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OpenQuake Hazard PSHA Input Model

mmpagani edited this page Nov 16, 2010 · 10 revisions

PSHA Input Model

Introduction

First step in the calculation of probabilistic seismic hazard is the creation of an Earthquake Rupture Forecast (ERF) i.e. a list of all the possible ruptures - with an associated probability of occurrence in a given time span - occurring on all the seismic sources considered in a given analysis.

In the simplest case, OpenQuake creates the ERF using the information contained in one input file formatted according to a unified PSHA input data model (defined in the course of GEM1 - the GEM kick-off project http://www.globalquakemodel.org/gem1) currently supporting four types of seismic sources. In particular, for each source type, a set of parameters specifies the data necessary to create a Seismic Source instance and successively calculate the comprehensive set of ruptures with their probability of occurrence.

The Seismic Sources currently supported by OpenQuake (version 0.1) are:

  • Area sources
  • Grid sources
  • Fault sources based on a
    • Simple geometry
    • Complex geometry

In more complicated cases (i.e. PSHA input models based on a Logic Tree structure) the number of ERFs to be created can reach very high numbers depending on the complexity (i.e. number and properties of branching levels).

Assumptions

  • OpenQuake 0.1 - The seismicity temporal occurrence model follows a Poisson process

User stories

  • OpenQuake 0.5 - Extend the Unified PSHA Input Data model so as to support additional source typologies

    • Additional source typologies:

      • Fault sources with a completely irregular surface
      • Segmented fault sources
      • Background sources
  • OpenQuake 0.5 - Generalize the use of different seismicity temporal occurrence models.

    • Temporal occurrence models:

      • Poisson
      • Brownian Time Passage

### Suggested Implementation

  • OpenQuake 0.5 - Extend the Unified PSHA Input Data model so as to support additional source typologies
  • OpenQuake 0.5 - Generalize the use of different seismicity temporal occurrence models.

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