Editing Earthquake (section)

=== Energy released ===
For every unit increase in seismic magnitude, there is a roughly thirty-fold increase in the energy released. For instance, an earthquake of magnitude 6.0 releases approximately 32 times as much energy as an earthquake of magnitude 5.0, and a 7.0 magnitude earthquake releases about 1,000 times as much energy as a 5.0 magnitude earthquake. An 8.6-magnitude earthquake releases the same amount of energy as 10,000 atomic bombs of the size used in [[World War II]].<ref>Geoscience Australia.{{full citation needed|date=December 2022}}</ref>

This is so because the energy released in an earthquake, and thus its magnitude, is proportional to the area of the fault that ruptures<ref>{{cite journal |last1=Wyss |first1=M. |year=1979 |title=Estimating expectable maximum magnitude of earthquakes from fault dimensions |journal=Geology |volume=7 |issue=7| pages=336–340 |bibcode=1979Geo.....7..336W |doi=10.1130/0091-7613(1979)7<336:EMEMOE>2.0.CO;2}}</ref> and the stress drop. Therefore, the greater the length and width of the faulted area, the greater the resulting magnitude. The most important parameter controlling the maximum earthquake magnitude on a fault, however, is not the maximum available length, but the available width because the latter varies by a factor of 20. Along converging plate margins, the dip angle of the rupture plane is very shallow, typically about 10 degrees.<ref>{{cite web |url=http://www.globalcmt.org/CMTsearch.html |title=Global Centroid Moment Tensor Catalog |publisher=Globalcmt.org |access-date=2011-07-24 |archive-date=2011-07-19 |archive-url=https://web.archive.org/web/20110719183137/http://www.globalcmt.org/CMTsearch.html |url-status=live }}</ref> Thus, the width of the plane within the top brittle crust of the Earth can reach {{cvt|50–100|km|||}} (such as in [[2011 Tōhoku earthquake and tsunami|Japan, 2011]], or in [[1964 Alaska earthquake|Alaska, 1964]]), making the most powerful earthquakes possible.