Is the Sequence of Quakes on Mars Poissonian?
Abstract
We analyze the sequence of events recorded by the InSight mission on Mars during approximately the first year on Mars. We consider four different types of events, as distinguished by spectral characteristics: events exciting only the 2.4 Hz ambient vibration band typical for Martian seismic data, events being confined to frequencies below or above that, and "broad band" events containing frequencies both above and below 2.4 Hz. In addition, we look at non-seismic events of which we know that they are temperature or temperature gradient driven and thus are not constant-rate Poisson processes.
The lag times between consecutive events generated by a constant-rate Poisson process follow an exponential distribution. The maximum likelihood estimate of this distribution's rate parameter should be constant in time. In addition, a Poisson process does not exhibit any periodicity in event times. For each type of events, we fit an exponential distribution to the distribution density of its lag times and compare the actual distribution to the spread expected from synthetic random sequences with the same event rate and event count. We apply a moving window technique to identify possible rate changes, and the spike train fourier transform, augmented with a Monte Carlo significance analysis, to identify possible periodicities in event occurrence times.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMDI51B0019K
- Keywords:
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- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 7299 General or miscellaneous;
- SEISMOLOGY