ⒺImproved Rapid Magnitude Estimation for a Community-Based, Low-Cost MEMS Accelerometer Network

over 180 Quake-Catcher Network (QCN) low-cost micro-electro-mechanical systems accelerometers were deployed in the Canterbury region. Using data recorded by this dense network from 2010 to 2013, we significantly improved the QCN rapid magni-tude estimation relationship. The previous scaling relationship (Lawrence et al., 2014) did not accurately estimate the magnitudes of nearby (<35 km) events. The new scal-ing relationship estimates earthquake magnitudes within 1 magnitude unit of the GNS Science GeoNet earthquake catalog magnitudes for 99 % of the events tested, within 0.5 magnitude units for 90 % of the events, and within 0.25 magnitude units for 57 % of the events. These magnitudes are reliably estimated within 3 s of the initial trigger recorded on at least seven stations. In this report, we present the methods used to calculate a new scaling relationship and demonstrate the accuracy of the revised mag-nitude estimates using a program that is able to retrospectively estimate event mag-nitudes using archived data. Online Material: Table of magnitude estimates for Quake-Catcher Network-detected events, and figures clarifying the linear fitting technique used to calculate the Chung et al. revised scaling relationship