I’m a graduate student at Rice University studying earth science. My research focuses on Kilauea volcano, the youngest volcano on the island of Hawaii. Kilauea has a large, mobile submarine south flank that slips along a fault between the volcanic edifice and oceanic crust (outlined in solid black line below; Morgan, 2006). Different slip behavior along this fault, otherwise known as a decollement, has been observed at specific portions of the south flank. I hypothesis variation in morphology or flank thickness along the decollement at these portions influences the type of slip behavior we observe. For example, the central portion of the south flank hosts a large embayment from the collapse of a giant, ancient landslide where slow-slip events occur. In contrast, the northeastern portion has a gradual slope of about 10 degrees with respect to the ocean floor, and experiences fast-slip events (e.g., high magnitude, high slip-rate). The southwestern portion also experiences high magnitude events and is similar to the central portion in terms of faulting and structure; however, the southwestern portion still supports a giant landslide feature called the Hilina slump. I’m using Discrete Element Modeling (DEM) techniques to simulate these portions of the south flank sliding along a decollement and compare their slip behavior.

DEMs are particle based simulations that can be easily manipulated to test objects of any shape and size. Particles within the system are subjected to gravity and obey Newton’s three laws of motion, similar to objects in nature. Bonds between particles can also be assigned to simulate cohesion within a structure – bonds will break when subdued to a critical stress. To create these models, I use a program created by my research advisor, Dr. Juli Morgan. Below is a figure of an example DEM raining down particles into an experiment apparatus from one of her previous papers (Morgan and McGovern, 2005).

Shown below is a DEM simulation of a Kilauea south flank cross section located at the southwestern portion that cuts through the Hilina slump. A back wall located on the left side of the apparatus pushes the flank to the left to simulate seaward forces from Kilauea’s magma chamber and diking in the southeast rift zone. The top plot shows how particles evolve over time; the middle plot shows volume strain (blue = contraction/stress increase; yellow = dilation/stress decrease); the bottom plot shows shear strain (blue = leftward motion/sliding; red = rightward motion/sliding). Earthquake events nucleating on decollement are visible in the middle plot where blue and yellow areas are located. Shear stress is found at the same location as the earthquake where the decollement unlocks, slides and releases built up stress (bottom plot). This large earthquake exhibited in this short video is located at the back of the flank where normal stresses are higher due to a greater overburden!