加勒比海地震风险:隐藏的危险

Tectonic Setting: A Hidden Seismic Zone

The Caribbean presents a seismic hazard that is often underestimated relative to the better-known 环太平洋火山带环绕太平洋的马蹄形地带，全球约90%的地震发生于此。该地带绵延40,000公里，包含452座火山。 nations, yet the region's tectonic setting is complex and capable of generating devastating earthquakes. The Caribbean Plate is bounded on multiple sides by different types of plate boundaries: 俯冲带一个构造板块潜入另一板块之下并进入地幔的区域。俯冲带产生世界上最大的地震（8.5级以上），并伴有深海沟和火山弧。 systems along the Lesser Antilles (eastern Caribbean) where the Atlantic portion of the North and South American Plates subducts westward beneath the Caribbean Plate, and 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 systems along the northern and southern plate margins where the Caribbean Plate slides laterally relative to the North and South American Plates.

The northern Caribbean plate boundary — running roughly east-west through Haiti, the Dominican Republic, Puerto Rico, and Cuba — involves both 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 strike-slip motion on major fault systems (including the Septentrional Fault in Haiti, the Enriquillo-Plantain Garden Fault System, and the Puerto Rico Trench area) and some compressional elements. The southern boundary along Venezuela and Trinidad involves similar complexity. The Lesser Antilles 俯冲带一个构造板块潜入另一板块之下并进入地幔的区域。俯冲带产生世界上最大的地震（8.5级以上），并伴有深海沟和火山弧。 creates a volcanic arc of islands including Montserrat, Saint Kitts, Martinique, and others with associated 火山地震与火山活动相关、由岩浆运动、气体压力或火山附近岩石破裂引起的地震。常成群发生，有时预示即将喷发。 activity. This varied boundary geometry means different Caribbean islands face very different seismic and volcanic hazard types.

The 2010 Haiti Earthquake: Urban Catastrophe

The January 12, 2010 Haiti Earthquake (magnitude 7.0) killed between 100,000 and 316,000 people — the death toll remains uncertain due to the disaster's scale overwhelming record-keeping capacity — making it one of the deadliest natural disasters in the Western Hemisphere's recorded history. The earthquake struck the Enriquillo-Plantain Garden Fault System approximately 25 kilometers west of Port-au-Prince, with the shallow 震源地震破裂在地球内部实际发生的位置，也称焦点。震源深度对地表感受到的震动方式有重大影响。 at only 13 kilometers depth generating strong shaking in the capital. The catastrophic scale of casualties reflected the near-total collapse of 无筋砌体未配置钢筋加固的砖石或砌块结构，对地震震动极为脆弱。无筋砌体建筑是全球地震死亡人数中占比最高的建筑类型。 construction across the densely populated metropolitan area.

Investigation of the Haiti earthquake revealed that virtually no enforcement of 抗震建筑规范为确保建筑物达到最低地震安全水平而制定的一套法律要求，涉及建筑的设计与施工，通常在重大地震暴露出新的薄弱环节后进行修订。 had occurred in Haiti for decades, and that even formal building code requirements were largely absent or inappropriate for the seismic hazard. The vast majority of buildings were constructed of low-quality concrete block masonry or rubble stone masonry without reinforcement, with heavy flat concrete roofs that pancaked during shaking. The combination of extreme poverty, institutional collapse, political instability, and dense urban construction had created a city of extraordinary physical vulnerability. The earthquake exposed a situation where the gap between the seismic hazard and the building stock's capacity to resist that hazard was virtually unlimited.

Puerto Rico and the Lesser Antilles: Ongoing Hazards

Puerto Rico sits at the complex boundary between the Caribbean and North American Plates, with active fault systems including the Puerto Rico Trench — the deepest point in the Atlantic Ocean — to the north and the Mona Canyon to the west. The January 2020 Puerto Rico Earthquake Sequence (mainshock magnitude 6.4) caused one death but significant damage, particularly in the southwestern corner of the island where a series of large 余震在同一断层区域内、发生于主震之后的较小地震。余震序列可持续数周至数年，最大余震的震级通常比主震低1.0至1.2级。 events continued for weeks. The sequence revealed vulnerabilities in Puerto Rico's building stock, including older pre-code construction and 软层（薄弱层）通常因车库或商铺等大开口而导致强度明显弱于上部楼层的建筑楼层（通常为首层）。软层是最常见的建筑倒塌机制。 apartment buildings that had been weakened by previous earthquakes and further damaged by Hurricane Maria in 2017.

