diff --git a/asm/fldeff_groundshake.s b/asm/fldeff_groundshake.s
index 81d92430e..09c155ef1 100644
--- a/asm/fldeff_groundshake.s
+++ b/asm/fldeff_groundshake.s
@@ -5,196 +5,6 @@
 
 	.text
 
-	thumb_func_start sub_81BE66C
-sub_81BE66C: @ 81BE66C
-	push {lr}
-	ldr r0, =gSaveBlock1Ptr
-	ldr r0, [r0]
-	ldrh r1, [r0, 0x4]
-	movs r0, 0xD0
-	lsls r0, 5
-	cmp r1, r0
-	bne _081BE690
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagGet
-	lsls r0, 24
-	lsrs r0, 24
-	b _081BE692
-	.pool
-_081BE690:
-	movs r0, 0
-_081BE692:
-	pop {r1}
-	bx r1
-	thumb_func_end sub_81BE66C
-
-	thumb_func_start sub_81BE698
-sub_81BE698: @ 81BE698
-	push {lr}
-	ldr r0, =gUnknown_0203CF18
-	ldr r0, [r0]
-	adds r0, 0x4
-	bl sub_8151E50
-	pop {r0}
-	bx r0
-	.pool
-	thumb_func_end sub_81BE698
-
-	thumb_func_start sub_81BE6AC
-sub_81BE6AC: @ 81BE6AC
-	ldr r1, =gUnknown_0203CF18
-	movs r0, 0
-	str r0, [r1]
-	bx lr
-	.pool
-	thumb_func_end sub_81BE6AC
-
-	thumb_func_start sub_81BE6B8
-sub_81BE6B8: @ 81BE6B8
-	push {r4,lr}
-	ldr r4, =gUnknown_0203CF18
-	ldr r0, [r4]
-	cmp r0, 0
-	beq _081BE6CC
-	movs r0, 0
-	str r0, [r4]
-	b _081BE718
-	.pool
-_081BE6CC:
-	ldr r0, =gSaveBlock1Ptr
-	ldr r0, [r0]
-	ldrh r1, [r0, 0x4]
-	movs r0, 0xD0
-	lsls r0, 5
-	cmp r1, r0
-	bne _081BE718
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagGet
-	lsls r0, 24
-	cmp r0, 0
-	beq _081BE718
-	movs r0, 0xC8
-	bl AllocZeroed
-	str r0, [r4]
-	adds r0, 0x4
-	bl sub_8151B3C
-	ldr r0, [r4]
-	adds r0, 0x4
-	ldr r1, =gUnknown_08617E18
-	bl sub_8151B68
-	ldr r0, [r4]
-	adds r0, 0x4
-	movs r1, 0x1
-	movs r2, 0x1
-	bl sub_8151CA8
-	ldr r0, =sub_81BE698
-	movs r1, 0xFF
-	bl CreateTask
-	ldr r1, [r4]
-	strb r0, [r1]
-_081BE718:
-	pop {r4}
-	pop {r0}
-	bx r0
-	.pool
-	thumb_func_end sub_81BE6B8
-
-	thumb_func_start sub_81BE72C
-sub_81BE72C: @ 81BE72C
-	push {r4,lr}
-	ldr r0, =gSaveBlock1Ptr
-	ldr r0, [r0]
-	ldrh r1, [r0, 0x4]
-	movs r0, 0xD0
-	lsls r0, 5
-	cmp r1, r0
-	bne _081BE788
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagGet
-	lsls r0, 24
-	cmp r0, 0
-	beq _081BE788
-	ldr r4, =gUnknown_0203CF18
-	ldr r0, [r4]
-	cmp r0, 0
-	beq _081BE788
-	ldr r0, =sub_81BE698
-	bl FuncIsActiveTask
-	lsls r0, 24
-	cmp r0, 0
-	beq _081BE766
-	ldr r0, [r4]
-	ldrb r0, [r0]
-	bl DestroyTask
-_081BE766:
-	ldr r0, [r4]
-	adds r0, 0x4
-	movs r1, 0x1
-	movs r2, 0x1
-	bl sub_8151D28
-	ldr r0, [r4]
-	adds r0, 0x4
-	movs r1, 0x1
-	movs r2, 0x1
-	bl sub_8151C50
-	ldr r0, [r4]
-	bl Free
-	movs r0, 0
-	str r0, [r4]
-_081BE788:
-	pop {r4}
-	pop {r0}
-	bx r0
-	.pool
-	thumb_func_end sub_81BE72C
-
-	thumb_func_start sub_81BE79C
-sub_81BE79C: @ 81BE79C
-	push {r4,lr}
-	ldr r0, =0x000040cb
-	bl VarGet
-	lsls r0, 16
-	cmp r0, 0
-	beq _081BE7B8
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagClear
-	b _081BE7EE
-	.pool
-_081BE7B8:
-	bl Random
-	lsls r0, 16
-	lsrs r4, r0, 16
-	movs r0, 0x1
-	ands r4, r0
-	movs r0, 0x9D
-	bl FlagGet
-	lsls r0, 24
-	lsrs r0, 24
-	cmp r0, 0x1
-	bne _081BE7D4
-	movs r4, 0x1
-_081BE7D4:
-	cmp r4, 0
-	beq _081BE7E6
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagSet
-	bl sub_81BE6B8
-	b _081BE7EE
-_081BE7E6:
-	movs r0, 0xA7
-	lsls r0, 1
-	bl FlagClear
-_081BE7EE:
-	pop {r4}
-	pop {r0}
-	bx r0
-	thumb_func_end sub_81BE79C
-
 	thumb_func_start sub_81BE7F4
 sub_81BE7F4: @ 81BE7F4
 	push {lr}
diff --git a/include/fldeff_groundshake.h b/include/fldeff_groundshake.h
index 685a6d27c..77af19876 100644
--- a/include/fldeff_groundshake.h
+++ b/include/fldeff_groundshake.h
@@ -1,7 +1,30 @@
 #ifndef GUARD_FLDEFF_GROUNDSHAKE_H
 #define GUARD_FLDEFF_GROUNDSHAKE_H
 
