Performance of the NCREE's on‐site warning system during the 5 February 2016 M_w 6.53 Meinong earthquake

Abstract

The National Center for Research on Earthquake Engineering in Taiwan has developed an on‐site earthquake early warning system (NEEWS). The Meinong earthquake with a moment magnitude of 6.53 and a focal depth of 14.6 km occurred on 5 February 2016 in southern Taiwan. It caused 117 deaths, injured 551, caused the collapse of six buildings, and serious damage to 247 buildings. During the Meinong earthquake, the system performance of 16 NEEWS stations was recorded. Based on a preassigned peak ground acceleration (PGA) threshold to issue alarms at different stations, no false alarms or missed alarms were issued during the earthquake. About 4 s to 33 s of lead time were provided by the NEEWS depending on the epicenter distance. In addition, the directivity of the earthquake source characteristic and also possibly the site effects were observed in the diagram of the distribution of PGA difference between the predicted PGA and the measured PGA.

How “good” are real‐time ground motion predictions from Earthquake Early Warning systems?

“…Real network‐based EEW systems with detection, processing, and transmission delays may not be fast enough to provide alerts for many of these cases. For such sites, only on‐site warning systems [e.g., Hsu et al ., ] may be fast enough to provide alerts with short but positive warning times. There is a small number of high‐intensity sites that have longer warning times; these are sites that locate in the direction of rupture propagation, close to the finite fault, but at considerable distance from the epicenter.…”

“…They thereby demonstrate that the predictions eventually match the observed ground motion levels, but not whether sufficiently accurate predictions became available before the strong shaking started. Studies that consider both accuracy and timeliness are rare, although there are notable exceptions [Hsu et al, 2016; Colombelli et al…”

Comparing the Performance of the NEEWS Earthquake Early Warning System Against the CWB System During the 6 February 2018 Mw 6.2 Hualien Earthquake

“…Because the effect of the source direction was not considered in the current embedded PGA prediction algorithm of the NEEWS, the distribution of the PGA difference-defined as the predicted PGA minus the measured PGA-may display the directivity associated with the earthquake source rupture direction (Hsu et al, 2016). Supporting information Figure S8 shows that most of the PGA differences for the region in the south of the epicenter (separated by the dotted red line in supporting information Figure S8) were negative.…”

“…Hsu, tyhsu@mail.ntust The NEEWS estimates the peak ground acceleration (PGA) of an imminent earthquake from the same station by relying on a recently developed support vector machine (SVM) technique. During the Meinong earthquake in 2016, which had a moment magnitude of 6.5, the performance of the NEEWS was remarkable, the details of which have been summarized and published (Hsu et al, 2013(Hsu et al, , 2016. These features include the predominant period, peak acceleration amplitude, peak velocity amplitude, peak displacement amplitude, cumulative absolute velocity, and the integral of the squared velocity.…”

New τc regression relationship derived from all P wave time windows for rapid magnitude estimation

“…An EEWS can issue alert messages to the target sites immediately after a destructive earthquake occurs and before the arrival of damaging S waves using rapidly determined source parameters and magnitude based on real-time data recorded by dense seismic arrays. After several decades of development, EEWSs for real-time earthquake hazard mitigation are now operational in many countries worldwide, such as Japan [Nakamura, 1988;Hoshiba et al, 2008], Turkey [Erdik et al, 2003;Sesetyan et al, 2011], Taiwan Hsu et al, 2016], Mexico [Espinosa-Aranda et al, 2009], and Romania [Allen et al, 2009]. EEWSs are in the development and testing stages in southern Italy [Satriano et al, 2011], California [Allen et al, 2009;Kuyuk et al, 2014], China [Peng et al, 2011;Peng et al, 2015;Zhang et al, 2016], Iran [Reza et al, 2013], northeastern Italy, Slovenia and Austria [Picozzi et al, 2015a], and southern Iberia [Picozzi et al, 2015b].…”