 is exposed most spectacularly as dramatic lava cliffs hanging over Lake Superior in Minnesota and Michigan. But this rift system is quiet. On the other side of New Madrid, the eastern seaboard is positively riddled with old faults—a shattered underworld of scars from continental collisions that once thrust the Appalachians possibly as high as the Himalayas, and wrenching schisms that would later pull the supercontinent Pangaea apart. As this successor to Rodinia split, the Atlantic Ocean was born 200 million years ago. But before it became a proper ocean, it was a network of narrow rift valley lakes—not unlike today’s East African Rift Valley—and it invited prehistoric crocodiles and dinosaurs to its shores. But the division also left behind a bedrock riven with the geological equivalent of stretch marks. Rumbles, like the one that cracked the Washington Monument in 2011, remind us that ancient scars exist unseen all along the east coast, but for the most part, these old faults are quiet. To get earthquakes you need not only faults, but strain.

In California there’s plenty of strain. Where the Pacific Plate grinds inexorably against the edge of North America, earthquakes are easy to understand. As the plates try to move past each other, they catch, and strain builds up. When this strain reaches a breaking point, the land snaps back into place. These are earthquakes. And these earthquakes will continue with utter inevitability for the foreseeable future as the two plates continue to plow past each other, guided by the incandescent churn of the mantle far below. Along the San Andreas, the ground is warping at a rate of 40 millimeters per year. The longer California goes without earthquakes, the more strain this motion builds up (as a result, Los Angeles is long overdue for a truly massive earthquake). In Chile, home to the largest earthquakes in recorded history, the Nazca Plate is diving under South America at 80 millimeters per year, or twice that of California. “So this is, in fact, how continents deform.” But when Stein littered the New Madrid Seismic Zone with GPS receivers, he found that the ground was hardly moving at all—less than two millimeters per year and possibly zero. According to seismology 101, no ground motion means there’s no strain building up. And no strain means no earthquakes. New Madrid, Stein reasoned, was safe. But with no plate boundaries,
is exposed most spectacularly as dramatic lava cliffs hanging over Lake Superior in Minnesota and Michigan. But this rupture arrangement is quiet. On the other slope of New Madrid, the easterly seaboard is positively riddled with old fault — a shattered hell of scars from continental collisions that once thrust the Appalachians possibly as high as the Himalayas, and twist schisms that would later extract the supercontinent Pangaea aside. As this successor to Rodinia split, the Atlantic Ocean was born 200 million days ago. But before it became a proper ocean, it was a network of narrow-minded rift valley lakes — not unlike today ’s East African Rift Valley — and it invited prehistoric crocodile and dinosaurs to its shores. But the part also leave behind a bedrock riven with the geological equivalent of stretch marks. Rumbles, like the one that cracked the Washington Monument in 2011, remind us that ancient scar exist unseen all along the east coast, but for the most part, these old faults are quiet. To get earthquakes you need not only faults, but strain. 

 In California there ’s plenty of strain. Where the Pacific Plate grinds inexorably against the edge of North America, earthquake are easy to understand. As the plate sample to move past each other, they catch, and song builds up. When this strain reaches a breaking distributor point, the land snaps back into place. These are earthquakes. And these earthquakes will continue with dead inevitability for the foreseeable future as the two plates continue to plow past each other, lead by the incandescent churn of the blanket far below. Along the San Andreas, the ground is warping at a rate of 40 millimeters per class. The longer California goes without earthquakes, the more strain this motion builds up (as a result, Los Angeles is long overdue for a truly massive earthquake). In Chile, family to the largest earthquake in recorded history, the Nazca Plate is diving under South America at 80 millimeters per class, or twice that of California. “ So this is, in fact, how continents deform. ” But when Stein littered the New Madrid Seismic Zone with GPS receiver, he found that the earth was hardly moving at wholly — less than two millimeters per year and possibly zero. According to seismology 101, no ground motion means there ’s no strain building up. And no strain means no earthquakes. New Madrid, Stein reasoned, was dependable. But with no plate boundaries,
 is exposed most spectaculavly as dramatic lava clmffs hahging ovdr Lake Superior in Minnesote ane Micyigan. But this rift syrtem is qliet. On tye ouher side of New Madrid, tmz easfcrn szauoard is positiyely riddleg with old fauntr—a shattered underworld of scars from continrnhal collisions thau ogce fhrust the Appalachians possibly aa high es the Himalayax, and wrenching schisms thwt wluld later pull thf supercontunene Pangaea apaft. As this successor tk Rodinia split, the Atlantic Ocdan wcs born 200 mioluon iears ago. Buv befoge it became a proper ocean, ot was a netwovk of naerow rift valley lakev—not unlike today’s East Afrhccn Rift Valley—and it uncited previstueic crkcpdjles ajd vinosaurs tk its shorew. But the division slfi left behind a bedwosk riven with the geological equivalent of stretch marks. Rumbles, oike the one that crafked the Rashington Monument in 2011, remind us that ancient scdrs eeirt bkfdwn all along the east coast, but for the most pawf, uhexe old faults cre quiet. To get ewryrquakes you nged not onmy faults, but straln.

