Hello Listers, With the recent sizemic activites taking place in southern Caliiforian, Mexico and China I thought I look up some information on meteorites and quakes and here are some articals I got back from the search.
First up is the moon Title: Shallow moonquakes - How they compare with earthquakes Authors: Nakamura, Y. Abstract Of three types of moonquakes strong enough to be detectable at large distances - deep moonquakes, meteoroid impacts and shallow moonquakes - only shallow moonquakes are similar in nature to earthquakes. A comparison of various characteristics of moonquakes with those of earthquakes indeed shows a remarkable similarity between shallow moonquakes and intraplate earthquakes: (1) their occurrences are not controlled by tides; (2) they appear to occur in locations where there is evidence of structural weaknesses; (3) the relative abundances of small and large quakes (b-values) are similar, suggesting similar mechanisms; and (4) even the levels of activity may be close. The shallow moonquakes may be quite comparable in nature to intraplate earthquakes, and they may be of similar origin. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1980LPSC...11.1847N&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf Title: The MOON micro-seismic noise : first estimates from meteorites flux simulations Authors: Lognonne, P.; Lefeuvre, M.; Johnson, C.; Weber, R. Abstract The Moon is considered to be a seismically quiet planet and most of the time, the Apollo seismograms were flat when not quakes was occuring. We show in this paper that this might not be the case if more sensitive data are recorded by future instruments and that a permanent micro-seismic noise is existing due to the continuous impacts of meteorites. We perform a modeling of this noise by using, as calibrated seismic data, those generated by the impacts of the Apollo S4B or LEM, by taking care on the scaling law, necessary to express the seismic force with respect to the mass and velocity of the impactors. We also parametrize the dependence of the amplitude of the seismic coda, associated to the maximum amplitude of the seismograms, with respect to the epicentral distance and to the source geometry. This enabling us to use the seismic data of the S4B impacts as empirical waveforms for the modeling of the natural impacts. The frequency/size law of meteoroids impacting the Moon and the associated probability of NEO impacts are however not known precisely. Uncertainties as large as a factor of 3-5 remain, especially for the moderate-sized impacts which are not observed on the Earth, due to the shielding by the atmosphere. We therefore use several meteoroid mass/frequency laws from the literature to generate, with a random simulator, a history of impacts on the Moon during a given period. The seismic signals generated by succession of seismic sources and estimate the frequency/amplitude relationship of such seismic signals. Our results finally provide an estimate for the meteoritic seismic background on the Moon. This background noise was not recorded by the Apollo seismic experiment due insufficient resolution. Such an estimate can be used in designing a new generation of lunar seismometers, for estimating the probability of detecting proposed impacts due to nuggets of strange quark matter , and to inform future lunar based experiments, which require very stable ground, such as optical interferometry moon-based telescopes or gravity waves detectors. http://adsabs.harvard.edu/abs/2008AGUFM.P51D..08L Title: Why the next generation of Moon exploration needs a global seismic network Authors: Neal, C. R. Abstract The 4-station Apollo Passive Seismic Experiment (APSE) network was completed in April 1972, and operated until it was switched off on 30 September 1977. During this time, the network demonstrated that the Moon exhibits seismic activity on a similar scale to that of an intraplate setting on Earth. However, there are significant gaps in our understanding of lunar seismicity and what it tells us about the lunar interior. For example, collection of seismic data that pass through the interior of the Moon are critical for determining the size, state and composition of the lunar core, the nature of the deep lunar mantle, determining the global extent of discontinuities, and mapping the extent of crust/mantle heterogeneities. Additionally, with the advent of a new era of lunar exploration and potential colonization, understanding the nature and extent of lunar seismicity is now required in terms of risk assessment for a permanent lunar habitat. The data needed to address all of these issues must be collected using a network of seismometers that is global in coverage. Lunar Seismic Events. There were four types of lunar seismic event defined by the APSE network. 1) Thermal moonquakes - the smallest magnitude event (associated with stresses induced by diurnal temperature changes at the lunar surface); 2) Deep moonquakes - magnitude ≤2 (>7,000 having been recognized occurring 700-1,200 km within the Moon and associated with Earth's tidal pull); 3) Meteoroid impacts (>1,700 events representing masses of 0.1 to 1,000 kg were recorded); 4) Shallow moonquakes - strongest type of event, with 7 of the 28 recorded events being magnitude 5 or greater although the exact causes of such quakes are not known (focal depths 50-200 km, but exact depths and locations are unknown as all recorded events were outside the APSE network). Relevance. Apart from a direct impact from a meteorite, shallow moonquakes offer the greatest potential seismic risk to a permanent lunar habitat, but the amount of epicentral ground motion associated with such events is difficult to estimate. Estimates of ground acceleration at the epicenter of a magnitude 5.7 shallow moonquake is estimated to be ˜ 0.75 m s‑2 for a focal depth of 25 km and ˜0.22 m s‑2 for a focal depth of 100 km. However, the estimates could be meaningless because the calculations were conducted using formulations for earthquakes and there are distinct differences in seismic wave transmission between the Moon and Earth. For example, the maximum signal from a shallow moonquake can last up to 10 minutes with a 1 slow tailing off that can continue for hours, indicating that damping is less efficient in the Moon than it is in the Earth. In other words, seismic energy is more efficiently propagated through the Moon, especially at higher frequencies. This is particularly significant for shallow moonquakes as they contain more energy at high frequencies than earthquakes of comparable total energy. In addition, the scattering properties of the regolith need to be fully evaluated. A Lunar Seismic Network: At this time, it is suspected, but not known, that seismic events could seriously compromise a permanent lunar habitat. In order to fully evaluate this risk, as well as answer fundamental science questions regarding the lunar interior, a long-lived, global lunar seismic network needs to be established. In order to achieve this, technological issues such as deployment and low mass power supplies that can supply consistent power over a period of at least 6 years need to be addressed. 2 http://adsabs.harvard.edu/abs/2006epsc.conf..291N Now lets move on to Mars Title: Floods on Mars released from groundwater by impact Authors: Wang, Chi-Yuen; Manga, Michael; Wong, Alex Abstract On Earth, large earthquakes commonly cause saturated soils to liquefy and streamflow to increase. We suggest that meteoritic impacts on Mars may have repeatedly caused similar liquefaction to enable violent eruption of groundwater. The amount of erupted water may be comparable to that required to produce catastrophic floods and to form outflow channels. http://adsabs.harvard.edu/abs/2005Icar..175..551W Now I am wondering because of the low gravity on the Moon's surface if in the past 4.5 billion years if there has been a big enough quakes to project the moons surface into space? Shawn Alan ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
