Real-time Finite Fault Rupture Detector (FinDer) for large earthquakes

A new real-time Global Navigation Satellite System (GNSS) analysis system named REGARD has been launched to provide finite-fault models for large earthquakes with magnitudes =8 in real time. The finite-fault estimates using GNSS positioning are free from saturation problems and are very robust for modeling large earthquakes. The REGARD system processes ∼1,200 stations of GEONET, and event detection and finite-fault model inversion routines are implemented. Tests for the case of the 2011 Tohoku earthquake (Mw9.0) and a simulated Nankai Trough earthquake (Mw8.7) show that the REGARD system can provide reliable finite-fault models for large earthquakes. Furthermore, operational real-time results for the 2016 Kumamoto earthquake (Mj7.3) demonstrated the capability of this system to model inland earthquakes. These results imply the possibility of improving tsunami simulations and/or hazard information using rapid finite-fault models. Efforts to integrate real-time GNSS with current warning systems are currently being implemented around the world, and the REGARD system will join these systems in the near future.

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Near‐Real‐Time Finite‐Fault Inversions for Large Earthquakes in Chile Using Strong‐Motion Data

Seismological Research Letters ◽

10.1785/0220180294 ◽

2019 ◽

Author(s):

Pablo Koch ◽

Francisco Bravo ◽

Sebastian Riquelme ◽

Jorge G. F. Crempien

Keyword(s):

Real Time ◽

Strong Motion ◽

Integrated System ◽

Origin Time ◽

Strong Motion Data ◽

Motion Data ◽

Finite Fault ◽

Set Up ◽

Finite Fault Model ◽

Large Earthquakes

ABSTRACT Recent efforts have been made to model the rupture process of large earthquakes in near‐real time (NRT) in Chile. In this study, we propose an automated procedure using strong‐motion data in an integrated system, which can characterize large earthquakes with a finite‐fault model (FFM) in NRT. We developed several heuristic rules using the preliminary W‐phase solutions to automatically set up the search ranges of the finite‐fault inversions. The results show using strong‐motion data and a W‐phase magnitude, it is possible to obtain a rapid kinematic FFM in just a few minutes after the earthquake origin time.

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Estimating Rupture Dimensions of Three Major Earthquakes in Sichuan, China, for Early Warning and Rapid Loss Estimates

Bulletin of the Seismological Society of America ◽

10.1785/0120190117 ◽

2020 ◽

Vol 110 (2) ◽

pp. 920-936 ◽

Cited By ~ 1

Author(s):

Jiawei Li ◽

Maren Böse ◽

Max Wyss ◽

David J. Wald ◽

Alexandra Hutchison ◽

...

Keyword(s):

Real Time ◽

Early Warning ◽

Line Source ◽

Source Parameters ◽

Strong Motion ◽

Preventive Action ◽

Fault Rupture ◽

S Wave ◽

Finite Fault ◽

Source Models

ABSTRACT Large earthquakes, such as Wenchuan in 2008, Mw 7.9, Sichuan, China, provide an opportunity for earthquake early warning (EEW), as many heavily shaken areas are far (∼50 km) from the epicenter and warning times could be sufficient (≥5 s) to take preventive action. On the other hand, earthquakes with magnitudes larger than ∼M 6.5 are challenging for EEW because source dimensions need to be defined to adequately estimate shaking. Finite-fault rupture detector (FinDer) is an approach to identify fault rupture extents from real-time seismic records. In this study, we playback local and regional onscale strong-motion waveforms of the 2008 Mw 7.9 Wenchuan, 2013 Mw 6.6 Lushan, and 2017 Mw 6.5 Jiuzhaigou earthquakes to study the performance of FinDer for the current layout of the China Strong Motion Network. Overall, the FinDer line-source models agree well with the observed spatial distribution of aftershocks and models determined from waveform inversion. However, because FinDer models are constructed to characterize seismic ground motions (as needed for EEW) instead of source parameters, the rupture length can be overestimated for events radiating high levels of high-frequency motions. If the strong-motion data used had been available in real time, 50%–80% of sites experiencing intensity modified Mercalli intensity IV–VII (light to very strong) and 30% experiencing VIII–IX (severe to violent) could have been issued a warning with 10 and 5 s, respectively, before the arrival of the S wave. We also show that loss estimates based on the FinDer line source are more accurate compared to point-source models. For the Wenchuan earthquake, for example, they predict a four to six times larger number of fatalities and injured, which is consistent with official reports. These losses could be provided 1/2∼3 hr faster than if they were based on more complex inversion rupture models.

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The 25 October 2010 Mentawai tsunami earthquake, from real-time discriminants, finite-fault rupture, and tsunami excitation

Geophysical Research Letters ◽

10.1029/2010gl046498 ◽

2011 ◽

Vol 38 (5) ◽

pp. n/a-n/a ◽

Cited By ~ 96

Author(s):

Andrew V. Newman ◽

Gavin Hayes ◽

Yong Wei ◽

Jaime Convers

Keyword(s):

Real Time ◽

Fault Rupture ◽

Finite Fault ◽

Tsunami Earthquake

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Status of Earthquake Early Warning in Switzerland

Frontiers in Earth Science ◽

10.3389/feart.2021.707654 ◽

2021 ◽

Vol 9 ◽

Author(s):

Frédérick Massin ◽

John Clinton ◽

Maren Böse

Keyword(s):

Real Time ◽

Open Source Software ◽

Early Warning ◽

Seismic Network ◽

Earthquake Early Warning ◽

Fault Rupture ◽

Time Data ◽

Origin Time ◽

P Waves ◽

Finite Fault

The Swiss Seismological Service (SED) at ETH has been developing methods and open-source software for Earthquake Early Warning (EEW) for more than a decade and has been using SeisComP for earthquake monitoring since 2012. The SED has built a comprehensive set of SeisComP modules that can provide EEW solutions in a quick and transparent manner by any seismic service operating SeisComP. To date, implementations of the Virtual Seismologist (VS) and Finite-Fault Rupture Detector (FinDer) EEW algorithms are available. VS provides rapid EEW magnitudes building on existing SeisComP detection and location modules for point-source origins. FinDer matches growing patterns of observed high-frequency seismic acceleration amplitudes with modeled templates to identify rupture extent, and hence can infer on-going finite-fault rupture in real-time. Together these methods can provide EEW for all event dimensions from moderate to great, if a high quality, EEW-ready, seismic network is available. In this paper, we benchmark the performance of this SeisComP-based EEW system using recent seismicity in Switzerland. Both algorithms are observed to be similarly fast and can often produce first EEW alerts within 4–6 s of origin time. In real time performance, the median delay for the first VS alert is 8.7 s after origin time (56 earthquakes since 2014, from M2.7 to M4.6), and 7 s for FinDer (10 earthquakes since 2017, from M2.7 to M4.3). The median value for the travel time of the P waves from event origin to the fourth station accounts for 3.5 s of delay; with an additional 1.4 s for real-time data sample delays. We demonstrate that operating two independent algorithms provides redundancy and tolerance to failures of a single algorithm. This is documented with the case of a moderate M3.9 event that occured seconds after a quarry blast, where picks from both events produced a 4 s delay in the pick-based VS, while FinDer performed as expected. Operating on the Swiss Seismic Network, that is being continuously optimised for EEW, the SED-ETHZ SeisComP EEW system is achieving performance that is comparable to operational EEW systems around the world.

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