Center for Earthquake Research and Information

Earthquake energy

The overall intensity of an earthquake is measured by a seismograph 

Elastic rebound

The faulting process in the Earth’s crust in which the 2 sides of a fault appear locked despite the motion of adjoining pieces of crust, but with accumulating strain they rupture suddenly, snapping to new positions relative, to each other generating an earthquake.

Epicenter vs. focus

- The area at the surface directly above the focus is the epicenter shock waves produced by an earthquake radiate outward through the crust from the focus and epicenter.

Yellowstone NP

the largest geyser locale in the world, contains thousands of hot springs

Venice, Italy

built on a sand bar, threatened by frequent low-level floods

U-tube analogy

water flows from the recharge area in Fayette County and under the city of Memphis

Sinking cities

Venice, Mexico City, Long Beach, Galveston/Houston, Las Vegas, San Joaquin Valley, New Orleans. A combination of lowering of the water table, sediment compaction, and rising sea level is endangering cities world wide

Memphis sand

texture is well sorted quartz, angular to sub angular, pristine

Free ground water

2 free ground water aquifers in the mid-south: The “Upland Complex” and Mississippi River alluvium

Fayette county

Diffuse flow

in sand aquifers

Contact spring

may form where a perched water table meets the ground surface

500 ft sand

The Memphis Aquifer, a vital source of groundwater in the Northern Mississippi Embayment. Memphis alone extracts about 220 million gallons per day

3000-5000 yr old water

Dye tracers suggest this long for water to flow from the recharge area to under Memphis

Three circle method

determined by plotting distances from 3 stations on a map as circles with radii equaling the distance from the quake epicenter

Seismic return times

forecasts based on seismic return times

Yellowstone National Park

home to volcanoes, hot spots, basins, geysers, and more

Year-without-a-summer

1816, due to the ash and other natural reactions from Tambora

Water vapor

the most abundant volcanic emission – heavy rains frequently accompany eruptions

Viscosity of lava

fluid resistance to flow, controls ease/difficulty of gases escaping to atmosphere

Vesuvius, 79 AD

The eruption of Mt. Vesuvius in 79 AD buried the cities of Pompeii and Herculaneum, Italy. It last erupted in 1944

Tuff

a rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption.

Tambora (1815)

30,000 dead; 1816 became known as the "Year Without a Summer" because of Tambora’s affect on North American and European weather. Crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th

Shield volcano

built almost entirely of fluid lava. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes. This results in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form

Pyroclastic flow

fast-moving clouds of superheated gas (1,000 °C (1,830 °F)) and rock, that reach speeds up to 700 km/h (450 mph). The flows normally hug the ground and travel downhill, but may spread laterally

Plate margin volcanoes

Most volcanoes occur along plate margins mid-ocean spreading ridges and plate convergence subduction zones.

Mt. St. Helens (1980)

57 dead; The eruption was predicted but the type and direction of the pyroclastic flow were unexpected. Emitted pyroclasts, clouds of ash and live steam 

Mt. Pelee

Martinique, Lesser Antilles; Pyroclastic flow flattened the city of St Pierre, 40,000 dead 

Lahar

mudflows composed of pyroclastic material mixed with rain water from a volcano. They typically find and flow along a river valley

Krakota (1883)

four explosions in western Australian that had great ash clouds, shockwaves, and tsunamis

Io

the innermost satellite of Jupiter, is the only planet other than Earth with ACTIVE volcanoes (nitrogen geysers occur on Triton); shield volcano

Hawaiian Islands

Hawaiian Islands are forming as the Pacific Plate moves northwest over a hot spot. The state of Hawaii is entirely composed of volcanic rock.

Geothermal areas

areas can be characterized with geysers, hot springs, mud pots, and fumaroles

Fissure eruption

A volcanic eruption where lava wells up through fissures in the earth's crust and spreads over a large area.

