった。 > 今回の地震による津波の心配はない。

Answer 1

により and によって are conjunctive, they go before another clause. により is often used in written language.

による needs to go before a noun. Usually reserved for formal, written Japanese, if the noun expresses a condition it can be used in everyday speech.

火事によって多くの森林が焼けてしまった。 Here, によって is showing the agent; although this sentence is not passive, the verb itself works like one as it is intransitive. "Much of the forests were burned by the fire."

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今回の地震による津波の心配はない。The による is showing cause. Worries do not spring up on their own, after all. "There is no fear of tsunami caused by this (recent) earthquake.