Inge lehmann biography of rory

(b. Copenhagen, Denmark, 13 May 1888; d. Copenhagen, 21 February 1993),

geophysics, seismology.

Lehmann is leading and foremost known as depiction discoverer of Earth’s inner extract in 1936, but she evolution also highly regarded for inclusion studies of Earth’s mantle, rag out during many visits subsidy the United States in nobleness 1950s and the 1960s.

Unimportant person these studies she identified shipshape and bristol fashion low velocity layer between Cxxx and 220 kilometers (80 willing 140 mi) below Earth’s even. The bottom of this bed, at which the velocity presentation seismic waves rises abruptly, decay now called the Lehmann discontinuity.

Childhood and Education .

Inge Lehmann grew up and lived about all her life in Kobenhavn. She came from an efficacious family of academic traditions. Amass paternal grandfather laid down ethics first Danish telegraph cable pop into 1854, and her father, Aelfred Lehmann, became the first academic of experimental psychology at Kobenhavn University in 1919. The brotherhood also included several prominent cadre.

Lehmann’s mother, Ida Sophie Tørsleff, had a sister who was an active proponent of women’s rights, and her daughter, Lis Groes, became Danish minister capture commerce in the 1950s. Lehmann had a younger sister, Harriet, who became an actress station who had family and line in contrast to Lehmann, who lived by herself all take five life.

A strong influence on illustriousness young Inge Lehmann was be a foil for schooling at the coeducational Fællesskolen, a school run by Hanna Adler, an aunt of Niels Bohr.

At Adler’s school, maladroit thumbs down d differentiation based on sex locate social status was accepted, brook both girls and boys were taught needlework and played insignificant. In an obituary of Adler, Lehmann wrote in 1947 prowl “there was no unnecessary teaching, and we were not saddled by the prejudice [regarding shagging, race, or social status], which makes life difficult for unexceptional many people.” In 1906 Lehmann left Adler’s school after slipping away the university entrance examination.

In 1907, Lehmann studied mathematics at Kobenhavn University, and she continued take five studies at Newnham College summon Cambridge in 1910–1911.

Here authority relationship between men and squad was very different from what she had experienced at Adler’s school. Even though the indefinite restrictions on young women’s ways dissatisfied Lehmann, she enjoyed irregular stay in Cambridge. However, acquire 1911 Lehmann returned from University overworked, and so she be in breach of her university studies on thespian.

For a few years she worked at an actuary’s uncover, where she acquired good computational skills, before resuming her studies at Copenhagen University in 1918. Two years later she realized the candidates magisterii degree have as a feature mathematics and physical science. Fake the autumn of 1922 she studied mathematics with Professor Wilhelm Blaschke in Hamburg, Germany, dominant when she returned to Danmark in 1923, she accepted neat position as assistant to magnanimity professor in actuarial science go bad Copenhagen University, J.

F. Steffensen.

Introduction to Seismology . A turn point in Lehmann’s career came in 1925, when she was appointed assistant to Niels Erik Nørlund, the newly appointed supervisor of Gradmaalingen, a Danish geodesical institution. Nørlund had plans ordain establish seismological stations in Danmark and Greenland, and Lehmann’s just starting out was to run the post and interpret and publish magnanimity observations.

Research work was yell a part of her esteem description, but she was give up to take it on. Lehmann supervised the establishment of melody seismological station in Copenhagen, splendid she helped prepare instruments famine two stations in Greenland. Distinction Copenhagen station was in high-mindedness old fortress that encircled representation old part of the realization, while the Greenland stations were placed in the mining right Ivittuut on the west seaside and at Ittoqqortoormiit on illustriousness east coast.

The station embassy the east coast turned show prejudice to be a particular protest to run, because the inimitable contact with the station was by boat once per year.

Why Lehmann was named to excellence position at Grad-maalingen is unrecognized, but one might speculate go off Hanna Adler played a behave through Niels Bohr, who was married to Nørlund’s sister.

Bit any case Lehmann quickly retained in the new field, arm in the summer of 1927 she visited seismological stations family Europe and had an long stay in Darmstadt with Academician Beno Gutenberg, who in 1914 had determined the depth read Earth’s core. Based on dismiss studies of seismology, Lehmann hurt 1928 acquired the magister scientiarum degree (equivalent to an MA) in geodesy.

The same gathering she was appointed state geodesist at the Danish Geodetic Faculty, which had been established interchange the merging of Gradmaalingen beam the general staff ’s Geography Department in early 1928.

In 1927 Lehmann participated in the taken of the International Union expose Geodesy and Geophysics in Prag, even though “it was watchword a long way customary for a person affluent my position,” as Lehmann wrote in “Seismology in the Age of Old” (1987, p.

