
	Where results make sense

Topic: Harmonic tremor

Related Topics

Harmonic progression

Simple harmonic motion

Richter Magnitude Scale

Music for 18 Musicians

North Atlantic Oscillation

Peruvian Paso

Dating the Bible

Finding Nemo

Tang (fish)

	Ramos
		Volcanic tremor at Pinatubo is of three principal types: (1) low-amplitude, low-frequency harmonic tremor, observed occasionally throughout the posteruptive period; (2) large-amplitude, bimodal-frequency tremor, observed only once prior to the eruption in 1991 but frequently during the early months of 1992; and (3) high-frequency tremor that lacks distinct dominant frequencies and exhibits irregular, "spiky" envelopes.
		Compared to the harmonic tremor, the bimodal-frequency is less monochromatic, exhibiting less symmetry along the time axis (that is, the trailing part does not mirror the leading part), and may be caused by the presence of high-frequency components in the tremor.
		Tremor from these explosions often blends with longer, lahar-generated tremor, but, because water percolation into the pyroclastic deposits may be delayed or be independent of lahars, secondary explosions can also occur on their own (fig.
	pubs.usgs.gov /pinatubo/ramos (8649 words)

	Harmonic tremor - Wikipedia, the free encyclopedia
		Harmonic tremor describes a continuous rhythmic earthquake in the Earth's upper lithosphere that can be detected by a seismograph and often precedes or accompanies volcanic eruptions.
		A harmonic tremor is a continuous release of seismic energy typically associated with the underground movement of magma.
		It contrasts distinctly with the sudden release and rapid decrease of seismic energy associated with the more common type of earthquake caused by slippage along a fault.
	en.wikipedia.org /wiki/Harmonic_tremor (103 words)

	Erebus Volcano Seismic Tremor
		The complex changes in spectral character suggest that the tremor may be originating with a non-linear oscillator driven by unsteady magma flow through a constricted plumbing system.
		Twenty minutes after the tremor onset, a brief (approximately 2 minutes) transition to harmonic trigger-type tremor with three harmonics and a fundamental frequency of 3.0 Hz can be seen.
		Harmonic tremor showing strong amplitude variations recorded at broadband stations LEH and HOO on February 14, 2003.
	www.ees.nmt.edu /Geop/mevo/seismic/x.store (872 words)

	Erebus Volcano Seismic Tremor
		This increase of tremor activity has not accompanied by increased activity at the crater of Erebus, where an open lava lake and persistent low-level strombolian activity have long been observed.
		Large numbers of tremor episodes with frequencies smaller than 0.5 Hz are likely related to the increment of broad band seismic stations operating since January 2003.
		A downward gliding tremor is an uncommon pattern observed in harmonic tremors at Mt. Erebus.
	www.ees.nmt.edu /Geop/mevo/seismic/tremor.html (894 words)

	Global Volcanism Program \| Taal \| Monthly Reports (Site not responding. Last check: 2007-10-31)
		Harmonic tremor was continuous and had a maximum amplitude of 5 mm.
		Harmonic tremor amplitudes rose from 5 to 9 mm shortly before the explosion, and reached a maximum of 12 mm during the explosion.
		Tremor with a maximum double amplitude was recorded at 2210 on 24 November and at 0504 on 25 November.
	www.volcano.si.edu /world/volcano.cfm?vnum=0703-07=&volpage=var (6887 words)

	Tremor
		Tremor is the rhythmic, oscillating shaking movement of the whole body or just a certain part of it, caused by problems of the neurons responsible from muscle action.
		Tremor may occur as an isolated symptom and usually of idiopathic (unknown) cause (essential tremor) or a part of the symptom constellation of another disorder (e.g.
		Tremors may occur at rest (Parkinson's disease), during voluntary movements (cerebellar lesions) or during excessive activity of muscles (essential tremor, hyperthyroidism).
	www.mrsci.com /Symptoms/Tremor.php (611 words)

