Et ecce terræmótus - "And behold there was a great earthquake" - is the second Psalm antiphon at Lauds on Easter Day. You can look this up at Divinum Officium ; just enter (for instance) 3-31-2013 for Easter's date, and then click "Laudes." (The Psalm number is according to the Vulgate; this is Psalm 100 for Anglicans):
Ant. Et ecce terræmótus * factus est magnus : Angelus enim Dómini descéndit de cælo, allelúja.
Ant. And behold there was a great earthquake, * for the Angel of the Lord descended from heaven, allelúja.
Psalmus 99. Jubilate
Jubiláte Deo, omnis terra: * servíte Dómino in lætítia.
2 Introíte in conspéctu ejus, * in exsultatióne.
3 Scitóte quóniam Dóminus ipse est Deus: * ipse fecit nos, et non ipsi nos.
4 Pópulus ejus, et oves páscuæ ejus: * introíte portas ejus in confessióne, átria ejus in hymnis: confitémini illi.
5 Laudáte nomen ejus: quóniam suávis est Dóminus, in ætérnum misericórdia ejus, * et usque in generatiónem et generatiónem véritas ejus.
Psalm 99. Jubilate
O be joyful in the Lord, all ye lands: * serve the Lord with gladness,
2 And come before his presence * with a song..
3 Be ye sure that the Lord he is God; * it is he that hath made us, and not we ourselves.
4 We are his people, and the sheep of his pasture : * O go your way into his gates with thanksgiving, and into his courts with praise; be ye thankful unto him.
5 Give praises unto his Name: for the Lord is gracious, his mercy is everlasting; * and his truth endureth from generation to generation.
Ant. Et ecce terræmótus factus est magnus : Angelus enim Dómini descéndit de cælo, allelúja.
Ant. And behold there was a great earthquake, for the Angel of the Lord descended from heaven, allelúja.
The text for the antiphon comes from Matthew 28:2:
1 Now after the Sabbath, toward the dawn of the first day of the week, Mary Magdalene and the other Mary went to see the tomb. 2 And behold, there was a great earthquake, for an angel of the Lord descended from heaven and came and rolled back the stone and sat on it. 3 His appearance was like lightning, and his clothing white as snow. 4 And for fear of him the guards trembled and became like dead men.
5 But the angel said to the women, “Do not be afraid, for I know that you seek Jesus who was crucified. 6 He is not here, for he has risen, as he said. Come, see the place where he lay. 7 Then go quickly and tell his disciples that he has risen from the dead, and behold, he is going before you to Galilee; there you will see him. See, I have told you.”
8 So they departed quickly from the tomb with fear and great joy, and ran to tell his disciples. 9 And behold, Jesus met them and said, “Greetings!” And they came up and took hold of his feet and worshiped him. 10 Then Jesus said to them, “Do not be afraid; go and tell my brothers to go to Galilee, and there they will see me.”
There is, again, no chant score or recording of this antiphon online (I'll wait for Jakub to come by for that! - or maybe I can find it in some manuscript someplace and transcribe it myself)....
(EDIT: Thanks, Jakub!
....but there's a rather famous mass of the same name, by the 14th/15th Century French composer Antoine Brumel. Missa Et ecce terræmótus - "The Earthquake Mass," that is - is an amazing piece in 12 voices, here sung by "Ensemble Clément Janequin, Les Sacqueboutiers De Toulouse; dir: Dominique Visse":
Some credits from the YouTube page:
Baritone Vocals -- Alain Buet, François Fauché, Malcolm Bothwell, Vincent Bouchot
Bass Vocals -- Antoine Sicot, Renaud Delaigue, Yves Bergé
Cornett -- Jean-Pierre Canihac, Marie Garnier-Marzullo, Philippe Matharel
Countertenor Vocals -- Bernhard Landauer, Dominique Visse, Frère Jean-Christophe Clair
Organ -- Jean-Marc Aymes, Laurent Stewart, Yasuko Uyama-Bouvard
Sackbut [Sacqueboute Basse] -- Bernard Fourtet, Fabien Dornic, Franck Poitrineau
Sackbut [Sacqueboute Ténor] -- Daniel Lassalle, Fabien Cherrier, Stephan Legée*
Tenor Vocals -- Bruno Boterf, Julian Podger
Here's something from Gimell records about Brumel and this mass:
It is hard to think of any other piece of music quite like the 12-part 'Earthquake' Mass by Antoine Brumel (c.1460-c.1520). Both in its employment of twelve voices for almost its entire length and in its musical effects, there is nothing comparable to it in the renaissance period, even if some of those effects may remind the listener of the 40-part motet Spem in alium (1) by Thomas Tallis (c.1505-1585). Brumel's masterpiece did not inaugurate a fashion for massive compositions; but it did quickly establish a formidable reputation for itself, admired throughout central Europe in the 16th century as an experiment which could not easily be repeated. It is tribute enough that the only surviving source was copied in Munich under the direct supervision of the late renaissance composer Orlandus Lassus (1532-1594), who nonetheless never tried to rival its idiom in his own work.
