Old Faithful Geyser

Q. What is the time between eruptions?

A. The time between eruptions is usually 30-40 minutes.

Q. How long does the eruption last?

A. The eruptions usually last between 2-6 minutes.

Q. How high does the geyser erupt?

A. Old Faithful Geyser of CA varies in the height of eruptions anywhere from 30 – 80 feet, averaging about 60 feet.

Q. How many gallons of water shoot out during one eruption?

A. The estimates are about 250 – 400 gallons for a short eruption of about one and a half minutes, and 400 – 1,000 gallons for one of four and a half minutes.

Q. How hot is the water that comes from Old Faithful Geyser of CA?

A. The water during an eruption has been measured at 350 degrees F in the earth before it meets the earth’s surface and 70 – 115 degrees F once in the air.

Q. What is the smell around geyser areas?

A. The smell is from trace amounts of hydrogen sulfide gas, sometimes called “rotten egg gas”. In larger concentration it is a poisonous gas but?concentration in the steam are small.

Q. When was the first geyser discovered?

A. It is not known exactly when the first geyser in the world was found. The first known reference to geysers is a short phrase in Homer’s Iliad that refers to a spout of water from a spring. This is thought to be a reference to a geyser in Turkey. One such spring, Gayser Suyu, is known to have existed near the site of Troy. The first references to Geysir, a geyser in Iceland, was in 1294. The Geysers in Yellowstone were certainly known to the Native Americans of the area although when they were discovered is not known. European explorers heard legends of thermal features as they encountered the Native Americans in the late 1700′s and early 1800′s. The geysers were not viewed by European explorers until the early 1800′s.

Volcanoes and Geysers

Q. Are volcanoes and geysers related?

A. The heat needed for geyser formation comes from liquid rock or magma when it is near the surface of the earth. That is why geysers and volcanoes are found in the same area. When the magma reaches the surface, a volcano is formed. On the surface the liquid rock is called lava.
Geysers, though rare, are found in the same geologic settings where volcanic heat sources are available. All volcanic areas do not have geysers, however. Geysers require a specific set of conditions in order to form. Other thermal features such as fumaroles and hot springs are common in volcanic areas and can also be heated by near surface magma bodies.

Earthquakes and Geysers

Q. How are earthquakes and geysers related?

A. Earthquakes are caused by movement of faults or plates under tremendous pressures. These movements heat the above rock which generate heat in volcanic magma chambers found near geysers. Geysers need heat to erupt as well as water.

Q. Are geysers earthquake predictors?

A. Old Faithful Geyser of California has been used as a predictor of earthquakes. As the pattern of eruptions will lengthen before an earthquake up to three hour intervals instead of thirty to forty minutes on the yearly average. Not all geysers can predict earthquakes due to their water source tends to run out. The researchers pointed out that other “old faithful-type geysers” may also be earthquake predictors. In the case of the Old Faithful Geyser in Yellowstone, it has been noted over time that the geyser is not an earthquake predictor, but rather an earthquake reactor as its eruption patterns change after earthquake activity.

Q. What is an earthquake?

A. An earthquake is caused by sudden slip on a fault. Stresses in the earth’s outer layer push the sides of the fault together. Stress builds up and the rocks slips suddenly, releasing energy in waves that travel through the rock to cause the shaking that we feel during an earthquake.

Q. What is a fault?

A. A fault is a thin zone of crushed rock between two blocks of rock, can be any length, from centimeters to thousands of kilometers. It is a fracture in the crust of the earth along which rocks on one side have moved relative to those on the other side. Most faults are the result of repeated displacements over a long period of time.

Q. Are there different types of faults?

A. Yes, there are three:
1) Normal “dip-slip” fault: The fault plane of a normal fault dips away from the uplifted crustal block. Faulting occurs in response to extension
2) Reverse “dip-slip” fault: The fault plane of a reverse fault dips beneath the uplifted crustal block. Faulting occurs in response to compression.
3) “Strike-slip” fault: Crustal blocks slide past each other. The slip may be left lateral or right lateral.

Q. What happens to a fault when an earthquake occurs?

A. Earthquakes occur on faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal or at some angle to the surface of the earth. The slip direction can also be at any angle.

Q. How do we know a fault exists?

A. 1) if the earthquake left surface evidence, such as surface ruptures or fault scarps (cliffs made by earthquakes); 2) if a large earthquake has broken the fault since we began instrumental recordings in 1932; and 3) if the faults produces small earthquakes that we can record with the denser seismographic network established in the 1970s.

Q. What is “surface rupture” in an earthquake?

A. Surface rupture occurs when movement on a fault deep within the earth breaks through to the surface. Not all earthquakes result in surface rupture. Fault rupture almost always follows preexisting faults, which are zones of weakness. Rupture may occur suddenly during an earthquake or slowly in the form of fault creep. Sudden displacements are more damaging to structures because they are accompanies by shaking.

Q. What is meant by “fault creep”?

A. Fault creep is the slow movement of faults in the earth’s crust. Examples of creep are well known along the Hayward Fault where it crosses highly developed areas in Contra Costa and Alameda Counties.

Q. How many earthquakes does the National Earthquake Information Center (NEIC) report yearly?

A. The NEIC locates about 12,000 to 14,000 earthquakes yearly or approximately ~35 per day around the world.

Q. What is earthquake intensity?

A. Earthquake intensity is a measure of the effects of ground shaking at a specific locality – typically measured as “magnitude”.

Q. What are the magnitude classes or levels?

A. Minor = 3; Light = 4; Moderate = 5; Strong = 6; Major = 7; Great = 8

Q. How are earthquakes measured?

A. By a seismographic network. Each seismic station in the network measures the movement of the ground at the site. The slip of block of rock over another in an earthquake releases energy that makes the ground vibrate. The vibration pushes the adjoining piece of ground and cause it to vibrate and thus the energy travel out from the earthquake in a wave.

Seismograph & Measurement

Q. What is a seismograph?

A. Seismographs are instruments used to record the motion of the ground during an earthquake – installed in the ground throughout the world and operate as seismographic network – 1st developed ~1890.

Q. What are seismograms?

A. The records (paper copy) produced by seismographs used to calculate the location and magnitude of an earthquake. Shows how the ground moves with the passage of time.

Q. How do you read seismograms?

A. The HORIZONTAL axis = time (measured in seconds); VERTICAL axis = ground displacement (usually measured in millimeters).