Coseismic Subsidence and Paleotsunami Run-Up Records from Latest Holocene Deposits in the Waatch Valley, Neah Bay, Northwest Washington, U.S.A.: Links to Great Earthquakes in the Northern Cascadia Margin
Coseismic Subsidence and Paleotsunami Run-Up Records from Latest Holocene Deposits in the Waatch Valley, Neah Bay, Northwest Washington, U.S.A.: Links to Great Earthquakes in the Northern Cascadia Margin
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美国华盛顿州西北部尼亚湾沃奇谷最新全新世矿床的同震沉降和古海啸上升记录：与卡斯卡迪亚边缘北部大地震的联系
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发表时间：
2012
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通讯作者：
Sarah L. Sterling
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作者：
C. Peterson;K. Cruikshank;M. Darienzo;G. Wessen;V. Butler;Sarah L. Sterling
彼得森，C.D.; Cruikshank，K.M.; Darienzo，M.E.; Wessen，G.C.;巴特勒，V.L.，和Sterling，S. L.，2013.美国华盛顿西北Neah湾Waatch山谷全新世沉积物的同震沉降和古海啸上升记录与卡斯卡迪亚边缘北方的大地震有关代表性的浅芯（1-2米深）从Waatch山谷（n = 10）和Neah湾后障湿地（n = 7）记录四个同震沉降事件和相关的古海啸洪水在过去的1300年中，在北中央卡斯卡迪亚边缘。三个沉降事件（SUB1，SUB 2b和SUB 3）与公元1700年的大地震有关，约1.1 ka和约1.3 ka。一个额外的沉降层（SUB 2a），这是新发现的研究区域，可能与广泛报道的古海啸洪水，在研究区域的0.7和0.9 ka之间。根据大型化石的证据，沃奇山谷的古沉降幅度不大（约0.5 - 1.0米），这是湿地突然掩埋的结果。四个向陆地变薄的砂层的古海啸起源被海洋硅藻类群和海滩沙粒的存在所证实。长波运行在低梯度的Waatch洪泛区范围从2.5到4.5公里的山谷距离目前的潮汐入口海岸线。Neah湾障壁脊的古海啸漫顶（1988年北美垂直基准面[NAVD 88]的6-8米高程）提供了胡安·德富卡海峡入口处古海啸最小上升高度的首次估计。
ABSTRACT Peterson, C.D.; Cruikshank, K.M.; Darienzo, M.E.; Wessen, G.C.; Butler, V.L., and Sterling, S.L., 2013. Coseismic subsidence and paleotsunami run-up records from latest Holocene deposits in the Waatch Valley, Neah Bay, northwest Washington, U.S.A.: links to great earthquakes in the northern Cascadia Margin. Representative shallow cores (1–2-m depth) from the Waatch Valley (n = 10) and from Neah Bay back-barrier wetlands (n = 7) record four coseismic subsidence events and associated paleotsunami inundations during the last 1300 years in the North Central Cascadia Margin. Three of the subsidence events (SUB1, SUB2b, and SUB3) correlate to reported great earthquakes dated at AD 1700, about 1.1 ka, and about 1.3 ka. An additional subsidence horizon (SUB2a), which is newly discovered in the study area, might correlate to a widely reported paleotsunami inundation, dated between 0.7 and 0.9 ka in the study region. The magnitudes of paleosubsidence in the Waatch Valley are modest (about 0.5−1.0 m), as based on macofossil evidence of abrupt wetland burial. Paleotsunami origins of the four landward thinning sand sheets are confirmed by the presence of ocean diatom taxa and beach sand grains. Long wave run-up in the low-gradient Waatch floodplain ranged from 2.5 to 4.5 km up-valley distance from the present tidal inlet shoreline. Paleotsunami overtopping of the Neah Bay barrier ridge (6–8-m elevation North American Vertical Datum of 1988 [NAVD88]) provides the first estimates of paleotsunami minimum run-up height at the entrance to the Juan de Fuca Strait.