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Unformatted text preview: Chapter 2: Where Earthquakes Occur • The first systematic and nonmystical treatment of earthquakes occurred in Greece, where its people experienced Aegean volcanoes and earthquakes along the Mediterranean Sea, sometimes accompanied by tsunamis/ o Straba noted that eq's occurred more frequently along the coast than inland. o Aristotle suggested that eq's were caused by rushing subterranean winds, igniting combustible materials underground. • Oldest records: Chinese. Catalog is thought to document every moderate to large eq in central China from 780 b.c. to the present o Most catastrophic eq: January 23rd, 1556: 830,000 people died. People lived in caves on the hillside called loess- little resistance to shaking. • United States and Canada: First recorded eq in Massachusetts in 1638, toppling stone chimney's to the ground. o Three rivers area of the lower St. lawrence river in southeastern Canada on February 5th, 1663. o California: Eq's recorded after 1800. • January 9th, 1857: Fort Tejon. One of the first indications of the rupture on the SAF. • Seismograph stations o 1906 SF eq was well recorded o 1960: 700 eq observatories was operating. o The US established the Worldwide Standardized Network of seismographs. • Distributed 120 to 60 countries. o More than 1000 observatories now. o 1997: most of the stations had been converted to the digital seismographic network. • Global Mosaic of Earthquakes o Active: Atlantic, Indian Oceans. Central America, Gulf of California • Volcanic eruptions are frequent, and eq's originating along these ridges often occur in "swarms". o Island Arcs: Dense concentrations of eq's • Aleutian arc, swimming westward from Alaska toward Kamchatka, Russia. • To the south: Japan, Marianas, islands around Australia, Tonga- Kermadec trench o Entire western coast of Central and South America • Eastern South America is almost free from eq's, central and North Canada, Siberia, West Africa, Australia o Europe • Active: Turkey, Greece, Yugoslavia, Italy, Spain, Portugal (November 1st 1775- tsunami which called 50k-75k ppl) • North of the Mediterranean margin, more stable....
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This note was uploaded on 05/11/2008 for the course GEOL 240Lxg taught by Professor 12:30-01:50pm during the Fall '07 term at USC.
- Fall '07