Grantee name: university of oregongrant number: G23AS00059PROJECT title: debris flow research in support of the rainier lahar detection systemproject dates: 09 15 2023 to 09 14 2026AWARD purpose:…

Grantee name: university of oregongrant number: G23AS00059PROJECT title: debris flow research in support of the rainier lahar detection systemproject dates: 09 15 2023 to 09 14 2026AWARD purpose: mount rainier in washington, USA, has historically produced water-ladenmass wasting events, referred to as debris flows or lahars, that have reached the denselypopulated puget sound lowlands. The rainier lahar detection system (rlds) is an earlywarning system currently being developed by the USGS in response to this hazard. The rldscomprises both the installation of additional seismometers to record lahars and or debris flows inmultiple drainages on the flanks of MT. Rainer and development of software capable of rapidlyidentifying lahars and quantifying features relevant to early warning (e.g. location, size, andvelocity). The development of such a system is challenging for multiple reasons. First, there is apaucity of seismic recordings of debris flows that can be used to validate phenomenologicalmodels. Second, we lack basic understanding of how lahars generate seismic waves and howtheir seismic signature changes as debris flow properties change. Finally, complex near-surfacepath and site effects alter the seismic signals between the source and the receiver in ways that aredifficult to model. The principal goals of the proposed work is make progress on each of theaforementioned challenges.actives to be performed: first, we propose to continue the dense, temporary deployments ofthe tahoma creek drainage and MT. ST. Helens to obtain more recordings of natural debris flowsthat can be used to validate models of debris flow physics. Second, to better understand howlahars generate seismic waves we propose to apply existing analytic and numerical models ofdebris flows to both man-made (i.e. those created at the USGS debris flume in the HJ andrewsexperimental forest in blue river, or) and natural flows recorded on a dense network at MT. ST.helens. Finally, to account for path effects, we have applied techniques taken from seismicimaging studies that derive empirical greens functions from the ambient seismic field. Thiswork will further improve and validate these techniques through additional comparisons withhammer blows and exploration of amplitude calibrations.deliverables and expected outcomes: the deliverables include prepared seismic datasetsfrom each deployment hosted at the earthscope archive. Other deliverables include publishedpapers, conference presentations and findings useful for the rainier lahar detection system.intended beneficiaries: stakeholders in the development of the rainier lahar detectionsystem, communities along the tahoma creek and puyallup drainagessubrecipient activities: n a