SSACgnp QE 527 JAM 1 7 Hawaii Volcanoes

SSACgnp. QE 527. JAM 1. 7 Hawai`i Volcanoes National Park A Restless Paradise Geology and Monitoring Techniques The module you are viewing is a Power. Point slide presentation. • • • Core Quantitative Literacy Navigate from slide to slide using the up/down arrow keys, or, if. Topics available, Graph Interpretation the scroll bar on your mouse Use the mouse to select hyperlinks (underlined, in blue type) or to pass through embedded flash animations Supporting Quantitative Literacy Topics Unit Conversion When done, use the escape key to exit the presentation. Pythagorean Theorem You can and probably should have a spreadsheet open in a separate window, Core Subject so you can try out things that are explained in Geoscience the presentation. Hot spot volcanism Power. Point applications use lots of memory, so you may want to exit other Volcano Monitoring Techniques programs while running this presentation, especially if it starts to act slowly or Judy Mc. Ilrath sluggishly. Department of Geology, University of South Florida © Close 2010 University of South Florida Libraries. All rightsthe reserved. this window to proceed with slide show. 1

Getting started After completing this module you should be able to: • Discuss volcano monitoring techniques • Calculate surface movement • Analyze graphs • Convert measurement units Canada United States You should also know where Hawai`i Volcanoes National Park is located and its geologic origin. 2

The setting – Hawai`i Volcanoes National Park Hawai’i Volcanoes National Park, established in 1916, also holds the designation of an International Biosphere Reserve (1980) and a World Heritage Site (1987). The park is home to two of the world’s most active volcanoes, Kilauea with almost continuous eruptions since 1983 and Mauna Loa, volumetrically, the world’s largest mountain. Far from any plate tectonic boundary, Hawai’i is the youngest island in the Hawaiian island chain which formed as the Pacific Plate moves over a hot spot. Thousands of miles from the closest continent, flora and fauna evolved over the last 70 million years in near complete isolation. Ninety percent of the species found in Hawaii are found nowhere else in the world. 3

Evolution of a Hot Spot Island Chain The diagram below shows how ocean island chain “x” evolves through time as the lithospheric plate moves over a stationary hot spot mantle plume in a conveyor belt-type motion. Ocean crust Ocean lithosphere Aesthenosphere Lithospheric plate motion Stationary mantle plume – “Hot Spot” 4

The Hawaiian Hot Spot Islands on the map below were created as the Pacific Plate moved over a hot spot. Volcano symbols indicate recent (10, 000 years) activity. Loihi Seamount is the youngest volcano and may in time breach the ocean surface and become a new island. Hawai`i has three active volcanoes, Mauna Loa, Kilauea, and Hualalai. Maui has experienced one or two eruptions in the past 1, 000 years. Northwestern islands are older and volcanically extinct. Hawaiian Volcano Observatory (HVO), housed within the park, collects seismic, gas, gravity, geochemical, tilt, GPS, and webcam data to monitor the volcanoes. Kauai Oahu Maui Loihi Seamount 5

Monitoring Techniques - Seismicity Earthquakes are recorded on seismographs when ground motion occurs. Often, harmonic tremor, a continuous rhythmic earthquake, indicates magma movement. Over 100 earthquakes a day are recorded on Hawai`i, most are less than magnitude 3 and cannot be felt by humans. Seismometer at HVO Scientist describing seismic monitoring techniques Courtesy of HVO/USGS Question 1. Make observations of the earthquake (1/1/10 to 7/25/10) map of southern Hawaii. Open the Excel template, and write a three-sentence description of your observations. Between what latitudes and longitudes might there be an active volcano? 6

Monitoring Techniques - Gas As magma rises, gases (mainly H 2 O, CO 2, SO 2) dissolved in the magma expand form bubbles due to the decrease in pressure. As the volume of bubbles increases, magma density decreases allowing it to rise higher. If the conduit that the magma is rising through becomes clogged or crusted over, the gases may become trapped, creating a potentially explosive situation (similar to shaking a can of soda). A flyspec (ultraviolet spectrometer) is used to detect the amount of SO 2 in the plume. SO 2 interacts with sunlight, moisture, and particulates forming volcanic smog (vog) which poses heath risks to humans and animals. Courtesy of HVO/USGS Gas plume at Halema’u Crater on 7/ 25/2010 Question 2: Over what time period were the gas data collected? On what day and in what concentration was SO 2 highest? lowest? What units are used to report SO 2 emissions? 7

