By Candy Olson

Fault lines = relief of stress Subduction: normal faulting reverse faulting strikeslip transform

tsunami nami/main.html nami/main.html Danger -Getting knocked about by debris -Being pulled out to sea

Observed phenomena Gas clouds-can be irritating, fatal, eclipse the sky Lightning Haze –before, during and after a quake Water/steam geiser Sand, coal or other mineral geiser Land splits, drops, or raises

seismograph Measurements 1 st in C.E. Han dynasty-invented by Chang Heng

1 st modern day seismograph in 1875 by Cecchi in Italy – used a suspended pendulum Work was done in 1880’s in Japan that continued to improve on Cecchi’s work gLinks.php gLinks.php

Types of measurement Richter scale: measures movement of suspended pen (seismograph) during a quake Seismic moment: measures how much and how far the Earth’s crust moves during a quake

Types of earthquakes Benioff zone- focus is deep in subduction zone Surface- focus is at or near the surface of the Earth’s crust hquakes/index.html

How do scientists know where the focus is? One station recording a quake gives a circle of possibilites. Two stations give two possibilities. Three stations finds the location of the epicenter. Four stations finds the depth/ focus.

Scientific advancement from studying earthquakes: Have learned that entire plates can shake in a great quake; Are learning what the interior of the Earth is made of/how it’s arranged. Are learning the geological history of the Earth.

Lab activity nky.htm nky.htm