Fig. 5.15! EQs not regular! recurrence time has a certain probability < 100% source: Abbott Natural Disasters 1
Fig. 5.16! recurrence time varies along same fault source: Abbott Natural Disasters Probability of EQ before 2032 30% chance for a mag 7 quake before 2032, for most places along SAF 90% chance for a mag 6 at Parkfield prognosis for before 2004 social media: earthquake risk increased by 1% what Caltech scientists really said: chance of 1/7000 increased to 1/100 warning called off 10/5 USGS monitors seismicity! USGS issues warnings! NO OTHER ENTITY! 2
Fig. 6.43 InSAR: Interferometric Synthetic Aperture Radar overlay satellite altimetry map before and after EQ interferogram -> fringes show amount of slip along fault Sep 17, 1999 Izmit, Turkey Earthquake SIO15-16: Lecture 8 Volcanic Eruption Styles Image: and NASA/JPL; Hazardswikipedia example: southern SAF last major EQ: 250 years ago, while north and middle SAF ruptured 1906 and 1857 typical co-seismic slip for big EQs: 7-10m relaxed loaded use stack of INSAR images to get strain rate extrapolate to 250yrs 3
Fig. 6.44 site amplification probability of strong shaking Fig. 6.45 SCEC: Southern California Earthquake Center http:movie 4
USGS Did-you-feel-it map Mw=7.2 El Mayor Easter (4 Apr) 2010 * understand shaking characteristics of EQs * improve local forecasts for strength of shaking Got water?...flashlight canned food 5
POPQUIZ #4 YOUR FULL NAME AND STUDENT ID# Which magnitude scale describes the damage from an earthquake? write your own pop quiz only! writing a pop quiz for your friend is cheating! Have you student ID ready. Mt. Vesuvius, Pompeii 79 A.D. 6
The Smithsonian Global Volcanic Program: http://www.volcano.si.edu/! homework 3: Mount Barujari -> Rinjani The Smithsonian Global Volcanic Program: http://www.volcano.si.edu/ ~ 1500 known eruptions in last 10,000 years (extinct vs. active/dormant) ~ 550 historical eruptions ~ 20 erupting now Colima (Tzapotépetl), Mexico Mt. Mayon, Philippines! Oct 2016: ash and smoke up 3500 m! 2014 alert level 3! 24,000 evacuee since 9/17! 54,000 evacuees since 9/24! 10/20 same evacuees but less volcanic activity! 11/30 deadly lahar (1266 killed) 7
death toll is increasing number of eruptions does not eruptions don t get more violent! exponential population growth! people move to volcanoes Image: S. Marshak Earth, Portrait of a Planet BASIC INGREDIENTS: 1) melting agent: (heat), decompression or volatiles 2) opening: crater, cracks (fissures) 3) dissolved gases: drive eruption (mainly H 2 O) Pressure A TYPICAL ERUPTION: - magma rises (hot, buoyant) against pressure gradient - releases dissolved gases -> form bubbles - bubbles increase ambient pressure - overcoming pressure from above -> eruption Magma 8
BENIGN ERUPTIONS: - lava flows easily - small spattering Pressure Image: S. Marshak Earth, Portrait of a Planet VIOLENT ERUPTIONS: - explosive - lots of gases - lots of water - different type of magma (GEYSERS) Magma Castle Geyser, Yellowstone not a volcano but small-scale model (regular) eruptions of hot water sign for hot crust beneath some located in volcanic field HAZARD AND BLESSING! geothermal power travertine tourism 9
Santorini, ~1600 B.C. " from Spanish for cauldron " volcano collapses on empty magma chamber " often explosive volcanism " tsunami if submarine short video 8-1 Fig. 6.14 Pinatubo (1991) Lava Flows (Flood Basalts) Ash/Tephra (air and ground) Pyroclastic Flows (hot gases and tephra); (300 km/h); volcanic hurricane Lahars (mudflows); (50km/h) Volcanic Gases Redoubt (1989) Tsunami (marine volcano collapse) Earthquakes Erosion/(submarine) Landslides Climate Change Nevado del Ruiz (1985) short videos 8-2a,b,c Lake Nios (1986) Pinatubo (1991) Nyiragongo (2002) SIO15-16: Lecture 8 Volcanic Eruption Styles and Hazards~1600 B.C. Santorini, 10