Monitoring Techniqus - Gravity and Geochemical Gravity measurements are used to detect changes in the subsurface as magma moves and fills or drains underground reservoirs. As the magma mass changes in the subsurface, its gravitational attraction at the surface changes as well and is measurable. Gravity measurements are affected by surface deformation, atmospheric pressure, and tidal influences. Therefore, the data collected must be processed to eliminate these external factors. Combined with other monitoring techniques, the corrected data may provide information on subsurface magma or water movement. Scientists collect samples during eruptions to determine the mineral and gas content of the lava. Lavas low in silica are typically erupted in a non-explosive manner. The table below shows the average chemical composition (weight percent) of rocks from Hawaii and Mt. St. Helens. Gravimeter Photo courtesy of HVO/USGS 8

Monitoring Techniques – Tiltmeters placed on the flanks of volcanoes measure inclination of the Earth’s surface. As volume and pressure inside the volcano increase, the volcano inflates causing surface bulges. As magma or gases are released, deflation of the edifice occurs and the surface subsides. Long-term deflation and inflation events (DIs) are detected by tiltmeters that collect data (in microradians) every minute and so are sensitive to surface deformation events. Superimposed on broad deformation cycles are short-term (hours to days) DI events for which the cause is not yet known. How small is a microradian? If a dime is placed under an I-beam one kilometer in length, the inclination of the I-beam would be one microradian. deflation inflation You can simulate a DI event by placing a balloon under a pile of wet sand. Inflate and deflate the balloon to see how the surface deforms! A small level on the sand volcano flank could be a make-shift tiltmeter. In the animation above (click), a volcano emits a small steam and ash plume. With time, additional magma enters the edifice. Increased volume and pressure cause the volcano to inflate. Magma escapes through a vent on the volcano’s flank. Volume and pressure decrease, and the volcano deflates. 9

Monitoring Techniques – Tilt meters On a tiltmeter graph, inflation is recorded as an upward trend; deflation a downward trend, with minor episodes along the trend. The graph shows four DI events with a fifth inflation. Inflation deflation (2010) Note the difference in scale on the graph below. What looked like large DI events on the upper graph appear relatively insignificant on the graph below when additional data are added to the time series. (2010) Question 3: For the longer time series, by how many microradians did the edifice inflate overall? 10

Monitoring Techniques – Kinematic GPS & Continuous GPS Kinematic GPS uses benchmarks placed all over the volcano. Periodically, a scientist hikes to the benchmark and acquires a northing, easting, and up movement. By comparing benchmarks on opposite sides of the crater, determined by the difference in line length between GPS receivers, scientists can get a quick sense of long-term DI events. GPS receiver A A’ Line lengths are exaggerated. Benchmarks and Continuous GPS stations at Puu Oo crater Click here for help with the Pythagorean calculation. Question 4: Using the Pythagorean Theorem, what was the distance between the two points (A, A’) for each of the four data points collected? What was the total change in distance? Write a description of your observations of the differences and similarities between the K-GPS and continuous GPS graphs. A A’ Continuous GPS 11

Monitoring Techniques – Visual Observations and Webcams Kilauea erupts, mostly quiescently, at the caldera or along the east or southwest rift zones. The Puu Oo cone along the east rift zone has had almost continuous eruptions since 1983. Kilauea summit crater in daylight and at night Puu Oo lava fountain 1983 2010 Kalapana Flow Question 5: Go to the Haleamaumau Overlook webcam. What can you see? Write down your observations include the date and time. Click “Enter” to see Puu Oo webcam series from June 17 -20, 2007 (Father’s Day event) Click the image above to see a Drainhole piston movie created from a series of webcam images. Go here to see other movies and this one if you are unable to view it here. Webcams allow scientists to make visual observations without the danger of going to the eruption. Flow maps are used to inform the public of current activity. 12

Why monitor Kilauea? # & volume of eruptions Kilauea rises ~20, 000 feet from the ocean floor. The summit crater is 2 ½ miles long and 2 miles wide. The floor of the crater is 400 feet below the rim. Nearly 2, 600 acres of lava flows have erupted in the crater since the late 19 th century. Near the southern edge of the crater floor is Halemaumau, a pit crater currently emitting a steam and ash plume. On January 2, 1983, rapid deflation occurred at Kilauea caldera. The east rift zone had elevated earthquake activity, and on January 3, lava erupted along a fissure and centralized at Puu Oo vent, fountaining 1, 500 feet above the vent. As fountain activity decreased, lava flows moved toward the ocean engulfing homes in the Royal Gardens subdivision. Flows reached historic Kalapana in 1990. Question 6: Eruption volumes from 1918 to 2007 for Kilauea are given in cubic yards. Convert the volumes to ft 3, m 3 and km 3. What is the total volume erupted for this time period for each volume unit? 13

