1. Geology 15 Mid Term II Review

2. Focal mechanisms are diagrams made from first motion seismologic records that show the possible motion on a fault, and the possible sense of motion on that fault. There are two possible fault planes for each focal mechanism.

3. http://earthquake.usgs.gov/earthquakes/world/10_largest_world.php

8. M = 7.1

13. Table 1. Earthquake Chronology Hokey Poky fault, Oregon, USA. Earthquake Number Site ASite BSite CSite D Age (yrs AD)RI Age (yrs AD)RI Age (yrs AD)RI Age (yrs AD)RI 11857 286 1857 45 1857 45 1812 108 21571 187 1812 265 1812 127 1704 145 31384 107 1547 187 1685 149 1559 122 41277 199 1360 276 1536 49 1437 124 51078 479 1084 17 1487 127 1313 140 6599 1067 111 1360 96 1173 242 7 956 114 1264 148 931 8 842 78 1116 100 9 764 119 1016 166 10 645 850 69 11 781 59 12 722 25 13 697 63 14 634 101 15 533 Average RI25213595147 this year2013 next expected EQ2109199219521959 time span125812121324881 Is the average Recurrence Interval about the same for each site?NO What can the Recurrence Interval say about this fault? (1) earthquakes did not rupture through each site for each earthquake for some reason. (2) the time between earthquakes varies so that we can interpret this fault to be uncharacteristic and unpredictable. (3) the RI at site C is much shorter than the RI of A. (4) the RI at sites B and D are intermediate compared to sites A and C. Which sites (A, B, C, or D) are more “due” for an earthquake? Adding the average RI to the age of the most recent earthquake gives us an estimate for when the next earthquake might occur ("next expected"). The first expected earthquake was at site C, then site D, site B, and lastly site A. Is the average Recurrence Interval about the same for each site? NO What can the Recurrence Interval say about this fault? (1) earthquakes did not rupture through each site for each earthquake for some reason. (2) the time between earthquakes varies so that we can interpret this fault to be uncharacteristic and unpredictable. (3) the RI at site C is much shorter than the RI of A. (4) the RI at sites B and D are intermediate compared to sites A and C. (5) the earthquakes that occur at all sites probably represent larger earthquakes. (6) the fault has different places that are more resistant to slipping (more friction) and this may make the fault slip at different rates. Which sites (A, B, C, or D) are more “due” for an earthquake? Adding the average RI to the age of the most recent earthquake gives us an estimate for when the next earthquake might occur ("next expected"). The first expected earthquake was at site C, then site D, site B, and lastly site A.