The dynamics of the stress state in Southern California based on the geomechanical model and current seismicity: Short term earthquake prediction

2017 ◽  
Vol 17 (1) ◽  
pp. 1-10
Author(s):  
V. G. Bondur ◽  
I. A. Garagash ◽  
M. B. Gokhberg
Keyword(s):  
Stress State ◽  
Earthquake Prediction ◽  
Southern California ◽  
Geomechanical Model ◽  
Short Term

The evolution of the stress state in Southern California based on the geomechanical model and current seismicity

2016 ◽  
Vol 52 (1) ◽  
pp. 117-128 ◽  
Author(s):  
V. G. Bondur ◽  
I. A. Garagash ◽  
M. B. Gokhberg ◽  
M. V. Rodkin
Keyword(s):  
Stress State ◽  
Southern California ◽  
Geomechanical Model

Alarm systems based on a pair of short-term earthquake precursors

1988 ◽  
Vol 78 (4) ◽  
pp. 1538-1549
Author(s):  
Giuseppe Grandori ◽  
Elisa Guagenti ◽  
Federico Perotti
Keyword(s):  
Statistical Analysis ◽  
Active Region ◽  
Southern California ◽  
Main Shock ◽  
Weak Shock ◽  
Earthquake Precursors ◽  
Alarm System ◽  
Short Term ◽  
Alarm Systems

Abstract A statistical analysis of the foreshock-main shock correlation for a seismically active region in Italy is presented. It is found that the probability that a weak shock be followed within 2 days by a main shock is of the order of 2 per cent, while the probability that a main shock be preceded by a foreshock is of the order of 50 per cent. These results are quite similar to those found by L. Jones (1985) for southern California. The effectiveness of alarm systems based on a pair of short-term earthquake precursors is then analyzed. In particular, the analysis shows under what conditions the precursor, consisting of potential foreshocks, could be combined with another precursor to provide a reasonably effective alarm system.

Preliminary analysis of meteorological and seasonal influences on crustal gas emission relevant to earthquake prediction

1981 ◽  
Vol 71 (1) ◽  
pp. 211-222
Author(s):  
Ronald W. Klusman ◽  
James D. Webster
Keyword(s):  
Soil Temperature ◽  
Earthquake Prediction ◽  
Barometric Pressure ◽  
Radon Emanation ◽  
Phase Lag ◽  
Gas Emission ◽  
Short Term ◽  
Mercury Emission ◽  
Thaw Cycle ◽  
Seasonal Influences

abstract The emission of gas from the Earth's crust is a complex process influenced by meteorological and seasonal parameters. The use of gas emission as a tool in earthquake prediction will require an understanding of these influences. Radon emanation has been integrated over weekly intervals and free mercury vapor emission over 212 hour intervals at a low seismic risk site in Colorado. Radon measured by the Track Etch® technique ranged from 136 to 1750 tracks/mm2 (81 to 1040 pC/liter) over the 1-yr period of the experiment. There was a strong correlation of radon emanation with: instrument vault temperature, barometric pressure, outside temperature, soil temperature, and whether or not the surface soil was frozen. Seasonal influences on radon emanation are important with 94 per cent of the variance being accounted for by the measured meteorological and seasonal parameters. Mercury concentrations in the instrument vault ranged from <1 to 53 ng/m3 over the 1 yr. Mercury emission correlates with vault temperature, vault relative humidity, outside temperature, barometric pressure, soil temperature and moisture, and the soil freeze-thaw cycle. Diurnal cycles are common but do not occur on all days. Other short-term noise in mercury emission is also important and phase shift or phase lag effects are important. Only 32 per cent of the variance in mercury emission can be accounted for by the measured meteorological and seasonal parameters. The short-term noise coupled with phase lags are important factors in mercury emission rates.

Statistical Monitoring and Early Forecasting of the Earthquake Sequence: Case Studies after the 2019 M 6.4 Searles Valley Earthquake, California

2020 ◽  
Vol 110 (4) ◽  
pp. 1781-1798 ◽  
Author(s):  
Yosihiko Ogata ◽  
Takahiro Omi
Keyword(s):  
Real Time ◽  
Case Studies ◽  
Seismic Activity ◽  
Southern California ◽  
Aftershock Sequence ◽  
Earthquake Sequence ◽  
Short Term ◽  
Probability Forecast ◽  
Background Rate ◽  
High Background

ABSTRACT This study considers the possible implementation of the operational short-term forecasting, and analysis of earthquake occurrences using a real-time hypocenter catalog of ongoing seismic activity, by reviewing case studies of the aftershocks of the Mw 6.4 Searles Valley earthquake that occurred before the Mw 7.1 Ridgecrest earthquake. First, the short-term prediction of spatiotemporal activity is required in real time along with the background seismic activity over a wide region to obtain practical probabilities of large earthquakes; snapshots from the continuous forecasts during the Searles Valley and Ridgecrest earthquake sequence are included to monitor the growth and migration of seismic activity over time. We found that the area in and around the rupture zone in southern California had a very high background rate. Second, we need to evaluate whether a first strong earthquake may be the foreshock for a further large earthquake; the rupture region in southern California had one of the highest such probabilities. Third, short-term probability forecast of early aftershocks are much desired despite the difficulties with data acquisition. The aftershock sequence of the Mw 6.4 Searles Valley event was found to significantly increase the probability of a larger earthquake, as seen in the foreshock sequence of the 2016 MJMA 7.4 Kumamoto, Japan, earthquake. Finally, detrending the temporal activity of all the aftershocks by stretching and shrinking the ordinary time scale according to the rate given by the Omori–Utsu formula or the epidemic-type aftershock sequence model, we observe the spatiotemporal occurrences in which seismicity patterns may be abnormal, such as relative quiescence, relative activation, or migrating activity. Such anomalies should be recorded and listed for the future evaluation of the probability of a possible precursor for a large aftershock or a new rupture nearby. An example of such anomalies in the aftershocks before the Mw 7.1 Ridgecrest earthquake is considered.

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