Weathering

group of processes involving chemical and physical reactions between the atmosphere and rocks; 2 types: mechanical and chemical

Tombstone lithology

slate tombstone is clear; limestone tombstone is unreadable

Talus

talus angle of repose is 50 degrees

Solution

dissolving of minerals by natural acids (carbonic acid forms when atmosphere carbon dioxide dissolves in water)

Solifluction

a type of mass wasting where waterlogged sediment moves slowly down slope, over impermeable material (due to frost heave that occurs normal to the slope, as well as to small-scale slippage)

Soils

soil liquefaction caused by earthquakes also triggers mass movement of soil; hematite stains soil red

Slump

the downward slipping of a mass of rock or unconsolidated material, moving as a unit, usually with backward rotation on a more or less horizontal axis parallel to a slope or cliff from which is descends. Slumps typically have a fault scarp.

Sand

sand angle of repose is about 35 degrees

Quick clay

a unique form of highly sensitive marine clay, with the tendency to change from a relatively stiff condition to a liquid mass when it is disturbed

Plant and animal wedging-plant growth

growing roots widen fractures; burrowing animals, mostly worms (both are mechanical weathering)

Particle size

decreases as total surface area increases (in chemical weathering)

Mechanical Weathering

physical disintegration (frost action, exfoliation, plant growth, burrowing animals); dominates in cold dry climates

Mass wasting

also known as slope movement or mass movement, is the geomorphic process by which soil, sand, regolith, and rock move downslope under the force of gravity. Types of mass wasting include creep, slides, flows, topples, and falls

Landslide

can be used for a variety of landscape processes including slumps, debris flows, rock falls, and mudflows

Loess

loess angle of repose is 90 degrees

Frost action

water expands as it freezes, expansion stresses cracks

Exfoliation

joints are surface-parallel fracture systems in rock often leading to erosion of concentric slabs

Debris flow

a moving mass of rock fragments, soil, and mud. May only move a few feet per year, or greater than 100 miles per hour

Creep

mass movement that is slow, not directly visible

Clay minerals

products of chemical weathering

Chemical Weathering

decomposition of rock by atmospheric oxygen, carbon dioxide and water forms new minerals

Carbonation

carbonic acid + feldspar forms clay minerals

Angle of repose

the angle between the surface of a pile and the ground. When bulk granular materials are poured onto a horizontal surface, a conical pile will form. Related to grain size, density, surface area, shape of the particles, coefficient of friction of the material, water content

Acid rain

sulfuric acid forms when coal containing pyrite (iron sulfide) is burned, forming SO3

Zone of saturation

look at phreatic

Zone of Aeration

look at vadose

Well logs

detailed record (a well log) of thegeologic formations penetrated by a borehole

Water witching

a type of divination employed in attempts to locate ground water

Water table

the surface where the water pressure head is equal to the atmospheric pressure(where gauge pressure = 0). It may be conveniently visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity

Vadose (aeration zone)

the part of Earth between the land surface and the top of the phreatic zone i.e. the position at which the groundwater (the water in the soil's pores) is at atmospheric pressure

Unsaturated zone

the part of Earth between the land surface and the top of the phreatic zone i.e. the position at which the groundwater (the water in the soil's pores) is at atmospheric pressure

Tritium

a radioactive isotope of hydrogen

Spring

also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the Earth from underground. Thus, a spring is a site where the aquifer surface meets the ground surface.

Soft water

removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water is more compatible with soap and extends the lifetime of plumbing

Saturated zone

the area in an aquifer, below the water table, in which relatively all pores and fractures are saturated with water

Salt water intrusion

the movement of saline water into freshwater aquifers, which can lead to contamination of drinking water sources and other consequences. Saltwater intrusion occurs naturally to some degree in most coastal aquifers, owing to the hydraulic connection between groundwater and seawater. Because saltwater has a higher mineral content than freshwater, it is denser and has a higher water pressure

Recharge area

hydrologic process where water moves downward from surface water to groundwater

Potentiometric surface

imaginary line where a given reservoir of fluid will "equalize out to" if allowed to flow

Porosity

describes the fraction of void space in the material, where the void may contain, for example, air or water

Pipe flow

liquid flow within a closed conduit (conduit in the sense of a means of containment).