The Lesser Antilles 俯冲带一个构造板块潜入另一板块之下并进入地幔的区域。俯冲带产生世界上最大的地震（8.5级以上），并伴有深海沟和火山弧。 creates 海啸由水下地震导致海底突然位移而产生的一系列海浪。海啸可以喷气机般的速度（时速700公里以上）穿越整个大洋盆地。 risk along the entire eastern Caribbean, with modeling studies suggesting that a magnitude 8+ megathrust rupture on the Lesser Antilles interface could generate significant 海啸由水下地震导致海底突然位移而产生的一系列海浪。海啸可以喷气机般的速度（时速700公里以上）穿越整个大洋盆地。 waves affecting Caribbean island coasts and the adjacent Atlantic coasts of North and South America. Historical records document tsunamis in the Lesser Antilles associated with major earthquakes in 1867 and 1843.

Liquefaction: The Hidden Ground Failure Hazard

Caribbean seismic risk is compounded by widespread 液化饱和松散土壤在强烈震动下暂时失去强度、表现如液体般的现象。可导致建筑物下沉、倾斜或陷入地下坍塌。 susceptibility in low-lying coastal areas, river deltas, and reclaimed land throughout the islands. 液化饱和松散土壤在强烈震动下暂时失去强度、表现如液体般的现象。可导致建筑物下沉、倾斜或陷入地下坍塌。 occurs when saturated, loosely packed sediments temporarily lose shear strength during earthquake shaking, causing the ground to behave temporarily as a fluid and leading to differential settlement, lateral movement of ground toward water bodies, and the failure of structures whose foundations are supported in liquefied soils.

Many Caribbean coastal communities and port areas are built on saturated alluvial or fill deposits with high 液化饱和松散土壤在强烈震动下暂时失去强度、表现如液体般的现象。可导致建筑物下沉、倾斜或陷入地下坍塌。 potential. Trinidad's east coast, Barbados' lowlands, much of coastal Haiti and the Dominican Republic, and Jamaica's coastal plains all have significant 液化饱和松散土壤在强烈震动下暂时失去强度、表现如液体般的现象。可导致建筑物下沉、倾斜或陷入地下坍塌。 susceptibility. Use Seismic Risk Checker to understand how specific Caribbean island locations combine ground motion hazard with potential 液化饱和松散土壤在强烈震动下暂时失去强度、表现如液体般的现象。可导致建筑物下沉、倾斜或陷入地下坍塌。 vulnerability for different soil types.

The 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 Complexity

The lateral motion along the 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 systems of the northern and southern Caribbean plate margins generates strike-slip earthquakes similar in character to the San Andreas or North Anatolian faults, but occurring in countries with far less seismic preparedness infrastructure. The 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 fault systems of Haiti, Cuba, Jamaica, and Trinidad represent seismic hazards that are scientifically well-understood but poorly managed in terms of building standards, public awareness, and emergency response capacity.

What Makes the Caribbean Unique

The Caribbean's seismic hazard is simultaneously hidden and extreme — hidden because the region is known for tropical tourism and hurricanes rather than earthquakes, and extreme because the tectonic setting generates genuinely dangerous earthquakes that are superimposed on a development context of poverty, fragile governance, and vulnerable construction. The 2010 Haiti disaster demonstrated what happens when a 转换型边界两个板块沿水平方向相互滑动错动的板块边界。加利福尼亚州的圣安德烈亚斯断层是转换型边界最著名的例子。 earthquake strikes a city with almost no earthquake-resistant construction; the question for the wider Caribbean region is whether the lessons of that event will drive preparedness improvements across other vulnerable island nations before the next major Caribbean earthquake reveals similar vulnerabilities elsewhere in the archipelago.