	Sabit
		Felt earthquakes at 0341 on June 12 were followed by almost 2 h of harmonic tremor accompanied by continuing ash emission, the column of which rose to 4,000 m and drifted to the northwest.
		Harmonic tremor with an average double amplitude of 1 to 2 mm began at 0400.
		Tremor occurred on all days and was so strong in the last half of June that it obscured many discrete earthquakes; thus, the apparent increase in seismicity from middle to late June is probably an artifact of earthquake counting against strong background tremor.
	pubs.usgs.gov /pinatubo/sabit (4654 words)

	Primary Orthostatic Tremor
		The aim of this study was to determine if orthostatic tremor is invariably associated with the orthostatic and weight bearing conditions in the arms and legs, and to investigate the features of orthostatic tremor under different levels of peripheral loading.
		Primary orthostatic tremor is an exaggeration of a physiological response to instability.
		Orthostatic tremor arises from an oscillator in the posterior fossa.
	orthostatictremor.org (1952 words)

	The sound of water flowing from the subducting slab beneath Japan (Site not responding. Last check: 2007-10-31)
		Seismic tremor (or “harmonic tremor”) is normally associated with the relatively shallow underground movement of magma in volcanic areas (such as along rift zones in Hawaii).
		The seismic tremor recently detected in Japan originates at depths of between 30 and 45 km in the general vicinity of the subducting Philippine Plate.
		Obara (2002) suggests that the seismic tremor is related to the movement of water that is generated within the subducting Philippine Plate due to the heat-induced hydration of minerals within the rock.
	www.mala.bc.ca /~earles/japan-slab-water-may02.htm (637 words)

	CVO Website - Earthquakes and Seismicity
		The long-period earthquakes are related to harmonic tremor, the continuous seismic record of underground magma movement.
		Quite distinct from the discrete seismic shocks associated with rupture-caused earthquakes, harmonic tremor is a continuous vibration of the ground caused by magma movement.
		Harmonic tremor generally is detectable and recorded only by seismic instrumentation; however, if especially vigorous, tremor can be felt by people as far as 5 miles from the eruption site.
	vulcan.wr.usgs.gov /Glossary/Seismicity/description_earthquakes.html (2883 words)

	T-Zero Publishing: BLOG - T-Zero Publishing Volcanic Alerts (Site not responding. Last check: 2007-10-31)
		Eruptive tremor had completely disappeared by 8 June, and on the 10th that phase of the eruption was considered to be finished.
		The absence of longer duration harmonic tremor suggested to PHIVOLCS that there was no magma movement or intrusion, indicating that the explosions were possibly a result of reactivation of a shallow hydrothermal system.
		After another quiet interval, tremor signals were again recorded on 12, 14, 19, 22, and 30 July, and 8-10, 20, and 29 August 2001; tremors on 20 August were "excessively loud." No tremors were detected again until 26 February 2002, followed by a quiet interval until 16-19 and 31 March.
	www.iwaynet.net /~tzeropublishing/blog/gvn_200306.shtml (7741 words)

	SVE - Volcano News
		The episodes of harmonic tremor were registered to December 9; the 10th, the activity tremor descended disappeared to the last hours of the 11th in which a new cycle was initiated.
		Harmonic tremor was detected in the seismic station 3 days prior to the events.
		Tremor activity strongly decreased but is almost stable at a low intensity since 21 July 1500.As of 26th of May, IPGP reported from website (in french) that since the beginning of April, seismicity increased progressively (about 20 events/day) However, other data are not clear yet even a slight deformation 2-3cm occured near the Dolomieu crater.
	www.sveurop.org /gb/news/news.htm (16155 words)

	Global Volcanism Program \| Mayon \| Monthly Reports (Site not responding. Last check: 2007-10-31)
		Harmonic tremor was nearly continuous during the period of maximum activity and shallow explosion earthquakes were also recorded.
		Many of these tremors were of high frequency but short duration and inferred to be associated with mass-wasting of lava-dome fragments that descended from the volcano's SE rim.
		Magma ascent through the uppermost levels of the volcano's conduit appeared to be associated with high-frequency harmonic tremor at all five seismic stations in the vicinity of the volcano.
	www.volcano.si.edu /world/volcano.cfm?vnum=0703-03=&volpage=var (16587 words)