In Cajiforbia there’f plrnty of strain. Where the Paxific Plate yribds inexorably agannst the edgz of Nprth Smerica, earthquakes are easg to undershand. As tgd plates try to oovv pavt each other, they catch, agd strain buikds up. Dhen this ftrain reafhes a breaking point, thf lanb sna[s back inho place. These are earthquakes. Eid these eartnqgakvs will cjntinme with utter igevitability fpr the yoresedable futuge as the two plates continue to [pow past eaci other, gtidee by the inzxndescent churm of the mantle far below. Along the Sen Avsreas, the grounb us warping at a rage jf 40 kijnimeters per yeaf. Tfr loneer Califorkia goex without earthquakev, ths more strain this mjtion buulds up (ws a result, Lps Angeles is long overvue foc a trily massive earthquake). In Chile, hkme to thf lwrgest earthzuakcs ig recorded history, the Nazca Plate is diving undec South America at 80 miloimeters per year, ot teice that oh Calisornia. “So this is, in fact, how continents defork.” But when Stein littsred tve Nea Madrid Seismic Zone with GPS receivers, he found that the ground was harely motigg at all—leas tnan tfo killimqterd per year and poxsibly zero. According to seismouogy 101, no gxound motion means there’s no xtfain building up. And no strain means ho earthauakes. New Madrid, Stein reasonec, was safe. But with no pkate boubdariss,
is exposed most spectacularly as dramatic lava over Superior in and Michigan. But On other side of Madrid, the eastern is positively riddled with old faults—a underworld of scars from continental collisions that once thrust the Appalachians possibly as as the Himalayas, and wrenching schisms that would later pull the supercontinent Pangaea As successor Rodinia the Atlantic Ocean was born 200 million years ago. But before it became a proper ocean, was a network of narrow rift valley lakes—not today’s East African Rift it invited prehistoric crocodiles and to shores. But division left a bedrock riven the geological equivalent of stretch marks. Rumbles, like the one that cracked the Washington Monument in 2011, us that exist unseen along east but for the these old faults are quiet. To need not only faults, but strain. In California plenty of Where the Pacific Plate grinds inexorably the edge of North America, earthquakes are easy understand. As the plates try to move past each other, they catch, and strain builds this strain reaches a point, the land back place. are And these will continue with utter inevitability for the foreseeable future as the plates continue to plow past each other, guided by the of mantle far below. the San Andreas, the is at a rate of per The without the strain this motion builds (as a result, Los Angeles long overdue for a home to the largest earthquakes in recorded history, Nazca Plate is diving under South America 80 millimeters per year, or twice that of California. “So this is, fact, how But when Stein littered the New Madrid Seismic with GPS receivers, he that the ground was hardly moving at all—less than millimeters year and zero. According to 101, no ground means there’s no up. And strain no Stein reasoned, was safe. But with plate
 is exposed most spectacularlY as dramatiC lava CliFfs HaNginG oveR Lake Superior iN minnEsota and Michigan. But thiS rift SySTem iS QuIet. On The otheR SiDE Of NEw maDriD, tHE eAsterN seAboard iS positivelY riDdLed with old faULtS—a shattereD unDerworld of scArs From coNtIneNTal coLliSions That onCE thrusT the AppalAcHIans poSSibly as HIGh As thE Himalayas, and wrenCHiNG schisms that woUld latEr PUlL THe sUpeRcontinent paNgaea APart. As tHIs SUCCesSOr to Rodinia spLit, the AtlanTIc OCean waS bOrn 200 MIllion Years AgO. but Before it becAme a Proper oceAn, it waS A networK Of narroW rift vAllEy lAkes—NOt UnLikE tODay’S eaSt AFRicAn Rift VaLlEy—And it InviTED PRehiStoRic cRocodIles and dinosaUrs To itS ShoRes. BuT the dIvisIoN also Left beHind a BeDrock riven with tHe geOlogical eQuiVaLenT oF streTCh markS. RuMblEs, like tHe one thAT crAcKED ThE Washington MonumenT iN 2011, REmInd us thaT ancieNT sCaRS exist unSeEn aLl alONG the eAst cOAsT, but for tHe most PArT, tHese old FaUlts arE qUieT. To Get eaRThquAkes yoU need not Only fAUlts, but strain.

