| Popis: |
Many upthrown stones were found on the source area for four big earthquakes.To estimate such a high acceleration, a seesaw type upthrow machine was construced and a boulder with a diameter greater than 25cm was upthrown.Small accelerometers were attached on the boulder and the base of the machine.When the boulder fly horizontally at a distance of S0-60 cm, the base acceleration reaches to 5-6gFrom the field survey for 1992 Landers, California, earthquake, it was found that small stoneswere not dislodged but only big stones with the weight of greater than 10kg were upthrown.We examine a frequency response depending on a weight of stone, by using a vibrator.For a frequency range of 40-80 Hz, acceleration of big stone was about 3 times greater than that of small stone. |