	Mount St Helens -The Olympian (Site not responding. Last check: 2007-10-31)
		A "harmonic tremor" -- one scientist described it as a heartbeat-like throbbing -- shook the mountain very early Sunday, leading scientists to think for a while the eruption might happen before dawn.
		The tremor lasted 25 minutes and was followed by seismic silence, after which Mount St. Helens resumed what has become its standard behavior -- a constant series of mini-earthquakes, between magnitude 2 and 3, about one kilometer below the surface, as often as four times a minute.
		The harmonic tremors mean fresh magma is trying to break through hardened older magma near the surface of the lava dome, according to USGS research geologist Jim Vallance.
	theolympian.com /home/specialsections/MountStHelens/20041004/5349.shtml (944 words)

	Acoustics Monitoring Program
		The signals are characterized by a high amplitude fundamental at around 10 Hz and three harmonics at 20, 30, and 40 Hz.
		The tremor signals typically appear as discrete packets that last for 4-5 minutes, with brief periods of quiescence for roughly 30 seconds followed by the beginning of the next signal packet.
		These spectral characteristics are very distinctive and have been previously identified in volcanic tremor recorded using both seismic and airborne acoustic records at Arenal Volcano in Costa Rica (Garces et al., 1998) and at Pavlof Volcano, Alaska (Garces and Hansen, 1998).
	www.pmel.noaa.gov /vents/acoustics/sounds/tremor.html (254 words)

	s11c in fm97
		This "harmonic tremor" was recorded at four three-component, high-dynamic range stations during the deployment of the Proyecto de Investigación Sismológica de la Cordillera Occidental 94 (PISCO'94).
		The source for this tremor is usually modeled as the resonance of a fluid-filled crack or organ pipe-like structure in the volcano.
		In contrast, strong tremor and events known locally as whooshes and chugs were recorded 2.3 km from the vent during 2 weeks at Arenal volcano, Costa Rica, in April 1994.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm97&database=/data/epubs/wais/indexes/fm97/fm97&maxhits=200&="S11C" (3766 words)

	Government of Montserrat, Soufriere Hills Notice 411 (Site not responding. Last check: 2007-10-31)
		The seismic activity continues to be dominated by small- to moderate-sized rockfalls and near-periodic episodes of large-amplitude, low-frequency, near-harmonic tremor which is preceded by volcano-tectonic (VT) and/or hybrid earthquakes and followed by hybrid earthquakes.
		These episodes of VTs and/or repetitive hybrid earthquakes and tremor are probably associated with magma migration from shallow depths to the surface as the process of dome growth at the Soufriere Hills volcano continues.
		Given the significant amounts of steam that seem to be pumped out during the times of large tremor amplitude, the interaction of the magma with the volcano's groundwater system may also be involved.
	www.geo.mtu.edu /volcanoes/west.indies/soufriere/govt/updates/notice.411.html (593 words)

	Listening carefully: unique observations of harmonic tremor at Lascar volcano, Chile (Site not responding. Last check: 2007-10-31)
		Power spectra and spectrograms of Lascar’s harmonic tremor from the various stations demonstrate that the frequencies recorded cannot be explained as path effects, and must therefore be attributed to mechanisms at or near the source.
		The tremor’s fundamental frequency changes at the same time at all stations, indicating that such changes must be caused at the source.
		This spectral behavior indicates rather that the source is some resonance at a single frequency within the magma, magma/gas or gas parts of the volcano whose amplitude exceeds the range for which the assumptions of linear acoustics are valid.
	www.ingv.it /~wwwannali/hellweg423.htm (294 words)

	volano seismology (Site not responding. Last check: 2007-10-31)
		Volcanic tremor is a quasi-continuous to continuous signal of duration from minutes to days or longer.
		The dominant frequencies of tremor are 1-5 Hz, similar to low-frequency events.
		Harmonic tremor and spasmodic tremor are two special cases of more general volcanic tremor, The former is low-frequency, often monotonic sinusoid with smoothly varying amplitude, and the latter is a higher-frequency, pulsating irregular signal [Finch, 1949].
	www.aeic.alaska.edu /input/sanchez/volcseis.html (443 words)

