7 posts tagged with "General-analysis"

Energy and moment are two independent measures of the strength of a seismic event. Their physical meaning and how they are calculated was described in a previous blog post. Analysis of the relationship between the energy and moment of events can provide insight into seismic sources. For example, blasts or ore pass noise, falsely processed as real events, tend to have distinct zones on an energy-moment chart. In general, events with higher-than-average energy are associated with high relative stress.

Two new charts have been added to the General Analysis application related to assessing hazard with the frequency-magnitude relationship.

Moment tensor analysis is a topic that carries a decent level of uncertainty and confusion for many people. So I'm going to lay it out as simply as I can. For this post, I'm not going to go into too many details on how moment tensors are actually calculated. But, I'm going to summarise the things I think are most important for geotechnical engineers to know for interpreting moment tensor results.

Moment tensors have been added to the General Analysis application in the recent update. Beach balls and principal axes can be viewed in the General Analysis 3D view. There is also a separate Moment Tensor window with a number of stereonets and mechanism charts. Two new training videos have been uploaded to the General Analysis (3D View) page that walkthrough the new tools.

The $a/b$ value is sometimes used as a measure of seismic hazard but there are some common mistakes made with this analysis and interpretation.

The default event local magnitude marker might not suit everyone. After all, a ML+1.0 might mean something completely different to you compared with the site next door.

The distance to survey filter has been around for a while but now we have added a couple of new charts to further investigate the relationship between seismicity and your input surveys. The charts have been added to the General Analysis application, under the Charts menu - look for Distance to Surveys.