Menetelmät. Tilastolliset Deterministiset. Alustava tieto Monitoroinnin suunnittelu --> riskianalyysi

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1 3 parametriä Aika Paikka Suuruus Menetelmät Tilastolliset Deterministiset Tektoniikka [kulunut aika; lapse time] Fysikaalinen malli [monitorointi] Aikaskaalat Pitkä aikaväli [tilastot] Alustava tieto Monitoroinnin suunnittelu --> riskianalyysi Keskipitkä aikaväli [malli] Lyhyt aikaväli [monitorointi, ennakointi] 37 San Andreas Järistysten toistuvuudesta 38

2 39 San Andreasin siirroksen episentrit 1970-luvulla 40

3 Eq probabilities, California dex.html Faults and plate motions in the San Francisco Bay Region. Faults in the region, principally the seven faults shown here and characterized in this report, accommodate about 40 mm/yr of mostly strike-slip motion between the Pacific and North American tectonic plates. Yellow lines show the locations of the 1868 M6.8 earthquake on the southern portion of the Hayward Fault and the 1989 M6.9 Loma Prieta earthquake near the San Andreas fault northeast of Monterey Bay. 42 Eq probabilities, California 43

4 Eq probabilities, California 44 Eq probabilities, California UAKES/FactSheets/When/ 45

5 Parkfield Earthquake September 28, 2004, eastern Monterey County, California. Parkfield activity - big quake Sept 28, :15 AM PDT plus 33 hours of aftershocks. USGS public domain image. Kuvia kirjasta Kakkuri-Hjelt: 8.11 Loma-Prietan alueen järistykset 47

6 Kuva kirjasta Kakkuri-Hjelt: 8.10 Loma-Prietan jälkijäristykset 48 Maanjäristyksen ennustaminen: ennakkoilmiöitä Ennakkoilmiöt (precursors) - biologiset (mm. eläinten poikkeava käyttäytyminen) - fysikaaliset esijäristykset jännitystilan muutokset sähkönjohtavuuden muutokset - kemialliset pohjaveden Rn-pitoisuus 49

7 Seismologiaa: eq. precursors 50 51

8 Ihmisen toiminnan aiheuttamat maanjäristykset: mm. maaperän kuormituksen muutos voi aiheuttaa seismisen aktiivisuuden kasvua, suuret padot (Hooverin pato), nesteen pumppaaminen maankamaraan, suuret hiilikaivos- ja kaasukenttäalueet 52 China The Haicheng evacuation After a series of foreshocks, some of which damaged buildings, local government leaders evacuated much of the populace before the devastating magnitude Haicheng earthquake. Although much discussion about the possibility of future earthquakes in NE China had taken place during the years preceding this earthquake, there was no prediction formulated that would have fit this event. [83] However, the Chinese government failed to predict the July 28, 1976 M7.8 Tangshan earthquake, which put Chinese earthquake prediction research in doubt for several years. In the late 1990s, there were over thirty false alarms unofficially announced in China. [84 The Xiuyan prediction On November 29, 1999 an earthquake of magnitude 5.3 [3] occurred at latitude and longitude , near Xiuyan. On November 28, 1999, the Seismological Bureau of Liaoning Province (a branch of the China Seismological Bureau) issued a prediction with the following parameters. [60] Location: Within a square of 1 degree by 1 degree, centered at latitude 40.5 degrees and longitude 123 degrees. Occurrence time: between 29 November and 8 December Magnitudes: Between 5.0 and 5.9. This means that the event was located only 10 km from the center of the specified area, occurred within the time window, and the magnitude range given. Thus, this was a good prediction. [59] The research activities, which lead to this prediction started on November 9 because two magnitude 4 earthquakes occurred. Another two magnitude 4 earthquakes occurred on November 25, and on November 26 a magnitude 4.4 earthquake triggered the report by seismologists to the local government, stating "if the earthquake swarm keeps increasing, then a earthquake is imminent; otherwise there would be a M6 earthquake expected to occur, but location cannot be sure (based on present data and knowledge)". [60] The local government's decision was to deploy imminent works to enhance the 53 preparedness, without issuing a prediction publicly. Because of this special deployment, there were no injuries and deaths during the earthquake, nor social panic before and after the earthquake. [59][60][85]