GSA Geophysics
Terms
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- Earthquake propagation speed
- 3-4 km/s
- Temperature gradient in Earth
- 20-30 degree/km
- Length of earthquake fault break
-
Active volcano: meters
Large quake: 100s kms
Boxing day 2004: 1300 km - Earthquake stress drops
- 1 to 10 MPa
- Sumatra earthquake seismic moment
- In 300-500 s period same as all in previous decade combined
- Sumatra 2004
-
1300 km length
200 km width
5.1 m fault displacement - Mexico City 1985
-
10 000 dead
50 000 injured
250 000 homeless - New Zealand subduction
- Southern part of slab subducting slowly, northern part rapidly so deeper earthquakes
- 1896 Sanriku Japan
-
Thrust: tsunami 38 m, 26 000 dead
Normal M8.6: Tsunami 23 m, 3100 dead - 2011 Honshu Japan
-
Mainshock M 9.1
Two aftershocks M 7.9 - RRR TJ
- Rodriguez TJ, Indian ocean
- FFR TJ
- Owen Fracture Zone and Carlsberg Ridge, NW Indian Ocean
- RFT TJ
- Rivera Plate near Gulf of CA
- TTT TJ
-
Off Japan
Eurasian, Pacific and Philippine Plates
Ryukyu, Japan and Izu-Ogasawara Trenches - Area of Fresnel Zone at MOHO
- 34 km2
- Seismic reflection vertical resolution
-
Sediments: 20 m layers
Basement: 80 m layers - Seismic velocity water
- 1.5 km/s
- Seismic velocity unconsolidated sediments
- 2.0 km/s
- Seismic velocity mantle
- 8.0 km/s
- Seismic velocity continental crust
- 6.5 km/s
- Sedimentary rock reflection coefficient
- 0.01-0.02
- MOHO definition
- Seismic p-wave velocity above 7.6 km/s
- Volcanic margin
- Hatton Bank margin, west of Rockall, part of Tertiary Igneous Province from N Atlantic rifting
- Non-volcanic margin
- Goban Spur off northern France
- Faroe Islands
- Coal seams in lavas
- Rockall continental margin
- Extrusive lava flows forming seaward dipping reflectors
- Deccan plateau basalts
-
65 Ma
Offshore volcanism along west Indian continental margin
Mascarene Basin fossil spreading center
Active ridge in Arabian Sea
Reunion Plume - Parana-Etendeka
-
120 Ma
Walvis hotspot
Rio Grande Rise and Walvis Ridge - Afar region flood basalts
- Thermal anomaly with 1000 km radius
- The Karoo flood basalts
-
170 Ma
Gondwana breakup in mid-Jurassic
Africa-Antarctica split