Permeability

a measure of the ability of a porous material(often, a rock or unconsolidated material) to allow fluids to pass through it

Phreatic (saturation) zone

area in an aquifer, below the water table, in which relatively all pores and fractures are saturated with water

Perched water table

surface where the water pressure head is equal to the atmospheric pressure(where gauge pressure = 0)

Meteoric water

the water derived from precipitation (snow and rain). This includes water from lakes, rivers, and ice melts, which all originate from precipitation indirectly

Memphis aquifer

best water in the world

Mars water

Was similar to earth’s water, but now exists almost exclusively as water ice

Juvenile water

water that exists within, and in equilibrium with, a magma or water-rich volatile fluids that are derived from a magma. This magmatic water is released to the atmosphere during a volcanic eruption. Magmatic water may also be released as hydrothermal fluids during the late stages of magmatic crystallization or solidification within the Earth's crust

Hydrologic cycle

aka Water cycle. describes the continuous movement of water on, above and below the surface of the Earth.

Hot springs AR

Oldest federal reserve. traditionally best known for the natural hot springs that give it its name

Hot spring

a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust

Hard water

water that has high mineral content. can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water

Ground subsidence

the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level.

Grain size

refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks

Geyser

a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapour phase (steam)

Dye tracers

tracking and tracing various flows using dye added to the liquid in question. The purpose of tracking may be an analysis of the flow itself, of the transport of something by the flow of the objects that convey the flow

Connate water

liquids that were trapped in the pores of sedimentary rocks as they were deposited. These liquids are largely composed of water, but also contain many mineral components as ions in solution

Confined ground water

stagnant and nasty

Cone-of-Depression

occurs in an aquifer when groundwater is pumped from a well. In an unconfined aquifer (water table), this is an actual depression of the water levels. In confined aquifers (artesian), the cone of depression is a reduction in the pressure head surrounding the pumped well

Caprock

a harder or more resistant rock type overlying a weaker or less resistant rock type. Common types of caprock are sandstone and ultramafic rock types

Artesian well

n artesian aquifer is a confined aquifer containing groundwater under positive pressure. This causes the water level in a well to rise to a point where hydrostatic equilibrium has been reached

Calcium and magnesium

Minerals in hard water

Aquifer

underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well

Aquiclude

a solid, impermeable area underlying or overlying an aquifer

Fault movement

Normal fault is when forces pull rocks apart the tension is called a normal fault-Reverse (Thrust) Fault is when compressional forces associated with converging plates force rocks to move upward along the fault plane. –Strike-Slip fault is if a movement along a fault plane is horizontal such as produced along a transform fault it forms a Strike-Slip Fault

Fluid injection

The introduction of gases or liquids under pressure into a reservoir to force oil into producing wells

Focus vs. epicenter

The area at the surface directly above the focus is the epicenter shock waves produced by an earthquake radiate outward through the crust from the focus and epicenter

Forecasting earthquakes

plotting the epicenters of earthquakes in the United States and southern California between 1899 and 1900. These occurrences give some indication of relative risk by region. The challenge is to discover how to predict the time and place for a quake in the short term

Forecasting EQs

analogous to weather forecasts; based on seismic return times

Interplate EQs

most earthquakes occur long tectonic plate boundaries. Concentrations: circum-pacific belt, Mediterranean-Himalayan belt, Mid-oceanic ridges (shallow-focus earthquakes)

Intraplate EQs

an earthquake that occurs in the interior of a tectonic plate. The New Madrid Seismic Zone

Liquefaction (soil)

occurs when water-saturated soil or sediment acts like a liquid during a quake

Lisbon EQ, 1755

atural causes rather than divine wrath; 60,000 dead

Magnitude scale

Richter magnitude (cannot exceed 9) and Moment magnitude (0-10+)

Mercalli Intensity

the effect an earthquake has on structures and people

Moment magnitude

MW = 0 to 10+, developed in the 1970s to succeed the Richter scale. The formulas are different, but retains the familiar continuum of magnitude values. Requires information about aftershocks to determine surface area of rupture (takes weeks to determine)

New Madrid Eqs

3 great quakes, Richter magnitude 8+; felt in Chicago all the way to the East coast. Sparse population and no confirmed deaths. 1500 felt aftershocks

