Estimating coseismic coastal uplift with an intertidal mussel: calibration for the 2010 Maule Chile earthquake (Mw = 8.8)
Estimating coseismic coastal uplift with an intertidal mussel: calibration for the 2010 Maule Chile earthquake (Mw = 8.8)
复制标题
用潮间带贻贝估算同震海岸隆起：2010 年智利马乌莱地震的校准 (Mw = 8.8)
DOI：
10.1016/j.quascirev.2012.03.012
复制
发表时间：
2012
影响因子：
4
通讯作者：
R. Norambuena
中科院分区：
文献类型：
--
作者：
D. Melnick;M. Cisternas;M. Moreno;R. Norambuena
在1835年菲茨罗伊的先驱测量之后，在几次大地震之后，同震海岸隆起已经使用固着潮间带生物进行了量化。密集的调查，这样的标志可以补充空间大地测量数据，以获得准确的分布断层滑动和地震分段。然而，基于不同的潮间带生物的隆起估计往往不同，因为很少的方法和比较研究。在这里，我们校准和估计海岸隆起在2010年智利马乌莱地震（Mw= 8.8）的南段使用>1100地震后的无柄贻贝Perumytilus purpuratus海拔测量。这种贻贝是南美洲太平洋沿岸所有沿着岩石海岸的主要竞争者，在那里它在中间潮间带形成独特的边缘或带。这些带以平均海平面为中心，其宽度应等于潮差的三分之一。我们在40%的站点测量了接近该值的皮带宽度，但由于皮带顶部的不均匀性，总体宽度变化很大;而皮带底部则相当规则。带顶部的不均匀性显然是由局部增强波飞溅，而带的基础均匀性控制的捕食。根据我们在地震破裂之外所做的测量，带底位于中间潮间带的底部，因此我们建议使用带底平均高程加上潮差的六分之一达到平均海平面来估计海岸隆起。在误差范围内，我们的估计与GPS位移一致，但与其他方法不同。大型逆冲断层滑动联合反演的比较表明，结合空间大地测量数据与潮间带生物的估计，可以局部增加滑动分布的细节。
Coseismic coastal uplift has been quantified using sessile intertidal organisms after several great earthquakes following FitzRoy's pioneer measurements in 1835. A dense survey of such markers may complement space geodetic data to obtain an accurate distribution of fault slip and earthquake segmentation. However, uplift estimates based on diverse intertidal organisms tend to differ, because of few methodological and comparative studies. Here, we calibrate and estimate coastal uplift in the southern segment of the 2010 Maule, Chile earthquake (Mw= 8.8) using >1100 post-earthquake elevation measurements of the sessile mussel Perumytilus purpuratus. This mussel is the predominant competitor for rocky shores all along the Pacific coast of South America, where it forms fringes or belts distinctively in the middle intertidal zone. These belts are centered at mean sea level and their width should equal one third of the tidal range. We measured belt widths close to this value at 40% of the sites, but overall widths are highly variable due to the unevenness in belt tops; belt bases, in turn, are rather regular. Belt top unevenness apparently results from locally-enhanced wave splash, whereas belt base evenness is controlled by predation. According to our measurements made beyond the earthquake rupture, the belt base is at the bottom of the middle intertidal zone, and thus we propose to estimate coastal uplift using the belt base mean elevation plus one sixth of the tidal range to reach mean sea level. Within errors our estimates agree with GPS displacements but differ from other methods. Comparisons of joint inversions for megathrust slip suggest combining space geodetic data with estimates from intertidal organisms may locally increase the detail of slip distributions.