Real-Time Characterization of Finite Rupture and Its Implication for Earthquake Early Warning: Application of FinDer to Existing and Planned Stations in Southwest China

• Published in: Frontiers in earth science (Lausanne) Vol. 9
• Main Authors: Li, Jiawei, Böse, Maren, Feng, Yu, Yang, Chen
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 15-07-2021
• Subjects: earthquake early warning; fault rupture; ground-motion prediction equation; national system for fast report of intensities and earthquake early warning; Sichuan-Yunnan region
• ISSN: 2296-6463; 2296-6463
• DOI: 10.3389/feart.2021.699560

Earthquake early warning (EEW) not only improves resilience against the risk of earthquake disasters, but also provides new insights into seismological processes. The
Fin
ite-Fault Rupture
De
tecto
r
(FinDer) is an efficient algorithm to retrieve line-source models of an ongoing earthquake from seismic real-time data. In this study, we test the performance of FinDer in the Sichuan-Yunnan region (98.5
o
E–106.0
o
E, 22.0
o
N–34.0
o
N) of China for two datasets: the first consists of seismic broadband and strong-motion records of 58 earthquakes with 5.0 ≤
M
S
≤ 8.0; the second comprises additional waveform simulations at sites where new stations will be deployed in the near future. We utilize observed waveforms to optimize the simulation approach to generate ground-motion time series. For both datasets the resulting FinDer line-source models agree well with the reported epicenters, focal mechanisms, and finite-source models, while they are computed faster compared to what traditional methods can achieve. Based on these outputs, we determine a theoretical relation that can predict for which magnitudes and station densities FinDer is expected to trigger, assuming that at least three neighboring stations must have recorded accelerations of 4.6 cm/s
2
or more. We find that FinDer likely triggers and sends out a report, if the average distance between the epicenter and the three closest stations,
D
epi
, is equal or smaller than log
10
(
M
a
+
b
) + c, where
a
= 1.91,
b
= 5.93, and
c
= 2.34 for
M = M
W
≥ 4.8, and
c
= 2.49 for
M = M
S
≥ 5.0, respectively. If the data used in this study had been available in real-time, 40–70% of sites experiencing seismic intensities of V-VIII (on both Chinese and MMI scales) and 20% experiencing IX-X could have been issued a warning 5–10 s before the
S-
wave arrives. Our offline tests provide a useful reference for the planned installation of FinDer in the nationwide EEW system of Chinese mainland.