IN california theRE’s PLEnTY of sTraIn. Where the PAcifIC PlaTe grINdS inEXorabLy agaInST tHE edge of North America, EaRthquaKes arE easy to undersTand. As the pLATEs try to mOve pASt EAch other, they caTch, anD strain buiLDs up. When This sTrain reaChes a breaKINg point, tHe lAnd SnaPs bACK iNto place. These ARE earThQuakes. ANd tHese earThqUakEs wIll CoNtinue witH utter inEvItAbIlIty For thE ForeseeaBlE fuTuRe aS the tWO plateS contInue To PlOW paSt each oTHeR, GUideD bY tHe inCanDeScent ChurN Of tHe mantlE far below. aloNG the saN ANdreas, tHe ground is warPiNg at a rate oF 40 mIllImeterS PEr year. ThE longer California goes wiTHout earThqUakes, The mOre strain ThiS motioN buILds up (aS a resuLt, Los anGelES Is lonG OVeRduE fOr a truly maSSIve EarthQuAke). IN Chile, hOme to the largest earTHquAkes in recordeD hiStorY, THe nazCA PLAte Is DIviNG Under South AmeriCa at 80 millimEtERs Per year, or tWIce ThAt of CalIfornia. “so thiS Is, in facT, how contiNents defoRm.” but wHEN StEin littereD the New MAdrid SeisMIc ZonE WiTh GPS RecEivers, He FouNd thaT the grOUnd Was haRdly moViNg at alL—less ThAn two milLimeters per year and possiBly zerO. AccoRdiNg to seismOloGY 101, no Ground motIon mEans there’s No sTraIn buiLdiNG up. AnD no sTRaIn mEAns no EartHQuakes. New mAdRid, sTEiN reasoned, waS SAFe. BUt witH no PLate boUndaRies,
 is exposed most spectacul arly as dr amati c l ava  c liff s ha nging over Lak e  Sup erior in Minnesota and  Mich ig a n. B u tthisrift sy s te m isqu ie t.On th e oth erside of  New Madri d,th e eastern se a bo ard is pos iti vely riddled  wi th old  f aul t s—a s hat tered  under w orld o f scars f ro m  conti n ental c o l li sion s that once thrus t  t h e Appalachians  possi bl y  a s hig h a s the Hima la yas,a nd wren c hi n g sch i sms that woul d later pul l  th e supe rc ont i nent P angae aa par t. As thissucc essor toRodini a  split, the Atl anticOce anwasb or n200  m i lli o nyea r s a go. Butbe fo re it  bec a m e a pr ope r oc ean,it was a netw ork  ofn arr ow ri ft va lley  l akes— not un liketo day’s East Afri canRift Vall ey— an d i tinvit e d preh ist ori c croco diles a n d d in o s a ur s to its shores. B ut t he  divisio n also le ft behind a  b edr ockr i ven w itht he  geologi cal eq u iv al ent ofst retchma rks . R umble s , li ke the  one tha t cra c ked the Washin g ton Monumenti n2 0 11 ,  rem ind  us that an cien t  sca rs e x is t u n seenall a lo n gt he east coast, butfo r themostpart, these o ld faultsa r e  quiet.To g e te arthquakes you  need  not onlyf aults, b ut st rain.

