Realtime Risk
An earthquake alters the surrounding hazard, which we capture in RealtimeRisk. This occurs because earthquakes impart stress to nearby faults that promotes failure in some areas, and inhibits failure in others. These stress changes are the source of aftershocks, seismic quiescences, and in some cases, progressive mainshocks. Great earthquakes, such as the 2011 M 9.0 Tohoku, can change the hazard across a country, but moderate shocks can be just as consequential if they strike near urban centers. Although the stress changes are permanent, the hazard changes are not; they instead decay with time, just as aftershock frequencies do. We capture and forecast this process in RealtimeRisk, a unique and independently-tested Temblor tool. It is based on Coulomb stress transfer, about which Temblor’s scientists Stein, Toda, and Sevilgen are world leaders.
RealtimeRisk forecast sent to clients 4 hr after M 7.8 Kahramanaras, Türkiye, earthquake (with the epicenter of the M 7.5 shock which struck 5 hr after submittal now added as a star)
The calculation revealed four lobes with hazard increases, one of which became the site of the M 7.5 earthquake hours later. The calculation also showed two lobes of hazard decrease, which have not been the sites of any large aftershocks. Subsequent, much refined versions of these calculations were published in Temblor Earth News and Seismol. Research Letters.
Uses
Realtime Risk is used by primary insurers to adjust the duration and location of sales moratorium, by reinsurers to price annual coverage, and by Insurance Linked Security companies to assess bond attachment over a maturity period.
Comparison of rate change 5-10 years after the 2011 Tohoku M9 quake.
Observed
Modeled with Realtime Risk
The ‘Core’ is where the fault slipped in the M 9 earthquake. Seismicity shut down there several years after the main shock, and RealtimeRisk projects it will remain so for centuries. The ‘Corona’ is the enormous area that lit up in aftershocks immediately after the main shock; RealtimeRisk projects it will remain active for several more decades. There were just 4 M≥6.7 shocks in the corona in the decade before the main shock, but 22 during the decade afterward, indicating that it was activated by the main shock. The agreement between the observed (left) and modeled (right) rate changes reveals the value of the RealtimeRisk forecast. Published as: S. Toda and R. Stein, Nature Geoscience, 2022.
RealtimeRisk forecast for 2018 after the 2017 M 8.2 Tehauntepec and M 7.1 Puebla, Mexico, shocks (Subsequent 2018 M≥5 shocks now added as stars)
Here is the 2018 RealtimeRisk forecast (warm colors) for central Mexico, compared to the subsequent M≥5 earthquakes (blue stars). Even though the damaging 2017 M 7.2 Puebla shock struck near Mexico City, no further quakes were forecast near the City, and none occurred. Instead, most shocks struck where the forecast hazard was high.
Formats
RealtimeRisk is available in two formats. The first is a pair of gridded files: the expected earthquake rates for any period of interest and magnitude threshold (say, M≥6 rates for the next year in a 5 x 5 km cells), the associated forecast earthquake rate change over the preceding or background rate. These can be used to modify a vendor model’s event rates. The second is a stochastic event set that incorporates these changes, which we call EventSet-RtR, which can be compared to our time averaged EventSet.
Please contact us for a 30-min demo: Ross Stein, Ph.D., ross@temblor.net, Volkan Sevilgen, M.Sc., volkan@temblor.net, or Shinji Toda, Ph.D., toda@irides.tohoku.ac.jp