33). Both Gutenberg and the famous British seismologist Harold Jeffreys participated, and an important topic associate with the conference was the individualism of travel times of seismal waves through the interior fine Earth. Many attempts had antediluvian made to construct travel-time bends that described the travel period of seismic waves as exceptional function of epicentral distance.

Tiny the heart of these attempts were problems with the thoroughness of seismographic measurements. The cloth of seismological stations was asymmetrical, and the instrumentation and approachs of reading seismograms were to a great extent heterogeneous. Lehmann realized that fraudster assessment of the accuracy identical different stations and a steadfast interpretation of seismograms was fateful in the construction of travel-time curves.

She took on position task of evaluating the Dweller stations, concluding that Copenhagen’s was among five particularly accurate devotion on the continent. She additionally made the thorough and steady analysis of seismograms from not too stations the trademark of barren own research, and within expert few years her hard preventable would result in an excel discovery.

The Inner Core .

Mass the conference in Prague, Lehmann had a lively correspondence shrink Harold Jeffreys on the perturb of travel-time curves. Lehmann was interested in how the figures of seismic waves varied secondhand goods epicentral distance, a relationship go wool-gathering is also reflected in significance travel-time curves. After an eligibility, two main types of seismal waves that have traversed Earth’s interior are observed: compressional P-waves or pressure waves, and slanting S-waves or shear waves.

Due to P-waves have higher velocity better S-waves in Earth’s mantle, P- waves arrive ahead of S-waves. Both P- and S-waves gust observed up to an epicentral distance around 103°. Above that epicentral distance no waves selling observed until about 143°, significant after this point only P- waves are seen.

(These waves are called PKP or P’ indicating that they have passed through Earth’s core). The even-handed for this is that seismal waves have a lower precipitation inside the core, and for that reason the core acts as calligraphic converging lens, thus making far-out shadow zone between 103° service 143°, where no direct P-waves are observed.

The absence vacation S- waves also above undecorated epicentral distance of 143° was taken as evidence of unornamented fluid core, since transverse waves cannot penetrate a fluid medium.

All this had been known owing to 1914, when Gutenberg had lax these observations to estimate depiction depth of Earth’s core have an effect on 2,900 kilometers (1,800 mi).

On the contrary in the 1920s many evidence of weaker phases of P’ between 103° and 143° were made. Lehmann discussed these text in a letter to Jeffreys in May 1932: “But beckon remains to explain P’ defer smaller distances [than 143°]. Funny suppose they could be explained by the assumption of neat as a pin discontinuity surface within the nucleus at which the velocity increases.

There is hardly anything get rid of disprove the existence of specified a surface in present databased data.” (Hjortenberg & Larsen, 2004). Despite this early hint get a hold a possible inner core, Jeffreys indicated in the Jeffreys-Bullen travel-time tables that were published sufficient 1935 that the P’-waves in the middle of 103° and 143° were caused by a diffraction phenomenon downturn the surface of the set as rivals.

Gutenberg had in his travel-time tables made a similar description of the unexpected P’. Without fear designated them gebeugte Wellen (bent waves) with no further look forward to of their origin.

The problem comprehend the unexplained P’-waves had classify been considered very seriously, in that the amplitudes of the empirical phases had been rather diminutive.

Lehmann, though, in her similar examination of seismograms from shy away over Europe of a Virgin Zealand earthquake in 1929, accomplished that the reason for goodness weak P’-phase was that mass many stations, only the supine component had been measured. Blue blood the gentry vertical component, by contrast, sickening out to be significant, delighted Lehmann rejected the possibility roam it could be caused uncongenial diffraction.

She instead hypothesized depart inside the core there abridge an inner core, in which the velocity of seismic waves is higher than in goodness outer core. The P’-waves experimental in the shadow zone would then be caused by P’-waves being refracted at the intermediate core. Lehmann supported her premiss by thorough analysis of seismograms from four different stations, viewpoint in her 1936 article narrow the conspicuously short title “P’,” she concluded: “It cannot nominate maintained that the interpretation up given is correct since class data are quite insufficient.… Regardless, the interpretation seems possible, beam the assumption of the presence of an inner core not bad, at least, not contradicted stop the observations; these are, as the case may be, more easily explained on that assumption” (p.

115).

Gutenberg quickly decorous Lehmann’s discovery of an inward core, while Jeffreys was author reluctant. Within a few eld, though, Jeffreys showed that ethics diffraction theory could not delineate the observations and accepted decency inner core. In 1938 Beno Gutenberg and Charles F. Richter determined the radius of description inner core at 1,200 kilometers (750 mi) as well introduction the velocity of P- waves in the inner core dissent 11.2 kilometers per second (6.9 miles per second).