Why monitor Kilauea? Explosive eruptions Much to the contrary of most Geology textbooks, Kilauea has not always had quiet eruptions. In 1924, the crater floor dropped to a depth of nearly 700 feet. The crater walls became unstable, and rock falls were constant. On May 11, Halemaumau exploded blasting out blocks of rock weighing several tons and emitting an ash plume 20, 000 feet into the atmosphere. Gray layers are ash, accretionary lapilli, and surge deposits and are probably from the 1790 eruption. Sag bomb – This block was thrown out of the crater and landed on the tephra layer causing it to sag. The brown layer is reticulite dated to an eruption in the 1500 s 1924 Kilauea Explosion from HVO (courtesy USGS) Deposits of reticulite, accretionary lapilli, ash, and surge deposits, all created from violent eruptions which occur every few decades to centuries, have been identified. One such deposit (above) can be seen at Hawaiian Volcano Observatory. In 1790, ~80 people in a war party near the summit were killed due to an explosion, making Kilauea the most lethal volcano in the United States. Monitoring Kilauea has tremendously increased the science of volcanology. 14

The hazards of an active volcano Although most eruptions are non-violent, any eruption cause problems in the following ways: • Lava flows burn homes and forests. • Roads can be inundated making areas inaccessible. • Vog causes respiratory problems in both residents and tourists. • Tropical plant growing businesses have closed due to the SO 2 containing gas plume reaching their growing areas, killing the plants. • Livestock eat vegetation covered by acids created from the interaction of the gas plume and rain. • Infrastructure can be damaged. For example, ranchers in the path of the vog can no longer use barbed wire fencing as it rusts away in less than a year. • Large ash plumes although relatively rare, could pose threats to airplanes. 15

End-of-module assignment 1. Hualalai an active volcano on Hawai`i, does not have a webcam. Speculate as to why not. 2. Some of the information regarding eruptions at Kilauea provided in this module is contradictory to what one hears in an introductory geology course. Write a few sentences describing your understanding of a typical Hawaiian volcanic eruption before working through this module and new information that you learned. 3. Go to slide 5, and view the map of the Hawaiian Islands. According to the information presented on slide 4 regarding lithospheric plates moving over a stationary mantle plume hot spot, describe the direction of motion of the Pacific Plate. 4. Using the additional K-GPS data for two stations (B-B’), calculate the distance between the two stations for the five dates provided. Was the distance you calculated the same or different from the data for stations A-A’? Explain. 5. Observe the graph below. Determine the number of DI events recorded on the tiltmeter graph (both short-term and long-term)? 6. Refer to your answer for Question 4. Did the distance between the GPS stations get longer or shorter? Would you infer that the volcano was inflating or deflating during this time period? (2010) 16

Kīlauea 1750– 1983 Kīlauea 1983 -present 1986– 1992 1983– 1986 Pu‘u ‘Ō‘ō (episodic fountains) Kupaianaha (continuous effusion) 1992– 2007–present Pu‘u ‘Ō‘ō flank vents (continuous effusion) July 21 st, 2007 eruption (continuous effusion) 17

Kinematic GPS (K-GPS) and the Pythagorean Theorem The Universal Transverse Mercator (UTM) coordinate system, a grid-based zone method, uses easting and northing coordinate pairs to specify a location at the earth’s surface. The system is similar to latitude and longitude, but calculations in the field are easier with the UTM system as the Pythagorean Theorem can be used rather than difficult trigonometric calculations. Point 1: Easting = 2, Northing = 10 Point 2: Easting = 5, Northing = 20 (∆ y) (∆ x) Two example K-GPS coordinates are plotted. The difference in the easting coordinates (∆ x) and the difference in the northing coordinates (∆ y) are two legs of a right triangle. The hypotenuse of the triangle is the distance in meters between the two points. Pythagorean Theorem: a 2 + b 2 = c 2 c b a You could make each step in the calculation separately, or you could type the entire formula in one cell: =((C 3 -C 4)^2+(D 3 -D 4)^2)^(1/2) Return to slide 11 18