Spatial and temporal evolution of stress and slip rate during the 2000 Tokai slow earthquake
Spatial and temporal evolution of stress and slip rate during the 2000 Tokai slow earthquake
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DOI：
10.1029/2004jb003426
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发表时间：
2006-03-23
影响因子：
3.9
通讯作者：
Hatanaka, Y
中科院分区：
文献类型：
--
作者：
Miyazaki, S;Segall, P;Hatanaka, Y
[1]我们调查了日本中部Suruga-South kai海槽东海地震空区的一次持续无声的逆冲事件。在此之前，1996年4月至1999年底的连续GPS数据显示，该地区相对于向陆地的板块向西北方向移动了大约2厘米/年。全球定位系统时间序列显示，2000年6月中旬出现了一次突然的速率变化，并持续到2005年年中。我们模拟了这种瞬时变形，我们称之为东海缓慢推覆滑移事件，它是由菲律宾海和阿穆里亚板块之间的界面滑动引起的。利用基于卡尔曼滤波的反演方法估计了滑移率的时空分布。我们的倒置揭示了两个慢速的次事件。第一次开始于2000年6月下旬，略早于宫宅-吉马火山喷发。2000年下半年，滑移轨迹向东南方向传播，2001年最大滑移速率约为15厘米/年。2001年初，第二个滑动轨迹开始向东北方向移动。滑动带的深度约为25公里，可能对应着从孕震带到自由滑动带的过渡带。截至2002年11月，该慢滑事件的累积矩震级为M-W，与6.8级相似。我们根据滑移历史计算了板界面上的剪应力变化。应力随滑动速率的变化显示出类似于高速破裂的轨迹；然而，最大速度比正常地震低8个数量级。
[1] We investigate an ongoing silent thrust event in the Tokai seismic gap along the Suruga-Nankai Trough, central Japan. Prior to the event, continuous GPS data from April 1996 to the end of 1999 show that this region displaced similar to 2 cm/yr to the northwest relative to the landward plate. The GPS time series show an abrupt change in rate in mid-June 2000 that continues as of mid-2005. We model this transient deformation, which we refer to as the Tokai slow thrust slip event, as caused by slip on the interface between the Philippine Sea and Amurian plates. The spatial and temporal distribution of slip rate is estimated with Kalman filter based inversion methods. Our inversions reveal two slow subevents. The first initiated in late June 2000 slightly before the Miyake-jima eruption. The locus of slip then propagated southeast in the second half of 2000, with maximum slip rates of about 15 cm/yr through 2001. A second locus of slip initiated to the northeast in early 2001. The depth of the slip zone is about 25 km, which may correspond to the transition zone from a seismogenic to a freely sliding zone. The cumulative moment magnitude of the slow slip event up to November 2002 is M-w similar to 6.8. We calculate shear stress changes on the plate interface from the slip histories. Stress change as a function of slip rate shows trajectories similar to that inferred for high-speed ruptures; however, the maximum velocity is 8 orders of magnitude less than in normal earthquakes.