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Chapter 7:Hazard Analysis—Earthquakes <br /> Continuous 2800 <br /> Fundamental flexure models <br /> a) T=25 for plates under island loads <br /> Variable infill 2%00 <br /> 23W n�„ 2300 <br /> b) ,T T=25 <br /> Broken plate 2800 Plate is broken, or so <br /> F weakened or thinned <br /> T,.-25 in the center, that it <br /> curves concave downward <br /> under the load. <br /> CO2 embrittlement <br /> Variable T 2800 enables deep seismicity. <br /> d) <br /> T,=25 <br /> (from A.B.Watts,Isostasy and <br /> flexure of the lithosphere, <br /> Cambridge Univ.press,2001) <br /> Figure 7-3. Fundamental flexural models for plates under island loads <br /> earthquake focal mechanisms: <br /> Center of lithosphere bending radial P-axis <br /> (deep P-axis radiant point) O tangential P-axis <br /> "flat"fault <br /> NW Mauna Kea Mauna Loa <br /> Kilauea SE <br /> volcanic edifice <br /> volcanic edifice 0 km <br /> M7.2 <br /> _ decollment 9-12 km <br /> O M6.0 (mixed P directions) (mixed P directions) neutral lane_ <br /> — — 20-22 km <br /> neutral plane ` (depth uncertain here) <br /> '.deep'Kilauea earthquake zone <br /> approx.elastic thickness 25^40 <br /> brokeno thin dplate— rr--- <br /> —>� km <br /> approx.maximum <br /> 60 km <br /> .................... � <br /> brittle earthquake depth <br /> maximum bending I sparse 20-55 km maximum bending <br /> and seismicity seismicity and seismicity <br /> Figure 7-4. Earthquake focal mechanisms in Hawaii <br /> The risks to property from earthquakes in the County of Hawaii are among the highest in the <br /> nation, with only San Francisco and San Jose, California having a greater annual loss per <br /> 7-3 Hawaii County Multi-Hazard Mitigation Plan <br />