Empirical Relationships Between Ground Motion Intensities and JMA Seismic Intensity Scale
- 1Inigo Insurance Ltd, 25 Fenchurch Avenue, London, United Kingdom
- 2Njord Centre, Department of Physics and Geosciences, University of Oslo, Oslo, Norway
Abstract
There is a growing appetite for parametric Japanese earthquake insurance products that use Japanese Meteorological Agency seismic intensity, IJMA, triggers. However, most earthquake risk models used to price these contracts do not compute IJMA directly, instead relying on conversions that introduce additional basis risk. Here, we present empirical parameterisations of IJMA as a function of all combinations of moment magnitude, hypocentral distance, peak ground acceleration (PGA), and spectral acceleration (Sa(T)) at 0.2, 0.3, 0.6, 1.0, 2.0, and 3.0 s, derived from earthquake risk model outputs. Parameterisations are fitted using ridge regression applied to 21,354 ground motion recordings from 112 Japanese earthquakes spanning January 1997 to December 2025. A parsimonious three-parameter model — combining PGA, Sa(0.3 s), and Sa(1.0 s) — outperforms a previously published parameterisation, substantially reducing both uncertainty and bias. When applied to a synthetic parametric insurance portfolio exposed to 25 years of Japanese seismicity, this parameterisation yields a measurable reduction in basis risk. These results support more reliable and transparent pricing of parametric earthquake insurance products.
Related
- Empirical Parameterizations of ULF Power and Drift Orbit Averaged Radial Diffusion Coefficients From Ground Magnetometers for Different MLT
- Impact of proposed wind turbines on seismic monitoring stations at the Xiaolangdi Reservoir
- Seismic imaging of the crust and upper mantle beneath Taiwan using full-waveform inversion of teleseismic body waves
- Mapping rockfall hazard and detecting precursory damage in rock slopes with passive seismic: Lessons from the La Praz case-study
- Multi-frequency seismo-acoustic measurements of synthetic ice with fluid inclusions: implications for seismic and through-ice acoustic estimation of sea-ice thickness
BibTeX
@article{ball2026empirical,
title = {{Empirical Relationships Between Ground Motion Intensities and JMA Seismic Intensity Scale}},
author = {Patrick Ball and Toby Sansom and Karina Loviknes},
journal = {Seismica},
year = {2026},
month = nov,
doi = {10.26443/seismica.v5i2.3166},
url = {https://doi.org/10.26443/seismica.v5i2.3166},
note = {CC BY},
}
RIS
TY - JOUR
TI - Empirical Relationships Between Ground Motion Intensities and JMA Seismic Intensity Scale
AU - Patrick Ball
AU - Toby Sansom
AU - Karina Loviknes
PY - 2026
DA - 2026/11/04
JO - Seismica
DO - 10.26443/seismica.v5i2.3166
UR - https://doi.org/10.26443/seismica.v5i2.3166
AB - There is a growing appetite for parametric Japanese earthquake insurance products that use Japanese Meteorological Agency seismic intensity, IJMA, triggers. However, most earthquake risk models used to price these contracts do not compute IJMA directly, instead relying on conversions that introduce additional basis risk. Here, we present empirical parameterisations of IJMA as a function of all combinations of moment magnitude, hypocentral distance, peak ground acceleration (PGA), and spectral acceleration (Sa(T)) at 0.2, 0.3, 0.6, 1.0, 2.0, and 3.0 s, derived from earthquake risk model outputs. Parameterisations are fitted using ridge regression applied to 21,354 ground motion recordings from 112 Japanese earthquakes spanning January 1997 to December 2025. A parsimonious three-parameter model — combining PGA, Sa(0.3 s), and Sa(1.0 s) — outperforms a previously published parameterisation, substantially reducing both uncertainty and bias. When applied to a synthetic parametric insurance portfolio exposed to 25 years of Japanese seismicity, this parameterisation yields a measurable reduction in basis risk. These results support more reliable and transparent pricing of parametric earthquake insurance products.
SN - 2816-9387
ER -