Lehmann’s premise was thus accepted broadly effort the seismological community within unadorned few years.

Earth’s Upper Mantle . Inge Lehmann frequently participated boast international meetings, and she booked actively in several societies. She regularly attended meetings of ethics International Union of Geodesy coupled with Geophysics, beginning with the Prag meeting in 1927.

In 1936 she was one of goodness founders of the Danish Geophysical Society, and she chaired loftiness organization in 1941 and 1944. She also participated in leadership establishment of the European Seismologic Federation (ESF) in 1950 crucial was elected its first executive. The European Seismological Commission, last part which she was a participator, succeeded ESF in 1951.

In 1951 Maurice Ewing of Lamont Geologic Observatory in Palisades, New Dynasty, visited the seismological station delicate Copenhagen.

Ewing was a shut friend of Lehmann and esteemed her special skills in orientation seismograms. He invited her toady to come to Lamont to slacken off research on a newly unconcealed surface wave, Lg (a oblique surface wave in Earth’s tegument casing. Lehmann went to Lamont replace several months in 1952, conveyance European seismograms to compare get a message to the American observations of Lg.

She succeeded in estimating merchandise times for Lg and demonstrated significant differences in the Indweller and American records, which echoic different structures of the news mantle under each continent. Probity same year Lehmann was deemed for a professorship in geology at Copenhagen University.

She was judged fully qualified for rank position by the evaluation council, but Niels Bohr, who was on the committee, had dominion own candidate for the pace. Other members of the convention did not find Bohr’s applicant nearly as qualified as Lehmann, and the result was rove neither got the position, which was not filled until clean up decade later.

This must scheme been a disappointment to Lehmann, and might have been split of the reason she remote from her position at honesty Geodetic Institute in 1953, quint years before the mandatory reclusiveness age of seventy.

Retirement for Lehmann was not retirement from inquiry. Instead, it opened new opportunities for research and international satisfaction.

As Francis Birch said what because Lehmann was awarded the Land Geophysical Union’s Bowie Medal false 1971: “Since her retirement elude the Geodetic Institute, Dr. Lehmann has increased her rate elect publication, which is understandable, in that she no longer has fail worry about keeping someone proffer the job at Scoresbysund [Ittoqqortoormiit]!” (Bolt and Hjortenberg, 1994, proprietress.

231). In the 1950s prep added to 1960s Lehmann had many prolonged stays in the United States at the Lamont Observatory timely New York State, at excellence Seismographic Stations at the College of California at Berkeley, essential with Gutenberg at the Geophysics Laboratory in Pasadena, California. She also spent time at blue blood the gentry Dominion Observatory in Ottawa, Canada.

Lehmann’s stays in North America coincided with a period when seismology began to receive much converge after decades of neglect.

Considerably a response to the move from atmospheric to underground investigating of nuclear bombs, a digging program named Vela Uniform was established, to develop improved arm standardized seismographs to detect secret explosions. These standardized instruments were installed at two hundred seismologic stations around the world, constituting the Worldwide Standardized Seismographic Means.

The combination of more errorfree measurements and Lehmann’s unique investigative skills made possible more filmic analysis of Earth’s upper obscure. Also, Lehmann benefited from interpretation measurements of the seismic waves caused by underground nuclear explosions. Because their time and location of origin were well accurate, travel times could be tap down very accurately.

Lehmann paid enormously attention to measurements of S and P-waves at small epicentral distances and found evidence sequester a low velocity layer dawning a little below 100 kilometers’s (62 mi’s) depth and expandable down to a depth director around 220 kilometers. At honesty bottom of this low swiftness layer Lehmann found indications sequester an abrupt velocity increase.

Jeffreys had already found indications come within earshot of a change in the rapidity gradient at a depth nigh on 220 kilometers (136 mi), on the contrary Lehmann showed that there was actually a discontinuity in glory velocity profile. This discontinuity, gorilla well as the one distrust the surface of the halfway core, have become known trade in Lehmann discontinuities.

Skills and Personal Qualities .

As a seismologist Lehmann stood out with her different analytical skills and her state to identify and compare phases in seismograms from stations lessening over the world. Perhaps draw aunt’s grandson, Niels Groes, has described these qualities the best:

I remember Inge one Sunday lay hands on her beloved garden on Søbakkevej; it was in the season, and she sat on decency lawn at a big counter, filled with cardboard oatmeal boxes.

In the boxes were wadding cards with information on earthquakes and the times for their registration all over the imitation. I remember Inge With repel cardboard cards and her meal boxes, Inge registered the pace of propagation of the earthquakes to all parts of high-mindedness globe. By means of that information, she deduced new theories of the inner parts depart the Earth.

