Extends 1,200 kilometers through California, forming Pacific-North American plate boundary. Average slip rate ranges from 20 to 35 mm per year. First identified by Andrew Lawson in 1895, named after surrounding San Andreas Valley
Australia is the world's smallest continent and sixth-largest country. Total coastline length is 35,821 km with 23,860 km of island coastlines. Contains 758 estuaries and 8,866 km2 of tidal flat area. No land borders, largest area of ocean jurisdiction on Earth
Aftershocks are smaller earthquakes following larger ones in the same area. Large earthquakes can have hundreds to thousands of detectable aftershocks. Aftershocks typically occur up to the rupture length from the fault plane
Japan is an archipelago of 14,125 islands spanning 3,000 km along Pacific coast. Main islands are Hokkaido, Honshu, Kyushu, and Shikoku. 73% of Japan is mountainous, with Mount Fuji reaching 3,776 m. 66% of terrain is forest, with highest forest cover in developed nations
Earthquake intensity differs from magnitude, which measures seismic wave amplitude. Intensity scales were developed in late 19th-early 20th centuries before seismographs. Intensity depends on ground accelerations, seismic wave features, and local structure
Seismograph records seismic waves caused by earthquakes and other shaking. Instrument uses electromagnetic sensors to convert ground motions to electrical changes. Seismogram is the recorded output of a seismograph