Rapid magnitude determination for earthquake early warning

Richard M Allen
University of Wisconsin-Madison

in "The many facets of seismic risk" edited by G. Manfredi, M.R. Pecce, and A. Zollo, Universita degli Studi di Napoli "Federico II", Napoli, Italy, p15-24, 2004.
This is the proceedings of the "Workshop on Multidisciplinary Approach to Seismic Risk Problems," Sant'Angelo dei Lombardi, September 22, 2003,

Introduction

The goal of an earthquake early warning system is to provide notification of ground shaking hazard before significant ground motion is felt. An operational system requires four components: (1) seismic network infrastructure, (2) rapid event characterization, (3) spatial hazard prediction, and (4) a notification system to warn of hazard. Here I present an overview of such an early warning system designed for use with a dense seismic network in the earthquake source region. Emphasis is placed on components (2) and (3) as they are common to implementation of the system in any region. The particular example described is for southern California; however, the same methodology could be utilized in the Irpinia region of Italy.

In many earthquake prone regions, including California, Japan, Taiwan, Italy, and Turkey, population centers are collocated with the earthquake source region. In such a case, hazard must be determined using the low amplitude P-wave which can be detected seconds before significant ground motion begins. The earthquake early warning methodology described here, named ElarmS, uses the P-wave arrival to estimate hazard and therefore has the potential to issue warning before damaging ground shaking begins, even at the epicenter of an earthquake.

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