Input
Regional seismic catalogs, usually from global seismic databases such as USGS, with historical and instrumental events.
Methodology
How SERRA works.
SERRA/MEL transforms earthquake catalogs into physical energy histories, detects reactivation stages, maps seismogenic systems and translates energy concentration into engineering-oriented seismic risk parameters.
Origin
Developed from the energy tradition of earthquake engineering.
SERRA/MEL was developed between 1999 and 2000 during research activities connected to the University of Tokyo and earthquake engineering studies in Japan. Its conceptual foundation is the idea that seismic hazard should not be reduced only to magnitude statistics, but examined through the physical behavior of energy accumulation and release.
Transformation
Magnitude values are transformed into physical released energy using the inverse energy–magnitude relationship.
Output
Energy curves, SIGSA maps, expected magnitude ranges, design acceleration estimates and seismic risk maps.
Step 1
Energy-magnitude inversion.
The first methodological step is to move from magnitude space into energy space. Because magnitude is logarithmic, it hides the enormous dominance of large events. In energy space, that dominance becomes visible and measurable.
SERRA treats the seismic catalog as a physical record of released tectonic energy.
Conceptual equation
Log(Es) = 1.5 · Ms + 11.8
Magnitude becomes energy; energy becomes a time series; the time series becomes the seismic fingerprint of the region.
Step 2
Seismic energy release curves.
Events are aggregated over time to construct energy-versus-time curves. These curves reveal periods of high release, recharge, recurrence, unusual concentration and potential reactivation.
Reactivation stages
Energy peaks identify seismic stages that may last years or decades depending on the scale of analysis.
Historical anomaly
Current energy levels can be compared with previous cycles to assess whether the region is below, near or above historical behavior.
Recurrence intervals
Intervals between energy peaks can support probabilistic windows of future reactivation, without claiming exact earthquake prediction.
Step 3
SIGSA: integrated seismically active systems.
A SIGSA is an integrated seismogenic system. Instead of treating each fault as an isolated element, SERRA groups related fault structures and seismic activity into a spatial-energy source that can be analyzed through time, energy and distance.
This makes SERRA especially useful in tectonically complex regions, where risk is not always controlled by the closest fault or by simple subduction distance.
Step 4
Hypocentral depth and structural impact.
The method can also analyze how earthquakes distribute with depth over time. A central SERRA observation is that reactivation stages tend to be associated with greater superficial seismicity, while quiet periods tend to show deeper activity.
Engineering meaning: high released energy combined with shallow hypocenters is one of the most destructive conditions for structures because less energy is attenuated before reaching the built environment.
Step 5
Risk mapping and design chain.
SERRA maps energy concentration spatially, estimates equivalent maximum magnitude, applies attenuation laws and produces parameters that can support seismic-resistant design and risk planning.
| Analytical stage | Meaning | Product |
|---|---|---|
| Catalog transformation | Magnitude to energy | Released-energy database |
| Temporal aggregation | Energy behavior through time | Energy release curves |
| SIGSA mapping | Energy by seismogenic system | Risk maps |
| Equivalent magnitude | Energy translated to event scale | Maximum Expected Magnitude |
| Attenuation | Motion expected at site | PGA / design acceleration |
Technical discussion
Request a methodology presentation.
THEK can present the SERRA workflow to universities, municipalities, engineering teams, risk managers and research partners.