A pupil of Josquin des Prés (c.1440-1521) and one of the leading Franco-Flemish composers around 1500, Brumel was famous throughout the 16th century. In a period which has left a large number of laments in memory of its great composers, Brumel received an exceptional number, more than Obrecht (c.1450-1505), Mouton (c.1459-1522) and Agricola (?1446-1506) put together. Thomas Morley (in A Plain and Easy Introduction to Practical Music, 1597) was probably the last writer to praise Brumel for his skill, the only master he ranked alongside Josquin, making particular reference to his ability in the art of canonic composition. Brumel is important to modern commentators because he was one of the few leading members of the Franco-Flemish school to be genuinely French, which is to say that he was born outside the boundaries of the Burgundian Empire, somewhere near Chartres. He was initially employed in France proper at the Cathedrals of Chartres and Laon and (in 1498) at Notre Dame in Paris where he was responsible for the education of the choirboys. However he seems to have had a restless temperament, which led to his dismissal on at least two occasions, and he soon began the peripatetic life of so many musicians of the renaissance period. There is evidence that he was employed in Geneva, Chambéry and probably Rome; but the high-point of his career was the fifteen years he spent as successor to Josquin and Obrecht at the court of Ferrara (between 1505 and 1520) in the retinue of Alfonso d'Este I.
Brumel's reputation as a writer of canons would not have been greatly increased by the simple example which underlies the Missa Et ecce terrae motus, for all that the presence of the canon plays an important role in understanding the unusual musical style of the whole. Brumel restricted his quotation of the Easter plainsong antiphon at Lauds, Et ecce terrae motus, to its first seven notes (which set the seven syllables of its title to D-D-B-D-E-D-D), working them in three-part canon between the third bass and the first two tenor parts during some of the Mass's 12-part passages. These statements occur in very long notes compared with the surrounding activity and their details may vary slightly from quotation to quotation (for example, which of the three voices begins and what the interval between them may be). By and large, though, the realisation of this canonic scaffolding is not rigorous and many of the sections of the mass are free of canon altogether.
However the influence of these slow-moving notes can be heard throughout the work, whether they are actually there or not, in the solid, slow-changing underlying chords. A casual listener to the Missa Et ecce terrae motus, confused at first by the teeming detail of the rhythmic patterns, may hear only some rather disappointing harmonies. Closer listening will reveal why Brumel chose to write in so many parts: he needed them to decorate his colossal harmonic pillars. In doing so he effectively abandoned polyphony in the sense of independent yet interrelated melodic lines, and resorted to sequences and figurations which were atypical of his time. The effect can even be akin to that of Islamic art: static, non-representational, tirelessly inventive in its use of abstract designs, which are intensified by their repetitive application. This style of writing is so effective that anyone who might be reminded of Tallis's Spem in alium would be unable to conceive of the need for another 28 parts.
The manuscript source for Brumel's 'Earthquake' Mass (Munich Bayerische Staatsbibliothek Mus. MS1) was copied for a performance in about 1570 at the Bavarian court. The names of the 33 court singers are given against the nine lower parts (the boys are not named), amongst whom Lassus sang Tenor II. Unfortunately the last folios, which contain the Agnus Dei, have rotted, leaving holes in the voice-parts. Any editor of the piece is presented with the unusual task of trying to guess where the notes which he can read might fit, as they are placed on the page in individual parts rather than in score; then re-compose what is missing. This was done for Gimell by Francis Knights. A further Agnus Dei, on the Et ecce terrae motus chant and attributed to Brumel, survives in Copenhagen; but it is widely thought not to belong to the 12-part Mass, since it is for six voices, which use different vocal ranges from those in the 12-part setting. In addition its musical style differs in various important respects from that of the larger work, not least in quoting many more than the first seven notes of the chant. For these reasons it has been omitted from this recording. The Mass is scored for three sopranos, one true alto, five wide-ranging tenors and three basses. The tessitura of all these parts (except perhaps that of the sopranos) is unpredictable to the point of eccentricity. Countertenor II, for example, has a range of two octaves and a tone, the widest vocal range I have ever met in renaissance music.