+struct InnerStruct203CF18
+{
+    u8 filler[0xC4];
+};
+
+
+struct Struct203CF18 {
+    u8 taskId;
+    struct InnerStruct203CF18 unk4;
+}; //size = 0xC8
+
+
+void sub_8151B68(struct InnerStruct203CF18 *, const u8*);
+void sub_8151B3C(struct InnerStruct203CF18 *);
+void sub_8151CA8(struct InnerStruct203CF18 *, u8, u8);
+void sub_8151C50(struct InnerStruct203CF18 *, u8, u8);
+void sub_8151D28(struct InnerStruct203CF18 *, u8, u8);
+void sub_8151E50(struct InnerStruct203CF18 *);
+
 void sub_81BE6B8(void);
 void sub_81BE72C(void);
 
+extern struct Struct203CF18 *gUnknown_0203CF18;
+
+extern const u8 gUnknown_08617E18[];
+
 #endif // GUARD_FLDEFF_GROUNDSHAKE_H
diff --git a/ld_script.txt b/ld_script.txt
index 5da05cf4b..4a9ac752c 100644
--- a/ld_script.txt
+++ b/ld_script.txt
@@ -258,6 +258,7 @@ SECTIONS {
         src/multiboot.o(.text);
         src/unk_81BAD84.o(.text);
         src/battle_controller_player_partner.o(.text);
+        src/fldeff_groundshake.o(.text);
         asm/fldeff_groundshake.o(.text);
         asm/fossil_specials.o(.text);
         src/berry_fix_program.o(.text);
diff --git a/src/fldeff_groundshake.c b/src/fldeff_groundshake.c
new file mode 100644
index 000000000..a4b36e539
--- /dev/null
+++ b/src/fldeff_groundshake.c
@@ -0,0 +1,85 @@
+#include "global.h"
+#include "constants/flags.h"
+#include "constants/songs.h"
+#include "event_data.h"
+#include "fldeff_groundshake.h"
+#include "malloc.h"
+#include "menu.h"
+#include "party_menu.h"
+#include "pokemon.h"
+#include "random.h"
+#include "sound.h"
+#include "sprite.h"
+#include "string_util.h"
+#include "strings.h"
+#include "task.h"
+
+bool8 sub_81BE66C(void)
+{
+    if (!(gSaveBlock1Ptr->location.mapGroup == 0x0 && gSaveBlock1Ptr->location.mapNum == 0x1A))
+        return 0;
+    return FlagGet(FLAG_0x14E);
+}
+
+void sub_81BE698(u8 taskId)
+{
+    sub_8151E50(&(gUnknown_0203CF18->unk4));
+}
+
+void sub_81BE6AC(void)
+{
+    gUnknown_0203CF18 = NULL;
+}
+
+void sub_81BE6B8(void)
+{
+    if(gUnknown_0203CF18 != NULL)
+    {
+        gUnknown_0203CF18 = NULL;
+        return;
+    }
+    if(!(gSaveBlock1Ptr->location.mapGroup == 0x0 && gSaveBlock1Ptr->location.mapNum == 0x1A) || !FlagGet(FLAG_0x14E))
+        return;
+
+    gUnknown_0203CF18 = (struct Struct203CF18 *)AllocZeroed(sizeof(struct Struct203CF18));
+    sub_8151B3C(&(gUnknown_0203CF18->unk4));
+    sub_8151B68(&(gUnknown_0203CF18->unk4), gUnknown_08617E18);
+    sub_8151CA8(&(gUnknown_0203CF18->unk4), 1, 1);
+    gUnknown_0203CF18->taskId = CreateTask(sub_81BE698, 0xFF);
+}
+
+void sub_81BE72C(void)
+{
+    if(!(gSaveBlock1Ptr->location.mapGroup == 0x0 && gSaveBlock1Ptr->location.mapNum == 0x1A) || !FlagGet(FLAG_0x14E) || gUnknown_0203CF18 == NULL)
+        return;
+    if(FuncIsActiveTask(sub_81BE698))
+        DestroyTask(gUnknown_0203CF18->taskId);
+    sub_8151D28(&(gUnknown_0203CF18->unk4), 1, 1);
+    sub_8151C50(&(gUnknown_0203CF18->unk4), 1, 1);
+    Free(gUnknown_0203CF18);
+    gUnknown_0203CF18 = NULL;
+}
+
+void sub_81BE79C(void)
+{
+    u16 rand;
+    bool8 chance;
+
+    if(VarGet(VAR_0x40CB) != 0)
+    {
+        FlagClear(FLAG_0x14E);
+        return;
+    }
+    rand = Random();
+    chance = rand & 1;
+    if(FlagGet(FLAG_0x09D) == TRUE)
+        chance = TRUE;
+    if(chance)
+    {
+        FlagSet(FLAG_0x14E);
+        sub_81BE6B8();
+        return;
+    }
+    FlagClear(FLAG_0x14E);
+}
+