WHAT IS AN EARTHQUAKE? Merriam-Webster Dictionary defines an earthquake as a shaking or trembling of the earth that is volcanic or tectonic in origin. http://questgarden.com/71/26/9/081013095448/
HOW DO EARTHQUAKES OCCUR? Earthquakes occur when two blocks of land suddenly slip past each other along a fault line(USGS). The location in which the earthquake starts is called the Hypocenter. The location directly above the hypocenter on the earth’s surface is called the Epicenter (USGS).
WHERE DO EARTHQUAKES OCCUREarthquakes occur along fault lines. There arethree major types of fault lines. Strike-slip Faults Normal Faults Reverse Faults
STRIKE-SLIP FAULTS Occur along transform boundaries The two blocks of land move sideways past each other on a horizontal plane (Plate- tectonics.org). http://www.google.com/imgres?hl=en&biw=1366&bih=667&gbv=2&tbm=isch&tbnid=S1G0- 0umWsfvyM:&imgrefurl=http://geomaps.wr.usgs.gov/parks/deform/gfaults.html&docid=N7wnKR tOalFgiM&imgurl=http://geomaps.wr.usgs.gov/parks/deform/strikeslip.gif&w=318&h=157&ei=IC pHT4KsGYixgwey- _SQDg&zoom=1&iact=hc&vpx=906&vpy=222&dur=2429&hovh=125&hovw=254&tx=138&ty=5 7&sig=103976019753380940988&page=1&tbnh=91&tbnw=184&start=0&ndsp=20&ved=1t:429, r:5,s:0
STRIKE-SLIP FAULTS CONT. Famous strike slip faults include the San Andreas fault in California and the Alpine Fault in New Zealand. Geology.com
NORMAL FAULTS Occur at divergent plate boundaries. The rocks on one side of the normal fault moves downward against the rocks on the other side (plate-tectonics.org).
REVERSE FAULTS Reverse faults occur at convergent boundaries. The rocks on one side of a reverse fault moves upward. This movement of rocks at reverse faults often causes earthquakes (plate-tectonics.org). claremontgeography12.blogspot.co m
HOW ARE EARTHQUAKES MEASURED? The Richter Scale is used to measure earthquake magnitude. On a 1-10 scale. 1 being the smallest, 10 being the largest. Measured with a device called a Seismograph. aggas2nd.blogspot.com
TYPES OF WAVES There are two types of waves associated with earthquakes. P-Waves S-waves
TYPES OF WAVES CONT. P-waves- Travel through solid rock and liquids. As it spreads out, it alternately pushes (compresses) and pulls (dilates) the rock (allshookup.org). web.ics.purdue.edu
TYPES OF WAVES CONT. Slower than P-waves Can only move through solid rock. As an S wave propagates, it shears the rock sideways at right angles to the direction of travel (allshookup.org). web.ics.purdue.edu
AFTERSHOCKS Smaller earthquakes that occur after the main earthquake. Aftershocks can last for weeks or months after an earthquake. The larger the main earthquake, the longer aftershocks will continue to occur(usgs.gov).
PROTECTING YOURSELF IN AN EARTHQUAKE “Drop, cover, and hold on!” Drop down to your knees Cover your head and neck Hold on to a sturdy structure (if available).