Performance test of an automated moment tensor determination system for the future "Tokai" earthquake
Performance test of an automated moment tensor determination system for the future "Tokai" earthquake
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DOI：
10.1186/bf03352250
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发表时间：
2000-01-01
影响因子：
3
通讯作者：
Dreger, DS
中科院分区：
文献类型：
--
作者：
Fukuyama, E;Dreger, DS
我们已经调查了如何使用FREESIA/ KIBAN宽带网络的自动矩张量测定（AMTD）系统可能会在未来的大地震。由于我们没有足够的经验与一个大的（M > 8）附近的地震，我们计算了合成波形，这样的事件，假设的几何配置的预期东海地震和几个断层破裂的情况。使用这个合成数据集，我们检查了AMTD系统的行为，以了解如何为这样的事件做准备。对于我们的合成东海地震数据，我们假设它的震源机制，断层尺寸，和标量地震矩。我们还假设了一个圆形破裂传播与恒定的破裂速度和位错上升时间。测试了均匀和非均匀滑动模型。结果表明，性能取决于震源位置（即单侧与双侧）和滑动的非均匀性程度。在我们进行的试验中，破裂方向性似乎比滑动不均匀性更重要。我们发现，对于这样的大地震，它是必要的，使用站在距离大于600公里，频率在0.005至0.02赫兹之间，以保持一个点源的假设，并恢复完整的标量地震矩和辐射模式。为了证实合成试验的结果，我们用观测到的宽频带波形分析了1993年北海道南生冲（M（J）7.8）和1995年科比（M（J）7.2）地震。对于科比地震，我们成功地恢复了力矩张量使用常规使用的频带（0.01-0.05赫兹位移）。然而，我们未能估计一个正确的解决方案，北海道南海冲地震使用相同的常规频带。在这种情况下，我们不得不使用0.005到0.02 Hz之间的频率来恢复力矩张量，从而确认了东海地震合成测试结果的有效性。
We have investigated how the automated moment tensor determination (AMTD) system using the FREESIA/ KIBAN broadband network is likely to behave during a future large earthquake. Because we do not have enough experience with a large (M > 8) nearby earthquake, we computed synthetic waveforms for such an event by assuming the geometrical configuration of the anticipated Tokai earthquake and several fault rupture scenarios. Using this synthetic data set, we examined the behavior of the AMTD system to learn how to prepare for such an event. For our synthetic Tokai event data we assume its focal mechanism, fault dimension, and scalar seismic moment. We also assume a circular rupture propagation with constant rupture velocity and dislocation rise time. Both uniform and heterogeneous slip models are tested. The results show that performance depends on both the hypocentral location (i.e. unilateral vs. bilateral) and the degree of heterogeneity of Slip. In the tests that we have performed the rupture directivity appears to be more important than slip heterogeneity. We find that for such large earthquakes it is necessary to use stations at distances greater than 600 km and frequencies between 0.005 to 0.02 Hz to maintain a point-source assumption and to recover the full scalar seismic moment and radiation pattern. In order to confirm the result of the synthetic test, we have analyzed the 1993 Hokkaido Nansei-oki (M(J)7.8) and the 1995 Kobe (M(J)7.2) earthquakes by using observed broadband waveforms. For the Kobe earthquake we successfully recovered the moment tensor by using the routinely used frequency band (0.01-0.05 Hz displacements). However, we failed to estimate a correct solution for the Hokkaido Nansei-oki earthquake by using the same routine frequency band. In this case, we had to use the frequencies between 0.005 to 0.02 Hz to recover the moment tensor, confirming the validity of the synthetic test result for the Tokai earthquake.