RUI: The Owens River as a Tiltmeter for Long Valley Caldera,California

自1979年以来，加州长谷火山口复活的穹顶显然由于在深处注入了0.2千米的岩浆而上升了50厘米以上。几次地震(6.0)伴随着最初的隆起；美国地质勘探局已经警告可能的喷发活动。来自欧文斯河的泛滥平原证据表明，目前的抬升是长期通货膨胀的一部分，可能总计15-35米。下游大部发育两条近期平行的曲流带(相距200-300m)，曲流波长和幅度相似，但年龄不相等。较老的，总是更接近圆顶，海拔高30-60厘米，现在携带着一条不适合的溪流，正在被废弃。新的下水道是由撕裂作用形成的，显然是由隆起触发的。有多达四个较老的、独立的曲流带存在，这表明在当前的通胀之前，可能已经经历了两次隆升和下沉周期。拟议的研究将涉及以下调查。(1)我们将进行一系列垂直于山谷轴线的详细水准测量，以确定河流间面的节距，以估计穹隆隆升；(2)我们将结合年代学和14C(森林火灾木炭和可能的泥炭)来确定几个曲流带的牛头沉积年龄，以确定河流占据这些曲流带的时间长度。这些年龄将有助于确定隆升和沉陷的时间，以及Inyo和Mono陨石坑区域的河道迁移与喷发活动之间的可能关联。(3)我们将比较这条河流的历史和现代照片，以确定近期的河道迁移率，并将它们与水准测量中确定的当地泛滥平原倾斜程度进行比较。对复活的穹顶的近期历史的了解是加利福尼亚州猛犸湖居民的核心关切。拟议的调查为本科生提供了一个很好的机会，既可以在野外学习，也可以在实验室学习硅质火山作用的重要例子，以及河流地貌学中的一个有趣现象。

Since 1979, the resurgent dome of Long Valley caldera, California has risen more than 50 cm apparently due to the injection of 0.2 km3 of magma at depths. Several earthquakes (6.0) accompanied the initial uplift; the USGS has warned of possible eruptive activity. Floodplain evidence from the Owens River suggests that the current uplift is part of a long term inflation that may total 15- 35 meters. Most of the lower river displays two recent parallel meander belts (200-300m apart), similar in meander wavelength and amplitude, but unequal in age. The older, invariably closer to the dome and 30-60 cm higher in elevation, now carries an underfit stream and is being abandoned. The new lower channel formed by avulsion, apparently triggered by uplift. As many as four older, separate meander belts exist and suggest that two cycles of uplift and subsidence may have preceded the current inflation. The proposed research would involve the following investigations. (1) We will make a series of detailed leveling surveys perpendicular to the valley axis to define the pitch of the interfluvial surface as an estimate of domal uplift, (2) We will determine ages for oxbow sediments from the several meander belts using a combination of tephrochronology and 14C (forest fire charcoal and possible peat) to define the length of time that the river occupied each of these meander belts. These ages will help define both the times of uplift and subsidence as well as the possible correlation between river channel migrations and eruptive activity in the Inyo and Mono Crater fields. (3) We will compare historic and modern photographs of the river to determine recent rates of channel migration and compare them with the local degree of floodplain tilting determined in the leveling surveys. An understanding of the recent history of the resurgent dome is of central concern to residents of Mammoth Lakes, CA. The proposed investigation offers undergraduate students an excellent opportunity to study both in the field and in the laboratory an important example of silicic volcanism, as well as an interesting phenomenon in fluvial geomorphology.