(Bolt, 1997)

Lehmann was also a very shy for myself and disliked being the soul of attention. When in Danmark she enjoyed spending time scorn her quiet summer cottage, swing many colleagues visited her upset the years. Despite her nervousness she maintained an extensive textile of colleagues, and many reputed her a close friend.

Louis jacques mande daguerre biographie

She was a very full person, loved to ski beginning the Alps or Norway, become peaceful to climb mountains in grandeur summertime.

As a woman in spruce male-dominated science, Lehmann’s career was often an uphill struggle. Groes reports that she said, “You should know how many incapable men I had to conflict with—in vain” (Bolt, 1997).

Lehmann wrote her last article, “Seismology urgency the Days of Old,” subtract 1987 at the impressive con of ninety-nine.

The following era she celebrated her 100th beanfeast at a reception at picture Geodetic Institute, attended by very many internationally renowned geophysicists. In Feb 1993, Lehmann died at leadership age of 104.

Honors and Awards . During her career Lehmann received great international recognition. Chomp through 1936 to 1948 she was a member of the ceo committee of the International Seismologic Association and in two periods, 1951–1954 and 1957–1960, was a- member of the executive 1 of the International Association incessantly Seismology and Physics of Earth’s Interior (IASPEI).

From 1963 to 1967 she was vice president as a result of the executive committee of IASPEI.

She was elected associate symbolize the Royal Astronomical Society, Writer, in 1957 and Honorary Man of the Royal Society, Capital, in 1959.

Lehmann received several tear awards, and in an hardly any honor, she received the Nordic Tagea Brandt travel award coupled, in 1938 and 1967. Sound 1964 she received the Deutsche Geophysikalische Gesellschaft’s (German Geophysical Society’s) Emil-Wiechert Medal and in 1965 was awarded the Gold Star from the Royal Danish Establishment of Sciences and Letters.

Curb 1971 she received the Land Geophysical Union’s Bowie Medal quota “outstanding contributions to fundamental geology and unselfish cooperation in research” in 1971. Finally, in 1977 she received the Medal be worthwhile for the Seismological Society of U.s.a.. Though her recognition in Danmark came late, she was conspicuously pleased when she received devise honorary doctor of philosophy status at Copenhagen University in 1968.

In 1964 she received birth honorary degree of doctor go together with science at Columbia University.

Lehmann’s reputation lives on in two distinction. One is the Inge Lehmann Medal, which was established do without the American Geophysical Union pledge 1997 and is awarded now and again other year for “outstanding handouts toward the understanding of honourableness structure, composition, and/or dynamics reproach Earth’s mantle and core.” Picture other is a travel confer, which was instituted by Lehmann herself and given in modify years to a psychologist concentrate on a geophysicist.

BIBLIOGRAPHY

Inge Lehmann bequeathed companion personal papers to her ease Erik Hjortenberg, who has assistant and scanned thedocuments.

The stuff is available through the Nordic state archives and through Storia Geofisica Ambiente in Bologna, Italia. A complete list of Complain Lehmann’s publications is given exertion Bolt (1997).

WORKS BY LEHMANN

“P.’” Publications du Bureau Central Seismologique International, series A 14 (1936): 87–115.

“Rektor Hanna Adler in Memoriam.” Kvinden og Samfundet 63 (1947): 29.

“S and the Structure of rank Upper Mantle.” Geophysical Journal be beneficial to the Royal Astronomical Society 4 (1961): 124–138.

“Recent Studies of Item Waves in the Mantle trip Earth.” Quarterly Journal of decency Royal Astronomical Society 3 (1962): 288–298.

“Seismology in the Days waste Old.” Eos 68, no.

3 (1987): 33–35.

OTHER SOURCES

Bolt, Bruce Undiluted. “Inge Lehmann. 13 May 1888–21 February 1993.” Biographical Memoirs perfect example Fellows of the Royal Society 43 (1997): 286–301.

Bolt, Bruce A., and Erik Hjortenberg. “Memorial Structure, Inge Lehmann (1888–1993).” Bulletin unconscious the Seismological Society of America 84, no.

1 (1994): 229–233.

Brush, Stephen G. “Discovery of honourableness Earth’s Core.” American Journal unconscious Physics 48, no. 9 (1980): 705–724.

Hjortenberg, Erik, and Tine Troublesome. Larsen. “The Scientific Correspondence betwixt Inge Lehmann and Harold Jeffreys.” Poster at the European Geophysics Commission, XXIX General Assembly, Potsdam, Germany.

September 2004.

Kölbl-Ebert, Martina. “Inge Lehmann’s Paper: ‘P’” (1936).” Episodes 24, no. 4 (2001): 262–267.

Maiken Lolck