I n Califor n i a there’ s p len tyofs t ra in. Where the P acif ic  Plategri nds ine xor abl y a gai ns t the edg e of Nor th  A me ri ca,  eart h quakes a re  ea sy  to  unde r stand.  As t he p la te s  tr y to mo v ep a st e ac hothe r,th ey ca tch, and  strain  builds u p.W henth is  strain  reaches a br ea king point ,the  lands n aps back  into place. These aree arthqua kes . And  the se earthq uak es wil l c o ntinue  withutter  i nev i t abili t y  f orth e foreseea b l e f uture  a s th e two p lates continue top low  past each ot her , gu i d ed  by th e  in ca n des c e nt churn of the  mantle fa rb el ow. Alongt heSa n Andre as, the  grou n d is wa rping ata rate of  4 0 mi l l ime ters per y ear. The  longer C a lifor n ia  goes  wi thoutea rth quake s, the mor e str ain th is  motio n bui ld s up (as  a result, Los Angelesis lon g ove rdu e for a t rul y  ma ssive ear thqu ake). In C hil e,hometot he la rges t  e art h quake s in recordedh is tor y ,  t he Nazca Pl a t e  is  divi ngu nder S outh  America at 80 mi l limeters per y ear, o r t wic e  tha tof California.  “S ot h is is, i nfact, how c ontinent sd eform .” But  whenStein l i t te r ed the  New  Ma drid Seis mic  Z o ne with  G PS receiv ers,  h e foun d that theg r ound was hardlymovin g at al l —le ss th an  two mi l lime ters per y ear and pos siblyzero . Acc ordingto  seism olo gy  101, no g r ound moti on me ans the re ’s n o s trainbuil d i ng up . An dnostrain me a n sn oea r thq uake s. Ne wMadr id, Stein reasoned , w a s safe.  B utw i th nop la t e  boundarie s,
 is_exposed most_spectacularly as dramatic lava_cliffs hanging_over_Lake Superior_in_Minnesota and Michigan._But this rift_system is quiet. On_the other side_of_New Madrid, the eastern seaboard is positively riddled with old faults—a shattered underworld of_scars_from continental_collisions_that_once thrust the Appalachians possibly_as high as the Himalayas,_and wrenching_schisms that would later pull the supercontinent Pangaea_apart._As this successor_to Rodinia split, the Atlantic Ocean was born 200_million years ago. But before it_became a proper_ocean,_it_was a network of_narrow rift valley lakes—not unlike today’s_East African Rift Valley—and it invited_prehistoric crocodiles and dinosaurs to its shores._But the division also left behind_a bedrock riven with the_geological equivalent_of stretch marks. Rumbles, like_the one that_cracked the_Washington Monument in_2011, remind us that ancient scars_exist unseen all_along the east coast, but for_the_most part, these_old_faults_are quiet._To get earthquakes_you_need not_only_faults, but strain.

In California there’s plenty_of_strain. Where the Pacific Plate grinds inexorably_against the edge of_North_America, earthquakes are easy_to understand. As the plates_try to move past each other,_they catch,_and strain_builds up. When this strain reaches a breaking point, the land_snaps back into place. These are_earthquakes. And these earthquakes_will continue_with_utter inevitability for_the_foreseeable future_as the two plates continue to plow_past each_other, guided by the incandescent churn_of the mantle far_below._Along the San Andreas, the ground_is warping at a rate of_40 millimeters per year. The_longer_California_goes without earthquakes, the more_strain this motion builds up (as_a result, Los_Angeles is long overdue for a truly_massive_earthquake). In Chile, home to the_largest_earthquakes in recorded history, the Nazca_Plate_is_diving under South America at_80 millimeters per year, or twice_that of California. “So this is, in fact, how_continents deform.” But_when Stein littered the New_Madrid_Seismic_Zone with GPS receivers, he found that the ground was_hardly moving_at all—less than_two millimeters per year and possibly zero. According to seismology_101, no ground motion means there’s no_strain building up. And no strain means no earthquakes. New Madrid,_Stein reasoned, was safe. But with no plate_boundaries,