Amphibious Array

We propose to use an array of ocean bottom seismometers to study the Cascadia subduction zone off of the west coast of Oregon and Washington. The motivation for selecting this region for the project is because it is an area where episodic tremor and slip is known to occur.  One of the reasons that it is important that we study this area is that there are millions of people that live in this region and it is geologically active with volcanoes and faults, yet we still do not have a great understanding of the geology here.  Another reason that this project is important is the fact that ocean bottom seismometers provide us with extremely poor data quality, which means that the methods developed on this data should be applicable to ocean bottom data that has been gathered from other regions around the globe.  This is also important because dropping seismometers into the ocean without making boreholes happens to be the least expensive way to deploy ocean bottom seismometers. The main goals of this project are to better constrain the boundary between the oceanic and continental crust, the structure of the oceanic crust in the outer rise, and to better locate and measure the intensity of episodic tremor and slip.  In order to do this, we need to improve the methods that are currently used to remove noise because ocean bottom data is typically the lowest quality data in the field of seismology, which typically makes interpretations of waveforms difficult.  Another goal of this proposal is to develop new methods for removing this noise from ocean bottom data that can be generalized to most ocean bottom data, and the current methods are not sufficient to make this data useful.  The last goal of the project is to characterize the variations of elastic properties in the crust and mantle lithosphere across Cascadia and the Pacific-North American plate boundary.  We will be using traditional methods to locate earthquakes and employing receiver function methods with improvement upon the most recent techniques of removing noise to make the worst quality data practical to use in the field of seismology.  This effort will have broad impacts on the field as a whole because it will allow us to obtain new knowledge about the geology in Cascadia, the Cascadian subduction zone, and the structures of the outer rise of the oceanic crust.  It will also allow for new methods of improving seismic data to be created that can be applied to many projects dealing with ocean bottom data, which is a practice that has not yet been mastered or even made practical for the most part.