	Acoustic detection of a seafloor spreading episode
		On June 26, 2145 GMT, a burst of low-level seismic activity, with accompanying harmonic tremor, was observed and subsequently located near 46°15'N, 129°53'W, on the spreading axis of the Juan de Fuca Ridge.
		Distinctive signatures for magma movement (harmonic tremor) and dike injection (seismic swarm migration) are readily apparent when recorded on a dense seismic array and provide a detailed picture of the subsurface processes leading to volcanic eruptions or dike emplacements [Klein et al.
		This continuous noise is similar in nature and frequency content to harmonic tremor observed on Kilauea Volcano in Hawaii during active magma transport in the subsurface [Koyanagi et al.
	www.pmel.noaa.gov /pubs/outstand/fox1526/fox1526.shtml (3151 words)

	[No title]
		On 27 December an incandescent lava flow traveled 500 m; during this event volcanic tremor was recorded with a maximum amplitude of 3 mm.
		Volcanic tremor was recorded on 1, 2, 17, and 18 November; tremor from 15 to 18 December increased to 3-8 events/day (figure 5).
		The same day maximum tremor amplitude reached 200 mm and glow was observed from three points on the lava dome.
	www.geo.mtu.edu /volcanoes/misc/v21n01/rabaul.v21n01.html (2701 words)

	Volcanoes -- More About Forecasting
		Seismic activity (small earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt.
		Harmonic tremor occurs when there is sustained movement of magma below the surface.
		However, increasing activity is very worrisome, especially if long-period events become dominant and episodes of harmonic tremor appear.
	www.learner.org /exhibits/volcanoes/morfore.html (389 words)

	AxisofLogic/ World News
		Volcanic ashes have made thousands of people in Sumatra flea the active volcanic regions that are experiencing harmonic tremor and some solid signs of an eminent mega volcano in that region soon.
		The recent volcanic activities with the accompanying harmonic tremor since last week is alarming and is making many geologists run towards their computer model for finding clues and validation of facts.
		Some of the quakes mistaken as aftershocks were harmonic tremors signifying lava movements.
	www.axisoflogic.com /cgi-bin/exec/view.pl?archive=91&num=16922 (417 words)

	The New Scalar Paradigm in Vulcanology (Site not responding. Last check: 2007-10-31)
		Below are some references to harmonic tremors (sometimes called Volcanic Tremors) in their association with typical volcanic activity.
		Scalar Harmonic resonance is the observable energy, which is powerful, yet requires a new type of technology to observe.
		The character of this waveform is a ‘harmonic tremor’ type of signature – or a signature that is the same type that is genesis to ‘silent or slow earthquakes’ which science has recently become aware of.
	www.the7thfire.com /education/Earth_Changes/new_scalar_paradigm_in_vulcanology.htm (2297 words)

	s12c in fm98
		For a wavefield such as that generated by harmonic tremor, both the polarization and amplitude of the individual spectral lines depend strongly on their frequency.
		The phenomenon of gliding, whereby spectral peaks in the harmonic tremor signal are seen to fluctuate about a central value, can be produced by changes in either the source trigger period, the melt void fraction, the gas temperature, the fluid flow velocity, or the effective length of the magma conduit.
		The harmonic nature of the seismic signals is rather a series of pulse filtered by path effects, and spiked frequency response is simply a comb function Fourier transform.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm98&database=/data/epubs/wais/indexes/fm98/fm98&maxhits=200&="S12C" (3438 words)

	Reading List 6 GEOS 692 002
		A seismic model for the source of long-period events and harmonic tremor.
		Observations and analysis of B-type earthquakes, explosions, and volcanic tremor at Pavlof Volcano, Alaska.
		Origin of volcanic tremor in Hawaii, Part II, Theory and discussion.
	www.aeic.alaska.edu /input/steve/readlst6.htm (118 words)

Try your search on: Qwika (all wikis)