Magnitude of the 23 January 2018 M7.9 Alaska Earthquake Estimated from Local Dense Seismic Records in Alaska
- 26 Downloads
We apply a novel method to estimate the magnitude of the 23 January 2018 M7.9 Alaska earth-quake using seismic stations recorded at local to regional distances in Alaska, US. We determine the source duration from back-projection results derived from the Alaska stations in a relatively compact azimuth range. Then we calculate the maximum P-wave displacements recorded on a wide azimuth range at distances of 8 to 15 degrees. Combining the source duration and the maximum P-wave displacements, we obtain magnitudes of 7.86–8.03 for the 23 January 2018 earthquake in 3–5 min, very close to the Mw 7.9 determined by the USGS and GCMT. This example validates the new approach for determining magnitude of large earthquakes using local to regional stations, and its time efficiency that magnitudes of large earthquakes can be accurately estimated within in 3–5 min after origin time. Therefore, further application of this new method would help accurate estimation of size of earthquakes that occur off shore and might cause tsunami hazards.
Key wordsrapid magnitude estimation back-projection real-time seismology tsunami warning geophysics
Unable to display preview. Download preview PDF.
This work was supported by the National Natural Science Foundation of China (No. 41474050), the Fundamental Research Funds for the Central Universities, the China University of Geosciences (Wuhan) (No. CUG170602), and the National Programme on Global Change and Air-Sea Interaction (No. GASI-GEOGE-02). Comments from Alex Hulko, Chengli Liu, and two anonymous reviewers have greatly improved the manuscript. The final publication is available at Springer via https://doi.org/10.1007/s12583-019-1215-z.
- Freymueller, J. T., Woodard, H., Cohen, S. C., et al., 2008. Active Deformation Processes in Alaska, Based on 15 Years of GPS Measurements. In: Freymueller, J. T., Haeussler, P. J., Wesson, R. L., et al., eds., Active Tectonics and Seismic Potential of Alaska, Geophys. Monogr. Ser., 179: 1–42. https://doi.org/10.1029/179gm02 CrossRefGoogle Scholar
- Kennett, B. L. N., Engdahl, E. R., 1991. Traveltimes for Global Earthquake Location and Phase Identification. Geophysical Journal International, 105(2): 429–465. https://doi.org/10.1111/j.1365-246x.1991.tb06724.x CrossRefGoogle Scholar
- Li, J., Liu, C. L., Zheng, Y., et al., 2017. Rupture Process of the M s 7.0 Lushan Earthquake Determined by Joint Inversion of Local Static GPS Records, Strong Motion Data, and Teleseismograms. Journal of Earth Science, 28(2): 404–410. https://doi.org/10.1007/s12583-017-0757-1 CrossRefGoogle Scholar
- Naugler, F. P., Wageman, J. M., 1973. Gulf of Alaska: Magnetic Anomalies, Fracture Zones, and Plate Interaction. Geological Society of America Bulletin, 84(5): 815–821. https://doi.org/10.1130/0016-7606(1973)84<1575:goamaf>2.0.co;2 CrossRefGoogle Scholar
- Rao, G., Cheng, Y. L., Lin, A. M., et al., 2017. Relationship between Landslides and Active Normal Faulting in the Epicentral Area of the AD 1556 M~8.5 Huaxian Earthquake, SE Weihe Graben (Central China). Journal of Earth Science, 28(3): 545–554. https://doi.org/10.1007/s12583-017-0900-z CrossRefGoogle Scholar
- Wang, D., Kawakatsu, H., Mori, J., et al., 2016. Backprojection Analyses from Four Regional Arrays for Rupture over a Curved Dipping Fault: The M w7.7 24 September 2013 Pakistan Earthquake. Journal of Geophysical Research: Solid Earth, 121(3): 1948–1961. https://doi.org/10.1002/2015jb012168 Google Scholar
- Zhang, H., Ge, Z. X., Ding, L. Y., 2011. Three Sub-Events Composing the 2011 off the Pacific Coast of Tohoku Earthquake (M w 9.0) Inferred from Rupture Imaging by Back-Projecting Teleseismic P Waves. Earth, Planets and Space, 63(7): 595–598. https://doi.org/10.5047/eps.2011.06.021 CrossRefGoogle Scholar