New Madrid seismic zone

earthquakes are generated along a right lateral strike-slip fault zone with a left stepping reverse fault down to the south

P (primary) waves

fast, travel 1 to 5 miles per second; compression body wave in which rock vibrates back and forth parallel to the direction of wave propagation, first wave to arrive at a seismometer, pass through solids, fluids, and gases

Precursors Earthquake prediction

the specification of the time, location, and magnitude of a future earthquake within stated limits, the next strong earthquake to occur in a region

Earthquake prediction

precise statement of time, location, and energy

R and L waves

Rayleigh, R, Waves: ground moves in an elliptical path opposite the direction of wave motion. Extremely destructive to buildings; Love (L) waves: side to side motion of the ground surface

Reelfoot Lake

did not exist on maps before 1812, appeared after New Madrid’s earthquakes

Richter Magnitude (ML)

scale is a base-10 logarithmic scale, magnitude is defined as the logarithm of the ratio of the amplitude of waves measured by a seismometere; distance to the focus from the recording station and amplitude of pen displacement on a Woodson-Tennent seismometer

S (secondary) wave

shear (transverse) body wave in which rock vibrates side to side perpendicular to the direction of wave propagation. Slower (2 to 5 km/sec), second wave to arrive at a seismometer, passes through solids only

San Andreas Fault

greatest seismic risk in the US

San Francisco EQ, 1906

established the relation between fault movement and EQs, thick structural walls did not withstand the EQ

Seismic return times

forecasts based on seismic return times

Seismic risk map

risk is greatest in California, the Washington to Oregon coast, West Alaska, and the Memphis region

Seismic waves

release energy, originate within the Earth, 2 general types are body and surface

Seismogram

paper or digital records of the earthquake vibrations

Seismometer

device used to detect and measure seismic waves

Southern Calif. Risk

greatest seismic risk in the US; San Andreas fault

Surface waves

travel along Earth’s surface away from the epicenter

Three circle method

determined by plotting distances from 3 stations on a map as circles with radii equaling the distance from the quake epicenter

Time-distance plot

travel time curve is used to determine distance to the focus; based on the time interval between the first P and S wave arrivals

Tokyo EQ, 1923

 demonstrated earthquake resistant building, the Imperial Hotel stayed intact

Tree rings

bald cypress tree-ring chronologies were not affected by 1811-1812 earthquakes, which means ring-width chronologies are dimensionless indices of growth for each year and are based on samples of exactly dated ring-width time series

Tsunami

seismic sea waves caused by sudden movement of the sea floor. Generally produced by MW8+ earthquakes; may also be generated by large undersea landslides or volcanic explosions. Travel 500 mph across open ocean

1816

known as the Year Without a Summer because of Tambora‘s affect on North American and European weather. Crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th century

Aleutian Islands

volcanic island arc formed as the Pacific Plate sub ducts under North America

Ash (volcanic)

consists of fragments of pulverized rock, minerals, and volcanic glass. Created during volcanic eruptions. Less than 2 mm in diameter. Often loosely used to refer to all explosive eruption products (correctly referred to as tephra) including particles larger than 2 mm. volcanic ash is formed during explosive eruptions when dissolved gases in magma expand and escape violently into the atmosphere.

Atmosphere temperature

Carbon dioxide is a dominant green house gas that controls global temperature

Basalt

basalt lava is very fluid and dominates oceanic volcanoes

Bombs (volcanic)

 blobs of molten lava that are blasted into the air

Caldera

volcanic collapse depression much larger than the original crater

Cascade Mountains

 forming as North American overrides the Juan de Fuca Plate, in Washington and Oregon

Cinder cone volcano

small, steeply sloping, composed of ash, active for a few years, located on contintents

Columbia River Plateau

created by huge eruptions of flood basalt burying part of the NW United States 14 to 17 million years ago (type of flood basalt)

Composite volcano

a tall, conical volcano built up by alternating layers of hardening lava and volcanic ash. Moderately to steeply sloping, constructed of alternating layers of ash and lava, unpredictable explosive eruptions for several years, intermittently active for 100,000 years, located on convergent plate boundaries