This document describes a method for earthquake forecasting based on statistical monitoring of ionosphere data from GPS stations. Daily GPS data is processed to extract ionospheric VTEC values every 10 minutes. A summation index analysis is performed to identify anomalies in the VTEC data between station pairs. Anomalies above 0.8 that cannot be explained by geomagnetic activity levels may indicate upcoming seismic or volcanic activity near the closer GPS station. The method has shown success in forecasting Chilean earthquakes up to 10 days ahead with an average of 7 days ahead and 86.2% forecast accuracy.

1. Earthquake Forecasting based on
Ionosphere Statistical Monitoring:
A BRIEF OF THE INTEGRATED METHOD FOR
IONOSPHERIC-SEISMIC MONITORING
CHILE-SISMOS 2012

2. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
1. DATA COLLECTING AND PROCESSING
The GPS data is obtained from the IGS stations and
others, at the UNAVCO server site. Daily files are
extracted in RINEX format. They content geodetic
measures and an estimation of the ionospheric signal
delay (∆t).

3. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
1. DATA COLLECTING AND PROCESSING
RINEX files are processed by Rinex GPS-TEC
software, provided by Gopi Seemala Ph.D (
Gopi.Seemala@BC.edu) . STD extension ASCII
output files contain the VTEC values measured every
10 minutes.
UT VTEC σTEC Lat
0.00 17.03 4.11 -34.38
0.10 16.89 3.99 -34.38
0.20 16.83 3.47 -34.38
0.30 17.08 3.33 -34.38
0.40 17.29 3.21 -34.38

4. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
2. STATISTICAL CALCULATION
A Summation Index analysis of the VTEC from 2 GPS-
TEC stations is performed (Pulinet et al. 2004)
C = Σ (f 1,i – af1) (f 2,i -af 2)
k(σ1σ2)
An upper percentage deviation of the analysis for each
GPS-TEC station values is also performed
UB = (x - UB) or UB = x 0.96 σ
UB
The daily or 3-hours kp index is arranged in a chart

5. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
3. INTERPRETATION OF RESULTS
A triangulation based on the Index Summation chart
is estimated for 3 stations: C(1, 2), C(2, 3), and C(3,1).
Every value >0.8 is compared against the peaks from
the upper percentage deviation and kp index trends.
GPS-TEC Source
Earthquake
Anomaly (C>0.8) will be present in the closer GPS-TEC
station

6. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
3. INTERPRETATION OF RESULTS
In days under kp<4, drops on the C charts (>0.8)
might be interpreted as ionospheric anomalies
produced by electro-chemical, or electromagnetic
emissions from the crustal region close to the faults
prior an earthquake, or a vulcano eruption.
Generally, there is an opposite behavior between the C
and UB% charts in the time that anomalies occur.
A peak in the 1020Ǻ Aerosol Optical Thickness
(AOT), is also observed in most of the cases. This is the
wavelength of the Radon (Rn).

7. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
3. INTERPRETATION OF RESULTS
K=4
UTC: 08:33:05 04/07/2012 5.2Mw Concepción (8 days ahead)

8. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
3. INTERPRETATION OF RESULTS
A “zoom” of the anomaly in the %UB chart provide a
dimensional analysis of the TEC disturbance:
Per Dovobrolsky’s equation magnitude can be estimated
Max: 28,26 40 1130.4 565.2 6.4
Min: 7,05 40 282 141 5.0
Aver: 17,65 40 706 353 5.9
UTC: 08:33:05 04/07/2012 5.2Mw Concepción (8 days ahead)

9. Earthquake Forecasting based on
Ionosphere Statistical Monitoring
3. INTERPRETATION OF RESULTS
LATEST RESULTS:
Date Anomaly Magnitude Estimated Date Date EQ Magnitude Days Ahead Efficiency %
5/19/2012 5.5 5/26/2012 5/28/2012 6.6 10 83.33
5/24/2012 5.6 6/1/2012 5/31/2012 4.6 7 82.14
5/29/2012 5.3 6/5/2012 6/6/2012 4.1 8 77.36
6/4/2012 5.9 6/12/2012 6/7/2012 5.8 3 98.31
6/15/2012 5.5 6/23/2012 6/23/2012 4.5 8 81.82
6/23/2012 5.9 7/1/2012 6/28/2012 5.2 5 88.14
6/25/2012 5.2 7/3/2012 7/4/2012 4.8 9 92.31
Ahead Average Days: 7
Efficiency: 86.2%